barnold
/
pgear
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

First commit

This commit is contained in:
barnold 2022-09-06 14:38:34 +01:00
commit 0f8abaaf3b
27 changed files with 2202 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

674
COPYING Normal file
View File

@ -0,0 +1,674 @@
GNU GENERAL PUBLIC LICENSE
Version 3, 29 June 2007
Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/>
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
Preamble
The GNU General Public License is a free, copyleft license for
software and other kinds of works.
The licenses for most software and other practical works are designed
to take away your freedom to share and change the works. By contrast,
the GNU General Public License is intended to guarantee your freedom to
share and change all versions of a program--to make sure it remains free
software for all its users. We, the Free Software Foundation, use the
GNU General Public License for most of our software; it applies also to
any other work released this way by its authors. You can apply it to
your programs, too.
When we speak of free software, we are referring to freedom, not
price. Our General Public Licenses are designed to make sure that you
have the freedom to distribute copies of free software (and charge for
them if you wish), that you receive source code or can get it if you
want it, that you can change the software or use pieces of it in new
free programs, and that you know you can do these things.
To protect your rights, we need to prevent others from denying you
these rights or asking you to surrender the rights. Therefore, you have
certain responsibilities if you distribute copies of the software, or if
you modify it: responsibilities to respect the freedom of others.
For example, if you distribute copies of such a program, whether
gratis or for a fee, you must pass on to the recipients the same
freedoms that you received. You must make sure that they, too, receive
or can get the source code. And you must show them these terms so they
know their rights.
Developers that use the GNU GPL protect your rights with two steps:
(1) assert copyright on the software, and (2) offer you this License
giving you legal permission to copy, distribute and/or modify it.
For the developers' and authors' protection, the GPL clearly explains
that there is no warranty for this free software. For both users' and
authors' sake, the GPL requires that modified versions be marked as
changed, so that their problems will not be attributed erroneously to
authors of previous versions.
Some devices are designed to deny users access to install or run
modified versions of the software inside them, although the manufacturer
can do so. This is fundamentally incompatible with the aim of
protecting users' freedom to change the software. The systematic
pattern of such abuse occurs in the area of products for individuals to
use, which is precisely where it is most unacceptable. Therefore, we
have designed this version of the GPL to prohibit the practice for those
products. If such problems arise substantially in other domains, we
stand ready to extend this provision to those domains in future versions
of the GPL, as needed to protect the freedom of users.
Finally, every program is threatened constantly by software patents.
States should not allow patents to restrict development and use of
software on general-purpose computers, but in those that do, we wish to
avoid the special danger that patents applied to a free program could
make it effectively proprietary. To prevent this, the GPL assures that
patents cannot be used to render the program non-free.
The precise terms and conditions for copying, distribution and
modification follow.
TERMS AND CONDITIONS
0. Definitions.
"This License" refers to version 3 of the GNU General Public License.
"Copyright" also means copyright-like laws that apply to other kinds of
works, such as semiconductor masks.
"The Program" refers to any copyrightable work licensed under this
License. Each licensee is addressed as "you". "Licensees" and
"recipients" may be individuals or organizations.
To "modify" a work means to copy from or adapt all or part of the work
in a fashion requiring copyright permission, other than the making of an
exact copy. The resulting work is called a "modified version" of the
earlier work or a work "based on" the earlier work.
A "covered work" means either the unmodified Program or a work based
on the Program.
To "propagate" a work means to do anything with it that, without
permission, would make you directly or secondarily liable for
infringement under applicable copyright law, except executing it on a
computer or modifying a private copy. Propagation includes copying,
distribution (with or without modification), making available to the
public, and in some countries other activities as well.
To "convey" a work means any kind of propagation that enables other
parties to make or receive copies. Mere interaction with a user through
a computer network, with no transfer of a copy, is not conveying.
An interactive user interface displays "Appropriate Legal Notices"
to the extent that it includes a convenient and prominently visible
feature that (1) displays an appropriate copyright notice, and (2)
tells the user that there is no warranty for the work (except to the
extent that warranties are provided), that licensees may convey the
work under this License, and how to view a copy of this License. If
the interface presents a list of user commands or options, such as a
menu, a prominent item in the list meets this criterion.
1. Source Code.
The "source code" for a work means the preferred form of the work
for making modifications to it. "Object code" means any non-source
form of a work.
A "Standard Interface" means an interface that either is an official
standard defined by a recognized standards body, or, in the case of
interfaces specified for a particular programming language, one that
is widely used among developers working in that language.
The "System Libraries" of an executable work include anything, other
than the work as a whole, that (a) is included in the normal form of
packaging a Major Component, but which is not part of that Major
Component, and (b) serves only to enable use of the work with that
Major Component, or to implement a Standard Interface for which an
implementation is available to the public in source code form. A
"Major Component", in this context, means a major essential component
(kernel, window system, and so on) of the specific operating system
(if any) on which the executable work runs, or a compiler used to
produce the work, or an object code interpreter used to run it.
The "Corresponding Source" for a work in object code form means all
the source code needed to generate, install, and (for an executable
work) run the object code and to modify the work, including scripts to
control those activities. However, it does not include the work's
System Libraries, or general-purpose tools or generally available free
programs which are used unmodified in performing those activities but
which are not part of the work. For example, Corresponding Source
includes interface definition files associated with source files for
the work, and the source code for shared libraries and dynamically
linked subprograms that the work is specifically designed to require,
such as by intimate data communication or control flow between those
subprograms and other parts of the work.
The Corresponding Source need not include anything that users
can regenerate automatically from other parts of the Corresponding
Source.
The Corresponding Source for a work in source code form is that
same work.
2. Basic Permissions.
All rights granted under this License are granted for the term of
copyright on the Program, and are irrevocable provided the stated
conditions are met. This License explicitly affirms your unlimited
permission to run the unmodified Program. The output from running a
covered work is covered by this License only if the output, given its
content, constitutes a covered work. This License acknowledges your
rights of fair use or other equivalent, as provided by copyright law.
You may make, run and propagate covered works that you do not
convey, without conditions so long as your license otherwise remains
in force. You may convey covered works to others for the sole purpose
of having them make modifications exclusively for you, or provide you
with facilities for running those works, provided that you comply with
the terms of this License in conveying all material for which you do
not control copyright. Those thus making or running the covered works
for you must do so exclusively on your behalf, under your direction
and control, on terms that prohibit them from making any copies of
your copyrighted material outside their relationship with you.
Conveying under any other circumstances is permitted solely under
the conditions stated below. Sublicensing is not allowed; section 10
makes it unnecessary.
3. Protecting Users' Legal Rights From Anti-Circumvention Law.
No covered work shall be deemed part of an effective technological
measure under any applicable law fulfilling obligations under article
11 of the WIPO copyright treaty adopted on 20 December 1996, or
similar laws prohibiting or restricting circumvention of such
measures.
When you convey a covered work, you waive any legal power to forbid
circumvention of technological measures to the extent such circumvention
is effected by exercising rights under this License with respect to
the covered work, and you disclaim any intention to limit operation or
modification of the work as a means of enforcing, against the work's
users, your or third parties' legal rights to forbid circumvention of
technological measures.
4. Conveying Verbatim Copies.
You may convey verbatim copies of the Program's source code as you
receive it, in any medium, provided that you conspicuously and
appropriately publish on each copy an appropriate copyright notice;
keep intact all notices stating that this License and any
non-permissive terms added in accord with section 7 apply to the code;
keep intact all notices of the absence of any warranty; and give all
recipients a copy of this License along with the Program.
You may charge any price or no price for each copy that you convey,
and you may offer support or warranty protection for a fee.
5. Conveying Modified Source Versions.
You may convey a work based on the Program, or the modifications to
produce it from the Program, in the form of source code under the
terms of section 4, provided that you also meet all of these conditions:
a) The work must carry prominent notices stating that you modified
it, and giving a relevant date.
b) The work must carry prominent notices stating that it is
released under this License and any conditions added under section
7. This requirement modifies the requirement in section 4 to
"keep intact all notices".
c) You must license the entire work, as a whole, under this
License to anyone who comes into possession of a copy. This
License will therefore apply, along with any applicable section 7
additional terms, to the whole of the work, and all its parts,
regardless of how they are packaged. This License gives no
permission to license the work in any other way, but it does not
invalidate such permission if you have separately received it.
d) If the work has interactive user interfaces, each must display
Appropriate Legal Notices; however, if the Program has interactive
interfaces that do not display Appropriate Legal Notices, your
work need not make them do so.
A compilation of a covered work with other separate and independent
works, which are not by their nature extensions of the covered work,
and which are not combined with it such as to form a larger program,
in or on a volume of a storage or distribution medium, is called an
"aggregate" if the compilation and its resulting copyright are not
used to limit the access or legal rights of the compilation's users
beyond what the individual works permit. Inclusion of a covered work
in an aggregate does not cause this License to apply to the other
parts of the aggregate.
6. Conveying Non-Source Forms.
You may convey a covered work in object code form under the terms
of sections 4 and 5, provided that you also convey the
machine-readable Corresponding Source under the terms of this License,
in one of these ways:
a) Convey the object code in, or embodied in, a physical product
(including a physical distribution medium), accompanied by the
Corresponding Source fixed on a durable physical medium
customarily used for software interchange.
b) Convey the object code in, or embodied in, a physical product
(including a physical distribution medium), accompanied by a
written offer, valid for at least three years and valid for as
long as you offer spare parts or customer support for that product
model, to give anyone who possesses the object code either (1) a
copy of the Corresponding Source for all the software in the
product that is covered by this License, on a durable physical
medium customarily used for software interchange, for a price no
more than your reasonable cost of physically performing this
conveying of source, or (2) access to copy the
Corresponding Source from a network server at no charge.
c) Convey individual copies of the object code with a copy of the
written offer to provide the Corresponding Source. This
alternative is allowed only occasionally and noncommercially, and
only if you received the object code with such an offer, in accord
with subsection 6b.
d) Convey the object code by offering access from a designated
place (gratis or for a charge), and offer equivalent access to the
Corresponding Source in the same way through the same place at no
further charge. You need not require recipients to copy the
Corresponding Source along with the object code. If the place to
copy the object code is a network server, the Corresponding Source
may be on a different server (operated by you or a third party)
that supports equivalent copying facilities, provided you maintain
clear directions next to the object code saying where to find the
Corresponding Source. Regardless of what server hosts the
Corresponding Source, you remain obligated to ensure that it is
available for as long as needed to satisfy these requirements.
e) Convey the object code using peer-to-peer transmission, provided
you inform other peers where the object code and Corresponding
Source of the work are being offered to the general public at no
charge under subsection 6d.
A separable portion of the object code, whose source code is excluded
from the Corresponding Source as a System Library, need not be
included in conveying the object code work.
A "User Product" is either (1) a "consumer product", which means any
tangible personal property which is normally used for personal, family,
or household purposes, or (2) anything designed or sold for incorporation
into a dwelling. In determining whether a product is a consumer product,
doubtful cases shall be resolved in favor of coverage. For a particular
product received by a particular user, "normally used" refers to a
typical or common use of that class of product, regardless of the status
of the particular user or of the way in which the particular user
actually uses, or expects or is expected to use, the product. A product
is a consumer product regardless of whether the product has substantial
commercial, industrial or non-consumer uses, unless such uses represent
the only significant mode of use of the product.
"Installation Information" for a User Product means any methods,
procedures, authorization keys, or other information required to install
and execute modified versions of a covered work in that User Product from
a modified version of its Corresponding Source. The information must
suffice to ensure that the continued functioning of the modified object
code is in no case prevented or interfered with solely because
modification has been made.
If you convey an object code work under this section in, or with, or
specifically for use in, a User Product, and the conveying occurs as
part of a transaction in which the right of possession and use of the
User Product is transferred to the recipient in perpetuity or for a
