Re: new module 'strerror_r-posix'

[Bruno Haible]

> Here's a draft proposal: A new module 'strerror_r-posix'. I wouldn't want
> to call it 'strerror_r' because that would be misunderstandable.

During testing, more portability problems appeared. Here's what I'm committing:


2010-11-11  Bruno Haible  <address@hidden>

        New module 'strerror_r-posix'.
        * lib/string.in.h (strerror_r): New declaration.
        * lib/strerror_r.c: New file.
        * m4/strerror_r.m4: New file.
        * m4/string_h.m4 (gl_HEADER_STRING_H_BODY): Check for the declaration
        of strerror_r.
        (gl_HEADER_STRING_H_DEFAULTS): Initialize GNULIB_STRERROR_R,
        HAVE_DECL_STRERROR_R, REPLACE_STRERROR_R.
        * modules/strerror_r-posix: New file.
        * modules/string (Makefile.am): Substitute GNULIB_STRERROR_R,
        HAVE_DECL_STRERROR_R, REPLACE_STRERROR_R.
        * doc/posix-functions/strerror_r.texi: Mention the new module and the
        portability problems.

--- lib/string.in.h.orig        Thu Nov 11 13:14:02 2010
+++ lib/string.in.h     Thu Nov 11 11:44:28 2010
@@ -902,6 +902,35 @@
                  "use gnulib module strerror to guarantee non-NULL result");
 #endif
 
+/* Map any int, typically from errno, into an error message.  Multithread-safe.
+   Uses the POSIX declaration, not the glibc declaration.  */
+#if @GNULIB_STRERROR_R@
+# if @REPLACE_STRERROR_R@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   undef strerror_r
+#   define strerror_r rpl_strerror_r
+#  endif
+_GL_FUNCDECL_RPL (strerror_r, int, (int errnum, char *buf, size_t buflen)
+                                   _GL_ARG_NONNULL ((2)));
+_GL_CXXALIAS_RPL (strerror_r, int, (int errnum, char *buf, size_t buflen));
+# else
+#  if address@hidden@
+_GL_FUNCDECL_SYS (strerror_r, int, (int errnum, char *buf, size_t buflen)
+                                   _GL_ARG_NONNULL ((2)));
+#  endif
+_GL_CXXALIAS_SYS (strerror_r, int, (int errnum, char *buf, size_t buflen));
+# endif
+# if @HAVE_DECL_STRERROR_R@
+_GL_CXXALIASWARN (strerror_r);
+# endif
+#elif defined GNULIB_POSIXCHECK
+# undef strerror_r
+# if HAVE_RAW_DECL_STRERROR_R
+_GL_WARN_ON_USE (strerror_r, "strerror_r is unportable - "
+                 "use gnulib module strerror_r-posix for portability");
+# endif
+#endif
+
 #if @GNULIB_STRSIGNAL@
 # if @REPLACE_STRSIGNAL@
 #  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
=============================== lib/strerror_r.c ===============================
/* strerror_r.c --- POSIX compatible system error routine

   Copyright (C) 2010 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 of the License, 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, see <http://www.gnu.org/licenses/>.  */

/* Written by Bruno Haible <address@hidden>, 2010.  */

#include <config.h>

/* Specification.  */
#include <string.h>

#include <errno.h>

#if HAVE_DECL_STRERROR_R && !(__GLIBC__ >= 2) && !EXTEND_STRERROR_R

/* The system's strerror_r function is OK, except that its third argument
   is 'int', not 'size_t'.  */

# include <limits.h>

int
strerror_r (int errnum, char *buf, size_t buflen)
# undef strerror_r
{
  int ret;

  if (buflen > INT_MAX)
    buflen = INT_MAX;

# ifdef __hpux
  /* On HP-UX 11.31, strerror_r always fails when buflen < 80.  */
  {
    char stackbuf[80];

    if (buflen < sizeof (stackbuf))
      {
        ret = strerror_r (errnum, stackbuf, sizeof (stackbuf));
        if (ret == 0)
          {
            size_t len = strlen (stackbuf);

            if (len < buflen)
              memcpy (buf, stackbuf, len + 1);
            else
              ret = ERANGE;
          }
      }
    else
      ret = strerror_r (errnum, buf, buflen);
  }
# else
  ret = strerror_r (errnum, buf, buflen);
# endif

# ifdef _AIX
  /* On AIX 6.1, strerror_r returns -1 and sets errno to EINVAL
     if buflen <= 1.  */
  if (ret < 0 && errno == EINVAL && buflen <= 1)
    {
      /* Retry with a larger buffer.  */
      char largerbuf[10];
      ret = strerror_r (errnum, largerbuf, sizeof (largerbuf));
      if (ret < 0 && errno == EINVAL)
        {
          /* errnum was out of range.  */
          return EINVAL;
        }
      else
        {
          /* buf was too small.  */
          return ERANGE;
        }
    }
# endif

