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authorThiago Macieira <thiago.macieira@intel.com>2015-03-12 23:17:18 -0700
committerThiago Macieira <thiago.macieira@intel.com>2015-03-16 19:28:13 +0000
commit4da46bbb9a1b97759f3552c58e1b6d48e290e8ef (patch)
treefb501da9de07db942d1ea64d1442804f7e7618c8
parentbb5d287cc3eb68e1e46e5c3eb0a2c3991900354d (diff)
forkfd: dynamically detect whether the Darwin waitid is broken
The Darwin kernel that came with Mac OS X 10.7 has a broken implementation of waitid when passed a P_ALL first argument. It does tell us that there is a process that can be wait()ed, but does not fill in the siginfo_t structure. See commit 9931fa9df4cb96a4006a3390db64f87e3b5bc1a0 for more information. Change-Id: Iee8cbc07c4434ce9b560ffff13cafa4c88cdabd6 Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
-rw-r--r--src/3rdparty/forkfd/forkfd.c35
1 files changed, 31 insertions, 4 deletions
diff --git a/src/3rdparty/forkfd/forkfd.c b/src/3rdparty/forkfd/forkfd.c
index a8205065c5..7d790b01fc 100644
--- a/src/3rdparty/forkfd/forkfd.c
+++ b/src/3rdparty/forkfd/forkfd.c
@@ -58,6 +58,10 @@
# include <sys/eventfd.h>
#endif
+#if _POSIX_VERSION-0 >= 200809L || _XOPEN_VERSION-0 >= 500
+# define HAVE_WAITID 1
+#endif
+
#if defined(__APPLE__)
/* Up until OS X 10.7, waitid(P_ALL, ...) will return success, but will not
* fill in the details of the dead child. That means waitid is not useful to us.
@@ -66,11 +70,9 @@
*/
# include <Availability.h>
# include <AvailabilityMacros.h>
-# if MAC_OS_X_VERSION_MIN_REQUIRED >= 1080
-# define HAVE_WAITID 1
+# if MAC_OS_X_VERSION_MIN_REQUIRED <= 1070
+# define HAVE_BROKEN_WAITID_ALL 1
# endif
-#elif _POSIX_VERSION-0 >= 200809L || _XOPEN_VERSION-0 >= 500
-# define HAVE_WAITID 1
#endif
#ifndef FFD_ATOMIC_RELAXED
@@ -115,6 +117,12 @@ static struct sigaction old_sigaction;
static pthread_once_t forkfd_initialization = PTHREAD_ONCE_INIT;
static ffd_atomic_int forkfd_status = FFD_ATOMIC_INIT(0);
+#ifdef HAVE_BROKEN_WAITID_ALL
+static int waitid_p_all_works = 0;
+#else
+static const int waitid_p_all_works = 1;
+#endif
+
static ProcessInfo *tryAllocateInSection(Header *header, ProcessInfo entries[], int maxCount)
{
/* we use ACQUIRE here because the signal handler might have released the PID */
@@ -246,6 +254,9 @@ static void sigchld_handler(int signum)
memset(&info, 0, sizeof info);
#ifdef HAVE_WAITID
+ if (!waitid_p_all_works)
+ goto search_arrays;
+
/* be optimistic: try to see if we can get the child that exited */
search_next_child:
/* waitid returns -1 ECHILD if there are no further children at all;
@@ -298,6 +309,8 @@ search_next_child:
* belongs to one of the chained SIGCHLD handlers. However, there might be another
* child that exited and does belong to us, so we need to check each one individually.
*/
+
+search_arrays:
#endif
for (i = 0; i < (int)sizeofarray(children.entries); ++i) {
@@ -352,6 +365,20 @@ chain_handler:
static void forkfd_initialize()
{
+#if defined(HAVE_BROKEN_WAITID_ALL)
+ pid_t pid = fork();
+ if (pid == 0) {
+ _exit(0);
+ } else if (pid > 0) {
+ siginfo_t info;
+ waitid(P_ALL, 0, &info, WNOWAIT | WEXITED);
+ waitid_p_all_works = (info.si_pid != 0);
+
+ // now really reap the child
+ waitid(P_PID, pid, &info, WEXITED);
+ }
+#endif
+
/* install our signal handler */
struct sigaction action;
memset(&action, 0, sizeof action);