strerror.c

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/*-------------------------------------------------------------------------
 *
 * strerror.c
 *    Replacements for standard strerror() and strerror_r() functions
 *
 * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/port/strerror.c
 *
 *-------------------------------------------------------------------------
 */
#include "c.h"
 
/*
 * Within this file, "strerror" means the platform's function not pg_strerror,
 * and likewise for "strerror_r"
 */
#undef strerror
#undef strerror_r
 
static char *gnuish_strerror_r(int errnum, char *buf, size_t buflen);
static char *get_errno_symbol(int errnum);
#ifdef WIN32
static char *win32_socket_strerror(int errnum, char *buf, size_t buflen);
#endif
 
 
/*
 * A slightly cleaned-up version of strerror()
 */
char *
pg_strerror(int errnum)
{
    static char errorstr_buf[PG_STRERROR_R_BUFLEN];
 
    return pg_strerror_r(errnum, errorstr_buf, sizeof(errorstr_buf));
}
 
/*
 * A slightly cleaned-up version of strerror_r()
 */
char *
pg_strerror_r(int errnum, char *buf, size_t buflen)
{
    char       *str;
 
    /* If it's a Windows Winsock error, that needs special handling */
#ifdef WIN32
    /* Winsock error code range, per WinError.h */
    if (errnum >= 10000 && errnum <= 11999)
        return win32_socket_strerror(errnum, buf, buflen);
#endif
 
    /* Try the platform's strerror_r(), or maybe just strerror() */
    str = gnuish_strerror_r(errnum, buf, buflen);
 
    /*
     * Some strerror()s return an empty string for out-of-range errno.  This
     * is ANSI C spec compliant, but not exactly useful.  Also, we may get
     * back strings of question marks if libc cannot transcode the message to
     * the codeset specified by LC_CTYPE.  If we get nothing useful, first try
     * get_errno_symbol(), and if that fails, print the numeric errno.
     */
    if (str == NULL || *str == '\0' || *str == '?')
        str = get_errno_symbol(errnum);
 
    if (str == NULL)
    {
        snprintf(buf, buflen, _("operating system error %d"), errnum);
        str = buf;
    }
 
    return str;
}
 
/*
 * Simple wrapper to emulate GNU strerror_r if what the platform provides is
 * POSIX.  Also, if platform lacks strerror_r altogether, fall back to plain
 * strerror; it might not be very thread-safe, but tough luck.
 */
static char *
gnuish_strerror_r(int errnum, char *buf, size_t buflen)
{
#ifdef HAVE_STRERROR_R
#ifdef STRERROR_R_INT
    /* POSIX API */
    if (strerror_r(errnum, buf, buflen) == 0)
        return buf;
    return NULL;                /* let caller deal with failure */
#else
    /* GNU API */
    return strerror_r(errnum, buf, buflen);
#endif
#else                           /* !HAVE_STRERROR_R */
    char       *sbuf = strerror(errnum);
 
    if (sbuf == NULL)           /* can this still happen anywhere? */
        return NULL;
    /* To minimize thread-unsafety hazard, copy into caller's buffer */
    strlcpy(buf, sbuf, buflen);
    return buf;
#endif
}
 