  /* Some old implementations may return (-1, EINVAL) instead of EINVAL.  */
  return (ret < 0 ? errno : ret);
}

#elif __GLIBC__ >= 2 && HAVE___XPG_STRERROR_R /* glibc >= 2.3.4 */ && 
!EXTEND_STRERROR_R

int
strerror_r (int errnum, char *buf, size_t buflen)
{
  extern int __xpg_strerror_r (int errnum, char *buf, size_t buflen);

  int ret = __xpg_strerror_r (errnum, buf, buflen);
  return (ret < 0 ? errno : 0);
}

#else /* (__GLIBC__ >= 2 ? !HAVE___XPG_STRERROR_R : !HAVE_DECL_STRERROR_R) || 
EXTEND_STRERROR_R */

# include "glthread/lock.h"

/* Use strerror(), with locking.  */

/* This lock protects the buffer returned by strerror().  We assume that
   no other uses of strerror() exist in the program.  */
gl_lock_define_initialized(static, strerror_lock)

int
strerror_r (int errnum, char *buf, size_t buflen)
{
  gl_lock_lock (strerror_lock);

  {
    char *errmsg = strerror (errnum);
    size_t len = strlen (errmsg);
    int ret;

    if (len < buflen)
      {
        memcpy (buf, errmsg, len + 1);
        ret = 0;
      }
    else
      ret = ERANGE;

    gl_lock_unlock (strerror_lock);

    return ret;
  }
}

#endif
=============================== m4/strerror_r.m4 ===============================
# strerror_r.m4 serial 1
dnl Copyright (C) 2002, 2007-2010 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.

AC_DEFUN([gl_FUNC_STRERROR_R],
[
  AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
  AC_REQUIRE([gl_HEADER_ERRNO_H])
  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles

  dnl Persuade Solaris <string.h> to declare strerror_r().
  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])

  dnl Some systems don't declare strerror_r() if _THREAD_SAFE and _REENTRANT
  dnl are not defined.
  AC_CHECK_DECLS_ONCE([strerror_r])
  if test $ac_cv_have_decl_strerror_r = no; then
    HAVE_DECL_STRERROR_R=0
  fi

  AC_CHECK_FUNCS([strerror_r])
  if test $ac_cv_func_strerror_r = yes; then
    if test -z "$ERRNO_H"; then
      dnl The POSIX prototype is:  int strerror_r (int, char *, size_t);
      dnl glibc's prototype:       char *strerror_r (int, char *, size_t);
      dnl AIX 5.1, OSF/1 5.1:      int strerror_r (int, char *, int);
      AC_CACHE_CHECK([for strerror_r with POSIX signature],
        [gl_cv_func_strerror_r_posix_signature],
        [AC_COMPILE_IFELSE(
           [AC_LANG_PROGRAM(
              [[#include <string.h>
                int strerror_r (int, char *, size_t);
              ]],
              [[return strerror (0);]])],
           [gl_cv_func_strerror_r_posix_signature=yes],
           [gl_cv_func_strerror_r_posix_signature=no])
        ])
      if test $gl_cv_func_strerror_r_posix_signature = yes; then
        dnl AIX 6.1 strerror_r fails by returning -1, not an error number.
        dnl HP-UX 11.31 strerror_r always fails when the buffer length argument
        dnl is less than 80.
        AC_CACHE_CHECK([whether strerror_r works],
          [gl_cv_func_strerror_r_works],
          [AC_RUN_IFELSE(
             [AC_LANG_PROGRAM(
                [[#include <errno.h>
                  #include <string.h>
                  int strerror_r (int, char *, size_t);
                ]],
                [[char buf[79];
                  return strerror (EACCES, buf, 0) < 0
                         || strerror_r (EACCES, buf, sizeof (buf)) != 0;
                ]])],
             [gl_cv_func_strerror_r_works=yes],
             [gl_cv_func_strerror_r_works=no],
             [
changequote(,)dnl
              case "$host_os" in
                       # Guess no on AIX.
                aix*)  gl_cv_func_strerror_r_works="guessing no";;
                       # Guess no on HP-UX.
                hpux*) gl_cv_func_strerror_r_works="guessing no";;
                       # Guess yes otherwise.
                *)     gl_cv_func_strerror_r_works="guessing yes";;
              esac
changequote([,])dnl
             ])
          ])
        case "$gl_cv_func_strerror_r_works" in
          *no) REPLACE_STRERROR_R=1 ;;
        esac
      else
        dnl The system's strerror() has a wrong signature. Replace it.
        REPLACE_STRERROR_R=1
        dnl glibc >= 2.3.4 has a function __xpg_strerror_r.
        AC_CHECK_FUNCS([__xpg_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.
      REPLACE_STRERROR_R=1
      AC_DEFINE([EXTEND_STRERROR_R], [1],
        [Define to 1 if strerror_r needs to be extended so that it handles the
         extra errno values.])
    fi
  fi
  if test $HAVE_DECL_STRERROR_R = 0 || test $REPLACE_STRERROR_R = 1; then
    AC_LIBOBJ([strerror_r])
    gl_PREREQ_STRERROR_R
  fi
])

