log_tree_diff: die when we fail to parse a commit

We currently call parse_commit and then assume we can
dereference the resulting "tree" struct field. If parsing
failed, however, that field is NULL and we end up
segfaulting.

Instead of a segfault, let's print an error message and die
a little more gracefully.

Note that this should never happen in practice, but may
happen in a corrupt repository.

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 a575564a15c1c340b36d10c90da8fa343692264d..26c1d5406d3b1229ffdd2b152a05dcb601ebe5ca 100644 (file)
--- a/commit.c
+++ b/commit.c
@@ -341,6 +341,13 @@ int parse_commit(struct commit *item)
        return ret;
 }
 
+void parse_commit_or_die(struct commit *item)
+{
+       if (parse_commit(item))
+               die("unable to parse commit %s",
+                   item ? sha1_to_hex(item->object.sha1) : "(null)");
+}
+
 int find_commit_subject(const char *commit_buffer, const char **subject)
 {
        const char *eol;

diff --git a/commit.h b/commit.h
index d912a9d4ac3fe36b2e69d48b1725f01bdf289b26..a3645dabf83bd25b1a8f66993bfbbfd2d8f922b0 100644 (file)
--- a/commit.h
+++ b/commit.h
@@ -49,6 +49,7 @@ struct commit *lookup_commit_or_die(const unsigned char *sha1, const char *ref_n
 
 int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size);
 int parse_commit(struct commit *item);
+void parse_commit_or_die(struct commit *item);
 
 /* Find beginning and length of commit subject. */
 int find_commit_subject(const char *commit_buffer, const char **subject);

diff --git a/log-tree.c b/log-tree.c
index a49d8e895d3ad24f00e8504ec3eccfbddead6b4c..11604b1e5e1f657903b2837a5fadfa72c610f849 100644 (file)
--- a/log-tree.c
+++ b/log-tree.c
@@ -734,7 +734,7 @@ static int log_tree_diff(struct rev_info *opt, struct commit *commit, struct log
        if (!opt->diff && !DIFF_OPT_TST(&opt->diffopt, EXIT_WITH_STATUS))
                return 0;
 
-       parse_commit(commit);
+       parse_commit_or_die(commit);
        sha1 = commit->tree->object.sha1;
 
        /* Root commit? */
@@ -759,7 +759,7 @@ static int log_tree_diff(struct rev_info *opt, struct commit *commit, struct log
                         * parent, showing summary diff of the others
                         * we merged _in_.
                         */
-                       parse_commit(parents->item);
+                       parse_commit_or_die(parents->item);
                        diff_tree_sha1(parents->item->tree->object.sha1,
                                       sha1, "", &opt->diffopt);
                        log_tree_diff_flush(opt);
@@ -774,7 +774,7 @@ static int log_tree_diff(struct rev_info *opt, struct commit *commit, struct log
        for (;;) {
                struct commit *parent = parents->item;
 
-               parse_commit(parent);
+               parse_commit_or_die(parent);
                diff_tree_sha1(parent->tree->object.sha1,
                               sha1, "", &opt->diffopt);
                log_tree_diff_flush(opt);