Make index file locking code reusable to others.

The framework to create lockfiles that are removed at exit is
first used to reliably write the index file, but it is
applicable to other things, so stop calling it "cache_file".

This also rewords a few remaining error message that called the
index file "cache file".

Signed-off-by: Junio C Hamano <junkio@cox.net>

Makefile

@@ -210,7 +210,7 @@ DIFF_OBJS = \
 
 LIB_OBJS = \
 	blob.o commit.o connect.o csum-file.o cache-tree.o base85.o \
-	date.o diff-delta.o entry.o exec_cmd.o ident.o index.o \
+	date.o diff-delta.o entry.o exec_cmd.o ident.o lockfile.o \
 	object.o pack-check.o patch-delta.o path.o pkt-line.o \
 	quote.o read-cache.o refs.o run-command.o dir.o \
 	server-info.o setup.o sha1_file.o sha1_name.o strbuf.o \

builtin-add.c

@@ -122,7 +122,7 @@ static int add_file_to_index(const char *path, int verbose)
 	return 0;
 }
 
-static struct cache_file cache_file;
+static struct lock_file lock_file;
 
 int cmd_add(int argc, const char **argv, char **envp)
 {
@@ -134,9 +134,9 @@ int cmd_add(int argc, const char **argv, char **envp)
 
 	git_config(git_default_config);
 
-	newfd = hold_index_file_for_update(&cache_file, get_index_file());
+	newfd = hold_lock_file_for_update(&lock_file, get_index_file());
 	if (newfd < 0)
-		die("unable to create new cachefile");
+		die("unable to create new index file");
 
 	if (read_cache() < 0)
 		die("index file corrupt");
@@ -181,7 +181,7 @@ int cmd_add(int argc, const char **argv, char **envp)
 
 	if (active_cache_changed) {
 		if (write_cache(newfd, active_cache, active_nr) ||
-		    commit_index_file(&cache_file))
+		    commit_lock_file(&lock_file))
 			die("Unable to write new index file");
 	}
 

builtin-apply.c

@@ -2072,7 +2072,7 @@ static void write_out_results(struct patch *list, int skipped_patch)
 	}
 }
 
-static struct cache_file cache_file;
+static struct lock_file lock_file;
 
 static struct excludes {
 	struct excludes *next;
@@ -2133,8 +2133,12 @@ static int apply_patch(int fd, const char *filename)
 		apply = 0;
 
 	write_index = check_index && apply;
-	if (write_index && newfd < 0)
-		newfd = hold_index_file_for_update(&cache_file, get_index_file());
+	if (write_index && newfd < 0) {
+		newfd = hold_lock_file_for_update(&lock_file,
+						  get_index_file());
+		if (newfd < 0)
+			die("unable to create new index file");
+	}
 	if (check_index) {
 		if (read_cache() < 0)
 			die("unable to read index file");
@@ -2312,8 +2316,8 @@ int cmd_apply(int argc, const char **argv, char **envp)
 
 	if (write_index) {
 		if (write_cache(newfd, active_cache, active_nr) ||
-		    commit_index_file(&cache_file))
-			die("Unable to write new cachefile");
+		    commit_lock_file(&lock_file))
+			die("Unable to write new index file");
 	}
 
 	return 0;

builtin-read-tree.c

@@ -853,7 +853,7 @@ static void prime_cache_tree(void)
 
 static const char read_tree_usage[] = "git-read-tree (<sha> | -m [--aggressive] [-u | -i] <sha1> [<sha2> [<sha3>]])";
 
-static struct cache_file cache_file;
+static struct lock_file lock_file;
 
 int cmd_read_tree(int argc, const char **argv, char **envp)
 {
@@ -864,9 +864,9 @@ int cmd_read_tree(int argc, const char **argv, char **envp)
 	setup_git_directory();
 	git_config(git_default_config);
 
