locking via lockfiles in posix systems. API:

lock, err = lfs.lock_dir(path, [seconds_stale]) Creates a lockfile (called lockfile.lfs) in <path> if it does not exist and returns the lock. If the lock already exists checks it it's stale, using the second parameter (default for the second parameter is INT_MAX, which in practice means the lock will never be stale. To free the the lock call lock:free(). In case of any errors it returns nil and the error message. In particular, if the lock exists and is not stale it returns the "File exists" message.
author: mascarenhas <mascarenhas> 2009-03-25 19:14:17 +0000
committer: mascarenhas <mascarenhas> 2009-03-25 19:14:17 +0000
commit: d21c4ae194f84338cbcd85a878fdeefa46fff4f7 (patch)
tree: 4efaccb5521e3deb4cadb68b21cc56f254cde560
parent: 342df4a5a3c67c4ff2567090d203280b6505f580 (diff)
download: luafilesystem-d21c4ae194f84338cbcd85a878fdeefa46fff4f7.tar.gz
luafilesystem-d21c4ae194f84338cbcd85a878fdeefa46fff4f7.tar.bz2
luafilesystem-d21c4ae194f84338cbcd85a878fdeefa46fff4f7.zip
1 files changed, 81 insertions, 1 deletions
diff --git a/src/lfs.c b/src/lfs.c
index a3bce1d..45adf4a 100644
--- a/src/lfs.c
+++ b/src/lfs.c
@@ -16,7 +16,7 @@
 **   lfs.touch (filepath [, atime [, mtime]])
 **   lfs.unlock (fh)
 **
-** $Id: lfs.c,v 1.56 2009/02/03 22:05:48 carregal Exp $
+** $Id: lfs.c,v 1.57 2009/03/25 19:14:17 mascarenhas Exp $
 */
 #ifndef _WIN32
@@ -84,6 +84,11 @@ typedef struct dir_data {
 #endif
 } dir_data;
+#define LOCK_METATABLE "lock metatable"
+typedef struct lfs_Lock {
+  int fd;
+  char *ln;
+} lfs_Lock;
 #ifdef _WIN32
 #ifdef __BORLANDC__
@@ -206,6 +211,64 @@ static int _file_lock (lua_State *L, FILE *fh, const char *mode, const long star
 }
 #ifdef _WIN32
+static int lfs_lock_dir(lua_State *L) {
+  luaL_error(L, "not implemented for Windows");
+}
+static int lfs_unlock_dir(lua_State *L) {
+  luaL_error(L, "not implemented for Windows");
+}
+#else
+static int lfs_lock_dir(lua_State *L) {
+  struct stat statbuf;
+  lfs_Lock *lock;
+  size_t pathl; int fd;
+  char *tmpln, *ln;
+  const char *template = "/lockfile.XXXXXX";
+  const char *lockfile = "/lockfile.lfs";
+  const char *path = luaL_checklstring(L, 1, &pathl);
+  time_t expires = (time_t)luaL_optint(L, 2, INT_MAX);
+  tmpln = (char*)malloc(pathl + strlen(template) + 1);
+  if(!tmpln) { lua_pushnil(L); lua_pushstring(L, strerror(errno)); return 2; }
+  strcpy(tmpln, path); strcat(tmpln, template);
+  fd = mkstemp(tmpln);
+  if(fd == -1) {
+    free(tmpln); lua_pushnil(L); lua_pushstring(L, strerror(errno)); return 2;
+  }
+  ln = (char*)malloc(pathl + strlen(lockfile) + 1);
+  if(!ln) { 
+    unlink(tmpln); free(tmpln); close(fd); lua_pushnil(L); 
+    lua_pushstring(L, strerror(errno)); return 2;
+  }
+  strcpy(ln, path); strcat(ln, lockfile);
+  while(symlink(tmpln, ln) == -1) {
+    if(errno == EEXIST) {
+      if(lstat(ln, &statbuf) == -1) goto fail;
+      if(time(NULL) - statbuf.st_mtimespec.tv_sec > expires) {
+        unlink(ln);
+        continue;
+      }
+    }
+    fail:
+      unlink(tmpln); free(tmpln); free(ln); close(fd);
+      lua_pushnil(L); lua_pushstring(L, strerror(errno)); return 2;
+  }
+  unlink(tmpln); free(tmpln);
+  lock = (lfs_Lock*)lua_newuserdata(L, sizeof(lfs_Lock));
+  lock->fd = fd; lock->ln = ln;
+  luaL_getmetatable (L, LOCK_METATABLE);
+  lua_setmetatable (L, -2);
+  return 1;
+}
+static int lfs_unlock_dir(lua_State *L) {
+  lfs_Lock *lock = luaL_checkudata(L, 1, LOCK_METATABLE);
+  unlink(lock->ln);
+  close(lock->fd);
+  free(lock->ln);
+  return 0;
+}
+#endif
+#ifdef _WIN32
 static int lfs_g_setmode (lua_State *L, FILE *f, int arg) {
  static const int mode[] = {_O_TEXT, _O_BINARY};
  static const char *const modenames[] = {"text", "binary", NULL};
@@ -433,6 +496,21 @@ static int dir_create_meta (lua_State *L) {
        return 1;
 }
+/*
+** Creates lock metatable.
