bugreport: collect list of populated hooks

Occasionally a failure a user is seeing may be related to a specific
hook which is being run, perhaps without the user realizing. While the
contents of hooks can be sensitive - containing user data or process
information specific to the user's organization - simply knowing that a
hook is being run at a certain stage can help us to understand whether
something is going wrong.

Without a definitive list of hook names within the code, we compile our
own list from the documentation. This is likely prone to bitrot, but
designing a single source of truth for acceptable hooks is too much
overhead for this small change to the bugreport tool.

Signed-off-by: Emily Shaffer <emilyshaffer@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

3 files changed, 68 insertions, 0 deletions

diff --git a/Documentation/git-bugreport.txt b/Documentation/git-bugreport.txt
index 643d1b2..7fe9aef 100644
--- a/Documentation/git-bugreport.txt
+++ b/Documentation/git-bugreport.txt
@@ -28,6 +28,7 @@ The following information is captured automatically:
  - 'git version --build-options'
  - uname sysname, release, version, and machine strings
  - Compiler-specific info string
+ - A list of enabled hooks
 
 This tool is invoked via the typical Git setup process, which means that in some
 cases, it might not be able to launch - for example, if a relevant config file
diff --git a/bugreport.c b/bugreport.c
index acacca8..aa8a489 100644
--- a/bugreport.c
+++ b/bugreport.c
@@ -3,6 +3,8 @@
 #include "strbuf.h"
 #include "help.h"
 #include "compat/compiler.h"
+#include "run-command.h"
+
 
 static void get_system_info(struct strbuf *sys_info)
 {
@@ -31,6 +33,53 @@ static void get_system_info(struct strbuf *sys_info)
 	get_libc_info(sys_info);
 }
 
+static void get_populated_hooks(struct strbuf *hook_info, int nongit)
+{
+	/*
+	 * NEEDSWORK: Doesn't look like there is a list of all possible hooks;
+	 * so below is a transcription of `git help hooks`. Later, this should
+	 * be replaced with some programmatically generated list (generated from
+	 * doc or else taken from some library which tells us about all the
+	 * hooks)
+	 */
+	static const char *hook[] = {
+		"applypatch-msg",
+		"pre-applypatch",
+		"post-applypatch",
+		"pre-commit",
+		"pre-merge-commit",
+		"prepare-commit-msg",
+		"commit-msg",
+		"post-commit",
+		"pre-rebase",
+		"post-checkout",
+		"post-merge",
+		"pre-push",
+		"pre-receive",
+		"update",
+		"post-receive",
+		"post-update",
+		"push-to-checkout",
+		"pre-auto-gc",
+		"post-rewrite",
+		"sendemail-validate",
+		"fsmonitor-watchman",
+		"p4-pre-submit",
+		"post-index-change",
+	};
+	int i;
+
+	if (nongit) {
+		strbuf_addstr(hook_info,
+			_("not run from a git repository - no hooks to show\n"));
+		return;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(hook); i++)
+		if (find_hook(hook[i]))
+			strbuf_addf(hook_info, "%s\n", hook[i]);
+}
+
 static const char * const bugreport_usage[] = {
 	N_("git bugreport [-o|--output-directory <file>] [-s|--suffix <format>]"),
 	NULL
@@ -114,6 +163,9 @@ int cmd_main(int argc, const char **argv)
 	get_header(&buffer, _("System Info"));
 	get_system_info(&buffer);
 
+	get_header(&buffer, _("Enabled Hooks"));
+	get_populated_hooks(&buffer, nongit_ok);
+
 	/* fopen doesn't offer us an O_EXCL alternative, except with glibc. */
 	report = open(report_path.buf, O_CREAT | O_EXCL | O_WRONLY, 0666);
 
diff --git a/t/t0091-bugreport.sh b/t/t0091-bugreport.sh
index 2e73658..526304f 100755
--- a/t/t0091-bugreport.sh
+++ b/t/t0091-bugreport.sh
@@ -57,5 +57,20 @@ test_expect_success 'can create leading directories outside of a git dir' '
 	nongit git bugreport -o foo/bar/baz
 '
 
+test_expect_success 'indicates populated hooks' '
+	test_when_finished rm git-bugreport-hooks.txt &&
+	test_when_finished rm -fr .git/hooks &&
+	rm -fr .git/hooks &&
+	mkdir .git/hooks &&
+	for hook in applypatch-msg prepare-commit-msg.sample
+	do
+		write_script ".git/hooks/$hook" <<-EOF || return 1
+		echo "hook $hook exists"
+		EOF
+	done &&
+	git bugreport -s hooks &&
+	grep applypatch-msg git-bugreport-hooks.txt &&
+	! grep prepare-commit-msg git-bugreport-hooks.txt
+'
 
 test_done