fish-shell/src/fallback.cpp

// This file only contains fallback implementations of functions which have been found to be missing
// or broken by the configuration scripts.
//
// Many of these functions are more or less broken and incomplete. lrand28_r internally uses the
// regular (bad) rand_r function, the gettext function doesn't actually do anything, etc.
#include "config.h"

// IWYU likes to recommend adding term.h when we want ncurses.h.
// IWYU pragma: no_include term.h
#include <dirent.h>  // IWYU pragma: keep
#include <errno.h>   // IWYU pragma: keep
#include <fcntl.h>   // IWYU pragma: keep
#include <limits.h>  // IWYU pragma: keep
#include <stdarg.h>  // IWYU pragma: keep
#include <stdio.h>   // IWYU pragma: keep
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>   // IWYU pragma: keep
#include <sys/types.h>  // IWYU pragma: keep
#include <unistd.h>
#include <wchar.h>
#include <wctype.h>
#if HAVE_GETTEXT
#include <libintl.h>
#endif
#if HAVE_NCURSES_H
#include <ncurses.h>  // IWYU pragma: keep
#elif HAVE_NCURSES_CURSES_H
#include <ncurses/curses.h>
#else
#include <curses.h>
#endif
#if HAVE_TERM_H
#include <term.h>  // IWYU pragma: keep
#elif HAVE_NCURSES_TERM_H
#include <ncurses/term.h>
#endif
#include <signal.h>  // IWYU pragma: keep
#include <wchar.h>   // IWYU pragma: keep

#include "common.h"    // IWYU pragma: keep
#include "fallback.h"  // IWYU pragma: keep
#include "util.h"      // IWYU pragma: keep

#ifdef TPARM_SOLARIS_KLUDGE
#undef tparm

/// Checks for known string values and maps to correct number of parameters.
char *tparm_solaris_kludge(char *str, ...) {
    long int param[9] = {};

    va_list ap;
    va_start(ap, str);

    if ((set_a_foreground && !strcmp(str, set_a_foreground)) ||
        (set_a_background && !strcmp(str, set_a_background)) ||
        (set_foreground && !strcmp(str, set_foreground)) ||
        (set_background && !strcmp(str, set_background)) ||
        (enter_underline_mode && !strcmp(str, enter_underline_mode)) ||
        (exit_underline_mode && !strcmp(str, exit_underline_mode)) ||
        (enter_standout_mode && !strcmp(str, enter_standout_mode)) ||
        (exit_standout_mode && !strcmp(str, exit_standout_mode)) ||
        (flash_screen && !strcmp(str, flash_screen)) ||
        (enter_subscript_mode && !strcmp(str, enter_subscript_mode)) ||
        (exit_subscript_mode && !strcmp(str, exit_subscript_mode)) ||
        (enter_superscript_mode && !strcmp(str, enter_superscript_mode)) ||
        (exit_superscript_mode && !strcmp(str, exit_superscript_mode)) ||
        (enter_blink_mode && !strcmp(str, enter_blink_mode)) ||
        (enter_italics_mode && !strcmp(str, enter_italics_mode)) ||
        (exit_italics_mode && !strcmp(str, exit_italics_mode)) ||
        (enter_reverse_mode && !strcmp(str, enter_reverse_mode)) ||
        (enter_shadow_mode && !strcmp(str, enter_shadow_mode)) ||
        (exit_shadow_mode && !strcmp(str, exit_shadow_mode)) ||
        (enter_secure_mode && !strcmp(str, enter_secure_mode)) ||
        (enter_bold_mode && !strcmp(str, enter_bold_mode))) {
        param[0] = va_arg(ap, long int);
    } else if (cursor_address && !strcmp(str, cursor_address)) {
        param[0] = va_arg(ap, long int);
        param[1] = va_arg(ap, long int);
    }

    va_end(ap);

    return tparm(str, param[0], param[1], param[2], param[3], param[4], param[5], param[6],
                 param[7], param[8]);
}

// Re-defining just to make sure nothing breaks further down in this file.
#define tparm tparm_solaris_kludge

