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[PATCH 1/2] strerror_r: fix OpenBSD behavior on 0


From: Eric Blake
Subject: [PATCH 1/2] strerror_r: fix OpenBSD behavior on 0
Date: Tue, 21 Jun 2011 10:36:39 -0600

OpenBSD treats strerror_r(0,,) as a success, but with a message
"Undefined error: 0"; while this is distinct from strerror_r(-1,,)
returning "Unknown error: -1", it does not imply success.  Meanwhile,
if buf is short enough for ERANGE, then we can't use strstr to look
for "Unknown" or "Undefined" in the resulting message, like we had
been doing for strerror().  Fix this by shifting the burden - now
the strerror-override code guarantees that 0 will have an
override when needed.

* lib/strerror-override.c (strerror_override): Also override 0
when needed.
* lib/strerror-override.h (strerror_override): Likewise.
* lib/strerror.c (strerror): Simplify, now that 0 override is done
earlier.
* lib/strerror_r.c (strerror_r): Likewise.
* m4/strerror.m4 (gl_FUNC_STRERROR): Split detection of 0
behavior...
(gl_FUNC_STRERROR_0): ...into new macro.
* m4/strerror_r.m4 (gl_FUNC_STRERROR_R): Replace strerror_r if 0
is overridden.
(gl_FUNC_STRERROR_R_WORKS): Avoid extra tests if 0 is broken.
* modules/strerror-override (Files): Add strerror.m4.
(configure.ac): Also provide override for 0 when needed.
* doc/posix-functions/strerror.texi (strerror): Document this.
* doc/posix-functions/perror.texi (perror): Likewise.

Signed-off-by: Eric Blake <address@hidden>
---

I'm pushing this; however, without patch 2, test-strerror_r still
fails on OpenBSD, but at a later point.

 ChangeLog                         |   20 +++++++++++++
 doc/posix-functions/perror.texi   |    2 +-
 doc/posix-functions/strerror.texi |    2 +-
 lib/strerror-override.c           |    5 +++
 lib/strerror-override.h           |    3 +-
 lib/strerror.c                    |   15 +---------
 lib/strerror_r.c                  |   11 -------
 m4/strerror.m4                    |   56 ++++++++++++++++++++++++++----------
 m4/strerror_r.m4                  |   17 ++++++-----
 modules/strerror-override         |    4 ++-
 10 files changed, 82 insertions(+), 53 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index d9e6fc0..6e5eaf4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,25 @@
 2011-06-21  Eric Blake  <address@hidden>

