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#include <stdarg.h>
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#include <sys/socket.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <syslog.h>
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#include <time.h>
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#include <signal.h>
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#include <string.h>
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#include <pthread.h>
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#include <errno.h>
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#include <fcntl.h>
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#include "libc.h"
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fix multiple bugs in syslog interfaces
1. as reported by William Haddon, the value returned by snprintf was
wrongly used as a length passed to sendto, despite it possibly
exceeding the buffer length. this could lead to invalid reads and
leaking additional data to syslog.
2. openlog was storing a pointer to the ident string passed by the
caller, rather than copying it. this bug is shared with (and even
documented in) other implementations like glibc, but such behavior
does not seem to meet the requirements of the standard.
3. extremely long ident provided to openlog, or corrupt ident due to
the above issue, could possibly have resulted in buffer overflows.
despite having the potential for smashing the stack, i believe the
impact is low since ident points to a short string literal in typical
application usage (and per the above bug, other usages will break
horribly on other implementations).
4. when used with LOG_NDELAY, openlog was not connecting the
newly-opened socket; sendto was being used instead. this defeated the
main purpose of LOG_NDELAY: preparing for chroot.
5. the default facility was not being used at all, so all messages
without an explicit facility passed to syslog were getting logged at
the kernel facility.
6. setlogmask was not thread-safe; no synchronization was performed
updating the mask. the fix uses atomics rather than locking to avoid
introducing a lock in the fast path for messages whose priority is not
in the mask.
7. in some code paths, the syslog lock was being unlocked twice; this
could result in releasing a lock that was actually held by a different
thread.
some additional enhancements to syslog such as a default identifier
based on argv[0] or similar may still be desired; at this time, only
the above-listed bugs have been fixed.
13 years ago
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#include "atomic.h"
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static int lock[2];
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fix multiple bugs in syslog interfaces
1. as reported by William Haddon, the value returned by snprintf was
wrongly used as a length passed to sendto, despite it possibly
exceeding the buffer length. this could lead to invalid reads and
leaking additional data to syslog.
2. openlog was storing a pointer to the ident string passed by the
caller, rather than copying it. this bug is shared with (and even
documented in) other implementations like glibc, but such behavior
does not seem to meet the requirements of the standard.
3. extremely long ident provided to openlog, or corrupt ident due to
the above issue, could possibly have resulted in buffer overflows.
despite having the potential for smashing the stack, i believe the
impact is low since ident points to a short string literal in typical
application usage (and per the above bug, other usages will break
horribly on other implementations).
4. when used with LOG_NDELAY, openlog was not connecting the
newly-opened socket; sendto was being used instead. this defeated the
main purpose of LOG_NDELAY: preparing for chroot.
5. the default facility was not being used at all, so all messages
without an explicit facility passed to syslog were getting logged at
the kernel facility.
6. setlogmask was not thread-safe; no synchronization was performed
updating the mask. the fix uses atomics rather than locking to avoid
introducing a lock in the fast path for messages whose priority is not
in the mask.
7. in some code paths, the syslog lock was being unlocked twice; this
could result in releasing a lock that was actually held by a different
thread.
some additional enhancements to syslog such as a default identifier
based on argv[0] or similar may still be desired; at this time, only
the above-listed bugs have been fixed.
13 years ago
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static char log_ident[32];
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static int log_opt;
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static int log_facility = LOG_USER;
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static int log_mask = 0xff;
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static int log_fd = -1;
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int setlogmask(int maskpri)
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{
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fix multiple bugs in syslog interfaces
1. as reported by William Haddon, the value returned by snprintf was
wrongly used as a length passed to sendto, despite it possibly
exceeding the buffer length. this could lead to invalid reads and
leaking additional data to syslog.
2. openlog was storing a pointer to the ident string passed by the
caller, rather than copying it. this bug is shared with (and even
documented in) other implementations like glibc, but such behavior
does not seem to meet the requirements of the standard.