#endif

int fish_mkstemp_cloexec(char *name_template) {
#if HAVE_MKOSTEMP
    // null check because mkostemp may be a weak symbol
    if (&mkostemp != nullptr) {
        return mkostemp(name_template, O_CLOEXEC);
    }
#endif
    int result_fd = mkstemp(name_template);
    if (result_fd != -1) {
        fcntl(result_fd, F_SETFD, FD_CLOEXEC);
    }
    return result_fd;
}

/// Fallback implementations of wcsdup and wcscasecmp. On systems where these are not needed (e.g.
/// building on Linux) these should end up just being stripped, as they are static functions that
/// are not referenced in this file.
__attribute__((unused)) static wchar_t *wcsdup_fallback(const wchar_t *in) {
    size_t len = wcslen(in);
    wchar_t *out = (wchar_t *)malloc(sizeof(wchar_t) * (len + 1));
    if (out == 0) {
        return 0;
    }

    memcpy(out, in, sizeof(wchar_t) * (len + 1));
    return out;
}

__attribute__((unused)) static int wcscasecmp_fallback(const wchar_t *a, const wchar_t *b) {
    if (*a == 0) {
        return *b == 0 ? 0 : -1;
    } else if (*b == 0) {
        return 1;
    }
    int diff = towlower(*a) - towlower(*b);
    if (diff != 0) {
        return diff;
    }
    return wcscasecmp_fallback(a + 1, b + 1);
}

__attribute__((unused)) static int wcsncasecmp_fallback(const wchar_t *a, const wchar_t *b,
                                                        size_t count) {
    if (count == 0) return 0;

    if (*a == 0) {
        return *b == 0 ? 0 : -1;
    } else if (*b == 0) {
        return 1;
    }
    int diff = towlower(*a) - towlower(*b);
    if (diff != 0) return diff;
    return wcsncasecmp_fallback(a + 1, b + 1, count - 1);
}

#if __APPLE__
#if __DARWIN_C_LEVEL >= 200809L
// Note parens avoid the macro expansion.
wchar_t *wcsdup_use_weak(const wchar_t *a) {
    if (&wcsdup != NULL) return (wcsdup)(a);
    return wcsdup_fallback(a);
}

int wcscasecmp_use_weak(const wchar_t *a, const wchar_t *b) {
    if (&wcscasecmp != NULL) return (wcscasecmp)(a, b);
    return wcscasecmp_fallback(a, b);
}

int wcsncasecmp_use_weak(const wchar_t *s1, const wchar_t *s2, size_t n) {
    if (&wcsncasecmp != NULL) return (wcsncasecmp)(s1, s2, n);
    return wcsncasecmp_fallback(s1, s2, n);
}
#else   // __DARWIN_C_LEVEL >= 200809L
wchar_t *wcsdup(const wchar_t *in) { return wcsdup_fallback(in); }
int wcscasecmp(const wchar_t *a, const wchar_t *b) { return wcscasecmp_fallback(a, b); }
int wcsncasecmp(const wchar_t *a, const wchar_t *b, size_t n) {
    return wcsncasecmp_fallback(a, b, n);
}
#endif  // __DARWIN_C_LEVEL >= 200809L
#else   // __APPLE__

#ifndef HAVE_WCSDUP
#ifndef HAVE_STD__WCSDUP
wchar_t *wcsdup(const wchar_t *in) { return wcsdup_fallback(in); }
#endif
#endif

#ifndef HAVE_WCSCASECMP
#ifndef HAVE_STD__WCSCASECMP
int wcscasecmp(const wchar_t *a, const wchar_t *b) { return wcscasecmp_fallback(a, b); }
#endif
#endif

#ifndef HAVE_WCSNCASECMP
#ifndef HAVE_STD__WCSNCASECMP
int wcsncasecmp(const wchar_t *a, const wchar_t *b, size_t n) {
    return wcsncasecmp_fallback(a, b, n);
}
#endif
#endif

#endif  // __APPLE__

#ifndef HAVE_WCSNDUP
wchar_t *wcsndup(const wchar_t *in, size_t c) {
    wchar_t *res = (wchar_t *)malloc(sizeof(wchar_t) * (c + 1));
    if (res == 0) {
        return 0;
    }
    wcslcpy(res, in, c + 1);
    return res;
}
#endif