fixed term (regardless of how the transaction is characterized), the
Corresponding Source conveyed under this section must be accompanied
by the Installation Information. But this requirement does not apply
if neither you nor any third party retains the ability to install
modified object code on the User Product (for example, the work has
been installed in ROM).
The requirement to provide Installation Information does not include a
requirement to continue to provide support service, warranty, or updates
for a work that has been modified or installed by the recipient, or for
the User Product in which it has been modified or installed. Access to a
network may be denied when the modification itself materially and
adversely affects the operation of the network or violates the rules and
protocols for communication across the network.
Corresponding Source conveyed, and Installation Information provided,
in accord with this section must be in a format that is publicly
documented (and with an implementation available to the public in
source code form), and must require no special password or key for
unpacking, reading or copying.
7. Additional Terms.
"Additional permissions" are terms that supplement the terms of this
License by making exceptions from one or more of its conditions.
Additional permissions that are applicable to the entire Program shall
be treated as though they were included in this License, to the extent
that they are valid under applicable law. If additional permissions
apply only to part of the Program, that part may be used separately
under those permissions, but the entire Program remains governed by
this License without regard to the additional permissions.
When you convey a copy of a covered work, you may at your option
remove any additional permissions from that copy, or from any part of
it. (Additional permissions may be written to require their own
removal in certain cases when you modify the work.) You may place
additional permissions on material, added by you to a covered work,
for which you have or can give appropriate copyright permission.
Notwithstanding any other provision of this License, for material you
add to a covered work, you may (if authorized by the copyright holders of
that material) supplement the terms of this License with terms:
a) Disclaiming warranty or limiting liability differently from the
terms of sections 15 and 16 of this License; or
b) Requiring preservation of specified reasonable legal notices or
author attributions in that material or in the Appropriate Legal
Notices displayed by works containing it; or
c) Prohibiting misrepresentation of the origin of that material, or
requiring that modified versions of such material be marked in
reasonable ways as different from the original version; or
d) Limiting the use for publicity purposes of names of licensors or
authors of the material; or
e) Declining to grant rights under trademark law for use of some
trade names, trademarks, or service marks; or
f) Requiring indemnification of licensors and authors of that
material by anyone who conveys the material (or modified versions of
it) with contractual assumptions of liability to the recipient, for
any liability that these contractual assumptions directly impose on
those licensors and authors.
All other non-permissive additional terms are considered "further
restrictions" within the meaning of section 10. If the Program as you
received it, or any part of it, contains a notice stating that it is
governed by this License along with a term that is a further
restriction, you may remove that term. If a license document contains
a further restriction but permits relicensing or conveying under this
License, you may add to a covered work material governed by the terms
of that license document, provided that the further restriction does
not survive such relicensing or conveying.
If you add terms to a covered work in accord with this section, you
must place, in the relevant source files, a statement of the
additional terms that apply to those files, or a notice indicating
where to find the applicable terms.
Additional terms, permissive or non-permissive, may be stated in the
form of a separately written license, or stated as exceptions;
the above requirements apply either way.
8. Termination.
You may not propagate or modify a covered work except as expressly
provided under this License. Any attempt otherwise to propagate or
modify it is void, and will automatically terminate your rights under
this License (including any patent licenses granted under the third
paragraph of section 11).
However, if you cease all violation of this License, then your
license from a particular copyright holder is reinstated (a)
provisionally, unless and until the copyright holder explicitly and
finally terminates your license, and (b) permanently, if the copyright
holder fails to notify you of the violation by some reasonable means
prior to 60 days after the cessation.
Moreover, your license from a particular copyright holder is
reinstated permanently if the copyright holder notifies you of the
violation by some reasonable means, this is the first time you have
received notice of violation of this License (for any work) from that
copyright holder, and you cure the violation prior to 30 days after
your receipt of the notice.
Termination of your rights under this section does not terminate the
licenses of parties who have received copies or rights from you under
this License. If your rights have been terminated and not permanently
reinstated, you do not qualify to receive new licenses for the same
material under section 10.
9. Acceptance Not Required for Having Copies.
You are not required to accept this License in order to receive or
run a copy of the Program. Ancillary propagation of a covered work
occurring solely as a consequence of using peer-to-peer transmission
to receive a copy likewise does not require acceptance. However,
nothing other than this License grants you permission to propagate or
modify any covered work. These actions infringe copyright if you do
not accept this License. Therefore, by modifying or propagating a
covered work, you indicate your acceptance of this License to do so.
10. Automatic Licensing of Downstream Recipients.
Each time you convey a covered work, the recipient automatically
receives a license from the original licensors, to run, modify and
propagate that work, subject to this License. You are not responsible
for enforcing compliance by third parties with this License.
An "entity transaction" is a transaction transferring control of an
organization, or substantially all assets of one, or subdividing an
organization, or merging organizations. If propagation of a covered
work results from an entity transaction, each party to that
transaction who receives a copy of the work also receives whatever
licenses to the work the party's predecessor in interest had or could
give under the previous paragraph, plus a right to possession of the
Corresponding Source of the work from the predecessor in interest, if
the predecessor has it or can get it with reasonable efforts.
You may not impose any further restrictions on the exercise of the
rights granted or affirmed under this License. For example, you may
not impose a license fee, royalty, or other charge for exercise of
rights granted under this License, and you may not initiate litigation
(including a cross-claim or counterclaim in a lawsuit) alleging that
any patent claim is infringed by making, using, selling, offering for
sale, or importing the Program or any portion of it.
11. Patents.
A "contributor" is a copyright holder who authorizes use under this
License of the Program or a work on which the Program is based. The
work thus licensed is called the contributor's "contributor version".
A contributor's "essential patent claims" are all patent claims
owned or controlled by the contributor, whether already acquired or
hereafter acquired, that would be infringed by some manner, permitted
by this License, of making, using, or selling its contributor version,
but do not include claims that would be infringed only as a
consequence of further modification of the contributor version. For
purposes of this definition, "control" includes the right to grant
patent sublicenses in a manner consistent with the requirements of
this License.
Each contributor grants you a non-exclusive, worldwide, royalty-free
patent license under the contributor's essential patent claims, to
make, use, sell, offer for sale, import and otherwise run, modify and
propagate the contents of its contributor version.
In the following three paragraphs, a "patent license" is any express
agreement or commitment, however denominated, not to enforce a patent
(such as an express permission to practice a patent or covenant not to
sue for patent infringement). To "grant" such a patent license to a
party means to make such an agreement or commitment not to enforce a
patent against the party.
If you convey a covered work, knowingly relying on a patent license,
and the Corresponding Source of the work is not available for anyone
to copy, free of charge and under the terms of this License, through a
publicly available network server or other readily accessible means,
then you must either (1) cause the Corresponding Source to be so
available, or (2) arrange to deprive yourself of the benefit of the
patent license for this particular work, or (3) arrange, in a manner
consistent with the requirements of this License, to extend the patent
license to downstream recipients. "Knowingly relying" means you have
actual knowledge that, but for the patent license, your conveying the
covered work in a country, or your recipient's use of the covered work
in a country, would infringe one or more identifiable patents in that
country that you have reason to believe are valid.
If, pursuant to or in connection with a single transaction or
arrangement, you convey, or propagate by procuring conveyance of, a
covered work, and grant a patent license to some of the parties
receiving the covered work authorizing them to use, propagate, modify
or convey a specific copy of the covered work, then the patent license
you grant is automatically extended to all recipients of the covered
work and works based on it.
A patent license is "discriminatory" if it does not include within
the scope of its coverage, prohibits the exercise of, or is
conditioned on the non-exercise of one or more of the rights that are
specifically granted under this License. You may not convey a covered
work if you are a party to an arrangement with a third party that is
in the business of distributing software, under which you make payment
to the third party based on the extent of your activity of conveying
the work, and under which the third party grants, to any of the
parties who would receive the covered work from you, a discriminatory
patent license (a) in connection with copies of the covered work
conveyed by you (or copies made from those copies), or (b) primarily
for and in connection with specific products or compilations that
contain the covered work, unless you entered into that arrangement,
or that patent license was granted, prior to 28 March 2007.
Nothing in this License shall be construed as excluding or limiting
any implied license or other defenses to infringement that may
otherwise be available to you under applicable patent law.
12. No Surrender of Others' Freedom.
If conditions are imposed on you (whether by court order, agreement or
otherwise) that contradict the conditions of this License, they do not
excuse you from the conditions of this License. If you cannot convey a
covered work so as to satisfy simultaneously your obligations under this
License and any other pertinent obligations, then as a consequence you may
not convey it at all. For example, if you agree to terms that obligate you
to collect a royalty for further conveying from those to whom you convey
the Program, the only way you could satisfy both those terms and this
License would be to refrain entirely from conveying the Program.
13. Use with the GNU Affero General Public License.
Notwithstanding any other provision of this License, you have
permission to link or combine any covered work with a work licensed
under version 3 of the GNU Affero General Public License into a single
combined work, and to convey the resulting work. The terms of this
License will continue to apply to the part which is the covered work,
but the special requirements of the GNU Affero General Public License,
section 13, concerning interaction through a network will apply to the
combination as such.
14. Revised Versions of this License.
The Free Software Foundation may publish revised and/or new versions of
the GNU General Public License from time to time. Such new versions will
be similar in spirit to the present version, but may differ in detail to
address new problems or concerns.
Each version is given a distinguishing version number. If the
Program specifies that a certain numbered version of the GNU General
Public License "or any later version" applies to it, you have the
option of following the terms and conditions either of that numbered
version or of any later version published by the Free Software
Foundation. If the Program does not specify a version number of the
GNU General Public License, you may choose any version ever published
by the Free Software Foundation.
If the Program specifies that a proxy can decide which future
versions of the GNU General Public License can be used, that proxy's
public statement of acceptance of a version permanently authorizes you
to choose that version for the Program.
Later license versions may give you additional or different
permissions. However, no additional obligations are imposed on any
author or copyright holder as a result of your choosing to follow a
later version.
15. Disclaimer of Warranty.
THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
16. Limitation of Liability.
IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
SUCH DAMAGES.
17. Interpretation of Sections 15 and 16.
If the disclaimer of warranty and limitation of liability provided
above cannot be given local legal effect according to their terms,
reviewing courts shall apply local law that most closely approximates
an absolute waiver of all civil liability in connection with the
Program, unless a warranty or assumption of liability accompanies a
copy of the Program in return for a fee.
END OF TERMS AND CONDITIONS
How to Apply These Terms to Your New Programs
If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these terms.
To do so, attach the following notices to the program. It is safest
to attach them to the start of each source file to most effectively
state the exclusion of warranty; and each file should have at least
the "copyright" line and a pointer to where the full notice is found.
<one line to give the program's name and a brief idea of what it does.>
Copyright (C) <year> <name of author>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
Also add information on how to contact you by electronic and paper mail.
If the program does terminal interaction, make it output a short
notice like this when it starts in an interactive mode:
<program> Copyright (C) <year> <name of author>
This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
This is free software, and you are welcome to redistribute it
under certain conditions; type `show c' for details.
The hypothetical commands `show w' and `show c' should show the appropriate
parts of the General Public License. Of course, your program's commands
might be different; for a GUI interface, you would use an "about box".
You should also get your employer (if you work as a programmer) or school,
if any, to sign a "copyright disclaimer" for the program, if necessary.
For more information on this, and how to apply and follow the GNU GPL, see
<http://www.gnu.org/licenses/>.
The GNU General Public License does not permit incorporating your program
into proprietary programs. If your program is a subroutine library, you
may consider it more useful to permit linking proprietary applications with
the library. If this is what you want to do, use the GNU Lesser General
Public License instead of this License. But first, please read
<http://www.gnu.org/philosophy/why-not-lgpl.html>.

