slime/src/platform.cpp

namespace Slime {

    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 = (char*)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
    }
}