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

From: Andrei Rybak <[email-masked]>
Date: Thu, 22 Jul 2021 22:50:52 +0200

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.

> +			die(_("invalid .git file: %s"), dir.buf);
> +		*nongit_ok = 1;
> +		break;
>   	case GIT_DIR_NONE:
>   		/*
>   		 * As a safeguard against setup_git_directory_gently_1 returning
> @@ -1266,8 +1284,7 @@ const char *setup_git_directory_gently(int *nongit_ok)
>   		 * set startup_info->have_repository to 1 when we did nothing to
>   		 * find a repository.
>   		 */
> -	default:
> -		BUG("unhandled setup_git_directory_1() result");
> +		BUG("setup_git_directory_1() should not return GIT_DIR_NONE");
>   	}
>   
>   	/*
> diff --git a/t/t0002-gitfile.sh b/t/t0002-gitfile.sh
> index 8440e6add1..176dc8c9dc 100755
> --- a/t/t0002-gitfile.sh
> +++ b/t/t0002-gitfile.sh
> @@ -21,13 +21,17 @@ test_expect_success 'initial setup' '
>   test_expect_success 'bad setup: invalid .git file format' '
>   	echo "gitdir $REAL" >.git &&
>   	test_must_fail git rev-parse 2>.err &&
> -	test_i18ngrep "invalid gitfile format" .err
> +	test_i18ngrep "invalid gitfile format" .err &&
> +
> +	git ls-remote "file://$REAL"
>   '
>   
>   test_expect_success 'bad setup: invalid .git file path' '
>   	echo "gitdir: $REAL.not" >.git &&
>   	test_must_fail git rev-parse 2>.err &&
> -	test_i18ngrep "not a git repository" .err
> +	test_i18ngrep "not a git repository" .err &&
> +
> +	git ls-remote "file://$REAL"
>   '
>   
>   test_expect_success 'final setup + check rev-parse --git-dir' '
>