#ifndef HAVE_WCSLCPY
/*$OpenBSD: strlcpy.c,v 1.8 2003/06/17 21:56:24 millert Exp $*/

/*
 * Copyright (c) 1998 Todd C. Miller <Todd.Miller@courtesan.com>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
size_t wcslcpy(wchar_t *dst, const wchar_t *src, size_t siz) {
    wchar_t *d = dst;
    const wchar_t *s = src;
    size_t n = siz;

    // Copy as many bytes as will fit.
    if (n != 0 && --n != 0) {
        do {
            if ((*d++ = *s++) == 0) break;
        } while (--n != 0);
    }

    // Not enough room in dst, add NUL and traverse rest of src.
    if (n == 0) {
        if (siz != 0) *d = '\0';  // NUL-terminate dst
        while (*s++)
            ;  // ignore rest of src
    }
    return s - src - 1;  // count does not include NUL
}
#endif

#ifndef HAVE_LRAND48_R
int lrand48_r(struct drand48_data *buffer, long int *result) {
    *result = rand_r(&buffer->seed);
    return 0;
}

int srand48_r(long int seedval, struct drand48_data *buffer) {
    buffer->seed = (unsigned int)seedval;
    return 0;
}
#endif

#ifndef HAVE_FUTIMES
int futimes(int fd, const struct timeval *times) {
    errno = ENOSYS;
    return -1;
}
#endif

#if HAVE_GETTEXT
char *fish_gettext(const char *msgid) {
    return gettext(msgid);
    ;
}

char *fish_bindtextdomain(const char *domainname, const char *dirname) {
    return bindtextdomain(domainname, dirname);
}

char *fish_textdomain(const char *domainname) { return textdomain(domainname); }
#else
char *fish_gettext(const char *msgid) { return (char *)msgid; }
char *fish_bindtextdomain(const char *domainname, const char *dirname) {
    UNUSED(domainname);
    UNUSED(dirname);
    return NULL;
}
char *fish_textdomain(const char *domainname) {
    UNUSED(domainname);
    return NULL;
}
#endif

#ifndef HAVE_KILLPG
int killpg(int pgr, int sig) {
    assert(pgr > 1);
    return kill(-pgr, sig);
}
#endif

// Big hack to use our versions of wcswidth where we know them to be broken, which is
// EVERYWHERE (https://github.com/fish-shell/fish-shell/issues/2199)
#ifndef HAVE_BROKEN_WCWIDTH
#define HAVE_BROKEN_WCWIDTH 1
#endif

#if !HAVE_BROKEN_WCWIDTH
int fish_wcwidth(wchar_t wc) { return wcwidth(wc); }
int fish_wcswidth(const wchar_t *str, size_t n) { return wcswidth(str, n); }
#else
static int mk_wcwidth(wchar_t wc);
static int mk_wcswidth(const wchar_t *pwcs, size_t n);
int fish_wcwidth(wchar_t wc) { return mk_wcwidth(wc); }
int fish_wcswidth(const wchar_t *str, size_t n) { return mk_wcswidth(str, n); }