5
ChangeLog Normal file
View File

@ -0,0 +1,5 @@
2010-10-12 Nick <barnold@tilde.club>
* Initial version.
ChangeLog ends here.

48
INSTALL Normal file
View File

@ -0,0 +1,48 @@
Installing from a distribution tarball
======================================
Basic Installation
------------------
The shell commands `./configure; make; sudo make install' should
configure, build, and install this package.
Please read on for cases where you might want to use a variation.
Use './configure --help' to see the configuration options.
OpenBSD
-------
`./configure' defaults the man directory to /usr/local/share/man. But
for OpenBSD you probably want to use this instead:
./configure --mandir=/usr/local/man
Other variations
----------------
If you find one, please let me know.
Installing from pristine source
===============================
$ autoreconf --install
then proceed as above.
Debianising
===========
Run 'autoreconf --install' (but not ./configure, etc), then
$ dh_make --single --copyright gpl3 --native --packagename pgear_0.2
and edit things under debian/.
--
Nick <barnold@tilde.club>

2
Makefile.am Normal file
View File

@ -0,0 +1,2 @@
SUBDIRS = doc src

24
README Normal file
View File

@ -0,0 +1,24 @@
This is the README file for the pgear program.
Copyright (C) Nick <barnold@tilde.club>
pgear is intended to simplify the use of PostgreSQL notification
events. It listens for an event and in response to each occurrence of
the event, performs an action. The action consists of running a
command with the function system(3) or of running SQL, at your option.
Possible use cases:
- The cached value of some lengthy calculation has been cleared; the
response is to perform the calculation and put the new value in
cache.
- A new customer signed up on your web site; the response is to send
her an email.
- Stock of a product fell below a threshold; the response is to
transmit a purchase order to the supplier.
See the file INSTALL for building and installation instructions.
pgear is free software. See the file COPYING for copying conditions.
Your questions and comments are welcome at <barnold@tilde.club>.