3. extremely long ident provided to openlog, or corrupt ident due to
the above issue, could possibly have resulted in buffer overflows.
despite having the potential for smashing the stack, i believe the
impact is low since ident points to a short string literal in typical
application usage (and per the above bug, other usages will break
horribly on other implementations).
4. when used with LOG_NDELAY, openlog was not connecting the
newly-opened socket; sendto was being used instead. this defeated the
main purpose of LOG_NDELAY: preparing for chroot.
5. the default facility was not being used at all, so all messages
without an explicit facility passed to syslog were getting logged at
the kernel facility.
6. setlogmask was not thread-safe; no synchronization was performed
updating the mask. the fix uses atomics rather than locking to avoid
introducing a lock in the fast path for messages whose priority is not
in the mask.
7. in some code paths, the syslog lock was being unlocked twice; this
could result in releasing a lock that was actually held by a different
thread.
some additional enhancements to syslog such as a default identifier
based on argv[0] or similar may still be desired; at this time, only
the above-listed bugs have been fixed.
13 years ago
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if (maskpri) return a_swap(&log_mask, maskpri);
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else return log_mask;
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}
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static const struct {
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short sun_family;
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char sun_path[9];
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} log_addr = {
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AF_UNIX,
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"/dev/log"
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};
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void closelog(void)
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{
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int cs;
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pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
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LOCK(lock);
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close(log_fd);
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log_fd = -1;
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UNLOCK(lock);
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pthread_setcancelstate(cs, 0);
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}
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fix multiple bugs in syslog interfaces
1. as reported by William Haddon, the value returned by snprintf was
wrongly used as a length passed to sendto, despite it possibly
exceeding the buffer length. this could lead to invalid reads and
leaking additional data to syslog.
2. openlog was storing a pointer to the ident string passed by the
caller, rather than copying it. this bug is shared with (and even
documented in) other implementations like glibc, but such behavior
does not seem to meet the requirements of the standard.
3. extremely long ident provided to openlog, or corrupt ident due to
the above issue, could possibly have resulted in buffer overflows.
despite having the potential for smashing the stack, i believe the
impact is low since ident points to a short string literal in typical
application usage (and per the above bug, other usages will break
horribly on other implementations).
4. when used with LOG_NDELAY, openlog was not connecting the
newly-opened socket; sendto was being used instead. this defeated the
main purpose of LOG_NDELAY: preparing for chroot.
5. the default facility was not being used at all, so all messages
without an explicit facility passed to syslog were getting logged at
the kernel facility.
6. setlogmask was not thread-safe; no synchronization was performed
updating the mask. the fix uses atomics rather than locking to avoid
introducing a lock in the fast path for messages whose priority is not
in the mask.
7. in some code paths, the syslog lock was being unlocked twice; this
could result in releasing a lock that was actually held by a different
thread.
some additional enhancements to syslog such as a default identifier
based on argv[0] or similar may still be desired; at this time, only
the above-listed bugs have been fixed.
13 years ago
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static void __openlog()
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{
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log_fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0);
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fix multiple bugs in syslog interfaces
1. as reported by William Haddon, the value returned by snprintf was
wrongly used as a length passed to sendto, despite it possibly
exceeding the buffer length. this could lead to invalid reads and
leaking additional data to syslog.
2. openlog was storing a pointer to the ident string passed by the
caller, rather than copying it. this bug is shared with (and even
documented in) other implementations like glibc, but such behavior
does not seem to meet the requirements of the standard.
3. extremely long ident provided to openlog, or corrupt ident due to
the above issue, could possibly have resulted in buffer overflows.
despite having the potential for smashing the stack, i believe the
impact is low since ident points to a short string literal in typical
application usage (and per the above bug, other usages will break
horribly on other implementations).
4. when used with LOG_NDELAY, openlog was not connecting the
newly-opened socket; sendto was being used instead. this defeated the
main purpose of LOG_NDELAY: preparing for chroot.
