Update.
1998-04-25 Mark Kettenis <kettenis@phys.uva.nl> * sysdeps/generic/utmp_file.c (TIMEOUT): New macro. (timeout_handler): New function. (LOCK_FILE, UNLOCK_FILE): New macros. Implement file locking with timeout. (getutent_r_file, internal_getut_r, getutline_r_file, pututline_file, updwtmp_file): Use LOCK_FILE and UNLOCK_FILE for locking.
This commit is contained in:
Ulrich Drepper
parent
298f256698
commit
efea715879
10
ChangeLog
10
ChangeLog
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@ -1,3 +1,13 @@
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1998-04-25 Mark Kettenis <kettenis@phys.uva.nl>
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* sysdeps/generic/utmp_file.c (TIMEOUT): New macro.
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(timeout_handler): New function.
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(LOCK_FILE, UNLOCK_FILE): New macros.
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Implement file locking with timeout.
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(getutent_r_file, internal_getut_r, getutline_r_file,
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pututline_file, updwtmp_file): Use LOCK_FILE and UNLOCK_FILE for
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locking.
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1998-05-18 11:38 Ulrich Drepper <drepper@cygnus.com>
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* iconvdata/run-iconv-test.sh: Extend library-path by iconvdata
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@ -21,6 +21,7 @@
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#include <assert.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <signal.h>
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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@ -37,6 +38,48 @@ static off_t file_offset;
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static struct utmp last_entry;
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/* Locking timeout. */
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#ifndef TIMEOUT
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# define TIMEOUT 1
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#endif
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/* Do-nothing handler for locking timeout. */
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static void timeout_handler (int signum) {};
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#define LOCK_FILE(fd, type) \
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{ \
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struct flock fl; \
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struct sigaction action, old_action; \
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unsigned int old_timeout; \
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\
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/* Cancel any existing alarm. */ \
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old_timeout = alarm (0); \
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\
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/* Establish signal handler. */ \
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action.sa_handler = timeout_handler; \
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sigemptyset (&action.sa_mask); \
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action.sa_flags = 0; \
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sigaction (SIGALRM, &action, &old_action); \
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\
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alarm (TIMEOUT); \
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\
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/* Try to get the lock. */ \
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memset (&fl, '\0', sizeof (struct flock)); \
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fl.l_type = (type); \
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fl.l_whence = SEEK_SET; \
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fcntl ((fd), F_SETLKW, &fl)
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#define UNLOCK_FILE(fd) \
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/* Unlock the file. */ \
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fl.l_type = F_UNLCK; \
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fcntl ((fd), F_SETLKW, &fl); \
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\
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/* Reset the signal handler and alarm. */ \
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sigaction (SIGALRM, &old_action, NULL); \
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alarm (old_timeout); \
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} while (0)
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/* Functions defined here. */
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static int setutent_file (void);
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static int getutent_r_file (struct utmp *buffer, struct utmp **result);
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@ -100,7 +143,6 @@ static int
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getutent_r_file (struct utmp *buffer, struct utmp **result)
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{
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ssize_t nbytes;
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struct flock fl; /* Information struct for locking. */
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assert (file_fd >= 0);
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@ -111,26 +153,12 @@ getutent_r_file (struct utmp *buffer, struct utmp **result)
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return -1;
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}
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/* XXX The following is not perfect. Instead of locking the file itself
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Marek Michalkiewicz <marekm@i17linuxb.ists.pwr.wroc.pl> suggests to
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use an extra locking file. */
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/* XXX I think using an extra locking file does not solve the
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problems. Instead we should set an alarm, which causes fcntl to
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fail, as in ../nis/lckcache.c.