43
configure.ac Normal file
View File

@ -0,0 +1,43 @@
# -*- Autoconf -*-
# Process this file with autoconf to produce a configure script.
AC_PREREQ([2.69])
AC_INIT([pgear], [0.3], [barnold@tilde.club], [], [https://tildegit.org/barnold/pgear])
AM_INIT_AUTOMAKE([-Wall -Werror foreign])
AC_CONFIG_SRCDIR([src/main.c])
AC_CONFIG_HEADERS([src/config.h])
# Checks for programs.
AC_PROG_CC
AC_PROG_INSTALL
AC_CHECK_PROG([FOUND_PG_CONFIG],[pg_config],[yes],[no])
if test x$FOUND_PG_CONFIG = xno; then
AC_MSG_ERROR([
The program `pg_config' is not on your PATH. You might need to
install the PostgreSQL client package or a package for PostgreSQL
development files. E.g. on Debian, install the package libpq-dev.])
fi
# For the Makefile to use in AM_CPPFLAGS and AM_LDFLAGS.
AC_SUBST([LIBPQ_FE_INCDIR],[`pg_config --includedir`])
AC_SUBST([LIBPQ_FE_LIBDIR],[`pg_config --libdir`])
# Checks for header files.
AC_HEADER_ASSERT
AC_CHECK_HEADERS([fcntl.h stdlib.h string.h sys/time.h syslog.h unistd.h])
# Checks for typedefs, structures, and compiler characteristics.
AC_HEADER_STDBOOL
AC_TYPE_PID_T
AC_C_RESTRICT
AC_TYPE_SSIZE_T
# Checks for library functions.
AC_FUNC_FORK
AC_CHECK_FUNCS([alarm atexit select strerror strtol])
AC_CONFIG_FILES([Makefile
src/Makefile
doc/pgear.1
doc/Makefile])
AC_OUTPUT

5
debian/changelog vendored Normal file
View File

@ -0,0 +1,5 @@
pgear (0.1) stable; urgency=low
* Debianisation.
-- Nick <barnold@tilde.club> Tue, 06 Sep 2022 14:25:09 +0000

1
debian/compat vendored Normal file
View File

@ -0,0 +1 @@
10

16
debian/control vendored Normal file
View File

@ -0,0 +1,16 @@
Source: pgear
Section: misc
Priority: extra
Maintainer: Nick <barnold@tilde.club>
Build-Depends: debhelper (>= 10.2.5), autotools-dev
Standards-Version: 3.9.8
Package: pgear
Architecture: any
Depends: ${shlibs:Depends}, ${misc:Depends}
Description: Listen for and respond to Postgres notification events.
pgear is intended to simplify the use of PostgreSQL notification
events. It listens for an event and responds to each occurrence of
the event by performing an action. The action consists of running a
command with the function system(3) or of running SQL, at your
option.

18
debian/copyright vendored Normal file
View File

@ -0,0 +1,18 @@
Copyright: 2022 Nick <barnold@tilde.club>
License: GPL-3.0+
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
.
This package is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
.
On Debian systems, the complete text of the GNU General
Public License version 3 can be found in "/usr/share/common-licenses/GPL-3".

1
debian/docs vendored Normal file
View File

@ -0,0 +1 @@
README

13
debian/rules vendored Executable file
View File

@ -0,0 +1,13 @@
#!/usr/bin/make -f
# -*- makefile -*-
# Sample debian/rules that uses debhelper.
# This file was originally written by Joey Hess and Craig Small.
# As a special exception, when this file is copied by dh-make into a
# dh-make output file, you may use that output file without restriction.
# This special exception was added by Craig Small in version 0.37 of dh-make.
# Uncomment this to turn on verbose mode.
#export DH_VERBOSE=1
%:
dh $@ --with autotools-dev

1
debian/source/format vendored Normal file
View File

@ -0,0 +1 @@
3.0 (native)

1
doc/Makefile.am Normal file
View File

@ -0,0 +1 @@
dist_man_MANS = pgear.1

157
doc/pgear.1.in Normal file
View File

@ -0,0 +1,157 @@
.\" Copyright (C), 2018 Nick <barnold@tilde.club>
.\" To test changes quickly, run: PAGER=cat man -l - < doc/pgear.1.in
.\" You may distribute this file under the terms of the GNU Free
.\" Documentation License.
.TH pgear 1 2022-09-06
.SH NAME
pgear \- listen for and respond to PostgreSQL notifications.
.SH SYNOPSIS
.B pgear [OPTION]... --run=\fICMD\fR \fINAME\fR
.br
.B pgear [OPTION]... --sql=\fISQL\fR \fINAME\fR
.SH DESCRIPTION
\fBpgear\fP is intended to simplify the use of PostgreSQL notification
events. On startup, it daemonizes, connects to a database and enters
its 'listen loop'.
.sp
On entering its listen loop, \fBpgear\fP issues 'LISTEN \fINAME\fR'
and runs \fICMD\fR or runs \fISQL\fR. Then it waits for occurrences of
the notification of \fINAME\fR, as produced by the PostgreSQL
\fBNOTIFY\fP statement. Running \fICMD\fR or \fISQL\fR is referred to
below as the 'response'.
.sp
On each receipt of a notification, \fBpgear\fP performs the response
and resumes waiting. It remains in this loop until:
.sp
.RS
\fBpgear\fP loses its database connection, see below.
.sp
A response returns a failure code. \fBpgear\fP logs the failure
and exits.
.sp
\fBpgear\fP receives a SIGINT or SIGTERM. \fBpgear\fP exits.
.RE
.sp
In the last case, the signal is blocked if it arrives while a response
is in progress. When the response is done, \fBpgear\fP exits.
.sp
Typically your \fICMD\fR or \fISQL\fR looks at some state in the
database to determine what (if anything) it needs to do, e.g. which
products are low on stock. \fBpgear\fP assumes that the response is
harmless if it has nothing to do.
.sp
If events for \fBpgear\fP occurred before \fBpgear\fP started, it
would be an unnecessary delay to do nothing until \fBpgear\fP receives
the next event. So \fBpgear\fP responds on entering its listen loop,
after it issues 'LISTEN \fINAME\fR' but before it starts waiting for
events. This sequence ensures that if the PostgreSQL server sends an
event just after the initial response, \fBpgear\fP still handles the
event; there is no gap where an event might be lost.
.sp
\fBpgear\fP runs \fICMD\fR with the \fBsystem\fP(3) function.
\fBpgear\fP runs \fISQL\fR on the database connection it acquires on
startup (or reacquires later). \fISQL\fR may not contain more than
one statement.
.sp
If \fBpgear\fP loses its database connection it periodically attempts
to reconnect. Attempts continue for a maximum of about one minute.
If all attempts fail, \fBpgear\fP logs the failure and exits. On an
attempt succeeding, \fBpgear\fP re-enters its listen loop. This
handles a brief outage such as a restart of the PostgreSQL cluster.
.SH "NOTIFICATION PAYLOAD"
From 9.0 releases onwards, PostgreSQL offers the ability to supply a
string, the \fBpayload\fP, with each notification.
If \fBpgear\fP is connected to a 9.0+ server, it will pass the payload
as the first and only argument to \fICMD\fR, if you used the
\fB--run\fP option. When there is no payload value, \fBpgear\fP
supplies an empty string as the argument value.
.sp
If \fBpgear\fP is connected to a 9.0+ server and you used the
\fB--sql\fP option, then \fBpgear\fP examines your \fISQL\fR for the
presence of the string "$1". If "$1" is present, \fBpgear\fP supplies
the payload as the parameter value, or, if there is no payload,
supplies an empty string as the parameter value. \fBpgear\fP will fail on
startup if you supply such \fISQL\fR (e.g. --sql='select myfunc($1)')
and the server version is earlier than 9.0.
.sp
.SH OPTIONS
Mandatory arguments to long options are mandatory for short options
too.
.TP
.B \-a, \-\-attached
Remain attached to your terminal and log to stdout and stderr. By
default \fBpgear\fP daemonizes and logs to \fBsyslog\fP(3).
.TP
.B \-c, \-\-connect=\fINAME\fR
Use the service named \fINAME\fR in the PostgreSQL connection service
file. By default \fBpgear\fP attempts to connect to the default
database of the user running \fBpgear\fP.
.TP
.B \-p, \-\-pidfile=\fIPIDFILE\fR
Write the process id into the file named \fIPIDFILE\fR and lock the
file. This provides control on the number of running instances of the
program. Use \fB--help\fP to see the default \fIPIDFILE\fR.
.TP
.B \-t, \-\-timeout=\fIN\fR
On daemonizing, the parent process waits \fIN\fR seconds for a signal
from the child that indicates whether the child completed its setup.
Use \fB--timeout=0\fP to have the parent wait indefinitely. Use
\fB--help\fP to see the default \fIN\fR. This option is ignored if
you use \fB--attached\fP.
.TP
.B \-v, \-\-verbose
Set logging verbosity. The verbosity starts at zero (silence except
for warnings and errors) and increases by 1 for each verbosity option
you supply.
.TP
.B \-\-help
Print help.
.TP
.B \-\-version
Print version number.
.SH EXAMPLES
Run in the foreground, connect to your default database, listen for
the event 'foo' and do nothing much in response:
.sp
.RS
.B pgear --attached -vvv --sql='SELECT NULL' foo
.RE
.sp
Run as a daemon, connect via the service 'fort', listen for 'speak'
and respond with a sagacious utterance in syslog:
.sp
.RS
.B PGSYSCONFDIR=~/mypgdir pgear \\\\
.RS
.br
.B --verbose --connect=fort \\\\
.br
.B --run='logger $(fortune -s)' speak
.RE
.RE
.SH FILES
If you use the \fB--connect\fP option, you need a
\fBpg_service.conf\fP connection service file, typically in
/etc/postgresql or /etc/postgresql-common. The example above uses the
environment variable \fBPGSYSCONFDIR\fP to point to a custom
directory.
.SH "SEE ALSO"
See \fBnotify\fP(7) or the PostgreSQL documentation on the
\fBNOTIFY\fP statement. See the PostgreSQL documentation for details
on the connection service file (for PostgreSQL 8.4, section 30.15).
.SH DIAGNOSTICS
The exit statuses of \fBpgear\fP starting in daemon mode are
.RS
.IP 0
Success, the child process completed its setup.
.IP 1
Failure, the child was unable to complete its setup.
.IP 2
Unknown, the parent timed out while waiting for the child.
.RE
.SH BUGS
Please report bugs to @PACKAGE_BUGREPORT@ or via the project page,
.br
<@PACKAGE_URL@>.
.SH AUTHOR
Nick <barnold@tilde.club>

