Re: temp file suffixes: mktemp DWIM

[Eric Blake]

Eric Blake <ebb9 <at> byu.net> writes:

> This currently gives exit status 1, because the atexit() handler recognizes 
> failure to print the file name to stdout, but leaves the temporary file 
> around.  Should we go ahead and manually flush/close stdout, rather than 
> relying on close_stdout, so that we can then remove the just-created file if 
we 
> detect write failure?  That way, if we fail to inform the user what just got 
> created, we are at least avoiding littering their file system with a random 
> file.
> 
> Fortunately, 'mktemp >&-' does not make the mistake of printing the just-
> created file as the contents of that file, since we close the fd returned by 
> mkstemp before printing anything.

How about the following?

From: Eric Blake <address@hidden>
Date: Wed, 4 Nov 2009 14:02:20 -0700
Subject: [PATCH] mktemp: don't leave file behind on write failure

* src/mktemp.c (main): Remove just-created file if stdout had
problems.
* bootstrap.conf (gnulib_modules): Add remove.
* tests/misc/close-stdout: Test it.
* NEWS: Document it.
---
 NEWS                    |    4 ++++
 bootstrap.conf          |    1 +
 src/mktemp.c            |   12 +++++++++++-
 tests/misc/close-stdout |    6 ++++++
 4 files changed, 22 insertions(+), 1 deletions(-)

diff --git a/NEWS b/NEWS
index 3f8baf0..4d1b4f5 100644
--- a/NEWS
+++ b/NEWS
@@ -17,6 +17,10 @@ GNU coreutils NEWS                                    -*- 
outline -*-
   This also affected sum, sha1sum, sha224sum, sha384sum and sha512sum.
   [the bug dates back to the initial implementation]

+  mktemp no longer leaves a temporary file behind if it was unable to
+  output the name of the file to stdout.
+  [the bug dates back to the initial implementation]
+
   nice -n -1 PROGRAM now runs PROGRAM even when its internal setpriority
   call fails with errno == EACCES.
   [the bug dates back to the initial implementation]
diff --git a/bootstrap.conf b/bootstrap.conf
index 7960546..b3a82e0 100644
--- a/bootstrap.conf
+++ b/bootstrap.conf
@@ -180,6 +180,7 @@ gnulib_modules="
   readutmp
   realloc
   regex
+  remove
   rename
   rmdir
   root-dev-ino
diff --git a/src/mktemp.c b/src/mktemp.c
index e645362..12acad8 100644
--- a/src/mktemp.c
+++ b/src/mktemp.c
@@ -23,6 +23,7 @@

 #include "system.h"

+#include "close-stream.h"
 #include "error.h"
 #include "filenamecat.h"
 #include "quote.h"
@@ -322,7 +323,16 @@ main (int argc, char **argv)
     }

   if (status == EXIT_SUCCESS)
-    puts (dest_name);
+    {
+      puts (dest_name);
+      /* If we created a file, but then failed to output the file
+         name, we should clean up the mess before failing.  */
+      if (!dry_run && close_stream (stdout))
+        {
+          remove (dest_name);
+          error (EXIT_FAILURE, errno, _("write error"));
+        }
+    }

 #ifdef lint
   free (dest_name);
diff --git a/tests/misc/close-stdout b/tests/misc/close-stdout
index fec1add..852c3c8 100755
--- a/tests/misc/close-stdout
+++ b/tests/misc/close-stdout
@@ -50,12 +50,18 @@ if "$p/src/test" -w /dev/stdout >/dev/null &&
    "$p/src/test" ! -w /dev/stdout >&-; then
   "$p/src/printf" 'foo' >&- 2>/dev/null && fail=1
   cp --verbose a b >&- 2>/dev/null && fail=1
+  rm -Rf tmpfile-?????? || fail=1
+  mktemp tmpfile-XXXXXX >&- 2>/dev/null && fail=1
+  test -e tmpfile-?????? && fail=1
 fi

 # Likewise for /dev/full, if /dev/full works.
 if test -w /dev/full && test -c /dev/full; then
   "$p/src/printf" 'foo' >/dev/full 2>/dev/null && fail=1
   cp --verbose a b >/dev/full 2>/dev/null && fail=1
+  rm -Rf tmpdir-?????? || fail=1
+  mktemp -d tmpdir-XXXXXX >/dev/full 2>/dev/null && fail=1
+  test -e tmpdir-?????? && fail=1
 fi

 Exit $fail
-- 
1.6.4.2