/* SPDX-License-Identifier: LGPL-2.1+ */
/*
 * Copyright (C) 2018 Red Hat, Inc.
 */

#include "nm-default.h"

#include "nm-errno.h"

#include <pthread.h>

/*****************************************************************************/

static NM_UTILS_LOOKUP_STR_DEFINE(
    _geterror,
#if 0
    enum _NMErrno,
#else
    int,
#endif
    NM_UTILS_LOOKUP_DEFAULT(NULL),

    NM_UTILS_LOOKUP_STR_ITEM(NME_ERRNO_SUCCESS, "NME_ERRNO_SUCCESS"),
    NM_UTILS_LOOKUP_STR_ITEM(NME_ERRNO_OUT_OF_RANGE, "NME_ERRNO_OUT_OF_RANGE"),

    NM_UTILS_LOOKUP_STR_ITEM(NME_UNSPEC, "NME_UNSPEC"),
    NM_UTILS_LOOKUP_STR_ITEM(NME_BUG, "NME_BUG"),
    NM_UTILS_LOOKUP_STR_ITEM(NME_NATIVE_ERRNO, "NME_NATIVE_ERRNO"),

    NM_UTILS_LOOKUP_STR_ITEM(NME_NL_ATTRSIZE, "NME_NL_ATTRSIZE"),
    NM_UTILS_LOOKUP_STR_ITEM(NME_NL_BAD_SOCK, "NME_NL_BAD_SOCK"),
    NM_UTILS_LOOKUP_STR_ITEM(NME_NL_DUMP_INTR, "NME_NL_DUMP_INTR"),
    NM_UTILS_LOOKUP_STR_ITEM(NME_NL_MSG_OVERFLOW, "NME_NL_MSG_OVERFLOW"),
    NM_UTILS_LOOKUP_STR_ITEM(NME_NL_MSG_TOOSHORT, "NME_NL_MSG_TOOSHORT"),
    NM_UTILS_LOOKUP_STR_ITEM(NME_NL_MSG_TRUNC, "NME_NL_MSG_TRUNC"),
    NM_UTILS_LOOKUP_STR_ITEM(NME_NL_SEQ_MISMATCH, "NME_NL_SEQ_MISMATCH"),
    NM_UTILS_LOOKUP_STR_ITEM(NME_NL_NOADDR, "NME_NL_NOADDR"),

    NM_UTILS_LOOKUP_STR_ITEM(NME_PL_NOT_FOUND, "not-found"),
    NM_UTILS_LOOKUP_STR_ITEM(NME_PL_EXISTS, "exists"),
    NM_UTILS_LOOKUP_STR_ITEM(NME_PL_WRONG_TYPE, "wrong-type"),
    NM_UTILS_LOOKUP_STR_ITEM(NME_PL_NOT_SLAVE, "not-slave"),
    NM_UTILS_LOOKUP_STR_ITEM(NME_PL_NO_FIRMWARE, "no-firmware"),
    NM_UTILS_LOOKUP_STR_ITEM(NME_PL_OPNOTSUPP, "not-supported"),
    NM_UTILS_LOOKUP_STR_ITEM(NME_PL_NETLINK, "netlink"),
    NM_UTILS_LOOKUP_STR_ITEM(NME_PL_CANT_SET_MTU, "cant-set-mtu"),

    NM_UTILS_LOOKUP_ITEM_IGNORE(_NM_ERRNO_MININT),
    NM_UTILS_LOOKUP_ITEM_IGNORE(_NM_ERRNO_RESERVED_LAST_PLUS_1), );

/**
 * nm_strerror():
 * @nmerr: the NetworkManager specific errno to be converted
 *   to string.
 *
 * NetworkManager specific error numbers reserve a range in "errno.h" with
 * our own defines. For numbers that don't fall into this range, the numbers
 * are identical to the common error numbers.
 *
 * Identical to strerror(), g_strerror(), nm_strerror_native() for error numbers
 * that are not in the reserved range of NetworkManager specific errors.
 *
 * Returns: (transfer none): the string representation of the error number.
 */
const char *
nm_strerror(int nmerr)
{
    const char *s;

    nmerr = nm_errno(nmerr);

    if (nmerr >= _NM_ERRNO_RESERVED_FIRST) {
        s = _geterror(nmerr);
        if (s)
            return s;
    }
    return nm_strerror_native(nmerr);
}

/*****************************************************************************/

/**
 * nm_strerror_native_r:
 * @errsv: the errno to convert to string.
 * @buf: the output buffer where to write the string to.
 * @buf_size: the length of buffer.
 *
 * This is like strerror_r(), with one difference: depending on the
 * locale, the returned string is guaranteed to be valid UTF-8.
 * Also, there is some confusion as to whether to use glibc's
 * strerror_r() or the POXIX/XSI variant. This is abstracted
 * by the function.
 *
 * Note that the returned buffer may also be a statically allocated
 * buffer, and not the input buffer @buf. Consequently, the returned
 * string may be longer than @buf_size.
 *
 * Returns: (transfer none): a NUL terminated error message. This is either a static
 *   string (that is never freed), or the provided @buf argument.
 */
const char *
nm_strerror_native_r(int errsv, char *buf, gsize buf_size)
{
    char *buf2;

    nm_assert(buf);
    nm_assert(buf_size > 0);

#if (_POSIX_C_SOURCE >= 200112L) && !_GNU_SOURCE
    /* XSI-compliant */
    {
        int errno_saved = errno;

        if (strerror_r(errsv, buf, buf_size) != 0) {
            g_snprintf(buf, buf_size, "Unspecified errno %d", errsv);
            errno = errno_saved;
        }
        buf2 = buf;
    }
#else
    /* GNU-specific */
    buf2 = strerror_r(errsv, buf, buf_size);
#endif

    /* like g_strerror(), ensure that the error message is UTF-8. */
    if (!g_get_charset(NULL) && !g_utf8_validate(buf2, -1, NULL)) {
        gs_free char *msg = NULL;

        msg = g_locale_to_utf8(buf2, -1, NULL, NULL, NULL);
        if (msg) {
            g_strlcpy(buf, msg, buf_size);
            buf2 = buf;
        }
    }

    return buf2;
}

/**
 * nm_strerror_native:
 * @errsv: the errno integer from <errno.h>
 *
 * Like strerror(), but strerror() is not thread-safe and not guaranteed
 * to be UTF-8.
 *
 * g_strerror() is a thread-safe variant of strerror(), however it caches
 * all returned strings in a dictionary. That means, using this on untrusted
 * error numbers can result in this cache to grow without limits.
 *
 * Instead, return a tread-local buffer. This way, it's thread-safe.
 *
 * There is a downside to this: subsequent calls of nm_strerror_native()
 * overwrite the error message.
 *
 * Returns: (transfer none): the text representation of the error number.
 */
const char *
nm_strerror_native(int errsv)
{
    static _nm_thread_local char *buf_static = NULL;
    char *                        buf;

    buf = buf_static;
    if (G_UNLIKELY(!buf)) {
        int           errno_saved = errno;
        pthread_key_t key;

        buf        = g_malloc(NM_STRERROR_BUFSIZE);
        buf_static = buf;

        if (pthread_key_create(&key, g_free) != 0 || pthread_setspecific(key, buf) != 0) {
            /* Failure. We will leak the buffer when the thread exits.
             *
             * Nothing we can do about it really. For Debug builds we fail with an assertion. */
            nm_assert_not_reached();
        }
        errno = errno_saved;
    }

    return nm_strerror_native_r(errsv, buf, NM_STRERROR_BUFSIZE);
}