-	newfd = hold_index_file_for_update(&cache_file, get_index_file());
+	newfd = hold_lock_file_for_update(&lock_file, get_index_file());
 	if (newfd < 0)
-		die("unable to create new cachefile");
+		die("unable to create new index file");
 
 	git_config(git_default_config);
 
@@ -981,7 +981,7 @@ int cmd_read_tree(int argc, const char **argv, char **envp)
 	}
 
 	if (write_cache(newfd, active_cache, active_nr) ||
-	    commit_index_file(&cache_file))
+	    commit_lock_file(&lock_file))
 		die("unable to write new index file");
 	return 0;
 }

builtin-rm.c

@@ -41,7 +41,7 @@ static int remove_file(const char *name)
 	return ret;
 }
 
-static struct cache_file cache_file;
+static struct lock_file lock_file;
 
 int cmd_rm(int argc, const char **argv, char **envp)
 {
@@ -53,7 +53,7 @@ int cmd_rm(int argc, const char **argv, char **envp)
 
 	git_config(git_default_config);
 
-	newfd = hold_index_file_for_update(&cache_file, get_index_file());
+	newfd = hold_lock_file_for_update(&lock_file, get_index_file());
 	if (newfd < 0)
 		die("unable to create new index file");
 
@@ -144,7 +144,7 @@ int cmd_rm(int argc, const char **argv, char **envp)
 
 	if (active_cache_changed) {
 		if (write_cache(newfd, active_cache, active_nr) ||
-		    commit_index_file(&cache_file))
+		    commit_lock_file(&lock_file))
 			die("Unable to write new index file");
 	}
 

cache.h

@@ -167,13 +167,13 @@ extern void fill_stat_cache_info(struct cache_entry *ce, struct stat *st);
 #define REFRESH_IGNORE_MISSING	0x0008	/* ignore non-existent */
 extern int refresh_cache(unsigned int flags);
 
-struct cache_file {
-	struct cache_file *next;
-	char lockfile[PATH_MAX];
+struct lock_file {
+	struct lock_file *next;
+	char filename[PATH_MAX];
 };
-extern int hold_index_file_for_update(struct cache_file *, const char *path);
-extern int commit_index_file(struct cache_file *);
-extern void rollback_index_file(struct cache_file *);
+extern int hold_lock_file_for_update(struct lock_file *, const char *path);
+extern int commit_lock_file(struct lock_file *);
+extern void rollback_lock_file(struct lock_file *);
 
 /* Environment bits from configuration mechanism */
 extern int trust_executable_bit;

checkout-index.c

@@ -168,7 +168,7 @@ static int checkout_all(void)
 static const char checkout_cache_usage[] =
 "git-checkout-index [-u] [-q] [-a] [-f] [-n] [--stage=[123]|all] [--prefix=<string>] [--temp] [--] <file>...";
 
-static struct cache_file cache_file;
+static struct lock_file lock_file;
 
 int main(int argc, char **argv)
 {
@@ -211,9 +211,8 @@ int main(int argc, char **argv)
 		if (!strcmp(arg, "-u") || !strcmp(arg, "--index")) {
 			state.refresh_cache = 1;
 			if (newfd < 0)
-				newfd = hold_index_file_for_update
-					(&cache_file,
-					 get_index_file());
+				newfd = hold_lock_file_for_update
+					(&lock_file, get_index_file());
 			if (newfd < 0)
 				die("cannot open index.lock file.");
 			continue;
@@ -262,7 +261,7 @@ int main(int argc, char **argv)
 		 */
 		if (state.refresh_cache) {
 			close(newfd); newfd = -1;
-			rollback_index_file(&cache_file);
+			rollback_lock_file(&lock_file);
 		}
 		state.refresh_cache = 0;
 	}
@@ -312,7 +311,7 @@ int main(int argc, char **argv)
 
 	if (0 <= newfd &&
 	    (write_cache(newfd, active_cache, active_nr) ||
-	     commit_index_file(&cache_file)))
-		die("Unable to write new cachefile");
+	     commit_lock_file(&lock_file)))
+		die("Unable to write new index file");
 	return 0;
 }

