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

On Thu, Jul 22 2021, Andrei Rybak wrote:

On 22/07/2021 16:07, Ævar Arnfjörð Bjarmason wrote:

quoted

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 <redacted>
Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
  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?