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authorRich Felker <dalias@aerifal.cx>2011-04-05 18:00:28 -0400
committerRich Felker <dalias@aerifal.cx>2011-04-05 18:00:28 -0400
commit729cb49f52c825ac44f437e1ff0865d9f0b3626a (patch)
tree18db05e36f16fcdfc1147f4ba1ea19a0ee4bea9c
parent918a40f257328a2d7490829b54687cd38d7b787b (diff)
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new framework to inhibit thread cancellation when needed
with these small changes, libc functions which need to call functions which are cancellation points, but which themselves must not be cancellation points, can use the CANCELPT_INHIBIT and CANCELPT_RESUME macros to temporarily inhibit all cancellation.
-rw-r--r--src/internal/libc.h2
-rw-r--r--src/thread/pthread_create.c16
-rw-r--r--src/thread/pthread_setcancelstate.c4
3 files changed, 17 insertions, 5 deletions
diff --git a/src/internal/libc.h b/src/internal/libc.h
index b80cbcc9..be88dc04 100644
--- a/src/internal/libc.h
+++ b/src/internal/libc.h
@@ -45,6 +45,8 @@ void __lockfile(FILE *);
#define CANCELPT_BEGIN CANCELPT(1)
#define CANCELPT_TRY CANCELPT(0)
#define CANCELPT_END CANCELPT(-1)
+#define CANCELPT_INHIBIT CANCELPT(2)
+#define CANCELPT_RESUME CANCELPT(-2)
extern char **__environ;
#define environ __environ
diff --git a/src/thread/pthread_create.c b/src/thread/pthread_create.c
index 284b45a0..52487001 100644
--- a/src/thread/pthread_create.c
+++ b/src/thread/pthread_create.c
@@ -57,9 +57,19 @@ static void cancel_handler(int sig, siginfo_t *si, void *ctx)
static void cancelpt(int x)
{
struct pthread *self = __pthread_self();
- if (self->canceldisable) return;
- if ((self->cancelpoint+=x)==1 && x>=0 && self->cancel)
- docancel(self);
+ switch (x) {
+ case 1:
+ self->cancelpoint++;
+ case 0:
+ if (self->cancel && self->cancelpoint==1 && !self->canceldisable)
+ docancel(self);
+ break;
+ case -1:
+ self->cancelpoint--;
+ break;
+ default:
+ self->canceldisable += x;
+ }
}
/* "rsyscall" is a mechanism by which a thread can synchronously force all
diff --git a/src/thread/pthread_setcancelstate.c b/src/thread/pthread_setcancelstate.c
index 23c38851..a85cc800 100644
--- a/src/thread/pthread_setcancelstate.c
+++ b/src/thread/pthread_setcancelstate.c
@@ -3,8 +3,8 @@
int pthread_setcancelstate(int new, int *old)
{
struct pthread *self = pthread_self();
- if (old) *old = self->canceldisable;
+ if (old) *old = self->canceldisable & 1;
if ((unsigned)new > 1) return EINVAL;
- self->canceldisable = new;
+ self->canceldisable = (self->canceldisable & ~1) | new;
return 0;
}