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>

Vasil Dimov committed Apr 15, 2020 at 20:32 UTC 8cf51561d1e15e8f5ad907df00884a7596737dcd

2 files changed +23

range-diff.c

+13

@@ -63,6 +63,8 @@ static int read_patches(const char *range, struct string_list *list,

63 "--output-indicator-old=<",

64 "--output-indicator-context=#",

65 "--no-abbrev-commit",

66 + "--pretty=medium",

67 + "--notes",

68 NULL);

69 if (other_arg)

70 argv_array_pushv(&cp.args, other_arg->argv);

@@ -106,6 +108,17 @@ static int read_patches(const char *range, struct string_list *list,

108 continue;

109 }

110

111 + if (!util) {

112 + error(_("could not parse first line of `log` output: "

113 + "did not start with 'commit ': '%s'"),

114 + line);

115 + string_list_clear(list, 1);

116 + strbuf_release(&buf);

117 + strbuf_release(&contents);

118 + finish_command(&cp);

119 + return -1;

120 + }

121 +

122 if (starts_with(line, "diff --git")) {

123 struct patch patch = { 0 };

124 struct strbuf root = STRBUF_INIT;

t/t3206-range-diff.sh

+10

@@ -513,6 +513,16 @@ test_expect_success 'range-diff overrides diff.noprefix internally' '

513 git -c diff.noprefix=true range-diff HEAD^...

514 '

515

516 +test_expect_success 'basic with modified format.pretty with suffix' '

517 + git -c format.pretty="format:commit %H%d%n" range-diff \

518 + master..topic master..unmodified

519 +'

520 +

521 +test_expect_success 'basic with modified format.pretty without "commit "' '

522 + git -c format.pretty="format:%H%n" range-diff \

523 + master..topic master..unmodified

524 +'

525 +

526 test_expect_success 'range-diff compares notes by default' '

527 git notes add -m "topic note" topic &&

528 git notes add -m "unmodified note" unmodified &&