# Prerequisites of lib/strerror_r.c.
AC_DEFUN([gl_PREREQ_STRERROR_R], [
  :
])
================================================================================
--- m4/string_h.m4.orig Thu Nov 11 13:14:02 2010
+++ m4/string_h.m4      Tue Nov  9 01:20:59 2010
@@ -5,7 +5,7 @@
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
 
-# serial 17
+# serial 18
 
 # Written by Paul Eggert.
 
@@ -28,8 +28,8 @@
   gl_WARN_ON_USE_PREPARE([[#include <string.h>
     ]],
     [memmem mempcpy memrchr rawmemchr stpcpy stpncpy strchrnul strdup
-     strncat strndup strnlen strpbrk strsep strcasestr strtok_r strsignal
-     strverscmp])
+     strncat strndup strnlen strpbrk strsep strcasestr strtok_r strerror_r
+     strsignal strverscmp])
 ])
 
 AC_DEFUN([gl_STRING_MODULE_INDICATOR],
@@ -75,6 +75,7 @@
   GNULIB_MBSSEP=0;      AC_SUBST([GNULIB_MBSSEP])
   GNULIB_MBSTOK_R=0;    AC_SUBST([GNULIB_MBSTOK_R])
   GNULIB_STRERROR=0;    AC_SUBST([GNULIB_STRERROR])
+  GNULIB_STRERROR_R=0;  AC_SUBST([GNULIB_STRERROR_R])
   GNULIB_STRSIGNAL=0;   AC_SUBST([GNULIB_STRSIGNAL])
   GNULIB_STRVERSCMP=0;  AC_SUBST([GNULIB_STRVERSCMP])
   HAVE_MBSLEN=0;        AC_SUBST([HAVE_MBSLEN])
@@ -94,6 +95,7 @@
   HAVE_STRSEP=1;                AC_SUBST([HAVE_STRSEP])
   HAVE_STRCASESTR=1;            AC_SUBST([HAVE_STRCASESTR])
   HAVE_DECL_STRTOK_R=1;         AC_SUBST([HAVE_DECL_STRTOK_R])
+  HAVE_DECL_STRERROR_R=1;       AC_SUBST([HAVE_DECL_STRERROR_R])
   HAVE_DECL_STRSIGNAL=1;        AC_SUBST([HAVE_DECL_STRSIGNAL])
   HAVE_STRVERSCMP=1;            AC_SUBST([HAVE_STRVERSCMP])
   REPLACE_MEMCHR=0;             AC_SUBST([REPLACE_MEMCHR])
@@ -103,6 +105,7 @@
   REPLACE_STRSTR=0;             AC_SUBST([REPLACE_STRSTR])
   REPLACE_STRCASESTR=0;         AC_SUBST([REPLACE_STRCASESTR])
   REPLACE_STRERROR=0;           AC_SUBST([REPLACE_STRERROR])
+  REPLACE_STRERROR_R=0;         AC_SUBST([REPLACE_STRERROR_R])
   REPLACE_STRNCAT=0;            AC_SUBST([REPLACE_STRNCAT])
   REPLACE_STRNDUP=0;            AC_SUBST([REPLACE_STRNDUP])
   REPLACE_STRNLEN=0;            AC_SUBST([REPLACE_STRNLEN])
=========================== modules/strerror_r-posix ===========================
Description:
strerror_r() function: get string describing error code.