lockfile.c

@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2005, Junio C Hamano
+ */
+#include <signal.h>
+#include "cache.h"
+
+static struct lock_file *lock_file_list;
+
+static void remove_lock_file(void)
+{
+	while (lock_file_list) {
+		if (lock_file_list->filename[0])
+			unlink(lock_file_list->filename);
+		lock_file_list = lock_file_list->next;
+	}
+}
+
+static void remove_lock_file_on_signal(int signo)
+{
+	remove_lock_file();
+	signal(SIGINT, SIG_DFL);
+	raise(signo);
+}
+
+int hold_lock_file_for_update(struct lock_file *lk, const char *path)
+{
+	int fd;
+	sprintf(lk->filename, "%s.lock", path);
+	fd = open(lk->filename, O_RDWR | O_CREAT | O_EXCL, 0666);
+	if (fd >=0 && !lk->next) {
+		lk->next = lock_file_list;
+		lock_file_list = lk;
+		signal(SIGINT, remove_lock_file_on_signal);
+		atexit(remove_lock_file);
+	}
+	return fd;
+}
+
+int commit_lock_file(struct lock_file *lk)
+{
+	char result_file[PATH_MAX];
+	int i;
+	strcpy(result_file, lk->filename);
+	i = strlen(result_file) - 5; /* .lock */
+	result_file[i] = 0;
+	i = rename(lk->filename, result_file);
+	lk->filename[0] = 0;
+	return i;
+}
+
+void rollback_lock_file(struct lock_file *lk)
+{
+	if (lk->filename[0])
+		unlink(lk->filename);
+	lk->filename[0] = 0;
+}
+

update-index.c

@@ -186,7 +186,7 @@ static void chmod_path(int flip, const char *path)
 	die("git-update-index: cannot chmod %cx '%s'", flip, path);
 }
 
-static struct cache_file cache_file;
+static struct lock_file lock_file;
 
 static void update_one(const char *path, const char *prefix, int prefix_length)
 {
@@ -489,9 +489,9 @@ int main(int argc, const char **argv)
 
 	git_config(git_default_config);
 
-	newfd = hold_index_file_for_update(&cache_file, get_index_file());
+	newfd = hold_lock_file_for_update(&lock_file, get_index_file());
 	if (newfd < 0)
-		die("unable to create new cachefile");
+		die("unable to create new index file");
 
 	entries = read_cache();
 	if (entries < 0)
@@ -645,8 +645,8 @@ int main(int argc, const char **argv)
  finish:
 	if (active_cache_changed) {
 		if (write_cache(newfd, active_cache, active_nr) ||
-		    commit_index_file(&cache_file))
-			die("Unable to write new cachefile");
+		    commit_lock_file(&lock_file))
+			die("Unable to write new index file");
 	}
 
 	return has_errors ? 1 : 0;

write-tree.c

@@ -11,15 +11,15 @@ static int missing_ok = 0;
 
 static const char write_tree_usage[] = "git-write-tree [--missing-ok]";
 
-static struct cache_file cache_file;
+static struct lock_file lock_file;
 
 int main(int argc, char **argv)
 {
 	int entries, was_valid, newfd;
 
 	setup_git_directory();
 
-	newfd = hold_index_file_for_update(&cache_file, get_index_file());
+	newfd = hold_lock_file_for_update(&lock_file, get_index_file());
 	entries = read_cache();
 	if (argc == 2) {
 		if (!strcmp(argv[1], "--missing-ok"))
@@ -45,7 +45,7 @@ int main(int argc, char **argv)
 			die("git-write-tree: error building trees");
 		if (0 <= newfd) {
 			if (!write_cache(newfd, active_cache, active_nr))
-				commit_index_file(&cache_file);
+				commit_lock_file(&lock_file);
 		}
 		/* Not being able to write is fine -- we are only interested
 		 * in updating the cache-tree part, and if the next caller