+*/
+static int lock_create_meta (lua_State *L) {
+        luaL_newmetatable (L, LOCK_METATABLE);
+        /* set its __gc field */
+        lua_newtable(L);
+        lua_pushcfunction(L, lfs_unlock_dir);
+        lua_setfield(L, -2, "free");
+        lua_setfield(L, -2, "__index");
+        lua_pushcfunction(L, lfs_unlock_dir);
+        lua_setfield(L, -2, "__gc");
+        return 1;
+}
 #ifdef _WIN32
 #ifndef S_ISDIR
@@ -688,11 +766,13 @@ static const struct luaL_reg fslib[] = {
        {"setmode", lfs_f_setmode},
        {"touch", file_utime},
        {"unlock", file_unlock},
+        {"lock_dir", lfs_lock_dir},
        {NULL, NULL},
 };
 int luaopen_lfs (lua_State *L) {
        dir_create_meta (L);
+        lock_create_meta (L);
        luaL_register (L, "lfs", fslib);
        set_info (L);
        return 1;
author	mascarenhas <mascarenhas>	2009-03-25 19:14:17 +0000
committer	mascarenhas <mascarenhas>	2009-03-25 19:14:17 +0000
commit	d21c4ae194f84338cbcd85a878fdeefa46fff4f7 (patch)
tree	4efaccb5521e3deb4cadb68b21cc56f254cde560
parent	342df4a5a3c67c4ff2567090d203280b6505f580 (diff)
download	luafilesystem-d21c4ae194f84338cbcd85a878fdeefa46fff4f7.tar.gz luafilesystem-d21c4ae194f84338cbcd85a878fdeefa46fff4f7.tar.bz2 luafilesystem-d21c4ae194f84338cbcd85a878fdeefa46fff4f7.zip

diff --git a/src/lfs.c b/src/lfs.c index a3bce1d..45adf4a 100644 --- a/src/lfs.c +++ b/src/lfs.c
@@ -16,7 +16,7 @@
16	** lfs.touch (filepath [, atime [, mtime]])	16	** lfs.touch (filepath [, atime [, mtime]])
17	** lfs.unlock (fh)	17	** lfs.unlock (fh)
18	**	18	**
19	** $Id: lfs.c,v 1.56 2009/02/03 22:05:48 carregal Exp $	19	** $Id: lfs.c,v 1.57 2009/03/25 19:14:17 mascarenhas Exp $
20	*/	20	*/
21		21
22	#ifndef _WIN32	22	#ifndef _WIN32
@@ -84,6 +84,11 @@ typedef struct dir_data {
84	#endif	84	#endif
85	} dir_data;	85	} dir_data;
86		86
		87	#define LOCK_METATABLE "lock metatable"
		88	typedef struct lfs_Lock {
		89	int fd;
		90	char *ln;
		91	} lfs_Lock;
87		92
88	#ifdef _WIN32	93	#ifdef _WIN32
89	#ifdef __BORLANDC__	94	#ifdef __BORLANDC__
@@ -206,6 +211,64 @@ static int _file_lock (lua_State L, FILE fh, const char *mode, const long star
206	}	211	}
207		212
208	#ifdef _WIN32	213	#ifdef _WIN32
		214	static int lfs_lock_dir(lua_State *L) {
		215	luaL_error(L, "not implemented for Windows");
		216	}
		217	static int lfs_unlock_dir(lua_State *L) {
		218	luaL_error(L, "not implemented for Windows");
		219	}
		220	#else
		221	static int lfs_lock_dir(lua_State *L) {
		222	struct stat statbuf;
		223	lfs_Lock *lock;
		224	size_t pathl; int fd;
		225	char tmpln, ln;
		226	const char *template = "/lockfile.XXXXXX";
		227	const char *lockfile = "/lockfile.lfs";
		228	const char *path = luaL_checklstring(L, 1, &pathl);
		229	time_t expires = (time_t)luaL_optint(L, 2, INT_MAX);
		230	tmpln = (char*)malloc(pathl + strlen(template) + 1);
		231	if(!tmpln) { lua_pushnil(L); lua_pushstring(L, strerror(errno)); return 2; }
