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/*
* Copyright (C) 2014-2023 Firejail Authors
*
* This file is part of firejail project
*
* 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 2 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, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "fnettrace.h"
void tail(const char *logfile) {
assert(logfile);
// wait for no more than 5 seconds for the logfile to appear in the filesystem
int cnt = 5;
while (access(logfile, R_OK) && cnt > 0)
cnt--;
if (cnt == 0)
exit(1);
off_t last_size = 0;
while (1) {
int fd = open(logfile, O_RDONLY);
if (fd == -1)
return;
off_t size = lseek(fd, 0, SEEK_END);
if (size < 0) {
close(fd);
return;
}
char *content = NULL;
int mmapped = 0;
if (size && size != last_size) {
content = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
close(fd);
if (content != MAP_FAILED)
mmapped = 1;
}
if (mmapped) {
printf("%.*s", (int) (size - last_size), content + last_size);
fflush(0);
munmap(content, size);
last_size = size;
}
sleep(1);
}
}
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