From 32b355a9902e6ce7aae68926fc3f2d05856fc299 Mon Sep 17 00:00:00 2001 From: NiteHawk Date: Sat, 16 Jul 2016 15:35:27 +0200 Subject: Add a 'target' field for symlinkattributes. It returns the resolved path of the symlink. Original version by Hisham , modified to use a different strategy for sizing the readlink() buffer. --- doc/us/manual.html | 2 ++ src/lfs.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++++- tests/test.lua | 2 ++ 3 files changed, 52 insertions(+), 1 deletion(-) diff --git a/doc/us/manual.html b/doc/us/manual.html index f5fbaf6..0ecb625 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..93c1419 100644 --- a/src/lfs.c +++ b/src/lfs.c @@ -849,11 +849,58 @@ 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 = NULL; + int tsize, size = 256; /* size = initial buffer capacity */ + while (1) { + target = realloc(target, size); + if (!target) /* failed to allocate */ + return 0; + tsize = readlink(file, target, size); + if (tsize < 0) { /* a readlink() error occurred */ + free(target); + return 0; + } + if (tsize < size) + break; + /* possibly truncated readlink() result, double size and retry */ + size *= 2; + } + 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_") -- cgit v1.2.3-55-g6feb