diff --git a/doc/us/manual.html b/doc/us/manual.html index 86c3406..4dc15bb 100644 --- a/doc/us/manual.html +++ b/doc/us/manual.html @@ -242,6 +242,8 @@ LuaFileSystem offers the following functions:
lfs.symlinkattributes (filepath [, aname])
Identical to lfs.attributes except that it obtains information about the link itself (not the file it refers to). + It also adds a target field, containing + the file name that the symlink points to. On Windows this function does not yet support links, and is identical to lfs.attributes.
diff --git a/src/lfs.c b/src/lfs.c index 446373c..49a8534 100644 --- a/src/lfs.c +++ b/src/lfs.c @@ -849,11 +849,73 @@ static int file_info (lua_State *L) { } +/* +** Push the symlink target to the top of the stack. +** Assumes the file name is at position 1 of the stack. +** Returns 1 if successful (with the target on top of the stack), +** 0 on failure (with stack unchanged, and errno set). +*/ +static int push_link_target(lua_State *L) { +#ifdef _WIN32 + errno = ENOSYS; + return 0; +#else + const char *file = luaL_checkstring(L, 1); + char *target; + int size, tsize; + if (lua_type(L, -1) == LUA_TTABLE) { + /* when symlinkattributes collects the whole table, + get the size from it */ + int size_type = lua_getfield(L, -1, "size"); + if (size_type != LUA_TNUMBER) { + lua_pop(L, 1); + errno = EINVAL; + return 0; + } + size = lua_tointeger(L, -1); + lua_pop(L, 1); + } else { + /* when we are just getting 'target', we need to run + lstat ourselves to get the size */ + STAT_STRUCT info; + if (LSTAT_FUNC(file, &info)) { + return 0; + } + size = info.st_size; + } + target = (char*) malloc(size + 1); + if (!target) { + return 0; + } + tsize = readlink(file, target, size); + if (tsize != size) { + free(target); + return 0; + } + target[tsize] = '\0'; + lua_pushlstring(L, target, tsize); + free(target); + return 1; +#endif +} + /* ** Get symbolic link information using lstat. */ static int link_info (lua_State *L) { - return _file_info_ (L, LSTAT_FUNC); + int ret; + if (lua_isstring (L, 2) && (strcmp(lua_tostring(L, 2), "target") == 0)) { + int ok = push_link_target(L); + return ok ? 1 : pusherror(L, "could not obtain link target"); + } + ret = _file_info_ (L, LSTAT_FUNC); + if (ret == 1 && lua_type(L, -1) == LUA_TTABLE) { + int ok = push_link_target(L); + if (ok) { + lua_setfield(L, -2, "target"); + } + } + return ret; } diff --git a/tests/test.lua b/tests/test.lua index 2842bc0..2331eec 100644 --- a/tests/test.lua +++ b/tests/test.lua @@ -91,6 +91,8 @@ io.flush() if lfs.link (tmpfile, "_a_link_for_test_", true) then assert (lfs.attributes"_a_link_for_test_".mode == "file") assert (lfs.symlinkattributes"_a_link_for_test_".mode == "link") + assert (lfs.symlinkattributes"_a_link_for_test_".target == tmpfile) + assert (lfs.symlinkattributes("_a_link_for_test_", "target") == tmpfile) assert (lfs.link (tmpfile, "_a_hard_link_for_test_")) assert (lfs.attributes (tmpfile, "nlink") == 2) assert (os.remove"_a_link_for_test_")