+       strerror_r: fix OpenBSD behavior on 0
+       * lib/strerror-override.c (strerror_override): Also override 0
+       when needed.
+       * lib/strerror-override.h (strerror_override): Likewise.
+       * lib/strerror.c (strerror): Simplify, now that 0 override is done
+       earlier.
+       * lib/strerror_r.c (strerror_r): Likewise.
+       * m4/strerror.m4 (gl_FUNC_STRERROR): Split detection of 0
+       behavior...
+       (gl_FUNC_STRERROR_0): ...into new macro.
+       * m4/strerror_r.m4 (gl_FUNC_STRERROR_R): Replace strerror_r if 0
+       is overridden.
+       (gl_FUNC_STRERROR_R_WORKS): Avoid extra tests if 0 is broken.
+       * modules/strerror-override (Files): Add strerror.m4.
+       (configure.ac): Also provide override for 0 when needed.
+       * doc/posix-functions/strerror.texi (strerror): Document this.
+       * doc/posix-functions/perror.texi (perror): Likewise.
+
+2011-06-21  Eric Blake  <address@hidden>
+
        perror: adjust array size
        * modules/perror (Depends-on): Add strerror-override.
        * lib/perror.c (perror): Use it to avoid magic number.
diff --git a/doc/posix-functions/perror.texi b/doc/posix-functions/perror.texi
index c11d2e6..0459abd 100644
--- a/doc/posix-functions/perror.texi
+++ b/doc/posix-functions/perror.texi
@@ -15,7 +15,7 @@ perror
 @item
 This function treats @code{errno} of 0 like failure, although POSIX
 requires that the message declare it as a success, on some platforms:
-FreeBSD 8.2, MacOS X 10.5.
+FreeBSD 8.2, OpenBSD 4.7, MacOS X 10.5.
 @item
 This function clobbers the @code{strerror} buffer on some platforms:
 Cygwin 1.7.9.
diff --git a/doc/posix-functions/strerror.texi 
b/doc/posix-functions/strerror.texi
index 931ab4f..21fc990 100644
--- a/doc/posix-functions/strerror.texi
+++ b/doc/posix-functions/strerror.texi
@@ -17,7 +17,7 @@ strerror
 @code{errno} or using a string similar to out-of-range values),
 although POSIX requires this to leave @code{errno} unchanged and
 report success, on some platforms:
-FreeBSD 8.2, MacOS X 10.5.
+FreeBSD 8.2, OpenBSD 4.7, MacOS X 10.5.
 @item
 This function fails to return a string for out-of-range integers on
 some platforms:
diff --git a/lib/strerror-override.c b/lib/strerror-override.c
index 4f8cda5..e103173 100644
--- a/lib/strerror-override.c
+++ b/lib/strerror-override.c
@@ -37,6 +37,11 @@ strerror_override (int errnum)
   /* These error messages are taken from glibc/sysdeps/gnu/errlist.c.  */
   switch (errnum)
     {
+#if REPLACE_STRERROR_0
+    case 0:
+      return "Success";
+#endif
+
 #if GNULIB_defined_ETXTBSY
     case ETXTBSY:
       return "Text file busy";
diff --git a/lib/strerror-override.h b/lib/strerror-override.h
index b8ef854..cab0196 100644
--- a/lib/strerror-override.h
+++ b/lib/strerror-override.h
@@ -40,7 +40,8 @@
     || GNULIB_defined_ENOTSUP \
     || GNULIB_defined_ESTALE \
     || GNULIB_defined_EDQUOT \
-    || GNULIB_defined_ECANCELED
+    || GNULIB_defined_ECANCELED \
+    || REPLACE_STRERROR_0
 extern const char *strerror_override (int errnum);
 # else
 #  define strerror_override(ignored) NULL
diff --git a/lib/strerror.c b/lib/strerror.c
index d0dd1af..63899ca 100644
--- a/lib/strerror.c
+++ b/lib/strerror.c
@@ -45,20 +45,7 @@ strerror (int n)
   if (msg)
     return (char *) msg;

-  /* FreeBSD rejects 0; see http://austingroupbugs.net/view.php?id=382.
-     MacOS X 10.5 does not distinguish 0 from -1.  */
-  if (n)
-    msg = strerror (n);
-  else
-    {
-      int saved_errno = errno;
-      errno = 0;
-      msg = strerror (n);
-      if (errno || (msg &&
-                    (strstr (msg, "nknown") || strstr (msg, "ndefined"))))
-        msg = "Success";
-      errno = saved_errno;
-    }
+  msg = strerror (n);

   /* Our strerror_r implementation might use the system's strerror
      buffer, so all other clients of strerror have to see the error
diff --git a/lib/strerror_r.c b/lib/strerror_r.c
index 46b47ed..0da9ba2 100644
--- a/lib/strerror_r.c
+++ b/lib/strerror_r.c
@@ -209,17 +209,6 @@ strerror_r (int errnum, char *buf, size_t buflen)
     if (ret < 0)
       ret = errno;

-    /* FreeBSD rejects 0; see http://austingroupbugs.net/view.php?id=382.
-       MacOS X 10.5 strerror_r differs from the strerror string for 0.  */
-    if (errnum == 0)
-      {
-# if defined __APPLE__ && defined __MACH__
-        ret = EINVAL;
-# endif
-        if (ret == EINVAL)
-          ret = safe_copy (buf, buflen, "Success");
-      }
-
 #else /* USE_SYSTEM_STRERROR */

