commit: provide a function to find a header in a buffer

Usually when we parse a commit, we read it line by line and
handle each individual line (e.g., parse_commit and
parse_commit_header).  Sometimes, however, we only care
about extracting a single header. Code in this situation is
stuck doing an ad-hoc parse of the commit buffer.

Let's provide a reusable function to locate a header within
the commit.  The code is modeled after pretty.c's
get_header, which is used to extract the encoding.

Since some callers may not have the "struct commit" to go
along with the buffer, we drop that parameter.  The only
thing lost is a warning for truncated commits, but that's
OK.  This shouldn't happen in practice, and even if it does,
there's no particular reason that this function needs to
complain about it. It either finds the header it was asked
for, or it doesn't (and in the latter case, the caller will
typically complain).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/commit.c b/commit.c
index ae7f2b10f4e08a549614346c8262b10503cca953..b6ffd623c89da5e800db37bcdb6437f2fb0fe98b 100644 (file)
--- a/commit.c
+++ b/commit.c
@@ -1660,3 +1660,25 @@ void print_commit_list(struct commit_list *list,
                printf(format, sha1_to_hex(list->item->object.sha1));
        }
 }
+
+const char *find_commit_header(const char *msg, const char *key, size_t *out_len)
+{
+       int key_len = strlen(key);
+       const char *line = msg;
+
+       while (line) {
+               const char *eol = strchrnul(line, '\n');
+
+               if (line == eol)
+                       return NULL;
+
+               if (eol - line > key_len &&
+                   !strncmp(line, key, key_len) &&
+                   line[key_len] == ' ') {
+                       *out_len = eol - line - key_len - 1;
+                       return line + key_len + 1;
+               }
+               line = *eol ? eol + 1 : NULL;
+       }
+       return NULL;
+}

diff --git a/commit.h b/commit.h
index a8cbf52f15ff01778ba61a5a888263d424b2d8d2..12f4fe10c19cf58961764d75f1adea29c37b1a87 100644 (file)
--- a/commit.h
+++ b/commit.h
@@ -313,6 +313,17 @@ extern struct commit_extra_header *read_commit_extra_headers(struct commit *, co
 
 extern void free_commit_extra_headers(struct commit_extra_header *extra);
 
+/*
+ * Search the commit object contents given by "msg" for the header "key".
+ * Returns a pointer to the start of the header contents, or NULL. The length
+ * of the header, up to the first newline, is returned via out_len.
+ *
+ * Note that some headers (like mergetag) may be multi-line. It is the caller's
+ * responsibility to parse further in this case!
+ */
+extern const char *find_commit_header(const char *msg, const char *key,
+                                     size_t *out_len);
+
 typedef void (*each_mergetag_fn)(struct commit *commit, struct commit_extra_header *extra,
                                 void *cb_data);
 

diff --git a/pretty.c b/pretty.c
index 3a1da6fd329efe1723bdb906a907ce4160c4633a..3a705576f3fd36f3b7b1bd2e82ee4460af637a38 100644 (file)
--- a/pretty.c
+++ b/pretty.c
@@ -547,31 +547,11 @@ static void add_merge_info(const struct pretty_print_context *pp,
        strbuf_addch(sb, '\n');
 }
 
-static char *get_header(const struct commit *commit, const char *msg,
-                       const char *key)
+static char *get_header(const char *msg, const char *key)
 {
-       int key_len = strlen(key);
-       const char *line = msg;
-
-       while (line) {
-               const char *eol = strchrnul(line, '\n'), *next;
-
-               if (line == eol)
-                       return NULL;
-               if (!*eol) {
-                       warning("malformed commit (header is missing newline): %s",
-                               sha1_to_hex(commit->object.sha1));
-                       next = NULL;
-               } else
-                       next = eol + 1;
-               if (eol - line > key_len &&
-                   !strncmp(line, key, key_len) &&
-                   line[key_len] == ' ') {
-                       return xmemdupz(line + key_len + 1, eol - line - key_len - 1);
-               }
-               line = next;
-       }
-       return NULL;
+       size_t len;
+       const char *v = find_commit_header(msg, key, &len);
+       return v ? xmemdupz(v, len) : NULL;
 }
 
 static char *replace_encoding_header(char *buf, const char *encoding)
@@ -617,11 +597,10 @@ const char *logmsg_reencode(const struct commit *commit,
 
        if (!output_encoding || !*output_encoding) {
                if (commit_encoding)
-                       *commit_encoding =
-                               get_header(commit, msg, "encoding");
+                       *commit_encoding = get_header(msg, "encoding");
                return msg;
        }
-       encoding = get_header(commit, msg, "encoding");
+       encoding = get_header(msg, "encoding");
        if (commit_encoding)
                *commit_encoding = encoding;
        use_encoding = encoding ? encoding : utf8;