18
src/Makefile.am Normal file
View File

@ -0,0 +1,18 @@
bin_PROGRAMS = pgear
pgear_SOURCES = \
daem.c daem.h \
lock.c lock.h \
logr.c logr.h \
main.c \
opts.c opts.h \
pger.c pger.h
AM_CPPFLAGS = -std=c99 -Wall -Werror -Wundef -I$(LIBPQ_FE_INCDIR) -D_FORTIFY_SOURCE=2
AM_CFLAGS = -W
AM_LDFLAGS = -L$(LIBPQ_FE_LIBDIR) -z relro
LIBS = -lpq
check: all
./pgear -h | grep 'Usage' >/dev/null
./pgear -V | grep '$(PACKAGE_STRING)' >/dev/null
@echo "*** ALL TESTS PASSED ***"

290
src/daem.c Normal file
View File

@ -0,0 +1,290 @@
#define _GNU_SOURCE
#include <assert.h>
#include <errno.h>
#include <signal.h>
#include <stdbool.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include "daem.h"
#include "logr.h"
#include "opts.h"
/* For use by the parent during daemonization. The parent process's
signal handler updates the outcome to communicate whether the child
setup completed normally.
*/
#define CHILD_UNKNOWN -1
#define CHILD_OK 0
#define CHILD_FAILED 1
#define CHILD_TIMEOUT 2
volatile sig_atomic_t child_outcome = CHILD_UNKNOWN;
/* For use by the child during daemonization (set after the fork() and
before the kernel reparents the child to init). The parent_pid is
the target for the child's signal indicating the outcome of the
child's setup.
*/
pid_t parent_pid = 0;
/* The signals that designate the outcomes of the child daemonizing.
*/
#define SIG_CHILD_OK SIGUSR1
#define SIG_CHILD_FAILED SIGUSR2
/*---------------------------------------------------------------------------*/
/* Close the given stream or exit.
*/
void
close_or_die (FILE *stream)
{
if (EOF == fclose(stream))
{
logg_exit("fclose failed: %s\n", strerror(errno));
}
return;
}
/*---------------------------------------------------------------------------*/
/* Handler for use by the parent during daemonization.
*/
void
catch_child_signal_or_timeout (int signum)
{
switch (signum)
{
case SIG_CHILD_OK:
child_outcome = CHILD_OK;
break;
case SIG_CHILD_FAILED:
child_outcome = CHILD_FAILED;
break;
case SIGALRM:
child_outcome = CHILD_TIMEOUT;
break;
default:
assert(false); /* Should be unreachable. */
logg_exit("bug: unexpected signal `%s'.", strsignal(signum));
}
return;
}
/*---------------------------------------------------------------------------*/
/* Set a handler to anticipate an outcome of the child completing its
setup.
*/
void
establish_handler (int signum)
{
struct sigaction sa;
sa.sa_handler = catch_child_signal_or_timeout;
sigemptyset(&sa.sa_mask);
sa.sa_flags = 0;
if (-1 == sigaction(signum, &sa, NULL))
{
logg_exit("failed sigaction for `%s': %s\n",
strsignal(signum), strerror(errno));
}
return;
}
/*---------------------------------------------------------------------------*/
/* As the parent process, wait for the child to signal that its setup
completed. This function doesn't return.
*/
void
parent_wait_for_child (sigset_t *old_mask)
{
logg(3, "parent waiting for child...\n");
/* Establish a handler for each anticipated outcome of child setup.
* Include a timeout unless the user asked for a zero timeout.
*/
establish_handler(SIG_CHILD_OK);
establish_handler(SIG_CHILD_FAILED);
if (0 != opts.timeout_sec)
{
establish_handler(SIGALRM);
alarm(opts.timeout_sec);
logg(3, "set alarm for %d sec.\n", opts.timeout_sec);
}
/* Wait for something to happen.
*/
while (CHILD_UNKNOWN == child_outcome) sigsuspend(old_mask);
switch (child_outcome)
{
case CHILD_OK:
logg(3, "child setup complete, quitting now.\n");
exit(EXIT_SUCCESS);
case CHILD_FAILED:
logg_exit("failed child setup.\n");
exit(2); // placates compiler warning
case CHILD_TIMEOUT:
logg(0, "timeout waiting for child setup.\n");
/* Distinguish timeout from a definite failure. */
exit(2);
default:
assert(false); /* Should be unreachable. */
logg_exit("bug: unexpected child outcome %d.\n", child_outcome);
}
assert(false); /* Should be unreachable. */
logg_exit("bug: parent wait escaped.\n");
}
/*---------------------------------------------------------------------------*/
/* As the child, send to the parent the signal designated as meaning
"I hit a problem and am exiting with failure".
*/
void
send_signal_child_failed (void)
{
logg(3, "%s about to signal `%s' to parent `%d'...\n",
__func__, strsignal(SIG_CHILD_FAILED), parent_pid);
if (-1 == kill(parent_pid, SIG_CHILD_FAILED))
{
/* Perhaps the parent process gave up waiting. Log and continue.
*/
logg(0, "%s failed to signal `%s' to `%d': %s\n",
__func__, strsignal(SIG_CHILD_FAILED),
parent_pid, strerror(errno));
}
return;
}
/*---------------------------------------------------------------------------*/
/* As the child, send to the parent the signal designated as meaning
"I'm OK".
*/
void
send_signal_child_ok (void)
{
logg(3, "%s about to signal `%s' to parent `%d'...\n",
__func__, strsignal(SIG_CHILD_OK), parent_pid);
/* Clear the exit trigger that would send an "I'm not OK" signal to
the parent, since we expect the parent to die imminently.
*/
atexit_fp = NULL;
if (-1 == kill(parent_pid, SIG_CHILD_OK))
{
/* Perhaps the parent process gave up waiting. Log and continue.
*/
logg(0, "%s failed to signal `%s' to `%d': %s\n",
__func__, strsignal(SIG_CHILD_OK),
parent_pid, strerror(errno));
}
return;
}
/*---------------------------------------------------------------------------*/
/* Reopen the given stream from /dev/null or exit.
*/
void
reopen_or_die (const char* opentype, FILE *stream)
{
if (NULL == freopen("/dev/null", opentype, stream))
{
logg_exit("freopen failed: %s\n", strerror(errno));
}
return;
}
/*---------------------------------------------------------------------------*/
void
daemonize (void)
{
/* Function is only to be called if self is not already daemonized.
*/
assert(1 < getppid());
logg(2, "starting to daemonize...\n");
/* Before forking, temporarily block SIGUSR[12] so an instance
of either is kept in the queue. This is in case the child
process sends its "I'm OK" or its "oh noes" signal before the
parent has its handlers ready.
*/
sigset_t old_mask, tmp_mask;
sigemptyset(&tmp_mask);
sigaddset(&tmp_mask, SIG_CHILD_OK);
sigaddset(&tmp_mask, SIG_CHILD_FAILED);
if (-1 == sigprocmask(SIG_BLOCK, &tmp_mask, &old_mask))
{
logg_exit("failed sigprocmask block, %s line %d: %s\n",
__FILE__, __LINE__, strerror(errno));
}
/* At this point, any SIGUSR[12] will be held until after the
parent_wait_for_child() call below.
*/
pid_t pid = fork();
if (pid < 0)
{
logg_exit("fork failed on %s\n", strerror(errno));
}
else if (pid > 0)
{
/* This is the soon-not-wanted parent process.
Listen for SIGUSR[12] from the child before quitting.
*/
parent_wait_for_child(&old_mask);
}
logg(3, "fork child continuing here.\n");
/* If the child exits for some (probably bad) reason before it
sends its "I'm OK" signal, then this will send the "I'm not
OK" signal to the parent on exit().
*/
atexit_fp = send_signal_child_failed;
/* Remove the temporary block on handling SIGUSR[12] since the
block is only for the parent.
*/
if (-1 == sigprocmask(SIG_UNBLOCK, &tmp_mask, NULL))
{
logg_exit("failed sigprocmask unblock, %s line %d: %s\n",
__FILE__, __LINE__, strerror(errno));
}
/* Remember our parent for signalling later. */
parent_pid = getppid();
/* Create a new session detached from its former parent. */
pid_t sid = setsid();
if (sid < 0)
{
logg_exit("setsid failed on %s\n", strerror(errno));
}
/* Change the current working directory so as not to obstruct a
umount or an rmdir.
*/
if (chdir("/") < 0)
{
logg_exit("chdir(\"/\") failed on %s\n", strerror(errno));
}
/* Close the standard streams... */
logg(3, "closing stdin...\n");
close_or_die(stdin);
logg(3, "closing stdout...\n");
close_or_die(stdout);
logg(3, "closing stderr...\n");
close_or_die(stderr);
/* ...and reopen them from /dev/null. */
logg(3, "reopening stdin...\n");
reopen_or_die("r", stdin);
logg(3, "reopening stdout...\n");
reopen_or_die("w", stdout);
logg(3, "reopening stderr...\n");
reopen_or_die("w", stderr);
logg(1, "daemonized.\n");
return;
}
/*---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/

