/* strerror_r.c --- POSIX compatible system error routine

   Copyright (C) 2010-2026 Free Software Foundation, Inc.

   This file is free software: you can redistribute it and/or modify

   it under the terms of the GNU Lesser General Public License as

   published by the Free Software Foundation; either version 2.1 of the

   License, or (at your option) any later version.

   This file 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 Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License

   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */

/* Written by Bruno Haible <bruno@clisp.org>, 2010.  */

#include <config.h>

/* Enable declaration of sys_nerr and sys_errlist in <errno.h> on NetBSD.  */

#define _NETBSD_SOURCE 1

/* Specification.  */

#include <string.h>

#include <errno.h>

#include <stdio.h>

#include <stdlib.h>

#if !HAVE_SNPRINTF

# include <stdarg.h>

#endif

#include "strerror-override.h"

#if STRERROR_R_CHAR_P && !defined _AIX

# if HAVE___XPG_STRERROR_R

_GL_EXTERN_C int __xpg_strerror_r (int errnum, char *buf, size_t buflen);

# endif

#elif HAVE_DECL_STRERROR_R

/* The system's strerror_r function's API is OK, except that its third argument

   is 'int', not 'size_t', or its return type is wrong.  */

# include <limits.h>

#else

/* Use the system's strerror().  Exclude glibc and cygwin because the

   system strerror_r has the wrong return type, and cygwin 1.7.9

   strerror_r clobbers strerror.  */

# undef strerror

# if defined __NetBSD__ || defined __hpux || (defined _WIN32 && !defined __CYGWIN__) || (defined __sun && !defined _LP64) || defined __CYGWIN__

/* No locking needed.  */

/* Get catgets internationalization functions.  */

#  if HAVE_CATGETS

#   include <nl_types.h>

#  endif

#ifdef __cplusplus

extern "C" {

#endif

/* Get sys_nerr, sys_errlist on HP-UX (otherwise only declared in C++ mode).  */

#  if defined __hpux

extern int sys_nerr;

extern char *sys_errlist[];

#  endif

/* Get sys_nerr on Solaris.  */

#  if defined __sun && !defined _LP64

extern int sys_nerr;

#  endif

#ifdef __cplusplus

}

#endif

# else

#  include "glthread/lock.h"

/* 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)

# endif

#endif

/* On MSVC, there is no snprintf() function, just a _snprintf().

   It is of lower quality, but sufficient for the simple use here.

   We only have to make sure to NUL terminate the result (_snprintf

   does not NUL terminate, like strncpy).  */

#if !HAVE_SNPRINTF

static int

local_snprintf (char *buf, size_t buflen, const char *format, ...)

{

  va_list args;

  va_start (args, format);

  int result = _vsnprintf (buf, buflen, format, args);

  va_end (args);

  if (buflen > 0 && (result < 0 || result >= buflen))

    buf[buflen - 1] = '\0';

  return result;

}

# undef snprintf

# define snprintf local_snprintf

#endif

/* Copy as much of MSG into BUF as possible, without corrupting errno.

   Return 0 if MSG fit in BUFLEN, otherwise return ERANGE.  */

static int

safe_copy (char *buf, size_t buflen, const char *msg)

{

  size_t len = strlen (msg);

  size_t moved = len < buflen ? len : buflen - 1;

  /* Although POSIX lets memmove corrupt errno, we don't

     know of any implementation where this is a real problem.  */

  memmove (buf, msg, moved);

  buf[moved] = '\0';

  return len < buflen ? 0 : ERANGE;

}

int

strerror_r (int errnum, char *buf, size_t buflen)

#undef strerror_r

{

  /* Filter this out now, so that rest of this replacement knows that

     there is room for a non-empty message and trailing NUL.  */

  if (buflen <= 1)

    {

      if (buflen)

        *buf = '\0';

      return ERANGE;

    }

  *buf = '\0';

  /* Check for gnulib overrides.  */

  {

    char const *msg = strerror_override (errnum);

    if (msg)

      return safe_copy (buf, buflen, msg);

  }

  {

    int ret;

    int saved_errno = errno;

    /* Due to the '#undef strerror_r' above, on AIX, we're always using

       the POSIX-compatible strerror_r function, regardless whether

       _LINUX_SOURCE_COMPAT is defined or not.  */

#if STRERROR_R_CHAR_P && !defined _AIX

    {

      ret = 0;

# if HAVE___XPG_STRERROR_R

      ret = __xpg_strerror_r (errnum, buf, buflen);

      /* ret is 0 upon success, or EINVAL or ERANGE upon failure.  */

# endif

      if (!*buf)

        {

          /* glibc 2.13 ... 2.34 (at least) don't touch buf upon failure.

