diff mbox series

[RFC] rev-parse: fix segfault with missing --path-format argument

Message ID 20210516120449.661636-1-wolf@oriole.systems (mailing list archive)
State New, archived
Headers show
Series [RFC] rev-parse: fix segfault with missing --path-format argument | expand

Commit Message

Wolfgang Müller May 16, 2021, 12:04 p.m. UTC
Calling "git rev-parse --path-format" without an argument segfaults
instead of giving an error message. Commit fac60b8925 (rev-parse: add
option for absolute or relative path formatting, 2020-12-13) added the
argument parsing code but forgot to handle NULL.

Returning an error makes sense here because there is no default value we
could use. Add a test case to verify.

Signed-off-by: Wolfgang Müller <wolf@oriole.systems>
---
Since this is my first contribution to the project and I'm still
learning the ropes, I left this patch as RFC.

For a bit of background information, I ran into this expecting the
following to work:

	git rev-parse --path-format relative --show-toplevel

I'm unsure how many git subcommands specifically require "=" between the
option and the argument, but before now I always expected things to
"just work" when leaving it out.

This fix is based on maint.

Thanks for your time and attention.

 builtin/rev-parse.c  | 2 ++
 t/t1500-rev-parse.sh | 4 ++++
 2 files changed, 6 insertions(+)

Comments

Junio C Hamano May 16, 2021, 12:53 p.m. UTC | #1
Wolfgang Müller <wolf@oriole.systems> writes:

> Calling "git rev-parse --path-format" without an argument segfaults
> instead of giving an error message. Commit fac60b8925 (rev-parse: add
> option for absolute or relative path formatting, 2020-12-13) added the
> argument parsing code but forgot to handle NULL.
>
> Returning an error makes sense here because there is no default value we
> could use. Add a test case to verify.
>
> Signed-off-by: Wolfgang Müller <wolf@oriole.systems>
> ---
> Since this is my first contribution to the project and I'm still
> learning the ropes, I left this patch as RFC.
>
> For a bit of background information, I ran into this expecting the
> following to work:
>
> 	git rev-parse --path-format relative --show-toplevel
>
> I'm unsure how many git subcommands specifically require "=" between the
> option and the argument, but before now I always expected things to
> "just work" when leaving it out.
>
> This fix is based on maint.
>
> Thanks for your time and attention.

Nicely done.

>  builtin/rev-parse.c  | 2 ++
>  t/t1500-rev-parse.sh | 4 ++++
>  2 files changed, 6 insertions(+)
>
> diff --git a/builtin/rev-parse.c b/builtin/rev-parse.c
> index 85bad9052e..7af8dab8bc 100644
> --- a/builtin/rev-parse.c
> +++ b/builtin/rev-parse.c
> @@ -759,6 +759,8 @@ int cmd_rev_parse(int argc, const char **argv, const char *prefix)
>  				continue;
>  			}
>  			if (opt_with_value(arg, "--path-format", &arg)) {
> +				if (!arg)
> +					die("--path-format requires an argument");

As die() is end-user facing, you'd probably want

	die(_("--path-format requires an argument"));

We do have untranslated die() nearby for the same option, which may
want to be cleaned up either in a preliminary patch, or in this same
patch as an unrelated fix "while we are at it".

>  				if (!strcmp(arg, "absolute")) {
>  					format = FORMAT_CANONICAL;
>  				} else if (!strcmp(arg, "relative")) {
> diff --git a/t/t1500-rev-parse.sh b/t/t1500-rev-parse.sh
> index deae916707..a1a8ce5265 100755
> --- a/t/t1500-rev-parse.sh
> +++ b/t/t1500-rev-parse.sh
> @@ -146,6 +146,10 @@ test_expect_success '--path-format can change in the middle of the command line'
>  	test_cmp expect actual
>  '
>  
> +test_expect_success '--path-format does not segfault without an argument' '
> +	test_must_fail git rev-parse --path-format --show-toplevel

The above is certainly worth testing for, but if we ever upgrade the
command line parser of "rev-parse" to be compatible with the parser
based on the parse-options API to allow both "--opt=val" and "--opt
val", it will start to fail for an entirely different reason, namely
"--show-toplevel" will be taken as the argument to "--path-format",
and we'd get "unknown argument to --path-format".  So it might be
prudent to test both, i.e.

	test_must_fail git rev-parse --path-format --show-toplevel &&
	test_must_fail git rev-parse --show-toplevel --path-format
Wolfgang Müller May 16, 2021, 2:31 p.m. UTC | #2
On 2021-05-16 21:53, Junio C Hamano wrote:

> As die() is end-user facing, you'd probably want
> 
> 	die(_("--path-format requires an argument"));
> 
> We do have untranslated die() nearby for the same option, which may
> want to be cleaned up either in a preliminary patch, or in this same
> patch as an unrelated fix "while we are at it".

I would not mind preparing a preliminary patch that cleans up all
untranslated user-facing calls to die(). My editor finds 15 of those in
rev-parse.c, and I think they all qualify.

If you'd rather not touch unrelated code paths I'll instead include it
in v2 as an unrelated fix in the same commit.