     /* Try to do what strerror (errnum) does, but without clobbering the
diff --git a/m4/strerror.m4 b/m4/strerror.m4
index 03a0b1a..ca05be6 100644
--- a/m4/strerror.m4
+++ b/m4/strerror.m4
@@ -1,4 +1,4 @@
-# strerror.m4 serial 15
+# strerror.m4 serial 16
 dnl Copyright (C) 2002, 2007-2011 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -8,33 +8,24 @@ AC_DEFUN([gl_FUNC_STRERROR],
 [
   AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
   AC_REQUIRE([gl_HEADER_ERRNO_H])
+  AC_REQUIRE([gl_FUNC_STRERROR_0])
   m4_ifdef([gl_FUNC_STRERROR_R_WORKS], [
     AC_REQUIRE([gl_FUNC_STRERROR_R_WORKS])
   ])
-  if test -z "$ERRNO_H"; then
+  if test "$ERRNO_H:$REPLACE_STRERROR_0" = :0; then
     AC_CACHE_CHECK([for working strerror function],
      [gl_cv_func_working_strerror],
      [AC_RUN_IFELSE(
         [AC_LANG_PROGRAM(
            [[#include <string.h>
-             #include <errno.h>
            ]],
-           [[int result = 0;
-             char *str;
-             if (!*strerror (-2)) result |= 1;
-             errno = 0;
-             str = strerror (0);
-             if (!*str) result |= 2;
-             if (errno) result |= 4;
-             if (strstr (str, "nknown") || strstr (str, "ndefined"))
-               result |= 8;
-             return result;]])],
+           [[if (!*strerror (-2)) return 1;]])],
         [gl_cv_func_working_strerror=yes],
         [gl_cv_func_working_strerror=no],
         [dnl Be pessimistic on cross-compiles for now.
-         gl_cv_func_working_strerror=no])
+         gl_cv_func_working_strerror="guessing no"])
     ])
-    if test $gl_cv_func_working_strerror = no; then
+    if test "$gl_cv_func_working_strerror" != yes; then
       dnl The system's strerror() fails to return a string for out-of-range
       dnl integers. Replace it.
       REPLACE_STRERROR=1
@@ -48,7 +39,40 @@ AC_DEFUN([gl_FUNC_STRERROR],
     ])
   else
     dnl The system's strerror() cannot know about the new errno values we add
-    dnl to <errno.h>. Replace it.
+    dnl to <errno.h>, or any fix for strerror(0). Replace it.
     REPLACE_STRERROR=1
   fi
 ])
+
+dnl Detect if strerror(0) passes (that is, does not set errno, and does not
+dnl return a string that matches strerror(-1)).
+AC_DEFUN([gl_FUNC_STRERROR_0],
+[
+  REPLACE_STRERROR_0=0
+  AC_CACHE_CHECK([whether strerror(0) succeeds],
+   [gl_cv_func_strerror_0_works],
+   [AC_RUN_IFELSE(
+      [AC_LANG_PROGRAM(
+         [[#include <string.h>
+           #include <errno.h>
+         ]],
+         [[int result = 0;
+           char *str;
+           errno = 0;
+           str = strerror (0);
+           if (!*str) result |= 1;
+           if (errno) result |= 2;
+           if (strstr (str, "nknown") || strstr (str, "ndefined"))
+             result |= 4;
+           return result;]])],
+      [gl_cv_func_strerror_0_works=yes],
+      [gl_cv_func_strerror_0_works=no],
+      [dnl Be pessimistic on cross-compiles for now.
+       gl_cv_func_strerror_0_works="guessing no"])
+  ])
+  if test "$gl_cv_func_strerror_0_works" != yes; then
+    REPLACE_STRERROR_0=1
+    AC_DEFINE([REPLACE_STRERROR_0], [1], [Define to 1 if strerror(0)
+      does not return a message implying success.])
+  fi
+])
diff --git a/m4/strerror_r.m4 b/m4/strerror_r.m4
index 8975827..f6aceff 100644
--- a/m4/strerror_r.m4
+++ b/m4/strerror_r.m4
@@ -1,4 +1,4 @@
-# strerror_r.m4 serial 11
+# strerror_r.m4 serial 12
 dnl Copyright (C) 2002, 2007-2011 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -20,7 +20,7 @@ AC_DEFUN([gl_FUNC_STRERROR_R],
   fi

