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[pf3gnuchains/gcc-fork.git] / libiberty / pex-unix.c

diff --git a/libiberty/pex-unix.c b/libiberty/pex-unix.c
index baf2bb4..85733a6 100644 (file)
--- a/libiberty/pex-unix.c
+++ b/libiberty/pex-unix.c
@@ -368,7 +368,8 @@ static void
 pex_child_error (struct pex_obj *obj, const char *executable,
                 const char *errmsg, int err)
 {
-#define writeerr(s) (void) write (STDERR_FILE_NO, s, strlen (s))
+  int retval = 0;
+#define writeerr(s) retval |= (write (STDERR_FILE_NO, s, strlen (s)) < 0)
   writeerr (obj->pname);
   writeerr (": error trying to exec '");
   writeerr (executable);
@@ -377,7 +378,9 @@ pex_child_error (struct pex_obj *obj, const char *executable,
   writeerr (": ");
   writeerr (xstrerror (err));
   writeerr ("\n");
-  _exit (-1);
+#undef writeerr
+  /* Exit with -2 if the error output failed, too.  */
+  _exit (retval == 0 ? -1 : -2);
 }
 
 /* Execute a child.  */
@@ -397,6 +400,12 @@ pex_unix_exec_child (struct pex_obj *obj, int flags, const char *executable,
   volatile int sleep_interval;
   volatile int retries;
 
+  /* We vfork and then set environ in the child before calling execvp.
+     This clobbers the parent's environ so we need to restore it.
+     It would be nice to use one of the exec* functions that takes an
+     environment as a parameter, but that may have portability issues.  */
+  char **save_environ = environ;
+
   sleep_interval = 1;
   pid = -1;
   for (retries = 0; retries < 4; ++retries)
@@ -450,7 +459,12 @@ pex_unix_exec_child (struct pex_obj *obj, int flags, const char *executable,
        }
 
       if (env)
-        environ = (char**) env;
+       {
+         /* NOTE: In a standard vfork implementation this clobbers the
+            parent's copy of environ "too" (in reality there's only one copy).
+            This is ok as we restore it below.  */
+         environ = (char**) env;
+       }
 
       if ((flags & PEX_SEARCH) != 0)
        {
@@ -468,6 +482,14 @@ pex_unix_exec_child (struct pex_obj *obj, int flags, const char *executable,
 
     default:
       /* Parent process.  */
+
+      /* Restore environ.
+        Note that the parent either doesn't run until the child execs/exits
+        (standard vfork behaviour), or if it does run then vfork is behaving
+        more like fork.  In either case we needn't worry about clobbering
+        the child's copy of environ.  */
+      environ = save_environ;
+
       if (in != STDIN_FILE_NO)
        {
          if (close (in) < 0)