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.

diff --git a/src/internal/libc.h b/src/internal/libc.h
index b80cbcc9ef61e033e41cd796abace1f465642e75..be88dc04c28cafd6a02c3ed73f6a70b4a8fb67a2 100644 (file)
--- 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 284b45a0f39c5639e8d7d4c0a1460d235c9e1983..52487001484ce8c1edfc08cd7b7027055c4a130d 100644 (file)
--- 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 23c38851a5910fe88aad2205dd35154d41708277..a85cc800f7c64f8736133c2fad6ec6bff3ee791f 100644 (file)
--- 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;
 }