[PATCH 1/4] convert: Safer handling of $Id$ contraction.

@@ -425,6 +425,7 @@ static int count_ident(const char *cp, unsigned long size)
 				cnt++;
 				break;
 			}
+			if (ch == '\n') break;
 		}
 	}
 	return cnt;

@@ -433,7 +434,7 @@ static int count_ident(const char *cp, unsigned long size)
 static int ident_to_git(const char *path, const char *src, size_t len,
                         struct strbuf *buf, int ident)
 {
-	char *dst, *dollar;
+	char *dst, *dollar, *nl;
 
 	if (!ident || !count_ident(src, len))
 		return 0;

@@ -455,6 +456,12 @@ static int ident_to_git(const char *path, const char *src, size_t len,
 			dollar = memchr(src + 3, '$', len - 3);
 			if (!dollar)
 				break;
+			nl = memchr(src + 3, '\n', len - 3);
+			if (nl && nl < dollar) {
+				/* Line break before the next dollar. */
+				continue;
+			}
+
 			memcpy(dst, "Id$", 3);
 			dst += 3;
 			len -= dollar + 1 - src;

@@ -470,7 +477,7 @@ static int ident_to_worktree(const char *path, const char *src, size_t len,
                              struct strbuf *buf, int ident)
 {
 	unsigned char sha1[20];
-	char *to_free = NULL, *dollar;
+	char *to_free = NULL, *dollar, *nl;
 	int cnt;
 
 	if (!ident)

@@ -514,6 +521,12 @@ static int ident_to_worktree(const char *path, const char *src, size_t len,
 				break;
 			}
 
+			nl = memchr(src + 3, '\n', len - 3);
+			if (nl && nl < dollar) {
+				/* Line break before the next dollar. */
+				continue;
+			}
+
 			len -= dollar + 1 - src;
 			src  = dollar + 1;
 		} else {

@@ -513,7 +513,10 @@ static int ident_to_worktree(const char *path, const char *src, size_t len,
 		} else if (src[2] == ':') {
 			/*
 			 * It's possible that an expanded Id has crept its way into the
-			 * repository, we cope with that by stripping the expansion out
+			 * repository, we cope with that by stripping the expansion out.
+			 * This is probably not a good idea, since it will cause changes
+			 * on checkout, which won't go away by stash, but let's keep it
+			 * for git-style ids.
 			 */
 			dollar = memchr(src + 3, '$', len - 3);
 			if (!dollar) {

@@ -527,6 +530,15 @@ static int ident_to_worktree(const char *path, const char *src, size_t len,
 				continue;
 			}
 
+			if ((src[3] != ' ') ||
+			    (memchr(src + 4, ' ', len - 4) != dollar-1)) {
+				/* There are spaces in unexpected places.
+				 * This is probably an id from some other
+				 * versioning system. Keep it for now.
+				 */
+				continue;
+			}
+
 			len -= dollar + 1 - src;
 			src  = dollar + 1;
 		} else {

@@ -1759,7 +1759,7 @@ static int read_old_data(struct stat *st, const char *path, struct strbuf *buf)
 	case S_IFREG:
 		if (strbuf_read_file(buf, path, st->st_size) != st->st_size)
 			return error("unable to open or read %s", path);
-		convert_to_git(path, buf->buf, buf->len, buf, 0);
+		convert_to_git(path, buf->buf, buf->len, buf, 0, 0);
 		return 0;
 	default:
 		return -1;

@@ -2050,7 +2050,7 @@ static struct commit *fake_working_tree_commit(const char *path, const char *con
 		if (strbuf_read(&buf, 0, 0) < 0)
 			die_errno("failed to read from stdin");
 	}
-	convert_to_git(path, buf.buf, buf.len, &buf, 0);
+	convert_to_git(path, buf.buf, buf.len, &buf, 0, 0);
 	origin->file.ptr = buf.buf;
 	origin->file.size = buf.len;
 	pretend_sha1_file(buf.buf, buf.len, OBJ_BLOB, origin->blob_sha1);

@@ -547,6 +547,11 @@ enum safe_crlf {
 	SAFE_CRLF_WARN = 2,
 };
 