             Therefore we have to fall back to strerror_r which, for valid

             errnum, returns a thread-safe untruncated string.  For invalid

             errnum, though, it returns a truncated string, which does not

             allow us to determine whether to return ERANGE or 0.  Thus we

             need to pass a sufficiently large buffer.  */

          char stackbuf[80];

          char *errstring = strerror_r (errnum, stackbuf, sizeof stackbuf);

          ret = errstring ? safe_copy (buf, buflen, errstring) : errno;

        }

    }

#elif HAVE_DECL_STRERROR_R

    if (buflen > INT_MAX)

      buflen = INT_MAX;

# ifdef __hpux

    /* On HP-UX 11.31, strerror_r always fails when buflen < 80; it

       also fails to change buf on EINVAL.  */

    {

      char stackbuf[80];

      if (buflen < sizeof stackbuf)

        {

          ret = strerror_r (errnum, stackbuf, sizeof stackbuf);

          if (ret == 0)

            ret = safe_copy (buf, buflen, stackbuf);

        }

      else

        ret = strerror_r (errnum, buf, buflen);

    }

# else

    ret = strerror_r (errnum, buf, buflen);

    /* Some old implementations may return (-1, EINVAL) instead of EINVAL.

       But on Haiku, valid error numbers are negative.  */

#  if !defined __HAIKU__

    if (ret < 0)

      ret = errno;

#  endif

# endif

# if defined _AIX || defined __HAIKU__

    /* AIX and Haiku return 0 rather than ERANGE when truncating strings; try

       again until we are sure we got the entire string.  */

    if (!ret && strlen (buf) == buflen - 1)

      {

        char stackbuf[STACKBUF_LEN];

        strerror_r (errnum, stackbuf, sizeof stackbuf);

        size_t len = strlen (stackbuf);

        /* STACKBUF_LEN should have been large enough.  */

        if (len + 1 == sizeof stackbuf)

          abort ();

        if (buflen <= len)

          ret = ERANGE;

      }

# else

    /* Solaris 10 does not populate buf on ERANGE.  OpenBSD 4.7

       truncates early on ERANGE rather than return a partial integer.

       We prefer the maximal string.  We set buf[0] earlier, and we

       know of no implementation that modifies buf to be an

       unterminated string, so this strlen should be portable in

       practice (rather than pulling in a safer strnlen).  */

    if (ret == ERANGE && strlen (buf) < buflen - 1)

      {

        char stackbuf[STACKBUF_LEN];

        /* STACKBUF_LEN should have been large enough.  */

        if (strerror_r (errnum, stackbuf, sizeof stackbuf) == ERANGE)

          abort ();

        safe_copy (buf, buflen, stackbuf);

      }

# endif

#else /* strerror_r is not declared.  */

    /* Try to do what strerror (errnum) does, but without clobbering the

       buffer used by strerror().  */

# if defined __NetBSD__ || defined __hpux || (defined _WIN32 && !defined __CYGWIN__) || defined __CYGWIN__ /* NetBSD, HP-UX, native Windows, Cygwin */

    /* NetBSD:         sys_nerr, sys_errlist are declared through _NETBSD_SOURCE

                       and <errno.h> above.

       HP-UX:          sys_nerr, sys_errlist are declared explicitly above.

       native Windows: sys_nerr, sys_errlist are declared in <stdlib.h>.

       Cygwin:         sys_nerr, sys_errlist are declared in <errno.h>.  */

    if (errnum >= 0 && errnum < sys_nerr)

      {

#  if HAVE_CATGETS && (defined __NetBSD__ || defined __hpux)

#   if defined __NetBSD__

        nl_catd catd = catopen ("libc", NL_CAT_LOCALE);

        const char *errmsg =

          (catd != (nl_catd)-1

           ? catgets (catd, 1, errnum, sys_errlist[errnum])

           : sys_errlist[errnum]);

#   endif

#   if defined __hpux

        nl_catd catd = catopen ("perror", NL_CAT_LOCALE);

        const char *errmsg =

          (catd != (nl_catd)-1

           ? catgets (catd, 1, 1 + errnum, sys_errlist[errnum])

           : sys_errlist[errnum]);

#   endif

#  else

        const char *errmsg = sys_errlist[errnum];

#  endif

        if (errmsg == NULL || *errmsg == '\0')

          ret = EINVAL;

        else

          ret = safe_copy (buf, buflen, errmsg);

#  if HAVE_CATGETS && (defined __NetBSD__ || defined __hpux)

        if (catd != (nl_catd)-1)

          catclose (catd);

#  endif

      }

    else

      ret = EINVAL;

# elif defined __sun && !defined _LP64 /* Solaris <= 9 32-bit */

    /* For a valid error number, the system's strerror() function returns

       a pointer to a not copied string, not to a buffer.  */

    if (errnum >= 0 && errnum < sys_nerr)

