From: Bruno Haible <bruno@clisp.org>
Date: Mon, 3 Nov 2003 20:43:03 +0000 (+0000)
Subject: Use waitid instead of waitpid when available.
X-Git-Tag: v0.13~175
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=830b1da32d335a967e6f796db02644dea27a8cff;p=thirdparty%2Fgettext.git

Use waitid instead of waitpid when available.
---

diff --git a/gettext-tools/ChangeLog b/gettext-tools/ChangeLog
index 084500d07..714018d8b 100644
--- a/gettext-tools/ChangeLog
+++ b/gettext-tools/ChangeLog
@@ -1,3 +1,7 @@
+2003-10-31  Bruno Haible  <bruno@clisp.org>
+
+	* configure.ac: Also check for waitid.
+
 2003-10-31  Bruno Haible  <bruno@clisp.org>
 
 	* configure.ac: Remove argument of FIX_MAKEFILE_COMPILE,
diff --git a/gettext-tools/configure.ac b/gettext-tools/configure.ac
index 880e7223a..e7e2c7bd2 100644
--- a/gettext-tools/configure.ac
+++ b/gettext-tools/configure.ac
@@ -102,7 +102,7 @@ dnl Checks for library functions.
 gl_FUNC_ALLOCA
 AC_FUNC_VPRINTF
 AC_CHECK_FUNCS([chown getcwd posix_spawn raise select strerror strtoul uname \
-utime utimes])
+utime utimes waitid])
 AC_REPLACE_FUNCS([atexit memmove memset stpcpy strcspn \
 strcasecmp strncasecmp strpbrk strstr vasprintf])
 AM_FUNC_GETLINE
diff --git a/gettext-tools/lib/ChangeLog b/gettext-tools/lib/ChangeLog
index e7ab59d09..f23bdee58 100644
--- a/gettext-tools/lib/ChangeLog
+++ b/gettext-tools/lib/ChangeLog
@@ -1,3 +1,8 @@
+2003-10-31  Bruno Haible  <bruno@clisp.org>
+
+	* wait-process.h (wait_process): Use waitid with WNOWAIT if available,
+	to avoid (extremely rare) race condition.
+
 2003-10-27  Bruno Haible  <bruno@clisp.org>
 
 	* stdbool_.h: Better support for BeOS.
diff --git a/gettext-tools/lib/wait-process.c b/gettext-tools/lib/wait-process.c
index 83f7b3967..26a889ca4 100644
--- a/gettext-tools/lib/wait-process.c
+++ b/gettext-tools/lib/wait-process.c
@@ -252,6 +252,85 @@ wait_subprocess (pid_t child, const char *progname,
 		 bool null_stderr,
 		 bool slave_process, bool exit_on_error)
 {
+#if HAVE_WAITID && defined WNOWAIT
+  /* Use of waitid() with WNOWAIT avoids a race condition: If slave_process is
+     true, and this process sleeps a very long time between the return from
+     waitpid() and the execution of unregister_slave_subprocess(), and
+     meanwhile another process acquires the same PID as child, and then - still
+     before unregister_slave_subprocess() - this process gets a fatal signal,
+     it would kill the other totally unrelated process.  */
+  siginfo_t info;
+  for (;;)
+    {
+      if (waitid (P_PID, child, &info, slave_process ? WNOWAIT : 0) < 0)
+	{
+# ifdef EINTR
+	  if (errno == EINTR)
+	    continue;
+# endif
+	  if (exit_on_error || !null_stderr)
+	    error (exit_on_error ? EXIT_FAILURE : 0, errno,
+		   _("%s subprocess"), progname);
+	  return 127;
+	}
+
+      /* info.si_code is set to one of CLD_EXITED, CLD_KILLED, CLD_DUMPED,
+	 CLD_TRAPPED, CLD_STOPPED, CLD_CONTINUED.  Loop until the program
+	 terminates.  */
+      if (info.si_code == CLD_EXITED
+	  || info.si_code == CLD_KILLED || info.si_code == CLD_DUMPED)
+	break;
+    }
+
+  /* The child process has exited or was signalled.  */
+
+  if (slave_process)
+    {
+      /* Unregister the child from the list of slave subprocesses, so that
+	 later, when we exit, we don't kill a totally unrelated process which
+	 may have acquired the same pid.  */
+      unregister_slave_subprocess (child);
+
+      /* Now remove the zombie from the process list.  */
+      for (;;)
+	{
+	  if (waitid (P_PID, child, &info, 0) < 0)
+	    {
+# ifdef EINTR
+	      if (errno == EINTR)
+		continue;
+# endif
+	      if (exit_on_error || !null_stderr)
+		error (exit_on_error ? EXIT_FAILURE : 0, errno,
+		       _("%s subprocess"), progname);
+	      return 127;
+	    }
+	  break;
+	}
+    }
+
+  switch (info.si_code)
+    {
+    case CLD_KILLED:
+    case CLD_DUMPED:
+      if (exit_on_error || !null_stderr)
+	error (exit_on_error ? EXIT_FAILURE : 0, 0,
+	       _("%s subprocess got fatal signal %d"),
+	       progname, info.si_status);
+      return 127;
+    case CLD_EXITED:
+      if (info.si_status == 127)
+	{
+	  if (exit_on_error || !null_stderr)
+	    error (exit_on_error ? EXIT_FAILURE : 0, 0,
+		   _("%s subprocess failed"), progname);
+	  return 127;
+	}
+      return info.si_status;
+    default:
+      abort ();
+    }
+#else
   /* waitpid() is just as portable as wait() nowadays.  */
   WAIT_T status;
 
@@ -262,11 +341,11 @@ wait_subprocess (pid_t child, const char *progname,
 
       if (result != child)
 	{
-#ifdef EINTR
+# ifdef EINTR
 	  if (errno == EINTR)
 	    continue;
-#endif
-#if 0 /* defined ECHILD */
+# endif
+# if 0 /* defined ECHILD */
 	  if (errno == ECHILD)
 	    {
 	      /* Child process nonexistent?! Assume it terminated
@@ -274,7 +353,7 @@ wait_subprocess (pid_t child, const char *progname,
 	      *(int *) &status = 0;
 	      break;
 	    }
-#endif
+# endif
 	  if (exit_on_error || !null_stderr)
 	    error (exit_on_error ? EXIT_FAILURE : 0, errno,
 		   _("%s subprocess"), progname);
@@ -311,4 +390,5 @@ wait_subprocess (pid_t child, const char *progname,
       return 127;
     }
   return WEXITSTATUS (status);
+#endif
 }