Allow saving an object from a pipe

In order to support getting data into git with scripts, this adds a
--stdin option to git-hash-object, which will make it read from stdin.

Signed-off-by: Daniel Barkalow <barkalow@iabervon.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

Documentation/git-hash-object.txt

@@ -8,7 +8,7 @@ git-hash-object - Computes object ID and optionally creates a blob from a file.
 
 SYNOPSIS
 --------
-'git-hash-object' [-t <type>] [-w] <file>
+'git-hash-object' [-t <type>] [-w] [--stdin] [--] <file>...
 
 DESCRIPTION
 -----------
@@ -29,6 +29,9 @@ OPTIONS
 -w::
 	Actually write the object into the object database.
 
+--stdin::
+	Read the object from standard input instead of from a file.
+
 Author
 ------
 Written by Junio C Hamano <junkio@cox.net>

cache.h

@@ -144,6 +144,7 @@ extern int ce_match_stat(struct cache_entry *ce, struct stat *st);
 extern int ce_modified(struct cache_entry *ce, struct stat *st);
 extern int ce_path_match(const struct cache_entry *ce, const char **pathspec);
 extern int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object, const char *type);
+extern int index_pipe(unsigned char *sha1, int fd, const char *type, int write_object);
 extern int index_path(unsigned char *sha1, const char *path, struct stat *st, int write_object);
 extern void fill_stat_cache_info(struct cache_entry *ce, struct stat *st);
 

hash-object.c

@@ -21,8 +21,16 @@ static void hash_object(const char *path, const char *type, int write_object)
 	printf("%s\n", sha1_to_hex(sha1));
 }
 
+static void hash_stdin(const char *type, int write_object)
+{
+	unsigned char sha1[20];
+	if (index_pipe(sha1, 0, type, write_object))
+		die("Unable to add stdin to database");
+	printf("%s\n", sha1_to_hex(sha1));
+}
+
 static const char hash_object_usage[] =
-"git-hash-object [-t <type>] [-w] <file>...";
+"git-hash-object [-t <type>] [-w] [--stdin] <file>...";
 
 int main(int argc, char **argv)
 {
@@ -53,6 +61,9 @@ int main(int argc, char **argv)
 			}
 			else if (!strcmp(argv[i], "--help"))
 				usage(hash_object_usage);
+			else if (!strcmp(argv[i], "--stdin")) {
+				hash_stdin(type, write_object);
+			}
 			else
 				die(hash_object_usage);
 		} 

sha1_file.c

@@ -1528,6 +1528,40 @@ int has_sha1_file(const unsigned char *sha1)
 	return find_sha1_file(sha1, &st) ? 1 : 0;
 }
 
+int index_pipe(unsigned char *sha1, int fd, const char *type, int write_object)
+{
+	unsigned long size = 4096;
+	char *buf = malloc(size);
+	int iret, ret;
+	unsigned long off = 0;
+	unsigned char hdr[50];
+	int hdrlen;
+	do {
+		iret = read(fd, buf + off, size - off);
+		if (iret > 0) {
+			off += iret;
+			if (off == size) {
+				size *= 2;
+				buf = realloc(buf, size);
+			}
+		}
+	} while (iret > 0);
+	if (iret < 0) {
+		free(buf);
+		return -1;
+	}
+	if (!type)
+		type = "blob";
+	if (write_object)
+		ret = write_sha1_file(buf, off, type, sha1);
+	else {
+		write_sha1_file_prepare(buf, off, type, sha1, hdr, &hdrlen);
+		ret = 0;
+	}
+	free(buf);
+	return ret;
+}
+
 int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object, const char *type)
 {
 	unsigned long size = st->st_size;