/*
 * This is an implementation of wcwidth() and wcswidth() (defined in
 * IEEE Std 1002.1-2001) for Unicode.
 *
 * http://www.opengroup.org/onlinepubs/007904975/functions/wcwidth.html
 * http://www.opengroup.org/onlinepubs/007904975/functions/wcswidth.html
 *
 * In fixed-width output devices, Latin characters all occupy a single
 * "cell" position of equal width, whereas ideographic CJK characters
 * occupy two such cells. Interoperability between terminal-line
 * applications and (teletype-style) character terminals using the
 * UTF-8 encoding requires agreement on which character should advance
 * the cursor by how many cell positions. No established formal
 * standards exist at present on which Unicode character shall occupy
 * how many cell positions on character terminals. These routines are
 * a first attempt of defining such behavior based on simple rules
 * applied to data provided by the Unicode Consortium.
 *
 * For some graphical characters, the Unicode standard explicitly
 * defines a character-cell width via the definition of the East Asian
 * FullWidth (F), Wide (W), Half-width (H), and Narrow (Na) classes.
 * In all these cases, there is no ambiguity about which width a
 * terminal shall use. For characters in the East Asian Ambiguous (A)
 * class, the width choice depends purely on a preference of backward
 * compatibility with either historic CJK or Western practice.
 * Choosing single-width for these characters is easy to justify as
 * the appropriate long-term solution, as the CJK practice of
 * displaying these characters as double-width comes from historic
 * implementation simplicity (8-bit encoded characters were displayed
 * single-width and 16-bit ones double-width, even for Greek,
 * Cyrillic, etc.) and not any typographic considerations.
 *
 * Much less clear is the choice of width for the Not East Asian
 * (Neutral) class. Existing practice does not dictate a width for any
 * of these characters. It would nevertheless make sense
 * typographically to allocate two character cells to characters such
 * as for instance EM SPACE or VOLUME INTEGRAL, which cannot be
 * represented adequately with a single-width glyph. The following
 * routines at present merely assign a single-cell width to all
 * neutral characters, in the interest of simplicity. This is not
 * entirely satisfactory and should be reconsidered before
 * establishing a formal standard in this area. At the moment, the
 * decision which Not East Asian (Neutral) characters should be
 * represented by double-width glyphs cannot yet be answered by
 * applying a simple rule from the Unicode database content. Setting
 * up a proper standard for the behavior of UTF-8 character terminals
 * will require a careful analysis not only of each Unicode character,
 * but also of each presentation form, something the author of these
 * routines has avoided to do so far.
 *
 * http://www.unicode.org/unicode/reports/tr11/
 *
 * Markus Kuhn -- 2007-05-26 (Unicode 5.0)
 *
 * Permission to use, copy, modify, and distribute this software
 * for any purpose and without fee is hereby granted. The author
 * disclaims all warranties with regard to this software.
 *
 * Latest version: http://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c
 */
struct interval {
    int first;
    int last;
};

// Auxiliary function for binary search in interval table.
static int bisearch(wchar_t ucs, const struct interval *table, int max) {
    int min = 0;

    if (ucs < table[0].first || ucs > table[max].last) return 0;
    while (max >= min) {
        int mid = (min + max) / 2;
        if (ucs > table[mid].last)
            min = mid + 1;
        else if (ucs < table[mid].first)
            max = mid - 1;  //!OCLINT(parameter reassignment)
        else
            return 1;
    }