> The above is certainly worth testing for, but if we ever upgrade the
> command line parser of "rev-parse" to be compatible with the parser
> based on the parse-options API to allow both "--opt=val" and "--opt
> val", it will start to fail for an entirely different reason, namely
> "--show-toplevel" will be taken as the argument to "--path-format",
> and we'd get "unknown argument to --path-format".  So it might be
> prudent to test both, i.e.
> 
> 	test_must_fail git rev-parse --path-format --show-toplevel &&
> 	test_must_fail git rev-parse --show-toplevel --path-format

I think I initially went for "--path-format --show-toplevel" because I
was under the assumption that --path-format needs another option it can
modify. It seems that this is not the case, so wouldn't it be simpler
here to do the following instead:

	test_must_fail git rev-parse --path-format

That way we do not have to worry about subsequent changes to other,
unrelated, options.
Junio C Hamano May 16, 2021, 9:59 p.m. UTC | #3
Wolfgang Müller <wolf@oriole.systems> writes:

> On 2021-05-16 21:53, Junio C Hamano wrote:
>
>> As die() is end-user facing, you'd probably want
>> 
>> 	die(_("--path-format requires an argument"));
>> 
>> We do have untranslated die() nearby for the same option, which may
>> want to be cleaned up either in a preliminary patch, or in this same
>> patch as an unrelated fix "while we are at it".
>
> I would not mind preparing a preliminary patch that cleans up all
> untranslated user-facing calls to die(). My editor finds 15 of those in
> rev-parse.c, and I think they all qualify.
>
> If you'd rather not touch unrelated code paths I'll instead include it
> in v2 as an unrelated fix in the same commit.

I am puzzled by the last paragraph.  Somebody who does not want to
see "unrelated" codepaths touched would appreciate if a commit that
fixes this segfault does not touch them at the same time.

In any case, I now counted existing die() messages in this file, and
among 15 of them, only 1 is marked with _(...).  I think that it
is the best to apply the patch as-is (without _(...)), adding one
untranslated message to the file.

Then, on top of this change, the 15 untranslated messages can be
marked with _(...) a separate commit (and it does not even have to
be done by you).

> I think I initially went for "--path-format --show-toplevel" because I
> was under the assumption that --path-format needs another option it can
> modify. It seems that this is not the case, so wouldn't it be simpler
> here to do the following instead:
>
> 	test_must_fail git rev-parse --path-format
>
> That way we do not have to worry about subsequent changes to other,
> unrelated, options.

That's good, too.  Simple.

Thanks.
Wolfgang Müller May 17, 2021, 7:19 a.m. UTC | #4
On 2021-05-17 06:59, Junio C Hamano wrote:

> >> We do have untranslated die() nearby for the same option, which may
> >> want to be cleaned up either in a preliminary patch, or in this
> >> same patch as an unrelated fix "while we are at it".
> >
> > I would not mind preparing a preliminary patch that cleans up all
> > untranslated user-facing calls to die(). My editor finds 15 of those
> > in rev-parse.c, and I think they all qualify.
> >
> > If you'd rather not touch unrelated code paths I'll instead include
> > it in v2 as an unrelated fix in the same commit.
> 
> I am puzzled by the last paragraph.  Somebody who does not want to see
> "unrelated" codepaths touched would appreciate if a commit that fixes
> this segfault does not touch them at the same time.

Apologies, I was being unclear here. I was meaning to offer either
cleaning up all calls to die() in a separate patch, or fixing only the
nearby occurrence that you mentioned in the same patch. I had implicitly
assumed you had seen the other untranslated messages already but only
wanted to fix the one for the same option (ie in a nearby, "related"
path).

> In any case, I now counted existing die() messages in this file, and
> among 15 of them, only 1 is marked with _(...).  I think that it
> is the best to apply the patch as-is (without _(...)), adding one
> untranslated message to the file.

Will do.

> Then, on top of this change, the 15 untranslated messages can be
> marked with _(...) a separate commit (and it does not even have to
> be done by you).

I don't mind doing this, so I'll include it.

> That's good, too.  Simple.
> 
> Thanks.

Thanks a lot for your feedback, I'll be sending v2 along shortly.
diff mbox series

Patch

diff --git a/builtin/rev-parse.c b/builtin/rev-parse.c
index 85bad9052e..7af8dab8bc 100644
--- a/builtin/rev-parse.c
+++ b/builtin/rev-parse.c
@@ -759,6 +759,8 @@  int cmd_rev_parse(int argc, const char **argv, const char *prefix)
 				continue;
 			}
 			if (opt_with_value(arg, "--path-format", &arg)) {
+				if (!arg)
+					die("--path-format requires an argument");
 				if (!strcmp(arg, "absolute")) {
 					format = FORMAT_CANONICAL;
 				} else if (!strcmp(arg, "relative")) {
diff --git a/t/t1500-rev-parse.sh b/t/t1500-rev-parse.sh
index deae916707..a1a8ce5265 100755
--- a/t/t1500-rev-parse.sh
+++ b/t/t1500-rev-parse.sh
@@ -146,6 +146,10 @@  test_expect_success '--path-format can change in the middle of the command line'
 	test_cmp expect actual
 '
 
+test_expect_success '--path-format does not segfault without an argument' '
+	test_must_fail git rev-parse --path-format --show-toplevel
+'
+
 test_expect_success 'git-common-dir from worktree root' '
 	echo .git >expect &&
 	git rev-parse --git-common-dir >actual &&