add --path option to git hash-object

The --path option allows us to pretend as if the contents being hashed
came from the specified path, and affects which input filter is used via
the attributes mechanism.  This is useful for hashing a temporary file
whose name is different from the path that is meant to have the hashed
contents.

Signed-off-by: Dmitry Potapov <dpotapov@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 13 insertions, 6 deletions

diff --git a/hash-object.c b/hash-object.c
index 489e8369d8..ce04d150a4 100644
--- a/hash-object.c
+++ b/hash-object.c
@@ -22,13 +22,14 @@ static void hash_fd(int fd, const char *type, int write_object, const char *path
 	maybe_flush_or_die(stdout, "hash to stdout");
 }
 
-static void hash_object(const char *path, const char *type, int write_object)
+static void hash_object(const char *path, const char *type, int write_object,
+			const char *vpath)
 {
 	int fd;
 	fd = open(path, O_RDONLY);
 	if (fd < 0)
 		die("Cannot open %s", path);
-	hash_fd(fd, type, write_object, path);
+	hash_fd(fd, type, write_object, vpath);
 }
 
 static void hash_stdin_paths(const char *type, int write_objects)
@@ -44,14 +45,14 @@ static void hash_stdin_paths(const char *type, int write_objects)
 				die("line is badly quoted");
 			strbuf_swap(&buf, &nbuf);
 		}
-		hash_object(buf.buf, type, write_objects);
+		hash_object(buf.buf, type, write_objects, buf.buf);
 	}
 	strbuf_release(&buf);
 	strbuf_release(&nbuf);
 }
 
 static const char * const hash_object_usage[] = {
-	"git hash-object [-t <type>] [-w] [--stdin] [--] <file>...",
+	"git hash-object [-t <type>] [-w] [--path=<file>] [--stdin] [--] <file>...",
 	"git hash-object  --stdin-paths < <list-of-paths>",
 	NULL
 };
@@ -60,12 +61,14 @@ static const char *type;
 static int write_object;
 static int hashstdin;
 static int stdin_paths;
+static const char *vpath;
 
 static const struct option hash_object_options[] = {
 	OPT_STRING('t', NULL, &type, "type", "object type"),
 	OPT_BOOLEAN('w', NULL, &write_object, "write the object into the object database"),
 	OPT_BOOLEAN( 0 , "stdin", &hashstdin, "read the object from stdin"),
 	OPT_BOOLEAN( 0 , "stdin-paths", &stdin_paths, "read file names from stdin"),
+	OPT_STRING( 0 , "path", &vpath, "file", "process file as it were from this path"),
 	OPT_END()
 };
 
@@ -85,6 +88,8 @@ int main(int argc, const char **argv)
 	if (write_object) {
 		prefix = setup_git_directory();
 		prefix_length = prefix ? strlen(prefix) : 0;
+		if (vpath && prefix)
+			vpath = prefix_filename(prefix, prefix_length, vpath);
 	}
 
 	if (stdin_paths) {
@@ -92,6 +97,8 @@ int main(int argc, const char **argv)
 			errstr = "Can't use --stdin-paths with --stdin";
 		else if (argc)
 			errstr = "Can't specify files with --stdin-paths";
+		else if (vpath)
+			errstr = "Can't use --stdin-paths with --path";
 	}
 	else if (hashstdin > 1)
 		errstr = "Multiple --stdin arguments are not supported";
@@ -102,14 +109,14 @@ int main(int argc, const char **argv)
 	}
 
 	if (hashstdin)
-		hash_fd(0, type, write_object, NULL);
+		hash_fd(0, type, write_object, vpath);
 
 	for (i = 0 ; i < argc; i++) {
 		const char *arg = argv[i];
 
 		if (0 <= prefix_length)
 			arg = prefix_filename(prefix, prefix_length, arg);
-		hash_object(arg, type, write_object);
+		hash_object(arg, type, write_object, vpath ? vpath : arg);
 	}
 
 	if (stdin_paths)