range-diff: fix a crash in parsing git-log output

`git range-diff` calls `git log` internally and tries to parse its
output. But `git log` output can be customized by the user in their
git config and for certain configurations either an error will be
returned by `git range-diff` or it will crash.

To fix this explicitly set the output format of the internally
executed `git log` with `--pretty=medium`. Because that cancels
`--notes`, add explicitly `--notes` at the end.

Also, make sure we never crash in the same way - trying to dereference
`util` which was never created and has remained NULL. It would happen
if the first line of `git log` output does not begin with 'commit '.

Alternative considered but discarded - somehow disable all git configs
and behave as if no config is present in the internally executed
`git log`, but that does not seem to be possible. GIT_CONFIG_NOSYSTEM
is the closest to it, but even with that we would still read
`.git/config`.

Signed-off-by: Vasil Dimov <vd@FreeBSD.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/range-diff.c b/range-diff.c
index f745567cf6719665cdfd23145335380f36e0c54b..5cc920be391d2e93a69899e8e6e4b487fbefa0a3 100644 (file)
--- a/range-diff.c
+++ b/range-diff.c
@@ -63,6 +63,8 @@ static int read_patches(const char *range, struct string_list *list,
                        "--output-indicator-old=<",
                        "--output-indicator-context=#",
                        "--no-abbrev-commit",
+                       "--pretty=medium",
+                       "--notes",
                        NULL);
        if (other_arg)
                argv_array_pushv(&cp.args, other_arg->argv);
@@ -106,6 +108,17 @@ static int read_patches(const char *range, struct string_list *list,
                        continue;
                }
 
+               if (!util) {
+                       error(_("could not parse first line of `log` output: "
+                               "did not start with 'commit ': '%s'"),
+                             line);
+                       string_list_clear(list, 1);
+                       strbuf_release(&buf);
+                       strbuf_release(&contents);
+                       finish_command(&cp);
+                       return -1;
+               }
+
                if (starts_with(line, "diff --git")) {
                        struct patch patch = { 0 };
                        struct strbuf root = STRBUF_INIT;

diff --git a/t/t3206-range-diff.sh b/t/t3206-range-diff.sh
index bd808f87ed5bdf0de3f07299cc25d877219aa7ee..e024cff65cb73e3d5db18ea417bd233618689008 100755 (executable)
--- a/t/t3206-range-diff.sh
+++ b/t/t3206-range-diff.sh
@@ -513,6 +513,16 @@ test_expect_success 'range-diff overrides diff.noprefix internally' '
        git -c diff.noprefix=true range-diff HEAD^...
 '
 
+test_expect_success 'basic with modified format.pretty with suffix' '
+       git -c format.pretty="format:commit %H%d%n" range-diff \
+               master..topic master..unmodified
+'
+
+test_expect_success 'basic with modified format.pretty without "commit "' '
+       git -c format.pretty="format:%H%n" range-diff \
+               master..topic master..unmodified
+'
+
 test_expect_success 'range-diff compares notes by default' '
        git notes add -m "topic note" topic &&
        git notes add -m "unmodified note" unmodified &&