source: ps/trunk/source/lib/sysdep/os/unix/unix.cpp

/* Copyright (c) 2021 Wildfire Games.
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#include "precompiled.h"

#include <unistd.h>
#include <stdio.h>
#include <wchar.h>

#include "lib/code_annotation.h"
#include "lib/utf8.h"
#include "lib/sysdep/os/unix/udbg.h"
#include "lib/sysdep/sysdep.h"

#include <boost/algorithm/string/replace.hpp>

#define GNU_SOURCE
#include <dlfcn.h>

#include <sys/wait.h>

#if OS_MACOSX
#define URL_OPEN_COMMAND "open"
#else
#define URL_OPEN_COMMAND "xdg-open"
#endif

bool sys_IsDebuggerPresent()
{
    return false;
}

std::wstring sys_WideFromArgv(const char* argv_i)
{
    // argv is usually UTF-8 on Linux, unsure about OS X..
    return wstring_from_utf8(argv_i);
}

// these are basic POSIX-compatible backends for the sysdep.h functions.
// Win32 has better versions which override these.

void sys_display_msg(const wchar_t* caption, const wchar_t* msg)
{
    fprintf(stderr, "%ls: %ls\n", caption, msg); // must not use fwprintf, since stderr is byte-oriented
}

#if OS_MACOSX || OS_ANDROID
static ErrorReactionInternal try_gui_display_error(const wchar_t* UNUSED(text), bool UNUSED(manual_break), bool UNUSED(allow_suppress), bool UNUSED(no_continue))
{
    // TODO: implement this, in a way that doesn't rely on X11
    // and doesn't occasionally cause crazy errors like
    // "The process has forked and you cannot use this
    // CoreFoundation functionality safely. You MUST exec()."

    return ERI_NOT_IMPLEMENTED;
}
#else
static ErrorReactionInternal try_gui_display_error(const wchar_t* text, bool manual_break, bool allow_suppress, bool no_continue)
{
    // We'll run xmessage via fork/exec.
    // To avoid bad interaction between fork and pthreads, the child process
    // should only call async-signal-safe functions before exec.
    // So prepare all the child's data in advance, before forking:

    Status err; // ignore UTF-8 errors
    std::string message = utf8_from_wstring(text, &err);

    // Replace CRLF->LF
    boost::algorithm::replace_all(message, "\r\n", "\n");

    // TODO: we ought to wrap the text if it's very long,
    // since xmessage doesn't do that and it'll get clamped
    // to the screen width

    const char* cmd = "/usr/bin/xmessage";

    char buttons[256] = "";
    const char* defaultButton = "Exit";

    if(!no_continue)
    {
        strcat_s(buttons, sizeof(buttons), "Continue:100,");
        defaultButton = "Continue";
    }

    if(allow_suppress)
        strcat_s(buttons, sizeof(buttons), "Suppress:101,");

    strcat_s(buttons, sizeof(buttons), "Break:102,Debugger:103,Exit:104");

    // Since execv wants non-const strings, we strdup them all here
    // and will clean them up later (except in the child process where
    // memory leaks don't matter)
    char* const argv[] = {
        strdup(cmd),
        strdup("-geometry"), strdup("x500"), // set height so the box will always be very visible
        strdup("-title"), strdup("0 A.D. message"), // TODO: maybe shouldn't hard-code app name
        strdup("-buttons"), strdup(buttons),
        strdup("-default"), strdup(defaultButton),
        strdup(message.c_str()),
        NULL
    };

    pid_t cpid = fork();
    if(cpid == -1)
    {
        for(char* const* a = argv; *a; ++a)
            free(*a);
        return ERI_NOT_IMPLEMENTED;
    }

    if(cpid == 0)
    {
        // This is the child process

        // Set ASCII charset, to avoid font warnings from xmessage
        setenv("LC_ALL", "C", 1);

        // NOTE: setenv is not async-signal-safe, so we shouldn't really use
        // it here (it might want some mutex that was held by another thread
        // in the parent process and that will never be freed within this
        // process). But setenv/getenv are not guaranteed reentrant either,
        // and this error-reporting function might get called from a non-main
        // thread, so we can't just call setenv before forking as it might
        // break the other threads. And we can't just clone environ manually
        // inside the parent thread and use execve, because other threads might
        // be calling setenv and will break our iteration over environ.
        // In the absence of a good easy solution, and given that this is only
        // an error-reporting function and shouldn't get called frequently,
        // we'll just do setenv after the fork and hope that it fails
        // extremely rarely.

        execv(cmd, argv);

        // If exec returns, it failed
        //fprintf(stderr, "Error running %s: %d\n", cmd, errno);
        exit(-1);
    }

    // This is the parent process

    // Avoid memory leaks
    for(char* const* a = argv; *a; ++a)
        free(*a);

    int status = 0;
    waitpid(cpid, &status, 0);

    // If it didn't exist successfully, fall back to the non-GUI prompt
    if(!WIFEXITED(status))
        return ERI_NOT_IMPLEMENTED;

    switch(WEXITSTATUS(status))
    {
    case 103: // Debugger
        udbg_launch_debugger();
        FALLTHROUGH;

    case 102: // Break
        if(manual_break)
            return ERI_BREAK;
        debug_break();
        return ERI_CONTINUE;

    case 100: // Continue
        if(!no_continue)
            return ERI_CONTINUE;
        // continue isn't allowed, so this was invalid input.
        return ERI_NOT_IMPLEMENTED;

    case 101: // Suppress
        if(allow_suppress)
            return ERI_SUPPRESS;
        // suppress isn't allowed, so this was invalid input.
        return ERI_NOT_IMPLEMENTED;

    case 104: // Exit
        abort();
        return ERI_EXIT;    // placebo; never reached

