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protect against data loss in some rare situations 

Examples:
  - you try to write file but disk is full
  - you have two Teliva files being edited at the same time

Both are situations where it's impossible to avoid some data loss.
However, we should now at least have some valid state of the .tlv file
saved to disk where we'd previously end up with a zero-size file or
garbage.
This commit is contained in:
Kartik K. Agaram 2021-12-16 21:27:45 -08:00
parent 2a6786fee5
commit 18f9f4e4f4
1 changed files with 32 additions and 3 deletions
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35
src/lua.c
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@ -346,25 +346,45 @@ static int handle_image (lua_State *L, char **argv, int n) {
#define CURRENT_DEFINITION_LEN 256
char Current_definition[CURRENT_DEFINITION_LEN+1] = {0};
extern int mkstemp(char *template);
extern FILE *fdopen(int fd, const char *mode);
void save_editor_state (int rowoff, int coloff, int cy, int cx) {
if (strlen(Current_definition) == 0) return;
FILE *out = fopen("teliva_editor_state", "w");
char outfilename[] = "teliva_editor_state_XXXXXX";
int outfd = mkstemp(outfilename);
if (outfd == -1) {
endwin();
perror("error in creating temporary file");
abort();
}
FILE *out = fdopen(outfd, "w");
assert(out != NULL);
fprintf(out, "__teliva_editor_state = {\n");
fprintf(out, " image = \"%s\", definition = \"%s\",\n", Image_name, Current_definition);
fprintf(out, " rowoff = %d, coloff = %d,\n", rowoff, coloff);
fprintf(out, " cy = %d, cx = %d,\n", cy, cx);
fprintf(out, "}\n");
fclose(out);
rename(outfilename, "teliva_editor_state");
}
void save_to_current_definition_and_editor_buffer (lua_State *L, const char *definition) {
int oldtop = lua_gettop(L);
strncpy(Current_definition, definition, CURRENT_DEFINITION_LEN);
int status = look_up_definition(L, Current_definition);
FILE *out = fopen("teliva_editor_buffer", "w");
char outfilename[] = "teliva_editor_buffer_XXXXXX";
int outfd = mkstemp(outfilename);
if (outfd == -1) {
endwin();
perror("error in creating temporary file");
abort();
}
FILE *out = fdopen(outfd, "w");
assert(out != NULL);
if (status)
fprintf(out, "%s", lua_tostring(L, -1));
fclose(out);
rename(outfilename, "teliva_editor_buffer");
lua_settop(L, oldtop);
}
@ -610,10 +630,19 @@ void save_note_to_editor_buffer (lua_State *L, int cursor) {
lua_rawgeti(L, -1, cursor);
lua_getfield(L, -1, "__teliva_note");
const char *contents = lua_tostring(L, -1);
FILE *out = fopen("teliva_editor_buffer", "w");
char outfilename[] = "teliva_editor_buffer_XXXXXX";
int outfd = mkstemp(outfilename);
if (outfd == -1) {
endwin();
perror("error in creating temporary file");
abort();
}
FILE *out = fdopen(outfd, "w");
assert(out != NULL);
if (contents != NULL)
fprintf(out, "%s", contents);
fclose(out);
rename(outfilename, "teliva_editor_buffer");
lua_pop(L, 3); /* contents, table at cursor, teliva_program */
}