   if test $ac_cv_func_strerror_r = yes; then
-    if test -z "$ERRNO_H"; then
+    if test "$ERRNO_H:$REPLACE_STRERROR_0" = :0; then
       if test $gl_cv_func_strerror_r_posix_signature = yes; then
         case "$gl_cv_func_strerror_r_works" in
           dnl The system's strerror_r has bugs.  Replace it.
@@ -32,7 +32,7 @@ AC_DEFUN([gl_FUNC_STRERROR_R],
       fi
     else
       dnl The system's strerror_r() cannot know about the new errno values we
-      dnl add to <errno.h>. Replace it.
+      dnl add to <errno.h>, or any fix for strerror(0). Replace it.
       REPLACE_STRERROR_R=1
     fi
   fi
@@ -41,7 +41,7 @@ AC_DEFUN([gl_FUNC_STRERROR_R],
 # Prerequisites of lib/strerror_r.c.
 AC_DEFUN([gl_PREREQ_STRERROR_R], [
   dnl glibc >= 2.3.4 and cygwin 1.7.9 have a function __xpg_strerror_r.
-  AC_CHECK_FUNCS([__xpg_strerror_r])
+  AC_CHECK_FUNCS_ONCE([__xpg_strerror_r])
   AC_CHECK_FUNCS_ONCE([catgets])
 ])

@@ -51,10 +51,11 @@ AC_DEFUN([gl_FUNC_STRERROR_R_WORKS],
 [
   AC_REQUIRE([gl_HEADER_ERRNO_H])
   AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_REQUIRE([gl_FUNC_STRERROR_0])

   AC_CHECK_FUNCS_ONCE([strerror_r])
   if test $ac_cv_func_strerror_r = yes; then
-    if test -z "$ERRNO_H"; then
+    if test "$ERRNO_H:$REPLACE_STRERROR_0" = :0; then
       dnl The POSIX prototype is:  int strerror_r (int, char *, size_t);
       dnl glibc, Cygwin:           char *strerror_r (int, char *, size_t);
       dnl AIX 5.1, OSF/1 5.1:      int strerror_r (int, char *, int);
@@ -116,8 +117,8 @@ changequote(,)dnl
                 aix*)  gl_cv_func_strerror_r_works="guessing no";;
                        # Guess no on HP-UX.
                 hpux*) gl_cv_func_strerror_r_works="guessing no";;
-                       # Guess no on FreeBSD.
-                freebsd*)  gl_cv_func_strerror_r_works="guessing no";;
+                       # Guess no on BSD variants.
+                *bsd*)  gl_cv_func_strerror_r_works="guessing no";;
                        # Guess yes otherwise.
                 *)     gl_cv_func_strerror_r_works="guessing yes";;
               esac
@@ -127,7 +128,7 @@ changequote([,])dnl
       else
         dnl The system's strerror() has a wrong signature.
         dnl glibc >= 2.3.4 and cygwin 1.7.9 have a function __xpg_strerror_r.
-        AC_CHECK_FUNCS([__xpg_strerror_r])
+        AC_CHECK_FUNCS_ONCE([__xpg_strerror_r])
         dnl In glibc < 2.14, __xpg_strerror_r does not populate buf on failure.
         dnl In cygwin < 1.7.10, __xpg_strerror_r clobbers strerror's buffer.
         if test $ac_cv_func___xpg_strerror_r = yes; then
diff --git a/modules/strerror-override b/modules/strerror-override
index bbdf7b8..0b72b46 100644
--- a/modules/strerror-override
+++ b/modules/strerror-override
@@ -5,13 +5,15 @@ Files:
 lib/strerror-override.h
 lib/strerror-override.c
 m4/sys_socket_h.m4
+m4/strerror.m4

 Depends-on:
 errno

 configure.ac:
 AC_REQUIRE([gl_HEADER_ERRNO_H])
-if test -n "$ERRNO_H"; then
+AC_REQUIRE([gl_FUNC_STRERROR_0])
+if test -n "$ERRNO_H" || test $REPLACE_STRERROR_0 = 1; then
   AC_LIBOBJ([strerror-override])
   gl_PREREQ_SYS_H_WINSOCK2
 fi
-- 
1.7.4.4




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