    }

    // Unexpected return value - fall back to the non-GUI prompt
    return ERI_NOT_IMPLEMENTED;
}
#endif

ErrorReactionInternal sys_display_error(const wchar_t* text, size_t flags)
{
    debug_printf("%s\n\n", utf8_from_wstring(text).c_str());

    const bool manual_break   = (flags & DE_MANUAL_BREAK  ) != 0;
    const bool allow_suppress = (flags & DE_ALLOW_SUPPRESS) != 0;
    const bool no_continue    = (flags & DE_NO_CONTINUE   ) != 0;

    // Try the GUI prompt if possible
    ErrorReactionInternal ret = try_gui_display_error(text, manual_break, allow_suppress, no_continue);
    if (ret != ERI_NOT_IMPLEMENTED)
        return ret;

#if OS_ANDROID
    // Android has no easy way to get user input here,
    // so continue or exit automatically
    if(no_continue)
        abort();
    else
        return ERI_CONTINUE;
#else
    // Otherwise fall back to the terminal-based input

    // Loop until valid input given:
    for(;;)
    {
        if(!no_continue)
            printf("(C)ontinue, ");
        if(allow_suppress)
            printf("(S)uppress, ");
        printf("(B)reak, Launch (D)ebugger, or (E)xit?\n");
        // TODO Should have some kind of timeout here.. in case you're unable to
        // access the controlling terminal (As might be the case if launched
        // from an xterm and in full-screen mode)
        int c = getchar();
        // note: don't use tolower because it'll choke on EOF
        switch(c)
        {
        case EOF:
        case 'd': case 'D':
            udbg_launch_debugger();
            FALLTHROUGH;

        case 'b': case 'B':
            if(manual_break)
                return ERI_BREAK;
            debug_break();
            return ERI_CONTINUE;

        case 'c': case 'C':
            if(!no_continue)
                return ERI_CONTINUE;
            // continue isn't allowed, so this was invalid input. loop again.
            break;
        case 's': case 'S':
            if(allow_suppress)
                return ERI_SUPPRESS;
            // suppress isn't allowed, so this was invalid input. loop again.
            break;

        case 'e': case 'E':
            abort();
            return ERI_EXIT;    // placebo; never reached
        }
    }
#endif
}


Status sys_StatusDescription(int err, wchar_t* buf, size_t max_chars)
{
    UNUSED2(err);
    UNUSED2(buf);
    UNUSED2(max_chars);

    // don't need to do anything: lib/errors.cpp already queries
    // libc's strerror(). if we ever end up needing translation of
    // e.g. Qt or X errors, that'd go here.
    return ERR::FAIL;
}

// note: just use the sector size: Linux aio doesn't really care about
// the alignment of buffers/lengths/offsets, so we'll just pick a
// sane value and not bother scanning all drives.
size_t sys_max_sector_size()
{
    // users may call us more than once, so cache the results.
    static size_t cached_sector_size;
    if(!cached_sector_size)
        cached_sector_size = sysconf(_SC_PAGE_SIZE);
    return cached_sector_size;
}

std::wstring sys_get_user_name()
{
    // Prefer LOGNAME, fall back on getlogin

    const char* logname = getenv("LOGNAME");
    if (logname && strcmp(logname, "") != 0)
        return std::wstring(logname, logname + strlen(logname));
    // TODO: maybe we should do locale conversion?

#if OS_ANDROID
#warning TODO: sys_get_user_name: do something more appropriate and more thread-safe
    char* buf = getlogin();
    if (buf)
        return std::wstring(buf, buf + strlen(buf));
#else
    char buf[256];
    if (getlogin_r(buf, ARRAY_SIZE(buf)) == 0)
        return std::wstring(buf, buf + strlen(buf));
#endif

    return L"";
}

Status sys_generate_random_bytes(u8* buf, size_t count)
{
    FILE* f = fopen("/dev/urandom", "rb");
    if (!f)
        WARN_RETURN(ERR::FAIL);

    while (count)
    {
        size_t numread = fread(buf, 1, count, f);
        if (numread == 0)
        {
            fclose(f);
            WARN_RETURN(ERR::FAIL);
        }
        buf += numread;
        count -= numread;
    }

    fclose(f);

    return INFO::OK;
}

Status sys_get_proxy_config(const std::wstring& UNUSED(url), std::wstring& UNUSED(proxy))
{
    return INFO::SKIPPED;
}

Status sys_open_url(const std::string& url)
{
    pid_t pid = fork();
    if (pid < 0)
    {
        debug_warn(L"Fork failed");
        return ERR::FAIL;
    }
    else if (pid == 0)
    {
        // we are the child

        execlp(URL_OPEN_COMMAND, URL_OPEN_COMMAND, url.c_str(), (const char*)NULL);

        debug_printf("Failed to run '" URL_OPEN_COMMAND "' command\n");

        // We can't call exit() because that'll try to free resources which were the parent's,
        // so just abort here
        abort();
    }
    else
    {
        // we are the parent

        // TODO: maybe we should wait for the child and make sure it succeeded

        return INFO::OK;
    }
}

FILE* sys_OpenFile(const OsPath& pathname, const char* mode)
{
    return fopen(OsString(pathname).c_str(), mode);
}