tar-tree: add the "tar.umask" config option

By default, git-tar-tree(1) sets file and directories modes to 0666
or 0777. While this is both useful and acceptable for projects such
as the Linux Kernel, it might be excessive for other projects. With
this variable, it becomes possible to tell git-tar-tree(1) to apply
a specific umask to the modes above. The special value "user"
indicates that the user's current umask will be used. This should be
enough for most projects, as it will lead to the same permissions as
git-checkout(1) would use. The default value remains 0, which means
world read-write.

Signed-off-by: Willy Tarreau <w@1wt.eu>
Acked-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <junkio@cox.net>

Documentation/config.txt

@@ -208,6 +208,17 @@ showbranch.default::
 	The default set of branches for gitlink:git-show-branch[1].
 	See gitlink:git-show-branch[1].
 
+tar.umask::
+	By default, git-link:git-tar-tree[1] sets file and directories modes
+	to 0666 or 0777. While this is both useful and acceptable for projects
+	such as the Linux Kernel, it might be excessive for other projects.
+	With this variable, it becomes possible to tell
+	git-link:git-tar-tree[1] to apply a specific umask to the modes above.
+	The special value "user" indicates that the user's current umask will
+	be used. This should be enough for most projects, as it will lead to
+	the same permissions as git-link:git-checkout[1] would use. The default
+	value remains 0, which means world read-write.
+
 user.email::
 	Your email address to be recorded in any newly created commits.
 	Can be overridden by the 'GIT_AUTHOR_EMAIL' and 'GIT_COMMITTER_EMAIL'

Documentation/git-tar-tree.txt

@@ -37,7 +37,20 @@ OPTIONS
 	Instead of making a tar archive from local repository,
 	retrieve a tar archive from a remote repository.
 
-Examples
+CONFIGURATION
+-------------
+By default, file and directories modes are set to 0666 or 0777. It is
+possible to change this by setting the "umask" variable in the
+repository configuration as follows :
+
+[tar]
+        umask = 002	;# group friendly
+
+The special umask value "user" indicates that the user's current umask
+will be used instead. The default value remains 0, which means world
+readable/writable files and directories.
+
+EXAMPLES
 --------
 git tar-tree HEAD junk | (cd /var/tmp/ && tar xf -)::
 

builtin-tar-tree.c

@@ -20,6 +20,7 @@ static char block[BLOCKSIZE];
 static unsigned long offset;
 
 static time_t archive_time;
+static int tar_umask;
 
 /* tries hard to write, either succeeds or dies in the attempt */
 static void reliable_write(const void *data, unsigned long size)
@@ -188,13 +189,13 @@ static void write_entry(const unsigned char *sha1, struct strbuf *path,
 	} else {
 		if (S_ISDIR(mode)) {
 			*header.typeflag = TYPEFLAG_DIR;
-			mode |= 0777;
+			mode = (mode | 0777) & ~tar_umask;
 		} else if (S_ISLNK(mode)) {
 			*header.typeflag = TYPEFLAG_LNK;
 			mode |= 0777;
 		} else if (S_ISREG(mode)) {
 			*header.typeflag = TYPEFLAG_REG;
-			mode |= (mode & 0100) ? 0777 : 0666;
+			mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
 		} else {
 			error("unsupported file mode: 0%o (SHA1: %s)",
 			      mode, sha1_to_hex(sha1));
@@ -293,6 +294,20 @@ static void traverse_tree(struct tree_desc *tree, struct strbuf *path)
 	}
 }
 
+int git_tar_config(const char *var, const char *value)
+{
+	if (!strcmp(var, "tar.umask")) {
+		if (!strcmp(value, "user")) {
+			tar_umask = umask(0);
+			umask(tar_umask);
+		} else {
+			tar_umask = git_config_int(var, value);
+		}
+		return 0;
+	}
+	return git_default_config(var, value);
+}
+
 static int generate_tar(int argc, const char **argv, char** envp)
 {
 	unsigned char sha1[20], tree_sha1[20];
@@ -305,7 +320,7 @@ static int generate_tar(int argc, const char **argv, char** envp)
 	current_path.len = current_path.eof = 0;
 
 	setup_git_directory();
-	git_config(git_default_config);
+	git_config(git_tar_config);
 
 	switch (argc) {
 	case 3: