[PATCH 2/3] test-perror: check for strerror interactions

[Eric Blake]

This uncovered a glibc bug, although not many people check for
perror failures, so for now I'm not working around it.
http://sourceware.org/bugzilla/show_bug.cgi?id=12792

* tests/macros.h (STREQ) Add macro.
* modules/perror-tests (Files): Add second test.
* tests/test-perror2.c (main): New file.
* doc/posix-functions/perror.texi (perror): Document glibc bug.

Signed-off-by: Eric Blake <address@hidden>
---
 ChangeLog                       |    6 ++
 doc/posix-functions/perror.texi |    4 ++
 modules/perror-tests            |    6 ++-
 tests/macros.h                  |    4 ++
 tests/test-perror2.c            |  110 +++++++++++++++++++++++++++++++++++++++
 5 files changed, 128 insertions(+), 2 deletions(-)
 create mode 100644 tests/test-perror2.c

diff --git a/ChangeLog b/ChangeLog
index 30bccca..5001637 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
 2011-05-20  Eric Blake  <address@hidden>

+       test-perror: check for strerror interactions
+       * tests/macros.h (STREQ) Add macro.
+       * modules/perror-tests (Files): Add second test.
+       * tests/test-perror2.c (main): New file.
+       * doc/posix-functions/perror.texi (perror): Document glibc bug.
+
        test-perror: rewrite to use init script
        * modules/perror-tests (Files): Add init.sh.
        * tests/test-perror.sh: Use temporary directory.
diff --git a/doc/posix-functions/perror.texi b/doc/posix-functions/perror.texi
index dc61217..2923106 100644
--- a/doc/posix-functions/perror.texi
+++ b/doc/posix-functions/perror.texi
@@ -16,4 +16,8 @@ perror

 Portability problems not fixed by Gnulib:
 @itemize
address@hidden
+POSIX requires that this function set the stream error bit (detected
+by @code{ferror}) on write failure, but not all platforms do this:
+glibc 2.13.
 @end itemize
diff --git a/modules/perror-tests b/modules/perror-tests
index bad23fd..9a6ba47 100644
--- a/modules/perror-tests
+++ b/modules/perror-tests
@@ -1,7 +1,9 @@
 Files:
 tests/init.sh
+tests/macros.h
 tests/signature.h
 tests/test-perror.c
+tests/test-perror2.c
 tests/test-perror.sh

 Depends-on:
@@ -9,5 +11,5 @@ Depends-on:
 configure.ac:

 Makefile.am:
-TESTS += test-perror.sh
-check_PROGRAMS += test-perror
+TESTS += test-perror.sh test-perror2
+check_PROGRAMS += test-perror test-perror2
diff --git a/tests/macros.h b/tests/macros.h
index 8922675..adb3744 100644
--- a/tests/macros.h
+++ b/tests/macros.h
@@ -62,3 +62,7 @@
    *not* work for function parameters of array type, because they are actually
    parameters of pointer type.  */
 #define SIZEOF(array) (sizeof (array) / sizeof (array[0]))
+
+/* STREQ (str1, str2)
+   Return true if two strings compare equal.  */
+#define STREQ(a, b) (strcmp (a, b) == 0)
diff --git a/tests/test-perror2.c b/tests/test-perror2.c
new file mode 100644
index 0000000..dfcabb4
--- /dev/null
+++ b/tests/test-perror2.c
@@ -0,0 +1,110 @@
+/* Test of perror() function.
+   Copyright (C) 2011 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+#include <config.h>
+
+#include <stdio.h>
+
+#include <errno.h>
+#include <string.h>
+#include <unistd.h>
+
+/* This test intentionally parses stderr.  So, we arrange to have fd 10
+   (outside the range of interesting fd's during the test) set up to
+   duplicate the original stderr.  */
+#define BACKUP_STDERR_FILENO 10
+#define ASSERT_STREAM myerr
+#include "macros.h"
+
+static FILE *myerr;
+
+#define BASE "test-perror2"
+
+int
+main (void)
+{
+  FILE *fp;
+
+  /* We change fd 2 later, so save it in fd 10.  */
+  if (dup2 (STDERR_FILENO, BACKUP_STDERR_FILENO) != BACKUP_STDERR_FILENO
+      || (myerr = fdopen (BACKUP_STDERR_FILENO, "w")) == NULL)
+    return 2;
+
+  ASSERT (freopen (BASE ".tmp", "w+", stderr) == stderr);
+
+  /* Test that perror does not clobber strerror buffer.  */
+  {
+    const char *msg1;
+    const char *msg2;
+    const char *msg3;
+    const char *msg4;
+    char *str1;
+    char *str2;
+    char *str3;
+    char *str4;
+
+    msg1 = strerror (ENOENT);
+    ASSERT (msg1);
+    str1 = strdup (msg1);
+    ASSERT (str1);
+
+    msg2 = strerror (ERANGE);
+    ASSERT (msg2);
+    str2 = strdup (msg2);
+    ASSERT (str2);
+
+    msg3 = strerror (-4);
+    ASSERT (msg3);
+    str3 = strdup (msg3);
+    ASSERT (str3);
+
+    msg4 = strerror (1729576);
+    ASSERT (msg4);
+    str4 = strdup (msg4);
+    ASSERT (str4);
+
+    errno = EACCES;
+    perror ("");
+    errno = -5;
+    perror ("");
+    ASSERT (!ferror (stderr));
+    ASSERT (msg1 == msg2 || msg1 == msg4 || STREQ (msg1, str1));
+    ASSERT (msg2 == msg4 || STREQ (msg2, str2));
+    ASSERT (msg3 == msg4 || STREQ (msg3, str3));
+    ASSERT (STREQ (msg4, str4));
+  }
+
+  /* Test that perror reports write failure.  */
+  {
+    ASSERT (freopen (BASE ".tmp", "r", stderr) == stderr);
+    ASSERT (setvbuf (stderr, NULL, _IOLBF, BUFSIZ) == 0);
+    errno = -1;
+    ASSERT (!ferror (stderr));
+    perror (NULL);
+    ASSERT (errno > 0);
+#if 0
+    /* Commented out until glibc behaves:
+       http://sourceware.org/bugzilla/show_bug.cgi?id=12792 */
+    ASSERT (ferror (stderr));
+#endif
+  }
+
+  ASSERT (fclose (stderr) == 0);
+  ASSERT (remove (BASE ".tmp") == 0);
+
+  return 0;
+}
-- 
1.7.4.4