    return 0;
}

// The following two functions define the column width of an ISO 10646 character as follows:
//
//    - The null character (U+0000) has a column width of 0.
//
//    - Other C0/C1 control characters and DEL will lead to a return
//      value of -1.
//
//    - Non-spacing and enclosing combining characters (general
//      category code Mn or Me in the Unicode database) have a
//      column width of 0.
//
//    - SOFT HYPHEN (U+00AD) has a column width of 1.
//
//    - Other format characters (general category code Cf in the Unicode
//      database) and ZERO WIDTH SPACE (U+200B) have a column width of 0.
//
//    - Hangul Jamo medial vowels and final consonants (U+1160-U+11FF)
//      have a column width of 0.
//
//    - Spacing characters in the East Asian Wide (W) or East Asian
//      Full-width (F) category as defined in Unicode Technical
//      Report #11 have a column width of 2.
//
//    - All remaining characters (including all printable
//      ISO 8859-1 and WGL4 characters, Unicode control characters,
//      etc.) have a column width of 1.
//
// This implementation assumes that wchar_t characters are encoded
// in ISO 10646.
static int mk_wcwidth(wchar_t ucs) {
    // Sorted list of non-overlapping intervals of non-spacing characters.
    // Generated by "uniset +cat=Me +cat=Mn +cat=Cf -00AD +1160-11FF +200B c".
    static const struct interval combining[] = {
        {0x0300, 0x036F},   {0x0483, 0x0486},   {0x0488, 0x0489},   {0x0591, 0x05BD},
        {0x05BF, 0x05BF},   {0x05C1, 0x05C2},   {0x05C4, 0x05C5},   {0x05C7, 0x05C7},
        {0x0600, 0x0603},   {0x0610, 0x0615},   {0x064B, 0x065E},   {0x0670, 0x0670},
        {0x06D6, 0x06E4},   {0x06E7, 0x06E8},   {0x06EA, 0x06ED},   {0x070F, 0x070F},
        {0x0711, 0x0711},   {0x0730, 0x074A},   {0x07A6, 0x07B0},   {0x07EB, 0x07F3},
        {0x0901, 0x0902},   {0x093C, 0x093C},   {0x0941, 0x0948},   {0x094D, 0x094D},
        {0x0951, 0x0954},   {0x0962, 0x0963},   {0x0981, 0x0981},   {0x09BC, 0x09BC},
        {0x09C1, 0x09C4},   {0x09CD, 0x09CD},   {0x09E2, 0x09E3},   {0x0A01, 0x0A02},
        {0x0A3C, 0x0A3C},   {0x0A41, 0x0A42},   {0x0A47, 0x0A48},   {0x0A4B, 0x0A4D},
        {0x0A70, 0x0A71},   {0x0A81, 0x0A82},   {0x0ABC, 0x0ABC},   {0x0AC1, 0x0AC5},
        {0x0AC7, 0x0AC8},   {0x0ACD, 0x0ACD},   {0x0AE2, 0x0AE3},   {0x0B01, 0x0B01},
        {0x0B3C, 0x0B3C},   {0x0B3F, 0x0B3F},   {0x0B41, 0x0B43},   {0x0B4D, 0x0B4D},
        {0x0B56, 0x0B56},   {0x0B82, 0x0B82},   {0x0BC0, 0x0BC0},   {0x0BCD, 0x0BCD},
        {0x0C3E, 0x0C40},   {0x0C46, 0x0C48},   {0x0C4A, 0x0C4D},   {0x0C55, 0x0C56},
        {0x0CBC, 0x0CBC},   {0x0CBF, 0x0CBF},   {0x0CC6, 0x0CC6},   {0x0CCC, 0x0CCD},
        {0x0CE2, 0x0CE3},   {0x0D41, 0x0D43},   {0x0D4D, 0x0D4D},   {0x0DCA, 0x0DCA},
        {0x0DD2, 0x0DD4},   {0x0DD6, 0x0DD6},   {0x0E31, 0x0E31},   {0x0E34, 0x0E3A},
        {0x0E47, 0x0E4E},   {0x0EB1, 0x0EB1},   {0x0EB4, 0x0EB9},   {0x0EBB, 0x0EBC},
        {0x0EC8, 0x0ECD},   {0x0F18, 0x0F19},   {0x0F35, 0x0F35},   {0x0F37, 0x0F37},
        {0x0F39, 0x0F39},   {0x0F71, 0x0F7E},   {0x0F80, 0x0F84},   {0x0F86, 0x0F87},
        {0x0F90, 0x0F97},   {0x0F99, 0x0FBC},   {0x0FC6, 0x0FC6},   {0x102D, 0x1030},
        {0x1032, 0x1032},   {0x1036, 0x1037},   {0x1039, 0x1039},   {0x1058, 0x1059},
        {0x1160, 0x11FF},   {0x135F, 0x135F},   {0x1712, 0x1714},   {0x1732, 0x1734},
        {0x1752, 0x1753},   {0x1772, 0x1773},   {0x17B4, 0x17B5},   {0x17B7, 0x17BD},
        {0x17C6, 0x17C6},   {0x17C9, 0x17D3},   {0x17DD, 0x17DD},   {0x180B, 0x180D},
        {0x18A9, 0x18A9},   {0x1920, 0x1922},   {0x1927, 0x1928},   {0x1932, 0x1932},
        {0x1939, 0x193B},   {0x1A17, 0x1A18},   {0x1B00, 0x1B03},   {0x1B34, 0x1B34},
        {0x1B36, 0x1B3A},   {0x1B3C, 0x1B3C},   {0x1B42, 0x1B42},   {0x1B6B, 0x1B73},
        {0x1DC0, 0x1DCA},   {0x1DFE, 0x1DFF},   {0x200B, 0x200F},   {0x202A, 0x202E},
        {0x2060, 0x2063},   {0x206A, 0x206F},   {0x20D0, 0x20EF},   {0x302A, 0x302F},
        {0x3099, 0x309A},   {0xA806, 0xA806},   {0xA80B, 0xA80B},   {0xA825, 0xA826},
        {0xFB1E, 0xFB1E},   {0xFE00, 0xFE0F},   {0xFE20, 0xFE23},   {0xFEFF, 0xFEFF},
        {0xFFF9, 0xFFFB},   {0x10A01, 0x10A03}, {0x10A05, 0x10A06}, {0x10A0C, 0x10A0F},
        {0x10A38, 0x10A3A}, {0x10A3F, 0x10A3F}, {0x1D167, 0x1D169}, {0x1D173, 0x1D182},
        {0x1D185, 0x1D18B}, {0x1D1AA, 0x1D1AD}, {0x1D242, 0x1D244}, {0xE0001, 0xE0001},
        {0xE0020, 0xE007F}, {0xE0100, 0xE01EF}};

