luadir.c

/* luaDIR API:
 * export function, which return iterator by directory
 * WARNING: not support non-ASCII paths
 *
 * name, isdir = dir(path)
 * - path    directory path
 * > name    current file/dir name
 * > isdir   name is directory
 */

#include <stdio.h>
#include <dirent.h>
#include <sys/stat.h>
#include <lua54/lauxlib.h>
#include <lua54/lua.h>

#define LD_DIR_MT "luadir.dir"
typedef struct {
    DIR* ptr;
    const char* path;
} dir_t;

static int ld_iter(lua_State* L);

static int ld_dir(lua_State* L) {
    const char* path = luaL_checkstring(L, 1);
    luaL_argcheck(L, path != NULL, 1, "path cannot be empty");

    dir_t* dir = lua_newuserdatauv(L, sizeof *dir, 0);
    if ((dir->ptr = opendir(path)) == NULL)
        luaL_error(L, "cannot open folder: %s", path);
    dir->path = path;

    (void)readdir(dir->ptr); // skip .
    (void)readdir(dir->ptr); // skip ..

    luaL_getmetatable(L, LD_DIR_MT);
    lua_setmetatable(L, -2);

    lua_pushcclosure(L, ld_iter, 1);
    return 1;
}

static int ld_iter(lua_State* L) {
    static char full_path[1024];

    dir_t* dir = luaL_checkudata(L, lua_upvalueindex(1), LD_DIR_MT);
    luaL_argcheck(L, dir != NULL, 1, "dir cannot be nil");

    struct dirent* de;
    if ((de = readdir(dir->ptr)) == NULL) return 0;

    if (snprintf(full_path, sizeof full_path,
        "%s/%s", dir->path, de->d_name) < 0)
        luaL_error(L, "full path is very long");

    struct stat st;
    if (stat(full_path, &st)) return 0;

    lua_pushstring(L, de->d_name);
    lua_pushboolean(L, S_ISDIR(st.st_mode));
    return 2;
}

static int ld_gc(lua_State* L) {
    dir_t* dir = luaL_checkudata(L, 1, LD_DIR_MT);
    if (dir->ptr) closedir(dir->ptr);
    return 0;
}

LUA_API int luaopen_luadir(lua_State* L) {
    luaL_newmetatable(L, LD_DIR_MT);
    lua_pushvalue(L, -1);
    lua_setfield(L, -2, "__index");
    lua_pushcfunction(L, ld_gc);
    lua_setfield(L, -2, "__gc");

    lua_pushcfunction(L, ld_dir);
    return 1;
}