5. the default facility was not being used at all, so all messages
without an explicit facility passed to syslog were getting logged at
the kernel facility.
6. setlogmask was not thread-safe; no synchronization was performed
updating the mask. the fix uses atomics rather than locking to avoid
introducing a lock in the fast path for messages whose priority is not
in the mask.
7. in some code paths, the syslog lock was being unlocked twice; this
could result in releasing a lock that was actually held by a different
thread.
some additional enhancements to syslog such as a default identifier
based on argv[0] or similar may still be desired; at this time, only
the above-listed bugs have been fixed.
13 years ago
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if (log_fd >= 0) connect(log_fd, (void *)&log_addr, sizeof log_addr);
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}
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void openlog(const char *ident, int opt, int facility)
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{
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int cs;
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pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
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LOCK(lock);
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fix multiple bugs in syslog interfaces
1. as reported by William Haddon, the value returned by snprintf was
wrongly used as a length passed to sendto, despite it possibly
exceeding the buffer length. this could lead to invalid reads and
leaking additional data to syslog.
2. openlog was storing a pointer to the ident string passed by the
caller, rather than copying it. this bug is shared with (and even
documented in) other implementations like glibc, but such behavior
does not seem to meet the requirements of the standard.
3. extremely long ident provided to openlog, or corrupt ident due to
the above issue, could possibly have resulted in buffer overflows.
despite having the potential for smashing the stack, i believe the
impact is low since ident points to a short string literal in typical
application usage (and per the above bug, other usages will break
horribly on other implementations).
4. when used with LOG_NDELAY, openlog was not connecting the
newly-opened socket; sendto was being used instead. this defeated the
main purpose of LOG_NDELAY: preparing for chroot.
5. the default facility was not being used at all, so all messages
without an explicit facility passed to syslog were getting logged at
the kernel facility.
6. setlogmask was not thread-safe; no synchronization was performed
updating the mask. the fix uses atomics rather than locking to avoid
introducing a lock in the fast path for messages whose priority is not
in the mask.
7. in some code paths, the syslog lock was being unlocked twice; this
could result in releasing a lock that was actually held by a different
thread.
some additional enhancements to syslog such as a default identifier
based on argv[0] or similar may still be desired; at this time, only
the above-listed bugs have been fixed.
13 years ago
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if (ident) {
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size_t n = strnlen(ident, sizeof log_ident - 1);
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memcpy(log_ident, ident, n);
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log_ident[n] = 0;
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} else {
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log_ident[0] = 0;
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}
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log_opt = opt;
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log_facility = facility;
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if ((opt & LOG_NDELAY) && log_fd<0) __openlog();
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UNLOCK(lock);
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pthread_setcancelstate(cs, 0);
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}
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static void _vsyslog(int priority, const char *message, va_list ap)
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{
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char timebuf[16];
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time_t now;
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struct tm tm;
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char buf[256];
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int errno_save = errno;
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int pid;
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int l, l2;
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int hlen;
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int fd;
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if (log_fd < 0) __openlog();
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fix multiple bugs in syslog interfaces
1. as reported by William Haddon, the value returned by snprintf was
wrongly used as a length passed to sendto, despite it possibly
exceeding the buffer length. this could lead to invalid reads and
leaking additional data to syslog.
2. openlog was storing a pointer to the ident string passed by the
caller, rather than copying it. this bug is shared with (and even
documented in) other implementations like glibc, but such behavior
does not seem to meet the requirements of the standard.
3. extremely long ident provided to openlog, or corrupt ident due to
the above issue, could possibly have resulted in buffer overflows.
despite having the potential for smashing the stack, i believe the
impact is low since ident points to a short string literal in typical
application usage (and per the above bug, other usages will break
horribly on other implementations).
4. when used with LOG_NDELAY, openlog was not connecting the
newly-opened socket; sendto was being used instead. this defeated the
main purpose of LOG_NDELAY: preparing for chroot.
