gl/tests/strerror_r.c

   1 /* strerror_r.c --- POSIX compatible system error routine
   2
   3    Copyright (C) 2010-2012 Free Software Foundation, Inc.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  17
  18 /* Written by Bruno Haible <bruno@clisp.org>, 2010.  */
  19
  20 #include <config.h>
  21
  22 /* Enable declaration of sys_nerr and sys_errlist in <errno.h> on NetBSD.  */
  23 #define _NETBSD_SOURCE 1
  24
  25 /* Specification.  */
  26 #include <string.h>
  27
  28 #include <errno.h>
  29 #include <stdio.h>
  30 #include <stdlib.h>
  31
  32 #include "strerror-override.h"
  33
  34 #if (__GLIBC__ >= 2 || defined __UCLIBC__ || defined __CYGWIN__) && HAVE___XPG_STRERROR_R /* glibc >= 2.3.4, cygwin >= 1.7.9 */
  35
  36 # define USE_XPG_STRERROR_R 1
  37 extern int __xpg_strerror_r (int errnum, char *buf, size_t buflen);
  38
  39 #elif HAVE_DECL_STRERROR_R && !(__GLIBC__ >= 2 || defined __UCLIBC__ || defined __CYGWIN__)
  40
  41 /* The system's strerror_r function is OK, except that its third argument
  42    is 'int', not 'size_t', or its return type is wrong.  */
  43
  44 # include <limits.h>
  45
  46 # define USE_SYSTEM_STRERROR_R 1
  47
  48 #else /* (__GLIBC__ >= 2 || defined __UCLIBC__ || defined __CYGWIN__ ? !HAVE___XPG_STRERROR_R : !HAVE_DECL_STRERROR_R) */
  49
  50 /* Use the system's strerror().  Exclude glibc and cygwin because the
  51    system strerror_r has the wrong return type, and cygwin 1.7.9
  52    strerror_r clobbers strerror.  */
  53 # undef strerror
  54
  55 # define USE_SYSTEM_STRERROR 1
  56
  57 # if defined __NetBSD__ || defined __hpux || ((defined _WIN32 || defined __WIN32__) && !defined __CYGWIN__) || defined __sgi || (defined __sun && !defined _LP64) || defined __CYGWIN__
  58
  59 /* No locking needed.  */
  60
  61 /* Get catgets internationalization functions.  */
  62 #  if HAVE_CATGETS
  63 #   include <nl_types.h>
  64 #  endif
  65
  66 /* Get sys_nerr, sys_errlist on HP-UX (otherwise only declared in C++ mode).
  67    Get sys_nerr, sys_errlist on IRIX (otherwise only declared with _SGIAPI).  */
  68 #  if defined __hpux || defined __sgi
  69 extern int sys_nerr;
  70 extern char *sys_errlist[];
  71 #  endif
  72
  73 /* Get sys_nerr on Solaris.  */
  74 #  if defined __sun && !defined _LP64
  75 extern int sys_nerr;
  76 #  endif
  77
  78 # else
  79
  80 #  include "glthread/lock.h"
  81
  82 /* This lock protects the buffer returned by strerror().  We assume that
  83    no other uses of strerror() exist in the program.  */
  84 gl_lock_define_initialized(static, strerror_lock)
  85
  86 # endif
  87
  88 #endif
  89
  90 /* On MSVC, there is no snprintf() function, just a _snprintf().
  91    It is of lower quality, but sufficient for the simple use here.
  92    We only have to make sure to NUL terminate the result (_snprintf
  93    does not NUL terminate, like strncpy).  */
  94 #if !HAVE_SNPRINTF
  95 static int
  96 local_snprintf (char *buf, size_t buflen, const char *format, ...)
  97 {
  98   va_list args;
  99   int result;
 100
 101   va_start (args, format);
 102   result = _vsnprintf (buf, buflen, format, args);
 103   va_end (args);
 104   if (buflen > 0 && (result < 0 || result >= buflen))
 105     buf[buflen - 1] = '\0';
 106   return result;
 107 }
 108 # define snprintf local_snprintf
 109 #endif
 110
 111 /* Copy as much of MSG into BUF as possible, without corrupting errno.