      {

        char *errmsg = strerror (errnum);

        if (errmsg == NULL || *errmsg == '\0')

          ret = EINVAL;

        else

          ret = safe_copy (buf, buflen, errmsg);

      }

    else

      ret = EINVAL;

# else

    gl_lock_lock (strerror_lock);

    {

      char *errmsg = strerror (errnum);

      /* For invalid error numbers, strerror() on HP-UX 11 returns an empty

         string.  */

      if (*errmsg == '\0')

        ret = EINVAL;

      else

        ret = safe_copy (buf, buflen, errmsg);

    }

    gl_lock_unlock (strerror_lock);

# endif

#endif

#if defined _WIN32 && !defined __CYGWIN__

    /* MSVC 14 defines names for many error codes in the range 100..140,

       but _sys_errlist contains strings only for the error codes

       < _sys_nerr = 43.  */

    if (ret == EINVAL)

      {

        const char *errmsg;

        switch (errnum)

          {

          case 100 /* EADDRINUSE */:

            errmsg = "Address already in use";

            break;

          case 101 /* EADDRNOTAVAIL */:

            errmsg = "Cannot assign requested address";

            break;

          case 102 /* EAFNOSUPPORT */:

            errmsg = "Address family not supported by protocol";

            break;

          case 103 /* EALREADY */:

            errmsg = "Operation already in progress";

            break;

          case 105 /* ECANCELED */:

            errmsg = "Operation canceled";

            break;

          case 106 /* ECONNABORTED */:

            errmsg = "Software caused connection abort";

            break;

          case 107 /* ECONNREFUSED */:

            errmsg = "Connection refused";

            break;

          case 108 /* ECONNRESET */:

            errmsg = "Connection reset by peer";

            break;

          case 109 /* EDESTADDRREQ */:

            errmsg = "Destination address required";

            break;

          case 110 /* EHOSTUNREACH */:

            errmsg = "No route to host";

            break;

          case 112 /* EINPROGRESS */:

            errmsg = "Operation now in progress";

            break;

          case 113 /* EISCONN */:

            errmsg = "Transport endpoint is already connected";

            break;

          case 114 /* ELOOP */:

            errmsg = "Too many levels of symbolic links";

            break;

          case 115 /* EMSGSIZE */:

            errmsg = "Message too long";

            break;

          case 116 /* ENETDOWN */:

            errmsg = "Network is down";

            break;

          case 117 /* ENETRESET */:

            errmsg = "Network dropped connection on reset";

            break;

          case 118 /* ENETUNREACH */:

            errmsg = "Network is unreachable";

            break;

          case 119 /* ENOBUFS */:

            errmsg = "No buffer space available";

            break;

          case 123 /* ENOPROTOOPT */:

            errmsg = "Protocol not available";

            break;

          case 126 /* ENOTCONN */:

            errmsg = "Transport endpoint is not connected";

            break;

          case 128 /* ENOTSOCK */:

            errmsg = "Socket operation on non-socket";

            break;

          case 129 /* ENOTSUP */:

            errmsg = "Not supported";

            break;

          case 130 /* EOPNOTSUPP */:

            errmsg = "Operation not supported";

            break;

          case 132 /* EOVERFLOW */:

            errmsg = "Value too large for defined data type";

            break;

          case 133 /* EOWNERDEAD */:

            errmsg = "Owner died";

            break;

          case 134 /* EPROTO */:

            errmsg = "Protocol error";

            break;

          case 135 /* EPROTONOSUPPORT */:

            errmsg = "Protocol not supported";

            break;

          case 136 /* EPROTOTYPE */:

            errmsg = "Protocol wrong type for socket";

            break;

          case 138 /* ETIMEDOUT */:

            errmsg = "Connection timed out";

            break;

          case 140 /* EWOULDBLOCK */:

            errmsg = "Operation would block";

            break;

          default:

            errmsg = NULL;

            break;

          }

        if (errmsg != NULL)

          ret = safe_copy (buf, buflen, errmsg);

      }

#endif

    if (ret == EINVAL && !*buf)

      {

        /* gcc 14 produces a

           "warning: 'Unknown error ' directive output truncated

            writing 14 bytes into a region of size 2"

           Thanks for the warning, but here the truncation is intentional.  */

#if _GL_GNUC_PREREQ (7, 1)

# pragma GCC diagnostic ignored "-Wformat-truncation"

#endif

#if defined __HAIKU__

        /* For consistency with perror().  */

        snprintf (buf, buflen, "Unknown Application Error (%d)", errnum);

#else

        snprintf (buf, buflen, "Unknown error %d", errnum);

#endif

        buf[buflen - 1] = '\0';

      }

    errno = saved_errno;

    return ret;

  }

}