22
src/daem.h Normal file
View File

@ -0,0 +1,22 @@
#ifndef DAEM_H
#define DAEM_H
/* Detach the process running self from its terminal. If it returns,
it returns to the child process created via fork().
The parent doesn't return. Instead it waits for its child either
to signal that it completed its setup or that it exited
prematurely; on either of those the parent exits with a success or
failure accordingly.
*/
void
daemonize (void);
/* For use by the child process so that, after daemonization, it can
signal the waiting parent that is has completed its setup (file
locking etc).
*/
void
send_signal_child_ok (void);
#endif

72
src/lock.c Normal file
View File

@ -0,0 +1,72 @@
#define _GNU_SOURCE
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <unistd.h>
#include "lock.h"
#include "logr.h"
void
lock_pidfile (const char *pidfile_name)
{
/* Acquire a file descriptor for the lock file.
*/
logg(3, "creating pid file `%s'...\n", pidfile_name);
int pidfile_fd = open(pidfile_name, O_RDWR | O_CREAT | O_FSYNC, 0640);
if ( pidfile_fd < 0 )
{
logg_exit("failed to create pid file: %s)", strerror(errno));
}
/* Attempt to lock the file.
*/
struct flock pidfile_lock = {
.l_type = F_WRLCK,
.l_whence = SEEK_END,
.l_start = 0,
.l_len = 0,
.l_pid = 0
};
logg(3, "locking pid file...\n");
if (-1 == fcntl(pidfile_fd, F_SETLK, &pidfile_lock))
{
logg_exit("failed to lock pid file: %s\n", strerror(errno));
}
logg(3, "lock acquired.\n");
/* Convert the process id into a string, preparatory to writing it
* into the pid file.
*/
char *pid_str;
int pid_str_size = asprintf(&pid_str, "%d\n", getpid());
if (pid_str_size < 0)
{
logg_exit("failed to allocate pid string: %s\n", strerror(errno));
}
logg(3, "pid_str is `%s' and its size is %d.\n", pid_str, pid_str_size);
/* GNU's libc info sternly states "always call `write' in a loop".
* Even for a few bytes?
*/
ssize_t bytes_left = pid_str_size;
ssize_t written = 0;
while (bytes_left > 0)
{
written = write(pidfile_fd, pid_str, bytes_left);
if (-1 == written)
{
logg_exit("failed to write to pid file: %s\n", strerror(errno));
}
bytes_left -= written;
}
free(pid_str);
logg(2, "acquired pid file `%s'.\n", pidfile_name);
return;
}
/*---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/

10
src/lock.h Normal file
View File

@ -0,0 +1,10 @@
#ifndef LOCK_H
#define LOCK_H
/* Create and lock a pid file with the given path and write the pid
* into it.
*/
void
lock_pidfile (const char *pidfile_name);
#endif

96
src/logr.c Normal file
View File

@ -0,0 +1,96 @@
#define _GNU_SOURCE
#include <assert.h>
#include <errno.h>
#include <stdbool.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <sys/types.h>
#include <unistd.h>
#include "config.h"
#include "logr.h"
#include "opts.h"
/* Initialize the atexit function to 'do nothing'.
*/
void (*atexit_fp) (void) = NULL;
/*---------------------------------------------------------------------------*/
/* Send a log message either to a stream or to syslog.
*/
void _vlogg
(
const bool is_err,
const unsigned char chattiness,
const char *template,
va_list ap
)
{
/* Error (and warnings) are always at chattiness zero.
*/
assert(!is_err || 0 == chattiness);
if (opts.is_attached)
{
/* Probably being run for debug purposes so use the standard
* streams.
*/
FILE *stream = ( ((0 == chattiness) || is_err) ? stderr : stdout );
fprintf(stream, "%s: ", PACKAGE_NAME);
vfprintf(stream, template, ap);
}
else
{
/* Running as a daemon so use syslog.
*/
openlog(PACKAGE_NAME, LOG_PID, LOG_USER);
int priority =
(
is_err ? LOG_ERR :
(0 == chattiness ? LOG_WARNING : LOG_INFO)
);
vsyslog(priority, template, ap);
closelog();
}
return;
}
/*---------------------------------------------------------------------------*/
void
logg (const unsigned char chattiness, const char *template, ...)
{
if (chattiness <= opts.verbosity)
{
va_list ap;
va_start(ap, template);
_vlogg(false, chattiness, template, ap);
va_end(ap);
}
return;
}
/*---------------------------------------------------------------------------*/
void
logg_exit (const char *template, ...)
{
va_list ap;
va_start(ap, template);
_vlogg(true, 0, template, ap);
va_end(ap);
if (NULL != atexit_fp)
{
logg(3, "%s calling atexit()...\n", __func__);
if (0 != atexit(atexit_fp))
{
logg(0, "atexit failed on %s\n", strerror(errno));
}
logg(3, "%s done calling atexit().\n", __func__);
};
logg(3, "%s about to call exit().\n", __func__);
exit(EXIT_FAILURE);
}
/*---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/

29
src/logr.h Normal file
View File

@ -0,0 +1,29 @@
#ifndef LOGR_H
#define LOGR_H
/* For clients to set an atexit function, triggered by calling
logg_exit(), see below.
*/
extern void (*atexit_fp) (void);
/* Write a message. If chattiness is zero, write it as a warning,
* else as information.
*
* Following the chattiness parameter, the signature imitates printf()
* and friends.
*/
void
logg (const unsigned char chattiness, const char *template, ...)
__attribute__ ((format (printf, 2, 3)));
/* Write a message as an error and exit with failure. Before calling
exit() it check whether atexit_fp (above) is set, and if so calls
atexit(atexit_fp). This way the client can choose some atexit
function and later clear it (by setting atexit_fp to NULL), which
is not possible with atexit() itself.
*/
void
logg_exit (const char *template, ...)
__attribute__ ((format (printf, 1, 2)));
#endif

64
src/main.c Normal file
View File

@ -0,0 +1,64 @@
#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <signal.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "daem.h"
#include "lock.h"
#include "logr.h"
#include "opts.h"
#include "pger.h"
int
main (int argc, char **argv)
{
/* Fill out the opts structure from the command line.
*/
init_opts_from_cmdline(argc, argv);
logg(2,
"is_attached `%d';\n"
"connect `%s';\n"
"pidfile_name `%s';\n"
"run `%s';\n"
"sql `%s';\n"
"timeout `%d';\n"
"verbosity `%d';\n"
"notification name `%s'.\n",
opts.is_attached,
opts.connect,
opts.pidfile_name,
opts.run,
opts.sql,
opts.timeout_sec,
opts.verbosity,
opts.ntn_name);
/* Are we willing and able to daemonize?
*/
bool is_daemonaic = (!opts.is_attached && 1 < getppid());
if (is_daemonaic) daemonize();
/* At this point, is_daemonaic being true means we're the child
since the parent does not return from daemonize(). Either way,
continue with setting up.
*/
lock_pidfile(opts.pidfile_name);
connect_to_db();
/* Setup finished. Signal the parent (if daemonized) that we setup
ok.
*/
if (is_daemonaic) send_signal_child_ok();
/* Listen and respond 'forever'.
*/
listen_loop();
logg(1, "leaving %s.\n", __func__);
return EXIT_SUCCESS;
}
/*---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/