+enum ident_mode {
+	IDENT_MODE_FALSE = 0,
+	IDENT_MODE_KEEP_FOREIGN = 1,
+};
+
 extern enum safe_crlf safe_crlf;
 
 enum branch_track {

@@ -996,7 +1001,8 @@ extern void trace_argv_printf(const char **argv, const char *format, ...);
 /* convert.c */
 /* returns 1 if *dst was used */
 extern int convert_to_git(const char *path, const char *src, size_t len,
-                          struct strbuf *dst, enum safe_crlf checksafe);
+                          struct strbuf *dst, enum safe_crlf checksafe,
+                          enum ident_mode identmode);
 extern int convert_to_working_tree(const char *path, const char *src, size_t len, struct strbuf *dst);
 
 /* add */

@@ -758,7 +758,7 @@ static void show_patch_diff(struct combine_diff_path *elem, int num_parent,
 			if (is_file) {
 				struct strbuf buf = STRBUF_INIT;
 
-				if (convert_to_git(elem->path, result, len, &buf, safe_crlf)) {
+				if (convert_to_git(elem->path, result, len, &buf, safe_crlf, 0)) {
 					free(result);
 					result = strbuf_detach(&buf, &len);
 					result_size = len;

@@ -432,7 +432,8 @@ static int count_ident(const char *cp, unsigned long size)
 }
 
 static int ident_to_git(const char *path, const char *src, size_t len,
-                        struct strbuf *buf, int ident)
+                        struct strbuf *buf, int ident,
+                        enum ident_mode identmode)
 {
 	char *dst, *dollar, *nl;
 

@@ -462,6 +463,18 @@ static int ident_to_git(const char *path, const char *src, size_t len,
 				continue;
 			}
 
+			if ((identmode == IDENT_MODE_KEEP_FOREIGN) &&
+			    ((src[3] != ' ') ||
+			     (memchr(src + 4, ' ', len - 4) != dollar-1))) {
+				/* Foreign id.
+				 * Contraction of these is inhibited during
+				 * status operations to avoid all files
+				 * containing such being marked as modified
+				 * on checkout. cf sha1_file.c:index_mem().
+				 */
+				continue;
+			}
+
 			memcpy(dst, "Id$", 3);
 			dst += 3;
 			len -= dollar + 1 - src;

@@ -594,7 +607,8 @@ static int git_path_check_ident(const char *path, struct git_attr_check *check)
 }
 
 int convert_to_git(const char *path, const char *src, size_t len,
-                   struct strbuf *dst, enum safe_crlf checksafe)
+                   struct strbuf *dst, enum safe_crlf checksafe,
+                   enum ident_mode identmode)
 {
 	struct git_attr_check check[3];
 	int crlf = CRLF_GUESS;

@@ -621,7 +635,7 @@ int convert_to_git(const char *path, const char *src, size_t len,
 		src = dst->buf;
 		len = dst->len;
 	}
-	return ret | ident_to_git(path, src, len, dst, ident);
+	return ret | ident_to_git(path, src, len, dst, ident, identmode);
 }
 
 int convert_to_working_tree(const char *path, const char *src, size_t len, struct strbuf *dst)

@@ -2113,7 +2113,7 @@ int diff_populate_filespec(struct diff_filespec *s, int size_only)
 		/*
 		 * Convert from working tree format to canonical git format
 		 */
-		if (convert_to_git(s->path, s->data, s->size, &buf, safe_crlf)) {
+		if (convert_to_git(s->path, s->data, s->size, &buf, safe_crlf, 0)) {
 			size_t size = 0;
 			munmap(s->data, s->size);
 			s->should_munmap = 0;

@@ -2419,7 +2419,8 @@ static int index_mem(unsigned char *sha1, void *buf, size_t size,
 	if ((type == OBJ_BLOB) && path) {
 		struct strbuf nbuf = STRBUF_INIT;
 		if (convert_to_git(path, buf, size, &nbuf,
-		                   write_object ? safe_crlf : 0)) {
+		                   write_object ? safe_crlf : 0,
+		                   write_object ? 0 : IDENT_MODE_KEEP_FOREIGN)) {
 			buf = strbuf_detach(&nbuf, &size);
 			re_allocated = 1;
 		}

@@ -533,6 +533,12 @@ core.sparseCheckout::
 	Enable "sparse checkout" feature. See section "Sparse checkout" in
 	linkgit:git-read-tree[1] for more information.
 
