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* syscalls.cc (locked_append): New.

Browse Source 
(updwtmp): Remove mutex code and call locked_append.
	(pututline): Ditto.
This commit is contained in:
Corinna Vinschen 2003-12-07 12:56:59 +00:00
parent ae2543ed76
commit 2e3ff06d3c
2 changed files with 34 additions and 29 deletions
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6
winsup/cygwin/ChangeLog
View File

@ -1,3 +1,9 @@
2003-12-07 Pierre Humblet <pierre.humblet@ieee.org>
* syscalls.cc (locked_append): New.
(updwtmp): Remove mutex code and call locked_append.
(pututline): Ditto.
2003-12-06 Christopher Faylor <cgf@redhat.com> 2003-12-06 Christopher Faylor <cgf@redhat.com>
* exceptions.cc (_threadinfo::remove): Avoid a linked list walk. * exceptions.cc (_threadinfo::remove): Avoid a linked list walk.

57
winsup/cygwin/syscalls.cc
View File

@ -2553,28 +2553,37 @@ ffs (int i)
return table[x >> a] + a; return table[x >> a] + a;
} }
static void
locked_append (int fd, const void * buf, size_t size)
{
struct __flock64 lock_buffer = {F_WRLCK, SEEK_SET, 0, 0, 0};
int count = 0;
do
if ((lock_buffer.l_start = lseek64 (fd, 0, SEEK_END)) != (_off64_t)-1
&& fcntl_worker (fd, F_SETLKW, &lock_buffer) != -1)
{
if (lseek64 (fd, 0, SEEK_END) != (_off64_t)-1)
write (fd, buf, size);
lock_buffer.l_type = F_UNLCK;
fcntl_worker (fd, F_SETLK, &lock_buffer);
break;
}
while (count++ < 1000
&& (errno == EACCES || errno == EAGAIN)
&& !usleep (1000));
}
extern "C" void extern "C" void
updwtmp (const char *wtmp_file, const struct utmp *ut) updwtmp (const char *wtmp_file, const struct utmp *ut)
{ {
/* Writing to wtmp must be atomic to prevent mixed up data. */
char mutex_name[CYG_MAX_PATH];
HANDLE mutex;
int fd; int fd;
mutex = CreateMutex (NULL, FALSE, shared_name (mutex_name, "wtmp_mutex", 0)); if ((fd = open (wtmp_file, O_WRONLY | O_BINARY, 0)) >= 0)
if (mutex)
while (WaitForSingleObject (mutex, INFINITE) == WAIT_ABANDONED)
;
if ((fd = open (wtmp_file, O_WRONLY | O_APPEND | O_BINARY, 0)) >= 0)
{ {
write (fd, ut, sizeof *ut); locked_append (fd, ut, sizeof *ut);
close (fd); close (fd);
} }
if (mutex)
{
ReleaseMutex (mutex);
CloseHandle (mutex);
}
} }
extern "C" void extern "C" void
@ -2783,25 +2792,15 @@ pututline (struct utmp *ut)
ut->ut_type, ut->ut_pid, ut->ut_line, ut->ut_id); ut->ut_type, ut->ut_pid, ut->ut_line, ut->ut_id);
debug_printf ("ut->ut_user '%s', ut->ut_host '%s'\n", debug_printf ("ut->ut_user '%s', ut->ut_host '%s'\n",
ut->ut_user, ut->ut_host); ut->ut_user, ut->ut_host);
/* Read/write to utmp must be atomic to prevent overriding data
by concurrent processes. */
char mutex_name[CYG_MAX_PATH];
HANDLE mutex = CreateMutex (NULL, FALSE,
shared_name (mutex_name, "utmp_mutex", 0));
if (mutex)
while (WaitForSingleObject (mutex, INFINITE) == WAIT_ABANDONED)
;
struct utmp *u; struct utmp *u;
if ((u = getutid (ut))) if ((u = getutid (ut)))
lseek (utmp_fd, -sizeof *ut, SEEK_CUR);
else
lseek (utmp_fd, 0, SEEK_END);
write (utmp_fd, ut, sizeof *ut);
if (mutex)
{ {
ReleaseMutex (mutex); lseek (utmp_fd, -sizeof *ut, SEEK_CUR);
CloseHandle (mutex); write (utmp_fd, ut, sizeof *ut);
} }
else
locked_append (utmp_fd, ut, sizeof *ut);
} }
extern "C" extern "C"