Subject: Re: [PATCH] setup: only die on invalid .git under RUN_SETUP

From: Ævar Arnfjörð Bjarmason <[email-masked]>
Date: Fri, 23 Jul 2021 11:33:30 +0200

On Thu, Jul 22 2021, Andrei Rybak wrote:

> On 22/07/2021 16:07, Ævar Arnfjörð Bjarmason wrote:
>> Change RUN_SETUP_GENTLY to stop dying if e.g. the .git is "not a
>> repo". This means that we now recover in cases like:
>>      $ echo "gitdir: /foo/bar" > .git
>>      $ git ls-remote https://github.com/torvalds/linux
>>      [... ls-remote output ...]
>> But not (as intended):
>>      $ git rev-parse HEAD
>>      fatal: not a git repository: /foo/bar
>> The relevant setup_git_directory_gently_1() invocation was added in
>> 01017dce546 (setup_git_directory_gently_1(): avoid die()ing,
>> 2017-03-13), but I could reproduce this as far back as Git v1.8.0. I
>> don't know if this ever worked, but it should.
>> Let's also use the compiler to check enum arms for us, instead of
>> having a "default" fall-though case, this changes code added in
>> ce9b8aab5d9 (setup_git_directory_1(): avoid changing global state,
>> 2017-03-13).
>> Reported-by: Tom Cook <[email-masked]>
>> Signed-off-by: Ævar Arnfjörð Bjarmason <[email-masked]>
>> ---
>>   setup.c            | 27 ++++++++++++++++++++++-----
>>   t/t0002-gitfile.sh |  8 ++++++--
>>   2 files changed, 28 insertions(+), 7 deletions(-)
>> diff --git a/setup.c b/setup.c
>> index eb9367ca5c..6ff145d58b 100644
>> --- a/setup.c
>> +++ b/setup.c
>> @@ -1033,7 +1033,8 @@ enum discovery_result {
>>   	/* these are errors */
>>   	GIT_DIR_HIT_CEILING = -1,
>>   	GIT_DIR_HIT_MOUNT_POINT = -2,
>> -	GIT_DIR_INVALID_GITFILE = -3
>> +	GIT_DIR_INVALID_GITFILE = -3,
>> +	GIT_DIR_GITFILE_NOT_A_REPO = -4,
>>   };
>>     /*
>> @@ -1118,8 +1119,11 @@ static enum discovery_result setup_git_directory_gently_1(struct strbuf *dir,
>>   				/* NEEDSWORK: fail if .git is not file nor dir */
>>   				if (is_git_directory(dir->buf))
>>   					gitdirenv = DEFAULT_GIT_DIR_ENVIRONMENT;
>> -			} else if (error_code != READ_GITFILE_ERR_STAT_FAILED)
>> +			} else if (error_code == READ_GITFILE_ERR_NOT_A_REPO) {
>> +				return GIT_DIR_GITFILE_NOT_A_REPO;
>> +			} else if (error_code != READ_GITFILE_ERR_STAT_FAILED) {
>>   				return GIT_DIR_INVALID_GITFILE;
>> +			}
>>   		}
>>   		strbuf_setlen(dir, offset);
>>   		if (gitdirenv) {
>> @@ -1209,6 +1213,8 @@ const char *setup_git_directory_gently(int *nongit_ok)
>>   	struct strbuf dir = STRBUF_INIT, gitdir = STRBUF_INIT;
>>   	const char *prefix = NULL;
>>   	struct repository_format repo_fmt = REPOSITORY_FORMAT_INIT;
>> +	int die_on_error = !nongit_ok;
>> +	enum discovery_result discovery;
>>     	/*
>>   	 * We may have read an incomplete configuration before
>> @@ -1231,7 +1237,9 @@ const char *setup_git_directory_gently(int *nongit_ok)
>>   		die_errno(_("Unable to read current working directory"));
>>   	strbuf_addbuf(&dir, &cwd);
>>   -	switch (setup_git_directory_gently_1(&dir, &gitdir, 1)) {
>> +	discovery = setup_git_directory_gently_1(&dir, &gitdir, die_on_error);
>> +
>> +	switch (discovery) {
>>   	case GIT_DIR_EXPLICIT:
>>   		prefix = setup_explicit_git_dir(gitdir.buf, &cwd, &repo_fmt, nongit_ok);
>>   		break;
>> @@ -1259,6 +1267,16 @@ const char *setup_git_directory_gently(int *nongit_ok)
>>   			    dir.buf);
>>   		*nongit_ok = 1;
>>   		break;
>> +	case GIT_DIR_GITFILE_NOT_A_REPO:
>> +		if (!nongit_ok)
>> +			die(_("not a git repository: %s"), dir.buf);
>> +		*nongit_ok = 1;
>> +		break;
>> +	case GIT_DIR_INVALID_GITFILE:
>> +		if (!nongit_ok)
>
> Variable die_on_error could be used in two `if`s above.

Re-reading my own code I think it's better just to drop die_on_error
entirely and use !nongit_ok consistently, as the rest of the function
does. What do yo think?