Files:
lib/strerror_r.c
m4/strerror_r.m4

Depends-on:
string
errno
extensions
lock
strerror

configure.ac:
gl_FUNC_STRERROR_R
gl_STRING_MODULE_INDICATOR([strerror_r])

Makefile.am:

Include:
<string.h>

License:
LGPLv2+

Maintainer:
Bruno Haible
================================================================================
--- modules/string.orig Thu Nov 11 13:14:02 2010
+++ modules/string      Tue Nov  9 01:21:10 2010
@@ -60,6 +60,7 @@
              -e 's|@''GNULIB_STRCASESTR''@|$(GNULIB_STRCASESTR)|g' \
              -e 's|@''GNULIB_STRTOK_R''@|$(GNULIB_STRTOK_R)|g' \
              -e 's|@''GNULIB_STRERROR''@|$(GNULIB_STRERROR)|g' \
+             -e 's|@''GNULIB_STRERROR_R''@|$(GNULIB_STRERROR_R)|g' \
              -e 's|@''GNULIB_STRSIGNAL''@|$(GNULIB_STRSIGNAL)|g' \
              -e 's|@''GNULIB_STRVERSCMP''@|$(GNULIB_STRVERSCMP)|g' \
              < $(srcdir)/string.in.h | \
@@ -79,6 +80,7 @@
              -e 's|@''HAVE_STRSEP''@|$(HAVE_STRSEP)|g' \
              -e 's|@''HAVE_STRCASESTR''@|$(HAVE_STRCASESTR)|g' \
              -e 's|@''HAVE_DECL_STRTOK_R''@|$(HAVE_DECL_STRTOK_R)|g' \
+             -e 's|@''HAVE_DECL_STRERROR_R''@|$(HAVE_DECL_STRERROR_R)|g' \
              -e 's|@''HAVE_DECL_STRSIGNAL''@|$(HAVE_DECL_STRSIGNAL)|g' \
              -e 's|@''HAVE_STRVERSCMP''@|$(HAVE_STRVERSCMP)|g' \
              -e 's|@''REPLACE_STPNCPY''@|$(REPLACE_STPNCPY)|g' \
@@ -88,6 +90,7 @@
              -e 's|@''REPLACE_STRDUP''@|$(REPLACE_STRDUP)|g' \
              -e 's|@''REPLACE_STRSTR''@|$(REPLACE_STRSTR)|g' \
              -e 's|@''REPLACE_STRERROR''@|$(REPLACE_STRERROR)|g' \
+             -e 's|@''REPLACE_STRERROR_R''@|$(REPLACE_STRERROR_R)|g' \
              -e 's|@''REPLACE_STRNCAT''@|$(REPLACE_STRNCAT)|g' \
              -e 's|@''REPLACE_STRNDUP''@|$(REPLACE_STRNDUP)|g' \
              -e 's|@''REPLACE_STRNLEN''@|$(REPLACE_STRNLEN)|g' \
--- doc/posix-functions/strerror_r.texi.orig    Thu Nov 11 13:14:02 2010
+++ doc/posix-functions/strerror_r.texi Thu Nov 11 13:00:49 2010
@@ -4,17 +4,13 @@
 
 POSIX specification:@* 
@url{http://www.opengroup.org/onlinepubs/9699919799/functions/strerror_r.html}
 
-Gnulib module: ---
+Gnulib module: strerror_r-posix
 
 Portability problems fixed by Gnulib:
 @itemize
address@hidden itemize
-
-Portability problems not fixed by Gnulib:
address@hidden
 @item
 This function is missing on some platforms:
-NetBSD 3.0, HP-UX 11, IRIX 6.5, Solaris 9, mingw.
+NetBSD 3.0, HP-UX 11.23, IRIX 6.5, Solaris 9, mingw.
 @item
 glibc has an incompatible version of this function.  The POSIX compliant code
 @smallexample
@@ -24,4 +20,35 @@
 @smallexample
 char *s = strerror_r (err, buf, buflen);
 @end smallexample
address@hidden
+This function is sometimes not declared in @code{<string.h>} on some platforms:
+glibc 2.8, OSF/1 5.1.
address@hidden
+The third argument is of type @code{int} instead of @code{size_t} on some
+platforms:
+AIX 5.1, OSF/1 5.1.
address@hidden
+When this function fails, it returns -1 and sets @code{errno}, instead of
+returning the error number, on some platforms:
+glibc 2.8 with @code{-D_POSIX_C_SOURCE=200112L}, AIX 6.1, OSF/1 5.1.
address@hidden
+This function does not support the error values that are specified by POSIX
+but not defined by the system, on some platforms:
+OpenBSD 4.0, OSF/1 5.1, NonStop Kernel, Cygwin 1.5.x.
address@hidden
+This function always fails when the third argument is less than 80 on some
+platforms:
+HP-UX 11.31.
address@hidden
+When the buffer is too small, this function does not fail, but instead
+truncates the result and returns 0 on some platforms:
+OSF/1 5.1.
address@hidden itemize
+
+Portability problems not fixed by Gnulib:
address@hidden
address@hidden
+When the buffer is too small, this function does not fail, but instead
+truncates the result and returns 0 on some platforms:
+AIX 6.1.
 @end itemize