    // Test for 8-bit control characters.
    if (ucs == 0) return 0;
    if (ucs < 32 || (ucs >= 0x7f && ucs < 0xa0)) return -1;

    // Binary search in table of non-spacing characters.
    if (bisearch(ucs, combining, sizeof(combining) / sizeof(struct interval) - 1)) return 0;

    // If we arrive here, ucs is not a combining or C0/C1 control character.
    return 1 + (ucs >= 0x1100 &&
                (ucs <= 0x115f || /* Hangul Jamo init. consonants */
                 ucs == 0x2329 || ucs == 0x232a ||
                 (ucs >= 0x2e80 && ucs <= 0xa4cf && ucs != 0x303f) || /* CJK ... Yi */
                 (ucs >= 0xac00 && ucs <= 0xd7a3) ||                  /* Hangul Syllables */
                 (ucs >= 0xf900 && ucs <= 0xfaff) || /* CJK Compatibility Ideographs */
                 (ucs >= 0xfe10 && ucs <= 0xfe19) || /* Vertical forms */
                 (ucs >= 0xfe30 && ucs <= 0xfe6f) || /* CJK Compatibility Forms */
                 (ucs >= 0xff00 && ucs <= 0xff60) || /* Fullwidth Forms */
                 (ucs >= 0xffe0 && ucs <= 0xffe6) || (ucs >= 0x20000 && ucs <= 0x2fffd) ||
                 (ucs >= 0x30000 && ucs <= 0x3fffd)));
}

static int mk_wcswidth(const wchar_t *pwcs, size_t n) {
    int width = 0;
    for (size_t i = 0; i < n; i++) {
        if (pwcs[i] == L'\0') break;

        int w = mk_wcwidth(pwcs[i]);
        if (w < 0) {
            width = -1;
            break;
        }
        width += w;
    }
    return width;
}
#endif  // HAVE_BROKEN_WCWIDTH

#ifndef HAVE_FLOCK
/*	$NetBSD: flock.c,v 1.6 2008/04/28 20:24:12 martin Exp $	*/

/*-
 * Copyright (c) 2001 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Todd Vierling.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * Emulate flock() with fcntl().
 */

int flock(int fd, int op) {
    int rc = 0;

    struct flock fl = {0};

    switch (op & (LOCK_EX | LOCK_SH | LOCK_UN)) {
        case LOCK_EX:
            fl.l_type = F_WRLCK;
            break;

        case LOCK_SH:
            fl.l_type = F_RDLCK;
            break;

        case LOCK_UN:
            fl.l_type = F_UNLCK;
            break;

        default:
            errno = EINVAL;
            return -1;
    }

    fl.l_whence = SEEK_SET;
    rc = fcntl(fd, op & LOCK_NB ? F_SETLK : F_SETLKW, &fl);

    if (rc && (errno == EAGAIN)) errno = EWOULDBLOCK;

    return rc;
}

#endif  // HAVE_FLOCK