path: root/src/time/timer_gettime.c
diff options
authorRich Felker <>2013-08-03 13:20:42 -0400
committerRich Felker <>2013-08-03 13:20:42 -0400
commit7356c2554e33cf16768616e8e3ae4a4f5a5aac17 (patch)
tree9510cb631685508d9ece852b7ce865e91a903589 /src/time/timer_gettime.c
parent14012b91f2b52f70fd3f3bb807fb880654337da5 (diff)
fix multiple bugs in SIGEV_THREAD timers
1. the thread result field was reused for storing a kernel timer id, but would be overwritten if the application code exited or cancelled the thread. 2. low pointer values were used as the indicator that the timer id is a kernel timer id rather than a thread id. this is not portable, as mmap may return low pointers on some conditions. instead, use the fact that pointers must be aligned and kernel timer ids must be non-negative to map pointers into the negative integer space. 3. signals were not blocked until after the timer thread started, so a race condition could allow a signal handler to run in the timer thread when it's not supposed to exist. this is mainly problematic if the calling thread was the only thread where the signal was unblocked and the signal handler assumes it runs in that thread.
Diffstat (limited to 'src/time/timer_gettime.c')
1 files changed, 5 insertions, 1 deletions
diff --git a/src/time/timer_gettime.c b/src/time/timer_gettime.c
index 5a858218..1d902075 100644
--- a/src/time/timer_gettime.c
+++ b/src/time/timer_gettime.c
@@ -1,8 +1,12 @@
#include <time.h>
+#include <limits.h>
#include "pthread_impl.h"
int timer_gettime(timer_t t, struct itimerspec *val)
- if ((uintptr_t)t >= 0x100000) t = ((pthread_t)t)->result;
+ if ((intptr_t)t < 0) {
+ pthread_t td = (void *)((uintptr_t)t << 1);
+ t = (void *)(uintptr_t)(td->timer_id & INT_MAX);
+ }
return syscall(SYS_timer_gettime, (long)t, val);