173
src/opts.c Normal file
View File

@ -0,0 +1,173 @@
#define _GNU_SOURCE
#include <assert.h>
#include <errno.h>
#include <getopt.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include "config.h"
#include "opts.h"
#define TIMEOUT_DEFAULT 5
#define TIMEOUT_MAX 3600
/* Initialize global program options.
*/
opts_t opts =
{
.connect = NULL,
.is_attached = false,
.ntn_name = NULL,
.pidfile_name = "/tmp/pgear.pid",
.run = NULL,
.sql = NULL,
.timeout_sec = TIMEOUT_DEFAULT,
.verbosity = 0
};
/*---------------------------------------------------------------------------*/
/* Print help, in response to the user asking for help or to the user
* misusing other options, and exit the program.
*/
void
print_usage (FILE* stream, int exit_code)
{
fprintf(stream, "Usage: %s [OPTION]... { --run=CMD | --sql=SQL } NAME\n",
PACKAGE_NAME);
fprintf(stream,
"Listen for notifications of NAME and in response run CMD or run SQL.\n"
"In SQL, use `$1' as the payload parameter, e.g. --sql='SELECT myfunc($1)'.\n\n"
"-a --attached Remain attached instead of daemonizing.\n"
"-c --connect=NAME Use this PostgreSQL connection configuration service name.\n"
"-p --pidfile=NAME Write pid to file NAME; default %s.\n"
"-t --timeout=N Wait Ns for startup; 0 means indefinitely; default %d.\n"
"-v --verbose Print verbose messages. Repeat for more verbosity.\n"
" --help Display this usage information.\n"
" --version Print version number.\n\n"
"Report bugs to <" PACKAGE_BUGREPORT ">. Home page <" PACKAGE_URL ">.\n",
opts.pidfile_name, TIMEOUT_DEFAULT
);
exit(exit_code);
}
/*---------------------------------------------------------------------------*/
/* Print version.
*/
void
print_version (void)
{
printf(PACKAGE_STRING
"\nCopyright (C) 2022 Nick <barnold@tilde.club>\n"
"License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.\n"
"This is free software: you are free to change and redistribute it.\n"
"There is NO WARRANTY, to the extent permitted by law.\n"
);
exit(EXIT_SUCCESS);
}
/*---------------------------------------------------------------------------*/
/* Return the timeout seconds in the expected range or die.
*/
unsigned int
get_timeout (const char *restrict optarg)
{
char *tail;
long int n = strtol(optarg, &tail, 10);
/* Demand we got an integer in the range and nothing else. */
if (n < 0 || TIMEOUT_MAX < n || '\0' != *tail)
{
fprintf(stderr, "%s: use a timeout in range 0..%d.\n",
PACKAGE_NAME, TIMEOUT_MAX);
print_usage(stderr, EXIT_FAILURE);
}
return (unsigned short) n;
}
/*---------------------------------------------------------------------------*/
void
init_opts_from_cmdline (int argc, char **argv)
{
/* The 1-char or -1 value returned by getopt_long().
*/
int next_option;
/* An array describing valid long options. */
const struct option long_options[] =
{
{ "attached", 0, NULL, 'a' },
{ "connect", 1, NULL, 'c' },
{ "help", 0, NULL, 'h' },
{ "pidfile", 1, NULL, 'p' },
{ "run", 1, NULL, 'r' },
{ "sql", 1, NULL, 's' },
{ "timeout", 1, NULL, 't' },
{ "verbose", 0, NULL, 'v' },
{ "version", 0, NULL, 'V' },
{ NULL, 0, NULL, 0 } /* Required at end of array. */
};
do
{
next_option = getopt_long(argc, argv, "ac:hp:r:s:t:vV", long_options, NULL);
switch (next_option)
{
case 'a':
opts.is_attached = true;
break;
case 'c':
opts.connect = optarg;
break;
case 'h':
print_usage(stdout, EXIT_SUCCESS);
assert(false); /* Should be unreachable. */
abort();
case 'p':
opts.pidfile_name = optarg;
break;
case 'r':
opts.run = optarg;
break;
case 's':
opts.sql = optarg;
break;
case 't':
opts.timeout_sec = get_timeout(optarg);
break;
case 'v':
++opts.verbosity;
break;
case 'V':
print_version();
assert(false); /* Should be unreachable. */
abort();
case '?': /* '?' for 'invalid option'. */
print_usage(stderr, EXIT_FAILURE);
assert(false); /* Should be unreachable. */
abort();
case -1: /* Done with options. */
break;
default:
assert(false); /* Should be unreachable. */
abort();
}
}
while (-1 != next_option);
/* Want exactly one of --sql or --run.
*/
if ((opts.run && opts.sql) || (!opts.run && !opts.sql))
{
print_usage(stderr, EXIT_FAILURE);
}
/* Want exactly one non-option argument, the notification name.
*/
if (1 != argc - optind) print_usage(stderr, EXIT_FAILURE);
opts.ntn_name = argv[optind];
return;
}
/*---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/

29
src/opts.h Normal file
View File

@ -0,0 +1,29 @@
#ifndef OPTS_H
#define OPTS_H
#include <stdbool.h>
/* To describe the program options.
*/
typedef struct
{
char* connect;
bool is_attached;
char* ntn_name;
char* pidfile_name;
char* run;
char* sql;
unsigned int timeout_sec;
unsigned char verbosity;
} opts_t;
/* Global program options.
*/
extern opts_t opts;
/* Set the global program options with valid values or terminate the
* program.
*/
void
init_opts_from_cmdline (int argc, char **argv);
#endif

