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.
#include "config.h"

// IWYU likes to recommend adding term.h when we want ncurses.h.
// IWYU pragma: no_include "term.h"
#include <errno.h>   // IWYU pragma: keep
#include <fcntl.h>   // IWYU pragma: keep
#include <limits.h>  // IWYU pragma: keep
#include <unistd.h>  // IWYU pragma: keep
#include <wctype.h>

#include <cstdlib>
#include <cwchar>
#if HAVE_GETTEXT
#include <libintl.h>
#endif
#if defined(TPARM_SOLARIS_KLUDGE)
#if HAVE_CURSES_H
#include <curses.h>  // IWYU pragma: keep
#elif HAVE_NCURSES_H
#include <ncurses.h>  // IWYU pragma: keep
#elif HAVE_NCURSES_CURSES_H
#include <ncurses/curses.h>  // IWYU pragma: keep
#endif
#if HAVE_TERM_H
#include <term.h>  // IWYU pragma: keep
#elif HAVE_NCURSES_TERM_H
#include <ncurses/term.h>
#endif
#endif
#include <signal.h>  // IWYU pragma: keep

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

#if defined(TPARM_SOLARIS_KLUDGE)
char *tparm_solaris_kludge(char *str, long p1, long p2, long p3, long p4, long p5, long p6, long p7,
                           long p8, long p9) {
    return tparm(str, p1, p2, p3, p4, p5, p6, p7, p8, p9);
}
#endif

/// Fallback implementations of wcsncasecmp 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.
// cppcheck-suppress unusedFunction
[[gnu::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);
}

[[gnu::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);
}

#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

#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 nullptr;
}
char *fish_textdomain(const char *domainname) {
    UNUSED(domainname);
    return nullptr;
}
#endif

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

static int fish_get_emoji_width(wchar_t c) {
    (void)c;
    return FISH_EMOJI_WIDTH;
}

// 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)
#include "widecharwidth/widechar_width.h"

int fish_wcwidth(wchar_t wc) {
    // The system version of wcwidth should accurately reflect the ability to represent characters
    // in the console session, but knows nothing about the capabilities of other terminal emulators
    // or ttys. Use it from the start only if we are logged in to the physical console.
    if (is_console_session()) {
        return wcwidth(wc);
    }

    // Check for VS16 which selects emoji presentation. This "promotes" a character like U+2764
    // (width 1) to an emoji (probably width 2). So treat it as width 1 so the sums work. See #2652.
    // VS15 selects text presentation.
    const wchar_t variation_selector_16 = L'\uFE0F', variation_selector_15 = L'\uFE0E';
    if (wc == variation_selector_16)
        return 1;
    else if (wc == variation_selector_15)
        return 0;

    // Check for Emoji_Modifier property. Only the Fitzpatrick modifiers have this, in range
    // 1F3FB..1F3FF. This is a hack because such an emoji appearing on its own would be drawn as
    // width 2, but that's unlikely to be useful. See #8275.
    if (wc >= 0x1F3FB && wc <= 0x1F3FF) return 0;

    int width = widechar_wcwidth(wc);

    switch (width) {
        case widechar_non_character:
        case widechar_nonprint:
        case widechar_combining:
        case widechar_unassigned:
            // Fall back to system wcwidth in this case.
            return wcwidth(wc);
        case widechar_ambiguous:
        case widechar_private_use:
            // TR11: "All private-use characters are by default classified as Ambiguous".
            return FISH_AMBIGUOUS_WIDTH;
        case widechar_widened_in_9:
            return fish_get_emoji_width(wc);
        default:
            assert(width > 0 && "Unexpectedly nonpositive width");
            return width;
    }
}

int fish_wcswidth(const wchar_t *str, size_t n) {
    int result = 0;
    for (size_t i = 0; i < n && str[i] != L'\0'; i++) {
        int w = fish_wcwidth(str[i]);
        if (w < 0) {
            result = -1;
            break;
        }
        result += w;
    }
    return result;
}