 112    Return 0 if MSG fit in BUFLEN, otherwise return ERANGE.  */
 113 static int
 114 safe_copy (char *buf, size_t buflen, const char *msg)
 115 {
 116   size_t len = strlen (msg);
 117   int ret;
 118
 119   if (len < buflen)
 120     {
 121       /* Although POSIX allows memcpy() to corrupt errno, we don't
 122          know of any implementation where this is a real problem.  */
 123       memcpy (buf, msg, len + 1);
 124       ret = 0;
 125     }
 126   else
 127     {
 128       memcpy (buf, msg, buflen - 1);
 129       buf[buflen - 1] = '\0';
 130       ret = ERANGE;
 131     }
 132   return ret;
 133 }
 134
 135
 136 int
 137 strerror_r (int errnum, char *buf, size_t buflen)
 138 #undef strerror_r
 139 {
 140   /* Filter this out now, so that rest of this replacement knows that
 141      there is room for a non-empty message and trailing NUL.  */
 142   if (buflen <= 1)
 143     {
 144       if (buflen)
 145         *buf = '\0';
 146       return ERANGE;
 147     }
 148   *buf = '\0';
 149
 150   /* Check for gnulib overrides.  */
 151   {
 152     char const *msg = strerror_override (errnum);
 153
 154     if (msg)
 155       return safe_copy (buf, buflen, msg);
 156   }
 157
 158   {
 159     int ret;
 160     int saved_errno = errno;
 161
 162 #if USE_XPG_STRERROR_R
 163
 164     {
 165       ret = __xpg_strerror_r (errnum, buf, buflen);
 166       if (ret < 0)
 167         ret = errno;
 168       if (!*buf)
 169         {
 170           /* glibc 2.13 would not touch buf on err, so we have to fall
 171              back to GNU strerror_r which always returns a thread-safe
 172              untruncated string to (partially) copy into our buf.  */
 173           safe_copy (buf, buflen, strerror_r (errnum, buf, buflen));
 174         }
 175     }
 176
 177 #elif USE_SYSTEM_STRERROR_R
 178
 179     if (buflen > INT_MAX)
 180       buflen = INT_MAX;
 181
 182 # ifdef __hpux
 183     /* On HP-UX 11.31, strerror_r always fails when buflen < 80; it
 184        also fails to change buf on EINVAL.  */
 185     {
 186       char stackbuf[80];
 187
 188       if (buflen < sizeof stackbuf)
 189         {
 190           ret = strerror_r (errnum, stackbuf, sizeof stackbuf);
 191           if (ret == 0)
 192             ret = safe_copy (buf, buflen, stackbuf);
 193         }
 194       else
 195         ret = strerror_r (errnum, buf, buflen);
 196     }
 197 # else
 198     ret = strerror_r (errnum, buf, buflen);
 199
 200     /* Some old implementations may return (-1, EINVAL) instead of EINVAL.  */
 201     if (ret < 0)
 202       ret = errno;
 203 # endif
 204
 205 # ifdef _AIX
 206     /* AIX returns 0 rather than ERANGE when truncating strings; try
 207        again until we are sure we got the entire string.  */
 208     if (!ret && strlen (buf) == buflen - 1)
 209       {
 210         char stackbuf[STACKBUF_LEN];
 211         size_t len;
 212         strerror_r (errnum, stackbuf, sizeof stackbuf);
 213         len = strlen (stackbuf);
 214         /* STACKBUF_LEN should have been large enough.  */
 215         if (len + 1 == sizeof stackbuf)
 216           abort ();
 217         if (buflen <= len)
 218           ret = ERANGE;
 219       }
 220 # else
 221     /* Solaris 10 does not populate buf on ERANGE.  OpenBSD 4.7
 222        truncates early on ERANGE rather than return a partial integer.