/*
 * Returns a symbol (e.g. "ENOENT") for an errno code.
 * Returns NULL if the code is unrecognized.
 */
static char *
get_errno_symbol(int errnum)
{
    switch (errnum)
    {
        case E2BIG:
            return "E2BIG";
        case EACCES:
            return "EACCES";
        case EADDRINUSE:
            return "EADDRINUSE";
        case EADDRNOTAVAIL:
            return "EADDRNOTAVAIL";
        case EAFNOSUPPORT:
            return "EAFNOSUPPORT";
#ifdef EAGAIN
        case EAGAIN:
            return "EAGAIN";
#endif
#ifdef EALREADY
        case EALREADY:
            return "EALREADY";
#endif
        case EBADF:
            return "EBADF";
#ifdef EBADMSG
        case EBADMSG:
            return "EBADMSG";
#endif
        case EBUSY:
            return "EBUSY";
        case ECHILD:
            return "ECHILD";
        case ECONNABORTED:
            return "ECONNABORTED";
        case ECONNREFUSED:
            return "ECONNREFUSED";
        case ECONNRESET:
            return "ECONNRESET";
        case EDEADLK:
            return "EDEADLK";
        case EDOM:
            return "EDOM";
        case EEXIST:
            return "EEXIST";
        case EFAULT:
            return "EFAULT";
        case EFBIG:
            return "EFBIG";
        case EHOSTDOWN:
            return "EHOSTDOWN";
        case EHOSTUNREACH:
            return "EHOSTUNREACH";
        case EIDRM:
            return "EIDRM";
        case EINPROGRESS:
            return "EINPROGRESS";
        case EINTR:
            return "EINTR";
        case EINVAL:
            return "EINVAL";
        case EIO:
            return "EIO";
        case EISCONN:
            return "EISCONN";
        case EISDIR:
            return "EISDIR";
#ifdef ELOOP
        case ELOOP:
            return "ELOOP";
#endif
        case EMFILE:
            return "EMFILE";
        case EMLINK:
            return "EMLINK";
        case EMSGSIZE:
            return "EMSGSIZE";
        case ENAMETOOLONG:
            return "ENAMETOOLONG";
        case ENETDOWN:
            return "ENETDOWN";
        case ENETRESET:
            return "ENETRESET";
        case ENETUNREACH:
            return "ENETUNREACH";
        case ENFILE:
            return "ENFILE";
        case ENOBUFS:
            return "ENOBUFS";
        case ENODEV:
            return "ENODEV";
        case ENOENT:
            return "ENOENT";
        case ENOEXEC:
            return "ENOEXEC";
        case ENOMEM:
            return "ENOMEM";
        case ENOSPC:
            return "ENOSPC";
        case ENOSYS:
            return "ENOSYS";
        case ENOTCONN:
            return "ENOTCONN";
        case ENOTDIR:
            return "ENOTDIR";
#if defined(ENOTEMPTY) && (ENOTEMPTY != EEXIST) /* same code on AIX */
        case ENOTEMPTY:
            return "ENOTEMPTY";
#endif
        case ENOTSOCK:
            return "ENOTSOCK";
#ifdef ENOTSUP
        case ENOTSUP:
            return "ENOTSUP";
#endif
        case ENOTTY:
            return "ENOTTY";
        case ENXIO:
            return "ENXIO";
#if defined(EOPNOTSUPP) && (!defined(ENOTSUP) || (EOPNOTSUPP != ENOTSUP))
        case EOPNOTSUPP:
            return "EOPNOTSUPP";
#endif
#ifdef EOVERFLOW
        case EOVERFLOW:
            return "EOVERFLOW";
#endif
        case EPERM:
            return "EPERM";
        case EPIPE:
            return "EPIPE";
        case EPROTONOSUPPORT:
            return "EPROTONOSUPPORT";
        case ERANGE:
            return "ERANGE";
#ifdef EROFS
        case EROFS:
            return "EROFS";
#endif
        case ESRCH:
            return "ESRCH";
        case ETIMEDOUT:
            return "ETIMEDOUT";
#ifdef ETXTBSY
        case ETXTBSY:
            return "ETXTBSY";
#endif
#if defined(EWOULDBLOCK) && (!defined(EAGAIN) || (EWOULDBLOCK != EAGAIN))
        case EWOULDBLOCK:
            return "EWOULDBLOCK";
#endif
        case EXDEV:
            return "EXDEV";
    }
 
    return NULL;
}
 
 
#ifdef WIN32
 
/*
 * Windows' strerror() doesn't know the Winsock codes, so handle them this way
 */
static char *
win32_socket_strerror(int errnum, char *buf, size_t buflen)
{
    static HANDLE handleDLL = INVALID_HANDLE_VALUE;
 
    if (handleDLL == INVALID_HANDLE_VALUE)
    {
        handleDLL = LoadLibraryEx("netmsg.dll", NULL,
                                  DONT_RESOLVE_DLL_REFERENCES | LOAD_LIBRARY_AS_DATAFILE);
        if (handleDLL == NULL)
        {
            snprintf(buf, buflen,
                     "winsock error %d (could not load netmsg.dll to translate: error code %lu)",
                     errnum, GetLastError());
            return buf;
        }
    }
 
    ZeroMemory(buf, buflen);
    if (FormatMessage(FORMAT_MESSAGE_IGNORE_INSERTS |
                      FORMAT_MESSAGE_FROM_SYSTEM |
                      FORMAT_MESSAGE_FROM_HMODULE,
                      handleDLL,
                      errnum,
                      MAKELANGID(LANG_ENGLISH, SUBLANG_DEFAULT),
                      buf,
                      buflen - 1,
                      NULL) == 0)
    {
        /* Failed to get id */
        snprintf(buf, buflen, "unrecognized winsock error %d", errnum);
    }
 
    return buf;
}
 
#endif                          /* WIN32 */