slime/src/platform.cpp

inline proc get_cwd() -> char* {
    const int buf_size = 2048;
    char* res = (char*)malloc(buf_size * sizeof(char));

#ifdef _MSC_VER
    _getcwd(res, buf_size);
#else
    getcwd(res, buf_size);
#endif

    return res;
}

inline proc change_cwd(char* dir) -> void {
#ifdef _MSC_VER
    _chdir(dir);
#else
    chdir(dir);
#endif
}


#ifdef _MSC_VER
int vasprintf(char **strp, const char *fmt, va_list ap) {
    // _vscprintf tells you how big the buffer needs to be
    int len = _vscprintf(fmt, ap);
    if (len == -1) {
        return -1;
    }
    size_t size = (size_t)len + 1;
    char *str = malloc(size);
    if (!str) {
        return -1;
    }
    // _vsprintf_s is the "secure" version of vsprintf
    int r = _vsprintf_s(str, len + 1, fmt, ap);
    if (r == -1) {
        free(str);
        return -1;
    }
    *strp = str;
    return r;
}

int asprintf(char **strp, const char *fmt, ...) {
    va_list ap;
    va_start(ap, fmt);
    int r = vasprintf(strp, fmt, ap);
    va_end(ap);
    return r;
}
#endif

proc get_exe_dir() -> char* {
#ifdef _MSC_VER
    DWORD last_error;
    DWORD result;
    DWORD path_size = 1024;
    char* path      = (char*)malloc(1024);

    while (true) {
        memset(path, 0, path_size);
        result     = GetModuleFileName(0, path, path_size - 1);
        last_error = GetLastError();

        if (0 == result) {
            free(path);
            path = 0;
            break;
        }
        else if (result == path_size - 1) {
            free(path);
            /* May need to also check for ERROR_SUCCESS here if XP/2K */
            if (ERROR_INSUFFICIENT_BUFFER != last_error) {
                path = 0;
                break;
            }
            path_size = path_size * 2;
            path = (char*)malloc(path_size);
        }
        else
            break;
    }

    if (!path) {
        fprintf(stderr, "Failure: %ld\n", last_error);
        return nullptr;
    }
    else {
        // remove the exe name, so we are only left with the path

        int index_in_path = -1;
        int last_backslash = -1;

        char c;
        while ((c = path[++index_in_path]) != '\0') {
            if (c == '\\')
                last_backslash = index_in_path;
        }

        // we are assuming there are some backslashes
        path[last_backslash+1] = '\0';

        return path;
    }
#else
    ssize_t  size = 512, i, n;
    char   *path, *temp;

    while (1) {
        size_t  used;

        path = (char*)malloc(size);
        if (!path) {
            errno = ENOMEM;
            return NULL;
        }

        used = readlink("/proc/self/exe", path, size);

        if (used == -1) {
            const int saved_errno = errno;
            free(path);
            errno = saved_errno;
            return NULL;
        } else
            if (used < 1) {
                free(path);
                errno = EIO;
                return NULL;
            }

        if ((size_t)used >= size) {
            free(path);
            size = (size | 2047) + 2049;
            continue;
        }

        size = (size_t)used;
        break;
    }

    /* Find final slash. */
    n = 0;
    for (i = 0; i < size; i++)
        if (path[i] == '/')
            n = i;

    /* Optimize allocated size,
       ensuring there is room for
       a final slash and a
       string-terminating '\0', */
    temp = path;
    path = (char*)realloc(temp, n + 2);
    if (!path) {
        free(temp);
        errno = ENOMEM;
        return NULL;
    }

    /* and properly trim and terminate the path string. */
    path[n+0] = '/';
    path[n+1] = '\0';

    return path;
#endif
}