 223        We prefer the maximal string.  We set buf[0] earlier, and we
 224        know of no implementation that modifies buf to be an
 225        unterminated string, so this strlen should be portable in
 226        practice (rather than pulling in a safer strnlen).  */
 227     if (ret == ERANGE && strlen (buf) < buflen - 1)
 228       {
 229         char stackbuf[STACKBUF_LEN];
 230
 231         /* STACKBUF_LEN should have been large enough.  */
 232         if (strerror_r (errnum, stackbuf, sizeof stackbuf) == ERANGE)
 233           abort ();
 234         safe_copy (buf, buflen, stackbuf);
 235       }
 236 # endif
 237
 238 #else /* USE_SYSTEM_STRERROR */
 239
 240     /* Try to do what strerror (errnum) does, but without clobbering the
 241        buffer used by strerror().  */
 242
 243 # if defined __NetBSD__ || defined __hpux || ((defined _WIN32 || defined __WIN32__) && !defined __CYGWIN__) || defined __CYGWIN__ /* NetBSD, HP-UX, native Windows, Cygwin */
 244
 245     /* NetBSD:         sys_nerr, sys_errlist are declared through _NETBSD_SOURCE
 246                        and <errno.h> above.
 247        HP-UX:          sys_nerr, sys_errlist are declared explicitly above.
 248        native Windows: sys_nerr, sys_errlist are declared in <stdlib.h>.
 249        Cygwin:         sys_nerr, sys_errlist are declared in <errno.h>.  */
 250     if (errnum >= 0 && errnum < sys_nerr)
 251       {
 252 #  if HAVE_CATGETS && (defined __NetBSD__ || defined __hpux)
 253 #   if defined __NetBSD__
 254         nl_catd catd = catopen ("libc", NL_CAT_LOCALE);
 255         const char *errmsg =
 256           (catd != (nl_catd)-1
 257            ? catgets (catd, 1, errnum, sys_errlist[errnum])
 258            : sys_errlist[errnum]);
 259 #   endif
 260 #   if defined __hpux
 261         nl_catd catd = catopen ("perror", NL_CAT_LOCALE);
 262         const char *errmsg =
 263           (catd != (nl_catd)-1
 264            ? catgets (catd, 1, 1 + errnum, sys_errlist[errnum])
 265            : sys_errlist[errnum]);
 266 #   endif
 267 #  else
 268         const char *errmsg = sys_errlist[errnum];
 269 #  endif
 270         if (errmsg == NULL || *errmsg == '\0')
 271           ret = EINVAL;
 272         else
 273           ret = safe_copy (buf, buflen, errmsg);
 274 #  if HAVE_CATGETS && (defined __NetBSD__ || defined __hpux)
 275         if (catd != (nl_catd)-1)
 276           catclose (catd);
 277 #  endif
 278       }
 279     else
 280       ret = EINVAL;
 281
 282 # elif defined __sgi || (defined __sun && !defined _LP64) /* IRIX, Solaris <= 9 32-bit */
 283
 284     /* For a valid error number, the system's strerror() function returns
 285        a pointer to a not copied string, not to a buffer.  */
 286     if (errnum >= 0 && errnum < sys_nerr)
 287       {
 288         char *errmsg = strerror (errnum);
 289
 290         if (errmsg == NULL || *errmsg == '\0')
 291           ret = EINVAL;
 292         else
 293           ret = safe_copy (buf, buflen, errmsg);
 294       }
 295     else
 296       ret = EINVAL;
 297
 298 # else
 299
 300     gl_lock_lock (strerror_lock);
 301
 302     {
 303       char *errmsg = strerror (errnum);
 304
 305       /* For invalid error numbers, strerror() on
 306            - IRIX 6.5 returns NULL,
 307            - HP-UX 11 returns an empty string.  */
 308       if (errmsg == NULL || *errmsg == '\0')
 309         ret = EINVAL;
 310       else
 311         ret = safe_copy (buf, buflen, errmsg);
 312     }
 313
 314     gl_lock_unlock (strerror_lock);
 315
 316 # endif
 317
 318 #endif
 319
 320     if (ret == EINVAL && !*buf)
 321       snprintf (buf, buflen, "Unknown error %d", errnum);
 322
 323     errno = saved_errno;
 324     return ret;
 325   }
 326 }