commit: copy merged signed tags to headers of merge commit

Now MERGE_HEAD records the tag objects without peeling, we could record
the result of manual conflict resolution via "git commit" without losing
the tag information. Introduce a new "mergetag" multi-line header field to
the commit object, and use it to store the entire contents of each signed
tag merged.

A commit header that has a multi-line payload begins with the header tag
(e.g. "mergetag" in this case), SP, the first line of payload, LF, and all
the remaining lines have a SP inserted at the beginning.

In hindsight, it would have been better to make "merge --continue" as the
way to continue from such an interrupted merge, not "commit", but this is
a backward compatibility baggage we would need to carry around for now.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/commit.c b/builtin/commit.c
index c46f2d18e10bcb3b1b458d4ae94d2d3522305632..4688a738f766ebc5166dce51da609332aa7303b0 100644 (file)
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -1425,7 +1425,6 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
                        pptr = &commit_list_insert(c->item, pptr)->next;
        } else if (whence == FROM_MERGE) {
                struct strbuf m = STRBUF_INIT;
-               struct commit *commit;
                FILE *fp;
 
                if (!reflog_msg)
@@ -1436,11 +1435,12 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
                        die_errno(_("could not open '%s' for reading"),
                                  git_path("MERGE_HEAD"));
                while (strbuf_getline(&m, fp, '\n') != EOF) {
-                       unsigned char sha1[20];
-                       if (get_sha1_hex(m.buf, sha1) < 0)
+                       struct commit *parent;
+
+                       parent = get_merge_parent(m.buf);
+                       if (!parent)
                                die(_("Corrupt MERGE_HEAD file (%s)"), m.buf);
-                       commit = lookup_commit_or_die(sha1, "MERGE_HEAD");
-                       pptr = &commit_list_insert(commit, pptr)->next;
+                       pptr = &commit_list_insert(parent, pptr)->next;
                }
                fclose(fp);
                strbuf_release(&m);

diff --git a/commit.c b/commit.c
index 83ff5035a74464b04aace07879dacd2abe5c2fdc..a33bc89d8e37c5af37c6f1b65b4faa78927ee2fa 100644 (file)
--- a/commit.c
+++ b/commit.c
@@ -840,14 +840,95 @@ struct commit_list *reduce_heads(struct commit_list *heads)
        return result;
 }
 
+static void handle_signed_tag(struct commit *parent, struct commit_extra_header ***tail)
+{
+       struct merge_remote_desc *desc;
+       struct commit_extra_header *mergetag;
+       char *buf;
+       unsigned long size, len;
+       enum object_type type;
+
+       desc = merge_remote_util(parent);
+       if (!desc || !desc->obj)
+               return;
+       buf = read_sha1_file(desc->obj->sha1, &type, &size);
+       if (!buf || type != OBJ_TAG)
+               goto free_return;
+       len = parse_signature(buf, size);
+       if (size == len)
+               goto free_return;
+       /*
+        * We could verify this signature and either omit the tag when
+        * it does not validate, but the integrator may not have the
+        * public key of the signer of the tag he is merging, while a
+        * later auditor may have it while auditing, so let's not run
+        * verify-signed-buffer here for now...
+        *
+        * if (verify_signed_buffer(buf, len, buf + len, size - len, ...))
+        *      warn("warning: signed tag unverified.");
+        */
+       mergetag = xcalloc(1, sizeof(*mergetag));
+       mergetag->key = xstrdup("mergetag");
+       mergetag->value = buf;
+       mergetag->len = size;
+
+       **tail = mergetag;
+       *tail = &mergetag->next;
+       return;
+
+free_return:
+       free(buf);
+}
+
+void append_merge_tag_headers(struct commit_list *parents,
+                             struct commit_extra_header ***tail)
+{
+       while (parents) {
+               struct commit *parent = parents->item;
+               handle_signed_tag(parent, tail);
+               parents = parents->next;
+       }
+}
+
+static void add_extra_header(struct strbuf *buffer,
+                            struct commit_extra_header *extra)
+{
+       strbuf_addstr(buffer, extra->key);
+       strbuf_add_lines(buffer, " ", extra->value, extra->len);
+}
+
+void free_commit_extra_headers(struct commit_extra_header *extra)
+{
+       while (extra) {
+               struct commit_extra_header *next = extra->next;
+               free(extra->key);
+               free(extra->value);
+               free(extra);
+               extra = next;
+       }
+}
+
+int commit_tree(const char *msg, unsigned char *tree,
+               struct commit_list *parents, unsigned char *ret,
+               const char *author)
+{
+       struct commit_extra_header *extra = NULL, **tail = &extra;
+       int result;
+
+       append_merge_tag_headers(parents, &tail);
+       result = commit_tree_extended(msg, tree, parents, ret, author, extra);
+       free_commit_extra_headers(extra);
+       return result;
+}
+
 static const char commit_utf8_warn[] =
 "Warning: commit message does not conform to UTF-8.\n"
 "You may want to amend it after fixing the message, or set the config\n"
 "variable i18n.commitencoding to the encoding your project uses.\n";
 
-int commit_tree(const char *msg, unsigned char *tree,
-               struct commit_list *parents, unsigned char *ret,
-               const char *author)
+int commit_tree_extended(const char *msg, unsigned char *tree,
+                        struct commit_list *parents, unsigned char *ret,
+                        const char *author, struct commit_extra_header *extra)
 {
        int result;
        int encoding_is_utf8;
@@ -868,8 +949,10 @@ int commit_tree(const char *msg, unsigned char *tree,
         */
        while (parents) {
                struct commit_list *next = parents->next;
+               struct commit *parent = parents->item;
+
                strbuf_addf(&buffer, "parent %s\n",
-                       sha1_to_hex(parents->item->object.sha1));
+                           sha1_to_hex(parent->object.sha1));
                free(parents);
                parents = next;
        }
@@ -881,6 +964,11 @@ int commit_tree(const char *msg, unsigned char *tree,
        strbuf_addf(&buffer, "committer %s\n", git_committer_info(IDENT_ERROR_ON_NO_NAME));
        if (!encoding_is_utf8)
                strbuf_addf(&buffer, "encoding %s\n", git_commit_encoding);
+
+       while (extra) {
+               add_extra_header(&buffer, extra);
+               extra = extra->next;
+       }
        strbuf_addch(&buffer, '\n');
 
        /* And add the comment */

diff --git a/commit.h b/commit.h
index 5b57eab578ee4fd10efedecfca59f2992e686a3c..c1a723ecdb877bbbb75fe9fcaf98cef7b7edb59b 100644 (file)
--- a/commit.h
+++ b/commit.h
@@ -181,9 +181,26 @@ static inline int single_parent(struct commit *commit)
 
 struct commit_list *reduce_heads(struct commit_list *heads);
 
+struct commit_extra_header {
+       struct commit_extra_header *next;
+       char *key;
+       char *value;
+       size_t len;
+};
+
+extern void append_merge_tag_headers(struct commit_list *parents,
+                                    struct commit_extra_header ***tail);
+
 extern int commit_tree(const char *msg, unsigned char *tree,
-               struct commit_list *parents, unsigned char *ret,
-               const char *author);
+                      struct commit_list *parents, unsigned char *ret,
+                      const char *author);
+
+extern int commit_tree_extended(const char *msg, unsigned char *tree,
+                               struct commit_list *parents, unsigned char *ret,
+                               const char *author,
+                               struct commit_extra_header *);
+
+extern void free_commit_extra_headers(struct commit_extra_header *extra);
 
 struct merge_remote_desc {
        struct object *obj; /* the named object, could be a tag */