Fixed bug #633

   Description From  Michael Stone   2008-09-25 19:27:29   (-) [reply]

To determine whether a pid is occupied with the kill(pid, 0) idiom, you have to
test

#include <signal.h>
#include <errno.h>
kill(pid, 0) < 0 && errno == ESRCH

not just

#include <signal.h>
kill(pid, 0) < 0

otherwise you get incorrect results when pid is running as a different user
(causing kill(pid, 0) to return -1 + EPERM).

src/audio/alsa/SDL_alsa_audio.c is certainly affected by this bug in both
1.2.13 and 1.3-trunk. It probably occurs in other places as well.

src/audio/alsa/SDL_alsa_audio.c

@@ -230,7 +230,7 @@ ALSA_WaitDevice(_THIS)
          */
         /* Check every 10 loops */
         if (this->hidden->parent && (((++cnt) % 10) == 0)) {
-            if (kill(this->hidden->parent, 0) < 0) {
+            if (kill(this->hidden->parent, 0) < 0 && errno == ESRCH) {
                 this->enabled = 0;
             }
         }

src/audio/arts/SDL_artsaudio.c

@@ -27,6 +27,7 @@
 #include <signal.h>
 #endif
 #include <unistd.h>
+#include <errno.h>
 
 #include "SDL_timer.h"
 #include "SDL_audio.h"
@@ -149,7 +150,7 @@ ARTS_WaitDevice(_THIS)
          */
         /* Check every 10 loops */
         if (this->hidden->parent && (((++cnt) % 10) == 0)) {
-            if (kill(this->hidden->parent, 0) < 0) {
+            if (kill(this->hidden->parent, 0) < 0 && errno == ESRCH) {
                 this->enabled = 0;
             }
         }

src/audio/dma/SDL_dmaaudio.c

@@ -417,7 +417,7 @@ DMA_WaitDevice(_THIS)
            that use a different process id for each thread.
          */
         if (parent && (((++cnt) % 10) == 0)) {  /* Check every 10 loops */
-            if (kill(parent, 0) < 0) {
+            if (kill(parent, 0) < 0 && errno == ESRCH) {
                 this->enabled = 0;
             }
         }

src/audio/esd/SDL_esdaudio.c

@@ -128,7 +128,7 @@ ESD_WaitDevice(_THIS)
          */
         /* Check every 10 loops */
         if (this->hidden->parent && (((++cnt) % 10) == 0)) {
-            if (kill(this->hidden->parent, 0) < 0) {
+            if (kill(this->hidden->parent, 0) < 0 && errno == ESRCH) {
                 this->enabled = 0;
             }
         }

src/audio/pulseaudio/SDL_pulseaudio.c

@@ -165,7 +165,7 @@ PULSEAUDIO_WaitDevice(_THIS)
          */
         /* Check every 10 loops */
         if (this->hidden->parent && (((++cnt) % 10) == 0)) {
-            if (kill(this->hidden->parent, 0) < 0) {
+            if (kill(this->hidden->parent, 0) < 0 && errno == ESRCH) {
                 this->enabled = 0;
             }
         }