375
src/pger.c Normal file
View File

@ -0,0 +1,375 @@
#define _GNU_SOURCE
#include <assert.h>
#include <errno.h>
#include <signal.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include "libpq-fe.h"
#include "logr.h"
#include "opts.h"
#include "pger.h"
/* The database connection.
*/
char *conninfo = "";
PGconn *conn;
/* To block SIG{INT,TERM} while a --run=CMD is in progress.
*/
sigset_t run_cmd_mask;
/* For use by the signal handler.
*/
volatile sig_atomic_t shutdown_signalled = 0;
/* Whether the server provides a payload and whether it's wanted
* by the --sql=SQL.
*/
bool is_pd_avail = false;
bool is_pd_want = false;
/* The function to invoke to respond to a notification. We'll set it to
* one of do_response_{cmd,sql} later.
*/
void (*do_response) (const PGnotify *notify) = NULL;
/*---------------------------------------------------------------------------*/
void
catch_signal_to_shutdown (int signum)
{
/* assert to silence compiler warning. */
assert(signum > 0);
shutdown_signalled = 1;
return;
}
/*---------------------------------------------------------------------------*/
/*
Run given SQL.
*/
void
do_sql (const char *sql, const PGnotify *notify)
{
PGresult *res = NULL;
logg(3, "%s running `%s'...\n", __func__, sql);
if (is_pd_want)
{
logg(3, "%s looking for a payload.\n", __func__);
const char * param_values[] = { notify ? notify->extra : "" };
res = PQexecParams(conn, sql, 1, NULL, param_values, NULL, NULL, 0);
}
else
{
logg(3, "%s no payload.\n", __func__);
res = PQexecParams(conn, sql, 0, NULL, NULL, NULL, NULL, 0);
}
ExecStatusType status = PQresultStatus(res);
switch (status)
{
/* These are 'good', nothing more to do. */
case PGRES_COMMAND_OK:
case PGRES_TUPLES_OK:
case PGRES_COPY_OUT:
case PGRES_COPY_IN:
break;
/* Anything else is 'bad'. */
default:
PQclear(res);
logg_exit("failed `%s': %s / %s\n",
sql, PQresStatus(status), PQerrorMessage(conn));
}
logg(3, "%s PQresStatus `%s'.\n", __func__, PQresStatus(status));
PQclear(res);
return;
}
/*---------------------------------------------------------------------------*/
/*
Run response SQL.
*/
void
do_response_sql (const PGnotify *notify)
{
do_sql(opts.sql, notify);
return;
}
/*---------------------------------------------------------------------------*/
/* Run response command.
*/
void
do_response_cmd (const PGnotify *notify)
{
char *cmd = NULL;
logg(3, "%s: notify is %s\n", __func__, notify ? "set" : "null");
if (is_pd_avail)
{
const char *payload = (notify ? notify->extra : NULL);
if (asprintf(&cmd, "%s \"%s\"", opts.run, payload) < 0)
{
logg_exit("failed to allocate cmd string: %s\n", strerror(errno));
}
logg(3, "cmd `%s'.\n", cmd);
}
else
{
cmd = opts.run;
}
logg(3, "performing `%s'...\n", cmd);
/* Before the run, temporarily block SIG{INT,TERM}. */
if (-1 == sigprocmask(SIG_BLOCK, &run_cmd_mask, NULL))
{
logg_exit("failed sigprocmask block, %s line %d: %s\n",
__FILE__, __LINE__, strerror(errno));
}
int sysret = system(cmd);
if (-1 == sysret) logg_exit("system() failed: %s\n", strerror(errno));
if (0 != sysret) logg_exit("system() failed, returned %d.\n", sysret);
/* Run succeeded so unblock. */
if (-1 == sigprocmask(SIG_UNBLOCK, &run_cmd_mask, NULL))
{
logg_exit("failed sigprocmask unblock, %s line %d: %s\n",
__FILE__, __LINE__, strerror(errno));
}
logg(3,"completed `%s'.\n", cmd);
if (is_pd_avail) free(cmd);
return;
}
/*---------------------------------------------------------------------------*/
/* Clean up the connection when no longer wanted.
*/
void
finish_conn (void)
{
logg(2, "%s about to call PQfinish...\n", __func__);
PQfinish(conn);
logg(2, "%s called PQfinish.\n", __func__);
return;
}
/*---------------------------------------------------------------------------*/
void
connect_to_db()
{
if (NULL != opts.connect)
{
if (asprintf(&conninfo, "service=%s", opts.connect) < 0)
{
logg_exit("failed to allocate conninfo string: %s\n", strerror(errno));
}
logg(3, "from connect option `%s', built conninfo string `%s'.\n",
opts.connect, conninfo);
}
logg(2, "connecting using conninfo string `%s'...\n", conninfo);
conn = PQconnectdb(conninfo);
if (CONNECTION_OK != PQstatus(conn))
{
logg_exit("failed connection with conninfo `%s': %s\n",
conninfo, PQerrorMessage(conn));
}
logg(3, "setting up handler for signals...\n");
struct sigaction sa;
sa.sa_handler = catch_signal_to_shutdown;
sigemptyset(&sa.sa_mask);
sa.sa_flags = 0;
if (-1 == sigaction(SIGTERM, &sa, NULL))
{
logg_exit("failed sigaction for `%s': %s\n",
strsignal(SIGTERM), strerror(errno));
}
if (-1 == sigaction(SIGINT, &sa, NULL))
{
logg_exit("failed sigaction for `%s': %s\n",
strsignal(SIGINT), strerror(errno));
}
/* Since we now have a connection, have it cleaned up on an orderly
exit.
*/
logg(3, "%s calling atexit()...\n", __func__);
if (0 != atexit(finish_conn))
{
logg(0, "atexit failed on %s\n", strerror(errno));
}
logg(3, "%s done calling atexit().\n", __func__);
/* Set the Postgres verbosity according to the logging verbosity.
*/
PGVerbosity pg_verbosity;
switch (opts.verbosity)
{
case 0:
pg_verbosity = PQERRORS_TERSE;
logg(3, "chose PGVerbosity terse.\n");
break;
case 1:
pg_verbosity = PQERRORS_DEFAULT;
logg(3, "chose PGVerbosity default.\n");
break;
default:
pg_verbosity = PQERRORS_VERBOSE;
logg(2, "chose PGVerbosity verbose.\n");
}
PQsetErrorVerbosity(conn, pg_verbosity);
if (opts.run)
{
/* Set the mask for blocking SIG{INT,TERM} while a --run=CMD is in
progress.
*/
sigemptyset(&run_cmd_mask);
sigaddset(&run_cmd_mask, SIGINT);
sigaddset(&run_cmd_mask, SIGTERM);
do_response = do_response_cmd;
}
else
{
do_response = do_response_sql;
}
logg(1, "connected to database `%s'.\n", PQdb(conn));
return;
}
/*---------------------------------------------------------------------------*/
void
set_payload_flags ()
{
int server_version = PQserverVersion(conn);
// Payload is available from 9.0+ servers.
is_pd_avail = (90000 <= server_version);
if (opts.sql)
{
// We'll pass the payload to the SQL if it has '$1' in it.
bool is_sql_parameterized = (bool) strstr(opts.sql, "$1");
if (!is_pd_avail && is_sql_parameterized)
{
logg_exit("sql `%s' wants a payload but "
"postgres version %d cannot supply one.\n",
opts.sql, server_version);
}
is_pd_want = (is_pd_avail && is_sql_parameterized);
}
logg(3, "payload available: %d; wanted for SQL: %d\n",
is_pd_avail, is_pd_want);
return;
}
/*---------------------------------------------------------------------------*/
void
inner_loop ()
{
logg(2, "acquiring socket from database connection...\n");
int sock = PQsocket(conn);
if (sock < 0)
{
logg(0, "error on PQsocket: %s\n", PQerrorMessage(conn));
return;
}
set_payload_flags();
/* Do the on-loop-entry response here, _after_ the LISTEN issued by
listen_loop() but before waiting on the socket 'sock'. This
ordering aims to prevent the possibility of a gap between the
on-loop-entry response and the LISTEN. A NOTIFY during that gap
would be missed because we would have finished the initial
response but not yet asked PostgreSQL to send us NOTIFYs.
*/
logg(2, "performing loop-entry response...\n");
do_response(NULL);
/* Create a file descriptor set containing the socket. */
fd_set input_mask;
FD_ZERO(&input_mask);
FD_SET(sock, &input_mask);
while (! shutdown_signalled)
{
logg(3, "waiting on select() inside the listen-forever loop...\n");
if (select(FD_SETSIZE, &input_mask, NULL, NULL, NULL) < 0)
{
logg(0, "select() failed: %s\n", strerror(errno));
break;
}
PQconsumeInput(conn);
PGnotify *notify;
while ((notify = PQnotifies(conn)) != NULL)
{
logg(3, "notify of '%s' received from pid %d\n",
notify->relname, notify->be_pid);
do_response(notify);
PQfreemem(notify);
}
}
logg(2, "falling out of %s.\n", __func__);
return;
}
/*---------------------------------------------------------------------------*/
void
listen_loop()
{
logg(1, "entering %s.\n", __func__);
/* todo: maybe optionalize max recon attempts and sleep time.
*/
const unsigned short rcn_attempt_max = 12;
const unsigned short rcn_sleep_s = 5;
/* Construct the LISTEN statement.
*/
char *listen_sql;
if (asprintf(&listen_sql, "LISTEN %s", opts.ntn_name) < 0)
{
logg_exit("failed to allocate listen_sql: %s\n", strerror(errno));
}
/* The number of reconnection attempts made since the connection was lost.
*/
unsigned short rcn_attempt = 0;
while (! shutdown_signalled)
{
/* Attempt to reconnect if we lose the database. */
if (CONNECTION_OK != PQstatus(conn))
{
rcn_attempt++;
if (rcn_attempt_max < rcn_attempt)
{
logg_exit("failed all %d reconnect attempts.\n", rcn_attempt_max);
}
/* PQreset() doesn't clear out the postgres error message, so
use PQfinish() + PQconnectdb() instead.
*/
PQfinish(conn);
logg(0, "reconnect attempt %d in %ds...\n", rcn_attempt, rcn_sleep_s);
sleep(rcn_sleep_s);
conn = PQconnectdb(conninfo);
}
if (CONNECTION_OK == PQstatus(conn))
{
if (0 < rcn_attempt)
{
logg(1, "reconnect attempt %d succeeded.\n", rcn_attempt);
}
rcn_attempt = 0;
logg(2, "about to issue listen command `%s'...\n", listen_sql);
do_sql(listen_sql, NULL);
inner_loop();
}
else
{
logg(0, "reconnect attempt %d failed: %s",
rcn_attempt, PQerrorMessage(conn));
}
}
free(listen_sql);
if (NULL != opts.connect) free(conninfo);
logg(2, "falling out of %s.\n", __func__);
return;
}
/*---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/

15
src/pger.h Normal file
View File

@ -0,0 +1,15 @@
#ifndef PGER_H
#define PGER_H
/* Establish the database connection.
*/
void
connect_to_db();
/* The listen-handle loop. The process normally spends nearly all of
its time in here.
*/
void
listen_loop();
#endif