This makes it easier to reuse the code from reading plain-text list of items
from a file and uses a struct urls to keep its state in a cleaner way.
+ some small code-style improvements and reshuffling.
Inspired by a question from NRK by mail about implementing a "read later"
feature.
(A quick local experiment shows it can be done in ~70 lines of added code).
Write it in a more verbose, clear and C90-style manner.
This workarounds a bug in scc too (reported upstream and will be fixed of
course). All tools in sfeed can now be compiled with minicurses-mode with the
scc compiler and musl libc without any modifications needed.
scc: http://www.simple-cc.org/
Multiple function calls should still be nested in a do { } while(0), but this
is hopefully obvious looking at the other lines.
While testing, gcc with -O0 created the same binary.
clang added a single jmp instruction.
This was used in commit a58fa45f25 and previous,
but the code for non-interactive process cleanup was later removed, so clearing
the struct is not not needed anymore, because it is unused.
This is only for plumbing in non-interactive mode in forkexec(), but not piping
content.
Probably obvious what the descriptors are, but also add a few comments to dup2
of the file descriptors (stdin, stdout, stderr).
To reproduce a behaviour:
Plumb script:
#!/bin/sh
dmenu
Then launch it:
SFEED_PLUMB_INTERACTIVE=0 SFEED_PLUMB=thescript sfeed_curses ~/.sfeed/feeds/*
The program now waits on input while in non-interactive mode and only seems to
hang.
After:
The program starts but just has no input passed to it.
- SIGINT: reword, canceling the line editor is the exception.
- Document the order of signal handling.
- Document interactive and non-interactive behaviour in a separate section and
in more detail.
Remove repetition for each *_INTERACTIVE environment variable.
- Document SIGINT and SIGTERM exit status.
- Typo: "statusbar" -> "status bar".
- Reword a few sentences.
With additional changes and feedback from adc, thanks!
From the mdoc(7) extended introduction[0]:
>To output a backslash, use the escape sequence ‘\e’. Never use the
>escape sequence ‘\\’ in any context.
0: https://mandoc.bsd.lv/mdoc/intro/escaping.html
Reported by Leon Fisher, thanks!
"Each signal should have its own sig_atomic_t variable if you want to
keep state for all of them independently."
A similar issue was referenced in a OpenBSD tech mailinglist thread:
https://marc.info/?l=openbsd-tech&m=162940120614641&w=2
- Wait on the exact process id and get its status.
- Handle SIGCHLD explicitly and reap zombie children: ignoring them by using
sigaction(SIGCHLD, &sa, NULL); would be racy in this case because sfeed_curses
has interactive and non-interactive programs.
Note while testing: if the markread program would be slow and in the meantime a
plumb process would exit. This signal is now pending and is a zombie process
until the SIGCHLD signal can be processed. This is fine.
This also fixes a regression from commit
30a70fa2da because SIGCHLD was ignored in the
parent for interactive processes aswell. This broke reading the exit status of
the markread program, reproducable by plumbing an item and then trying to mark
it as read (with SFEED_URL_FILE set).
This is not clearly defined by the C99 standard.
Define ctype-like macros to force it to be ASCII / UTF-8 (not extended ASCII or
something like noticed on OpenBSD 3.8).
(In practise modern libc libraries are all ASCII and UTF-8-compatible. Otherwise
this would break many programs)
It is unspecified if the C locale iscntrl is compatible with ASCII or not.
Noticed when testing on OpenBSD 3.8 which uses extended ASCII and also uses the
C1 range for control-characters. This breaks support with UTF-8.
Reference:
https://en.wikipedia.org/wiki/C0_and_C1_control_codes#C1_control_codes_for_general_use
C1 table.
Force an own definition of an ASCII-compatible control-character range since
sfeed expects input to be UTF-8 (or converted from iconv) and so output to be
UTF-8 aswell.
This is a regression from the introduced change.
Else wait(&status) returned -1 and status was uninitialized.
The status of the returned program in the markread() function is used to
visually show it as read/unread. If the program failed it is assumed the
program could not mark it and so it is visually unchanged.
Just to be sure also initialize status to -1 (which can never happen normally)
since the exitstatus range is 0-255.
https://man.openbsd.org/wait#ERRORS
[ECHILD]: "No status from the terminated child process is available because the calling
process has asked the system to discard such status by ignoring the signal
SIGCHLD or setting the flag SA_NOCLDWAIT for that signal."
From POSIX:
Consequences of Process Termination:
https://pubs.opengroup.org/onlinepubs/9699919799/functions/_Exit.html#tag_16_01_03_01
"
[XSI] [Option Start] If the parent process of the calling process has set its
SA_NOCLDWAIT flag or has set the action for the SIGCHLD signal to SIG_IGN:
The process' status information (see Status Information), if any, shall be
discarded.
The lifetime of the calling process shall end immediately. If SA_NOCLDWAIT is
set, it is implementation-defined whether a SIGCHLD signal is sent to the
parent process.
If a thread in the parent process of the calling process is blocked in wait(),
waitpid(), or waitid(), and the parent process has no remaining child processes
in the set of waited-for children, the wait(), waitid(), or waitpid() function
shall fail and set errno to [ECHILD].
"
Noticed on Linux (but not on OpenBSD).
To reproduce:
- SFEED_PLUMBER_INTERACTIVE=0 SFEED_PLUMBER="less" sfeed_curses ~/.sfeed/feeds/*
- Then open and close the child program.
- Notice it becoming a zombie or "<defunct>" in the process table.
randomuser
Hiltjo Posthuma
NRK
Anders Damsgaard