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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;
fd = open(filename, O_RDWR);
if (fd < 0) {
fprintf(stderr, "open failed (%s)\n", strerror(errno));
goto out;
}
ret = flock(fd, LOCK_EX | LOCK_NB);
if ((ret == 0) || (errno != EWOULDBLOCK)) {
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,
};
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;
}
ret = flock(fd, LOCK_EX);
if (ret < 0) {
fprintf(stderr, "flock 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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