mktemp, sort, tac: don't use undefined after mkstemp failure

When mkstemp fails, the template buffer may have undefined
contents, so we must not print it.
* src/sort.c (create_temp_file): Use temp_dir, not "file"
when diagnosing failed mkstemp, because "file" may be undefined.
* tests/misc/sort-merge: Adjust for new expected output.
Jeph Cowan and Ralf Wildenhues reported the test failure:
http://thread.gmane.org/gmane.comp.gnu.coreutils.bugs/14235/focus=14257
* src/tac.c (copy_to_temp): Don't use template buffer after
failed mkstemp call, since its contents may be undefined.
* tests/misc/tac (pipe-bad-tmpdir): New test for the above.
* src/mktemp.c (main): Save a copy of the template string,
solely for use in case mkstemp fails.
* tests/misc/mktemp (pipe-bad-tmpdir): New test for the above.

3 files changed, 12 insertions, 6 deletions

diff --git a/src/mktemp.c b/src/mktemp.c
index 8a09231f9..d745e6069 100644
--- a/src/mktemp.c
+++ b/src/mktemp.c
@@ -242,20 +242,24 @@ main (int argc, char **argv)
                    quote (template));
         }
 
-      dest_name = file_name_concat (dest_dir, template, NULL);
+      template = file_name_concat (dest_dir, template, NULL);
     }
   else
     {
-      dest_name = xstrdup (template);
+      template = xstrdup (template);
     }
 
+  /* Make a copy to be used in case of diagnostic, since failing
+     mkstemp may leave the buffer in an undefined state.  */
+  dest_name = xstrdup (template);
+
   if (create_directory)
     {
       int err = mkdtemp_len (dest_name, x_count, dry_run);
       if (err != 0)
         {
           error (0, errno, _("failed to create directory via template %s"),
-                 quote (dest_name));
+                 quote (template));
           status = EXIT_FAILURE;
         }
     }
@@ -265,7 +269,7 @@ main (int argc, char **argv)
       if (fd < 0 || (!dry_run && close (fd) != 0))
         {
           error (0, errno, _("failed to create file via template %s"),
-                 quote (dest_name));
+                 quote (template));
           status = EXIT_FAILURE;
         }
     }
diff --git a/src/sort.c b/src/sort.c
index b932a51b3..92f400a96 100644
--- a/src/sort.c
+++ b/src/sort.c
@@ -741,7 +741,8 @@ create_temp_file (int *pfd)
   errno = saved_errno;
 
   if (fd < 0)
-    die (_("cannot create temporary file"), file);
+    error (SORT_FAILURE, errno, _("cannot create temporary file in %s"),
+	   quote (temp_dir));
 
   *pfd = fd;
   return node;
diff --git a/src/tac.c b/src/tac.c
index 9cf6d60dc..c83986f59 100644
--- a/src/tac.c
+++ b/src/tac.c
@@ -454,7 +454,8 @@ copy_to_temp (FILE **g_tmp, char **g_tempfile, int input_fd, char const *file)
   fd = mkstemp (template);
   if (fd < 0)
     {
-      error (0, errno, _("cannot create temporary file %s"), quote (tempfile));
+      error (0, errno, _("cannot create temporary file in %s"),
+	     quote (tempdir));
       return false;
     }