5. the default facility was not being used at all, so all messages
without an explicit facility passed to syslog were getting logged at
the kernel facility.
6. setlogmask was not thread-safe; no synchronization was performed
updating the mask. the fix uses atomics rather than locking to avoid
introducing a lock in the fast path for messages whose priority is not
in the mask.
7. in some code paths, the syslog lock was being unlocked twice; this
could result in releasing a lock that was actually held by a different
thread.
some additional enhancements to syslog such as a default identifier
based on argv[0] or similar may still be desired; at this time, only
the above-listed bugs have been fixed.
13 years ago
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if (!(priority & LOG_FACMASK)) priority |= log_facility;
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now = time(NULL);
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gmtime_r(&now, &tm);
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strftime(timebuf, sizeof timebuf, "%b %e %T", &tm);
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pid = (log_opt & LOG_PID) ? getpid() : 0;
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l = snprintf(buf, sizeof buf, "<%d>%s %n%s%s%.0d%s: ",
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priority, timebuf, &hlen, log_ident, "["+!pid, pid, "]"+!pid);
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errno = errno_save;
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l2 = vsnprintf(buf+l, sizeof buf - l, message, ap);
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if (l2 >= 0) {
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fix multiple bugs in syslog interfaces
1. as reported by William Haddon, the value returned by snprintf was
wrongly used as a length passed to sendto, despite it possibly
exceeding the buffer length. this could lead to invalid reads and
leaking additional data to syslog.
2. openlog was storing a pointer to the ident string passed by the
caller, rather than copying it. this bug is shared with (and even
documented in) other implementations like glibc, but such behavior
does not seem to meet the requirements of the standard.
3. extremely long ident provided to openlog, or corrupt ident due to
the above issue, could possibly have resulted in buffer overflows.
despite having the potential for smashing the stack, i believe the
impact is low since ident points to a short string literal in typical
application usage (and per the above bug, other usages will break
horribly on other implementations).
4. when used with LOG_NDELAY, openlog was not connecting the
newly-opened socket; sendto was being used instead. this defeated the
main purpose of LOG_NDELAY: preparing for chroot.
5. the default facility was not being used at all, so all messages
without an explicit facility passed to syslog were getting logged at
the kernel facility.
6. setlogmask was not thread-safe; no synchronization was performed
updating the mask. the fix uses atomics rather than locking to avoid
introducing a lock in the fast path for messages whose priority is not
in the mask.
7. in some code paths, the syslog lock was being unlocked twice; this
could result in releasing a lock that was actually held by a different
thread.
some additional enhancements to syslog such as a default identifier
based on argv[0] or similar may still be desired; at this time, only
the above-listed bugs have been fixed.
13 years ago
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if (l2 >= sizeof buf - l) l = sizeof buf - 1;
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else l += l2;
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if (buf[l-1] != '\n') buf[l++] = '\n';
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if (send(log_fd, buf, l, 0) < 0 && (log_opt & LOG_CONS)) {
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fd = open("/dev/console", O_WRONLY|O_NOCTTY|O_CLOEXEC);
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if (fd >= 0) {
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dprintf(fd, "%.*s", l-hlen, buf+hlen);
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close(fd);
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}
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}
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if (log_opt & LOG_PERROR) dprintf(2, "%.*s", l-hlen, buf+hlen);
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}
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}
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void __vsyslog(int priority, const char *message, va_list ap)
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{
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int cs;
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if (!(log_mask & LOG_MASK(priority&7)) || (priority&~0x3ff)) return;
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pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
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LOCK(lock);
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_vsyslog(priority, message, ap);
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UNLOCK(lock);
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pthread_setcancelstate(cs, 0);
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}
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void syslog(int priority, const char *message, ...)
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{
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va_list ap;
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va_start(ap, message);
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__vsyslog(priority, message, ap);
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va_end(ap);
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}
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weak_alias(__vsyslog, vsyslog);
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