		232	strcpy(tmpln, path); strcat(tmpln, template);
		233	fd = mkstemp(tmpln);
		234	if(fd == -1) {
		235	free(tmpln); lua_pushnil(L); lua_pushstring(L, strerror(errno)); return 2;
		236	}
		237	ln = (char*)malloc(pathl + strlen(lockfile) + 1);
		238	if(!ln) {
		239	unlink(tmpln); free(tmpln); close(fd); lua_pushnil(L);
		240	lua_pushstring(L, strerror(errno)); return 2;
		241	}
		242	strcpy(ln, path); strcat(ln, lockfile);
		243	while(symlink(tmpln, ln) == -1) {
		244	if(errno == EEXIST) {
		245	if(lstat(ln, &statbuf) == -1) goto fail;
		246	if(time(NULL) - statbuf.st_mtimespec.tv_sec > expires) {
		247	unlink(ln);
		248	continue;
		249	}
		250	}
		251	fail:
		252	unlink(tmpln); free(tmpln); free(ln); close(fd);
		253	lua_pushnil(L); lua_pushstring(L, strerror(errno)); return 2;
		254	}
		255	unlink(tmpln); free(tmpln);
		256	lock = (lfs_Lock*)lua_newuserdata(L, sizeof(lfs_Lock));
		257	lock->fd = fd; lock->ln = ln;
		258	luaL_getmetatable (L, LOCK_METATABLE);
		259	lua_setmetatable (L, -2);
		260	return 1;
		261	}
		262	static int lfs_unlock_dir(lua_State *L) {
		263	lfs_Lock *lock = luaL_checkudata(L, 1, LOCK_METATABLE);
		264	unlink(lock->ln);
		265	close(lock->fd);
		266	free(lock->ln);
		267	return 0;
		268	}
		269	#endif
		270
		271	#ifdef _WIN32
209	static int lfs_g_setmode (lua_State L, FILE f, int arg) {	272	static int lfs_g_setmode (lua_State L, FILE f, int arg) {
210	static const int mode[] = {_O_TEXT, _O_BINARY};	273	static const int mode[] = {_O_TEXT, _O_BINARY};
211	static const char *const modenames[] = {"text", "binary", NULL};	274	static const char *const modenames[] = {"text", "binary", NULL};
@@ -433,6 +496,21 @@ static int dir_create_meta (lua_State *L) {
433	return 1;	496	return 1;
434	}	497	}
435		498
		499	/*
		500	** Creates lock metatable.
		501	*/
		502	static int lock_create_meta (lua_State *L) {
		503	luaL_newmetatable (L, LOCK_METATABLE);
		504	/* set its __gc field */
		505	lua_newtable(L);
		506	lua_pushcfunction(L, lfs_unlock_dir);
		507	lua_setfield(L, -2, "free");
		508	lua_setfield(L, -2, "__index");
		509	lua_pushcfunction(L, lfs_unlock_dir);
		510	lua_setfield(L, -2, "__gc");
		511	return 1;
		512	}
		513
436		514
437	#ifdef _WIN32	515	#ifdef _WIN32
438	#ifndef S_ISDIR	516	#ifndef S_ISDIR
@@ -688,11 +766,13 @@ static const struct luaL_reg fslib[] = {
688	{"setmode", lfs_f_setmode},	766	{"setmode", lfs_f_setmode},
689	{"touch", file_utime},	767	{"touch", file_utime},
690	{"unlock", file_unlock},	768	{"unlock", file_unlock},
		769	{"lock_dir", lfs_lock_dir},
691	{NULL, NULL},	770	{NULL, NULL},
692	};	771	};
693		772
694	int luaopen_lfs (lua_State *L) {	773	int luaopen_lfs (lua_State *L) {
695	dir_create_meta (L);	774	dir_create_meta (L);
		775	lock_create_meta (L);
696	luaL_register (L, "lfs", fslib);	776	luaL_register (L, "lfs", fslib);
697	set_info (L);	777	set_info (L);
698	return 1;	778	return 1;