+core.refilterOnAdd::
+	Enable "refilter on add" feature. This causes source files to be
+	behave as if they were checked out after a linkgit:git-add[1].
+	This is typically usefull if eg the `ident` attribute is active,
+	in which case the $Id$ tags will be updated.
+
 add.ignore-errors::
 	Tells 'git add' to continue adding files when some files cannot be
 	added due to indexing errors. Equivalent to the '--ignore-errors'

@@ -540,6 +540,7 @@ extern int read_replace_refs;
 extern int fsync_object_files;
 extern int core_preload_index;
 extern int core_apply_sparse_checkout;
+extern int core_refilter_on_add;
 
 enum safe_crlf {
 	SAFE_CRLF_FALSE = 0,

@@ -523,6 +523,11 @@ static int git_default_core_config(const char *var, const char *value)
 		return 0;
 	}
 
+	if (!strcmp(var, "core.refilteronadd")) {
+		core_refilter_on_add = git_config_bool(var, value);
+		return 0;
+	}
+
 	/* Add other config variables here and to Documentation/config.txt. */
 	return 0;
 }

@@ -52,6 +52,7 @@ enum object_creation_mode object_creation_mode = OBJECT_CREATION_MODE;
 char *notes_ref_name;
 int grafts_replace_parents = 1;
 int core_apply_sparse_checkout;
+int core_refilter_on_add;
 
 /* Parallel index stat data preload? */
 int core_preload_index = 0;

@@ -2459,6 +2459,54 @@ int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object,
 	return ret;
 }
 
+static int refilter_fd(int fd, struct stat *st, const char *path)
+{
+	int ret = -1;
+	size_t size = xsize_t(st->st_size);
+	struct strbuf gbuf = STRBUF_INIT;
+
+	if (!S_ISREG(st->st_mode)) {
+		struct strbuf sbuf = STRBUF_INIT;
+		if (strbuf_read(&sbuf, fd, 4096) >= 0)
+			ret = convert_to_git(path, sbuf.buf, sbuf.len, &gbuf, safe_crlf, 0);
+		else
+			ret = -1;
+		strbuf_release(&sbuf);
+	} else if (size) {
+		void *buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
+		ret = convert_to_git(path, buf, size, &gbuf, safe_crlf, 0);
+		munmap(buf, size);
+	} else
+		ret = -1;
+
+	if (ret > 0) {
+		/* Something happened during conversion to git.
+		 * Now convert it back, and save the result.
+		 */
+		struct strbuf obuf = STRBUF_INIT;
+
+		lseek(fd, 0, SEEK_SET);
+
+		if (convert_to_working_tree(path, gbuf.buf, gbuf.len, &obuf)) {
+			if (write_or_whine(fd, obuf.buf, obuf.len, path))
+				ftruncate(fd, obuf.len);
+			else
+				ret = -1;
+		} else {
+			if (write_or_whine(fd, gbuf.buf, gbuf.len, path))
+				ftruncate(fd, gbuf.len);
+			else
+				ret = -1;
+		}
+
+		strbuf_release(&obuf);
+	}
+	strbuf_release(&gbuf);
+
+	close(fd);
+	return ret;
+}
+
 int index_path(unsigned char *sha1, const char *path, struct stat *st, int write_object)
 {
 	int fd;

@@ -2473,6 +2521,15 @@ int index_path(unsigned char *sha1, const char *path, struct stat *st, int write
 		if (index_fd(sha1, fd, st, write_object, OBJ_BLOB, path) < 0)
 			return error("%s: failed to insert into database",
 				     path);
+		if (write_object && core_refilter_on_add) {
+			fd = open(path, O_RDWR);
+			if (fd < 0)
+				return error("open(\"%s\"): %s", path,
+					     strerror(errno));
+			if (refilter_fd(fd, st, path) < 0)
+				return error("%s: failed to refilter file",
+					     path);
+		}
 		break;
 	case S_IFLNK:
 		if (strbuf_readlink(&sb, path, st->st_size)) {