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#include <sys/file.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/wait.h>
#ifndef linux
#define fstat64(fd, st) fstat(fd, st)
#endif
int
run_child (char *filename)
{
int fd = -1, ret = -1;
struct flock lock = {0, };
int ppid = 0;
fd = open (filename, O_RDWR);
if (fd < 0) {
fprintf (stderr, "open failed (%s)\n", strerror (errno));
goto out;
}
ppid = getppid ();
lock.l_type = F_WRLCK;
lock.l_whence = SEEK_SET;
lock.l_start = 0;
lock.l_len = 0;
ret = fcntl (fd, F_GETLK, &lock);
if (ret < 0) {
fprintf (stderr, "GETLK failed (%s)\n", strerror (errno));
goto out;
}
if ((lock.l_type == F_UNLCK) ||
(ppid != lock.l_pid)) {
fprintf (stderr, "no locks present, though parent has held "
"one\n");
ret = -1;
goto out;
}
ret = 0;
out:
return ret;
}
int
main (int argc, char *argv[])
{
int fd = -1, ret = -1, status = 0;
char *filename = NULL, *cmd = NULL;
struct stat stbuf = {0, };
struct flock lock = {0, };
if (argc != 3) {
fprintf (stderr, "Usage: %s <filename> "
"<gluster-cmd-to-trigger-graph-switch>\n", argv[0]);
goto out;
}
filename = argv[1];
cmd = argv[2];
fd = open (filename, O_RDWR | O_CREAT, 0);
if (fd < 0) {
fprintf (stderr, "open (%s) failed (%s)\n", filename,
strerror (errno));
goto out;
}
lock.l_type = F_WRLCK;
lock.l_whence = SEEK_SET;
lock.l_start = 0;
lock.l_len = 0;
ret = fcntl (fd, F_SETLK, &lock);
if (ret < 0) {
fprintf (stderr, "fcntl failed (%s)\n", strerror (errno));
goto out;
}
system (cmd);
/* wait till graph switch completes */
ret = fstat64 (fd, &stbuf);
if (ret < 0) {
fprintf (stderr, "fstat64 failure (%s)\n", strerror (errno));
goto out;
}
sleep (10);
/* By now old-graph would be disconnected and locks should be cleaned
* up if they are not migrated. Check that by trying to acquire a lock
* on a new fd opened by another process on same file.
*/
ret = fork ();
if (ret == 0) {
ret = run_child (filename);
} else {
wait (&status);
if (WIFEXITED(status)) {
ret = WEXITSTATUS(status);
} else {
ret = 0;
}
}
out:
return ret;
}
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