blob: e581e35cdaa082e9a8d916f45d766e0a3bd387dc [file] [log] [blame] [raw]
/* Secure Shout Host Oriented Unified Talk
* Copyright 2015-2022 Rivoreo
*
* 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.
*/
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <limits.h>
#include <assert.h>
int fgetline(FILE *f, char *line, size_t len) {
size_t i = 0;
int c;
if(len > INT_MAX) len = INT_MAX;
while((c = fgetc(f)) != '\n') {
if(c == EOF) {
if(!i) return -1;
break;
}
if(i >= len - 1) return -2;
line[i++] = c;
}
line[i] = 0;
return i;
}
int fbackwardoverwrite(FILE *f, size_t len) {
long int offset = ftell(f);
if(offset < 0) return -1;
if(len > (size_t)offset) {
#if 0
errno = ERANGE;
return -1;
#else
len = offset;
#endif
}
long int overwrite_start = offset - len;
char buffer[1024];
size_t item_count, ss = 0;
long int current_offset;
do {
item_count = fread(buffer, sizeof buffer, 1, f);
if(!item_count && ferror(f)) return -1;
current_offset = ftell(f);
long int s = current_offset - offset - ss;
fseek(f, overwrite_start + ss , SEEK_SET);
if(!s) break;
if(!fwrite(buffer, s, 1, f)) return -1;
ss += s;
} while(item_count && fseek(f, current_offset, SEEK_SET) != -1);
if(ferror(f)) return -1;
clearerr(f);
fflush(f);
assert((size_t)ftell(f) == (size_t)overwrite_start + ss);
if(ftruncate(fileno(f), ftell(f)) < 0) return -1;
return fseek(f, overwrite_start, SEEK_SET);
}