int
main(int argc, char *argv[])
{
int fd, numRead, cmd, status;
char lock, cmdCh, whence, line[MAX_LINE];
struct flock fl;
long long len, st;
int *fdList;
int fileNum, j;
if (argc < 2 || strcmp(argv[1], "--help") == 0)
usageErr("%s file...\n", argv[0]);
fdList = calloc(argc, sizeof(int));
if (fdList == NULL)
errExit("calloc");
for (j = 1; j < argc; j++) {
fdList[j] = open(argv[j], O_RDWR);
if (fdList[j] == -1)
errExit("open (%s)", argv[j]);
}
/* Inform user what type of locking is in effect for each file. */
printf("File Locking\n");
printf("---- -------\n");
for (j = 1; j < argc; j++)
printf("%-10s %s\n", argv[j], mandLockingEnabled(fdList[j]) ?
"mandatory" : "advisory");
printf("\n");
printf("Enter ? for help\n");
for (;;) { /* Prompt for locking command and carry it out */
printf("PID=%ld> ", (long) getpid());
fflush(stdout);
if (fgets(line, MAX_LINE, stdin) == NULL) /* EOF */
exit(EXIT_SUCCESS);
line[strlen(line) - 1] = '\0'; /* Remove trailing '\n' */
if (*line == '\0')
continue; /* Skip blank lines */
if (line[0] == '?') {
displayCmdFmt(argc, argv, fdList);
continue;
}
whence = 's'; /* In case not otherwise filled in */
if (argc == 2) { /* Just 1 file arg on command line? */
fileNum = 1; /* Then no need to read a file number */
numRead = sscanf(line, " %c %c %lld %lld %c",
&cmdCh, &lock, &st, &len, &whence);
} else {
numRead = sscanf(line, "%d %c %c %lld %lld %c",
&fileNum, &cmdCh, &lock, &st, &len, &whence);
}
fl.l_start = st;
fl.l_len = len;
if (fileNum < 1 || fileNum >= argc) {
printf("File number must be in range 1 to %d\n", argc-1);
continue;
}
fd = fdList[fileNum];
if (!((numRead >= 4 && argc == 2) || (numRead >= 5 && argc > 2)) ||
strchr("gswGSW", cmdCh) == NULL ||
strchr("rwu", lock) == NULL || strchr("sce", whence) == NULL) {
printf("Invalid command!\n");
continue;
}
cmd =
#ifdef __linux__
(cmdCh == 'G') ? F_OFD_GETLK : (cmdCh == 'S') ? F_OFD_SETLK :
(cmdCh == 'W') ? F_OFD_SETLKW :
#endif
(cmdCh == 'g') ? F_GETLK : (cmdCh == 's') ? F_SETLK : F_SETLKW;
#ifdef __linux__
fl.l_pid = 0; /* Required for 'OFD' locking commands */
#endif
fl.l_type = (lock == 'r') ? F_RDLCK : (lock == 'w') ? F_WRLCK : F_UNLCK;
fl.l_whence = (whence == 'c') ? SEEK_CUR :
(whence == 'e') ? SEEK_END : SEEK_SET;
status = fcntl(fd, cmd, &fl); /* Perform request... */
if (cmd == F_GETLK
#ifdef __linux__
|| cmd == F_OFD_GETLK
#endif
) {
if (status == -1) {
errMsg("fcntl");
} else {
if (fl.l_type == F_UNLCK)
printf("[PID=%ld] Lock can be placed\n", (long) getpid());
else /* Locked out by someone else */
printf("[PID=%ld] Denied by %s lock on %lld:%lld "
"(held by PID %ld)\n", (long) getpid(),
(fl.l_type == F_RDLCK) ? "READ" : "WRITE",
(long long) fl.l_start,
(long long) fl.l_len, (long) fl.l_pid);
}
} else {
if (status == 0)
printf("[PID=%ld] %s\n", (long) getpid(),
(lock == 'u') ? "unlocked" : "got lock");
else if (errno == EAGAIN || errno == EACCES)
printf("[PID=%ld] failed (incompatible lock)\n",
(long) getpid());
else if (errno == EDEADLK) /* F_SETLKW */
printf("[PID=%ld] failed (deadlock)\n", (long) getpid());
else
errMsg("fcntl");
}
}
}
int
main(int argc, char *argv[])
{
int fd, numRead, cmd, status;
char lock, cmdCh, whence, line[MAX_LINE];
struct flock fl;
long long len, st;
if (argc != 2 || strcmp(argv[1], "--help") == 0)
usageErr("%s file\n", argv[0]);
fd = open(argv[1], O_RDWR);
if (fd == -1)
errExit("open (%s)", argv[1]);
printf("Enter ? for help\n");
for (;;) { /* Prompt for locking command and carry it out */
printf("PID=%ld> ", (long) getpid());
fflush(stdout);
if (fgets(line, MAX_LINE, stdin) == NULL) /* EOF */
exit(EXIT_SUCCESS);
line[strlen(line) - 1] = '\0'; /* Remove trailing '\n' */
if (*line == '\0')
continue; /* Skip blank lines */
if (line[0] == '?') {
displayCmdFmt();
continue;
}
whence = 's'; /* In case not otherwise filled in */
numRead = sscanf(line, "%c %c %lld %lld %c", &cmdCh, &lock,
&st, &len, &whence);
fl.l_start = st;
fl.l_len = len;
if (numRead < 4 || strchr("gsw", cmdCh) == NULL ||
strchr("rwu", lock) == NULL || strchr("sce", whence) == NULL) {
printf("Invalid command!\n");
continue;
}
cmd = (cmdCh == 'g') ? F_GETLK : (cmdCh == 's') ? F_SETLK : F_SETLKW;
fl.l_type = (lock == 'r') ? F_RDLCK : (lock == 'w') ? F_WRLCK : F_UNLCK;
fl.l_whence = (whence == 'c') ? SEEK_CUR :
(whence == 'e') ? SEEK_END : SEEK_SET;
status = fcntl(fd, cmd, &fl); /* Perform request... */
if (cmd == F_GETLK) { /* ... and see what happened */
if (status == -1) {
errMsg("fcntl - F_GETLK");
} else {
if (fl.l_type == F_UNLCK)
printf("[PID=%ld] Lock can be placed\n", (long) getpid());
else /* Locked out by someone else */
printf("[PID=%ld] Denied by %s lock on %lld:%lld "
"(held by PID %ld)\n", (long) getpid(),
(fl.l_type == F_RDLCK) ? "READ" : "WRITE",
(long long) fl.l_start,
(long long) fl.l_len, (long) fl.l_pid);
}
} else { /* F_SETLK, F_SETLKW */
if (status == 0)
printf("[PID=%ld] %s\n", (long) getpid(),
(lock == 'u') ? "unlocked" : "got lock");
else if (errno == EAGAIN || errno == EACCES) /* F_SETLK */
printf("[PID=%ld] failed (incompatible lock)\n",
(long) getpid());
else if (errno == EDEADLK) /* F_SETLKW */
printf("[PID=%ld] failed (deadlock)\n", (long) getpid());
else
errMsg("fcntl - F_SETLK(W)");
}
}
}
