[Fix v1] builtin/ls-files.c: add error check on lstat for modified files

[Fix v1] builtin/ls-files.c: add error check on lstat for modified files

[randall.s.becker]

From: "Randall S. Becker" <rsbecker@nexbridge.com>

The result from lstat, checking whether a file has been deleted, is now
included priot to calling id_modified when showing modified files. Prior
to this fix, it is possible that files that were deleted could show up
as being modified because the lstat error was unchecked.

Reported-by: Joe Ranieri <jranieri@grammatech.com>
Signed-off-by: Randall S. Becker <rsbecker@nexbridge.com>
---
 builtin/ls-files.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/builtin/ls-files.c b/builtin/ls-files.c
index 29a8762d4..fc21f4795 100644
--- a/builtin/ls-files.c
+++ b/builtin/ls-files.c
@@ -348,7 +348,7 @@ static void show_files(struct repository *repo, struct dir_struct *dir)
 			err = lstat(fullname.buf, &st);
 			if (show_deleted && err)
 				show_ce(repo, dir, ce, fullname.buf, tag_removed);
-			if (show_modified && ie_modified(repo->index, ce, &st, 0))
+			if (show_modified && !err && ie_modified(repo->index, ce, &st, 0))
 				show_ce(repo, dir, ce, fullname.buf, tag_modified);
 		}
 	}
-- 
2.12.3

Re: [Fix v1] builtin/ls-files.c: add error check on lstat for modified files

[Ramsay Jones]

On 17/02/2019 16:34, randall.s.becker@rogers.com wrote:
> From: "Randall S. Becker" <rsbecker@nexbridge.com>
> 
> The result from lstat, checking whether a file has been deleted, is now
> included priot to calling id_modified when showing modified files. Prior

s/priot/prior/; s/id_modified/ie_modified/

> to this fix, it is possible that files that were deleted could show up
> as being modified because the lstat error was unchecked.
> 
> Reported-by: Joe Ranieri <jranieri@grammatech.com>
> Signed-off-by: Randall S. Becker <rsbecker@nexbridge.com>
> ---
>  builtin/ls-files.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/builtin/ls-files.c b/builtin/ls-files.c
> index 29a8762d4..fc21f4795 100644
> --- a/builtin/ls-files.c
> +++ b/builtin/ls-files.c
> @@ -348,7 +348,7 @@ static void show_files(struct repository *repo, struct dir_struct *dir)
>  			err = lstat(fullname.buf, &st);
>  			if (show_deleted && err)

To be pedantic, this should probably check for (err == ENOENT), since
lstat() can fail for several reasons which don't imply that the path
has been deleted. However, that is unlikely.

No reason to include such a check in this patch, of course.

ATB,
Ramsay Jones

>  				show_ce(repo, dir, ce, fullname.buf, tag_removed);
> -			if (show_modified && ie_modified(repo->index, ce, &st, 0))
> +			if (show_modified && !err && ie_modified(repo->index, ce, &st, 0))
>  				show_ce(repo, dir, ce, fullname.buf, tag_modified);
>  		}
>  	}
> 

RE: [Fix v1] builtin/ls-files.c: add error check on lstat for modified files

[Randall S. Becker]

On February 17, 2019 12:05, Ramsay Jones wrote:
> On 17/02/2019 16:34, randall.s.becker@rogers.com wrote:
> > From: "Randall S. Becker" <rsbecker@nexbridge.com>
> >
> > The result from lstat, checking whether a file has been deleted, is
> > now included priot to calling id_modified when showing modified files.
> > Prior
> 
> s/priot/prior/; s/id_modified/ie_modified/
> 
> > to this fix, it is possible that files that were deleted could show up
> > as being modified because the lstat error was unchecked.
> >
> > Reported-by: Joe Ranieri <jranieri@grammatech.com>
> > Signed-off-by: Randall S. Becker <rsbecker@nexbridge.com>
> > ---
> >  builtin/ls-files.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/builtin/ls-files.c b/builtin/ls-files.c index
> > 29a8762d4..fc21f4795 100644
> > --- a/builtin/ls-files.c
> > +++ b/builtin/ls-files.c
> > @@ -348,7 +348,7 @@ static void show_files(struct repository *repo,
> struct dir_struct *dir)
> >  			err = lstat(fullname.buf, &st);
> >  			if (show_deleted && err)
> 
> To be pedantic, this should probably check for (err == ENOENT), since
> lstat() can fail for several reasons which don't imply that the path has been
> deleted. However, that is unlikely.