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Mark Kettenis <kettenis@phys.uva.nl>. */
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/* Try to get the lock. */
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memset (&fl, '\0', sizeof (struct flock));
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fl.l_type = F_RDLCK;
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fl.l_whence = SEEK_SET;
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fcntl (file_fd, F_SETLK, &fl);
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LOCK_FILE (file_fd, F_RDLCK);
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/* Read the next entry. */
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nbytes = read (file_fd, &last_entry, sizeof (struct utmp));
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/* And unlock the file. */
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fl.l_type = F_UNLCK;
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fcntl (file_fd, F_SETLKW, &fl);
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UNLOCK_FILE (file_fd);
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if (nbytes != sizeof (struct utmp))
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{
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@ -180,13 +208,8 @@ static int
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internal_getut_r (const struct utmp *id, struct utmp *buffer)
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{
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int result = -1;
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struct flock fl;
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/* Try to get the lock. */
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memset (&fl, '\0', sizeof (struct flock));
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fl.l_type = F_RDLCK;
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fl.l_whence = SEEK_SET;
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fcntl (file_fd, F_SETLKW, &fl);
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LOCK_FILE (file_fd, F_RDLCK);
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#if _HAVE_UT_TYPE - 0
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if (id->ut_type == RUN_LVL || id->ut_type == BOOT_TIME
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@ -237,9 +260,7 @@ internal_getut_r (const struct utmp *id, struct utmp *buffer)
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result = 0;
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unlock_return:
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/* And unlock the file. */
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fl.l_type = F_UNLCK;
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fcntl (file_fd, F_SETLK, &fl);
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UNLOCK_FILE (file_fd);
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return result;
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}
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@ -278,8 +299,6 @@ static int
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getutline_r_file (const struct utmp *line, struct utmp *buffer,
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struct utmp **result)
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{
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struct flock fl;
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assert (file_fd >= 0);
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if (file_offset == -1l)
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@ -288,11 +307,7 @@ getutline_r_file (const struct utmp *line, struct utmp *buffer,
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return -1;
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}
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/* Try to get the lock. */
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memset (&fl, '\0', sizeof (struct flock));
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fl.l_type = F_RDLCK;
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fl.l_whence = SEEK_SET;
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fcntl (file_fd, F_SETLKW, &fl);
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LOCK_FILE (file_fd, F_RDLCK);
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while (1)
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{
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@ -322,9 +337,7 @@ getutline_r_file (const struct utmp *line, struct utmp *buffer,
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*result = buffer;
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unlock_return:
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/* And unlock the file. */
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fl.l_type = F_UNLCK;
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fcntl (file_fd, F_SETLK, &fl);
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UNLOCK_FILE (file_fd);
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return ((*result == NULL) ? -1 : 0);
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}
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@ -333,7 +346,6 @@ unlock_return:
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static struct utmp *
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pututline_file (const struct utmp *data)
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{
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struct flock fl; /* Information struct for locking. */
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struct utmp buffer;
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struct utmp *pbuf;
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int found;
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@ -356,11 +368,7 @@ pututline_file (const struct utmp *data)
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else
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found = internal_getut_r (data, &buffer);
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/* Try to lock the file. */
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memset (&fl, '\0', sizeof (struct flock));
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fl.l_type = F_WRLCK;
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fl.l_whence = SEEK_SET;
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fcntl (file_fd, F_SETLK, &fl);
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LOCK_FILE (file_fd, F_WRLCK);
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if (found < 0)
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{
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@ -401,9 +409,7 @@ pututline_file (const struct utmp *data)
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}
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unlock_return:
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/* And unlock the file. */
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fl.l_type = F_UNLCK;
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fcntl (file_fd, F_SETLK, &fl);
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UNLOCK_FILE (file_fd);
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return pbuf;
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}
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@ -423,7 +429,6 @@ static int
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updwtmp_file (const char *file, const struct utmp *utmp)
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{
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int result = -1;
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struct flock fl;
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off_t offset;
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int fd;
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@ -432,11 +437,7 @@ updwtmp_file (const char *file, const struct utmp *utmp)
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if (fd < 0)
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return -1;
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/* Try to get the lock. */
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memset (&fl, '\0', sizeof (struct flock));
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fl.l_type = F_WRLCK;
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fl.l_whence = SEEK_SET;
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fcntl (fd, F_SETLK, &fl);
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LOCK_FILE (fd, F_WRLCK);
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/* Remember original size of log file. */
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offset = lseek (fd, 0, SEEK_END);
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@ -461,9 +462,7 @@ updwtmp_file (const char *file, const struct utmp *utmp)
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result = 0;
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unlock_return:
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/* And unlock the file. */
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fl.l_type = F_UNLCK;
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fcntl (fd, F_SETLKW, &fl);
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UNLOCK_FILE (fd);
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/* Close WTMP file. */
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close (fd);
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