pipe: Set errno upon failure.

2 files changed, 8 insertions, 2 deletions

diff --git a/lib/pipe.c b/lib/pipe.c
index 6986525081..1c81d14523 100644
--- a/lib/pipe.c
+++ b/lib/pipe.c
@@ -128,6 +128,7 @@ create_pipe (const char *progname,
   int nulloutfd;
   int stdinfd;
   int stdoutfd;
+  int saved_errno;
 
   /* FIXME: Need to free memory allocated by prepare_spawn.  */
   prog_argv = prepare_spawn (prog_argv);
@@ -203,6 +204,8 @@ create_pipe (const char *progname,
                             (const char **) environ);
         }
     }
+  if (child == -1)
+    saved_errno = errno;
   if (stdinfd >= 0)
     close (stdinfd);
   if (stdoutfd >= 0)
@@ -225,12 +228,13 @@ create_pipe (const char *progname,
   if (child == -1)
     {
       if (exit_on_error || !null_stderr)
-        error (exit_on_error ? EXIT_FAILURE : 0, errno,
+        error (exit_on_error ? EXIT_FAILURE : 0, saved_errno,
                _("%s subprocess failed"), progname);
       if (pipe_stdout)
         close (ifd[0]);
       if (pipe_stdin)
         close (ofd[1]);
+      errno = saved_errno;
       return -1;
     }
 
@@ -350,6 +354,7 @@ create_pipe (const char *progname,
           close (ofd[0]);
           close (ofd[1]);
         }
+      errno = err;
       return -1;
     }
   posix_spawn_file_actions_destroy (&actions);
diff --git a/lib/pipe.h b/lib/pipe.h
index 2f23903ab4..7517892ba4 100644
--- a/lib/pipe.h
+++ b/lib/pipe.h
@@ -36,7 +36,8 @@ extern "C" {
    one or two file descriptors for communication with the subprocess.
    If the subprocess creation fails: if exit_on_error is true, the main
    process exits with an error message; otherwise, an error message is given
-   if null_stderr is false, then -1 is returned and fd[] remain uninitialized.
+   if null_stderr is false, then -1 is returned, with errno set, and fd[]
+   remain uninitialized.
 
    After finishing communication, the caller should call wait_subprocess()
    to get rid of the subprocess in the process table.