That would be very platform specific error checking. lstat can fail for a variety of other reasons also leaving the file deleted (like a symlink issue), but you are correct. I was following the prior line's model of checking for consistency.

> No reason to include such a check in this patch, of course.
> 
> ATB,
> Ramsay Jones
> 
> >  				show_ce(repo, dir, ce, fullname.buf,
> tag_removed);
> > -			if (show_modified && ie_modified(repo->index, ce,
> &st, 0))
> > +			if (show_modified && !err && ie_modified(repo-
> >index, ce, &st, 0))
> >  				show_ce(repo, dir, ce, fullname.buf,
> tag_modified);
> >  		}
> >  	}
> >

This was just to address what Joe reported earlier. It seemed like an easy one to address.

Regards,
Randall

Re: [Fix v1] builtin/ls-files.c: add error check on lstat for modified files

[Junio C Hamano]

randall.s.becker@rogers.com writes:

> From: "Randall S. Becker" <rsbecker@nexbridge.com>
>
> The result from lstat, checking whether a file has been deleted, is now
> included priot to calling id_modified when showing modified files. Prior

s/priot/prior/

> to this fix, it is possible that files that were deleted could show up
> as being modified because the lstat error was unchecked.
>
> Reported-by: Joe Ranieri <jranieri@grammatech.com>
> Signed-off-by: Randall S. Becker <rsbecker@nexbridge.com>
> ---
>  builtin/ls-files.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

The justification for the change reads quite convincing.  Is it
merely "it is _possible_ ... _could_ show up", though?  The code is
iterating over the in-core index, so if you add a blob at path F in
the index then remove that regular file F from the working tree,
when it is the cache entry for "F"'s turn to get inspected, lstat()
would say ENOENT, (show_deleted && err) would show tag_removed, and
ie_modified() gets a garbage &st and ie_match_stat() would say
"modified", no?  

> diff --git a/builtin/ls-files.c b/builtin/ls-files.c
> index 29a8762d4..fc21f4795 100644
> --- a/builtin/ls-files.c
> +++ b/builtin/ls-files.c
> @@ -348,7 +348,7 @@ static void show_files(struct repository *repo, struct dir_struct *dir)
>  			err = lstat(fullname.buf, &st);
>  			if (show_deleted && err)
>  				show_ce(repo, dir, ce, fullname.buf, tag_removed);
> -			if (show_modified && ie_modified(repo->index, ce, &st, 0))
> +			if (show_modified && !err && ie_modified(repo->index, ce, &st, 0))
>  				show_ce(repo, dir, ce, fullname.buf, tag_modified);
>  		}
>  	}

And the implementation of the change looks OK.

I wonder if there is an easy way to cover this with a test or two.
Wouldn't it be just the matter of doing something like this

	test_expect_success 'allow telling modified and deleted ones apart' '
		>testfile &&
		git add testfile &&
		rm testfile &&
		echo C testfile >expect &&
		git ls-files -m -d -t testfile >actual &&
		test_cmp expect actual
	'

in some existing test file for ls-files, perhaps in t3004 (ls-files-basic)?

I went back to the original discussion of the "BUG" around mid Feb
2019, and didn't find anybody worried about backward compatibility.
As "ls-files -[dm...t]" is marked semi-deprecated, perhaps breaking
the current users does not matter that much ;-)