[PATCH] Allow git-mergetool to handle paths with a leading space

[PATCH] Allow git-mergetool to handle paths with a leading space

[Rogan Dawes]

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Signed-off-by: Rogan Dawes <rogan@dawes.za.net>

---
I am working on a project which has the root directory constructed with 
a leading space. i.e. ./ dir/. "read" skips the leading space char, and 
ends up with an incorrect filename, which can then not be found. Setting 
IFS=\n solves this problem.

Thanks to Mikachu and Tv on #git for assistance and suggestions.

Unfortunately, Thunderbird is not very easy to convince not to mangle 
patches, so I am attaching the patch as well. Sorry.

diff --git a/git-mergetool.sh b/git-mergetool.sh
index 2f31fa2..8521ca3 100755
--- a/git-mergetool.sh
+++ b/git-mergetool.sh
@@ -394,7 +394,7 @@ if test $# -eq 0 ; then
                 exit 0
         fi
         echo Merging the files: $files
-       git ls-files -u | sed -e 's/^[^ ]*      //' | sort -u | while read i
+       git ls-files -u | sed -e 's/^[^ ]*      //' | sort -u | while 
IFS=\n read i
         do
                 printf "\n"
                 merge_file "$i" < /dev/tty > /dev/tty

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diff --git a/git-mergetool.sh b/git-mergetool.sh
index 2f31fa2..8521ca3 100755
--- a/git-mergetool.sh
+++ b/git-mergetool.sh
@@ -394,7 +394,7 @@ if test $# -eq 0 ; then
 		exit 0
 	fi
 	echo Merging the files: $files
-	git ls-files -u | sed -e 's/^[^	]*	//' | sort -u | while read i
+	git ls-files -u | sed -e 's/^[^	]*	//' | sort -u | while IFS=\n read i
 	do
 		printf "\n"
 		merge_file "$i" < /dev/tty > /dev/tty

Re: [PATCH] Allow git-mergetool to handle paths with a leading space

[Junio C Hamano]

Rogan Dawes <rogan@dawes.za.net> writes:

> Signed-off-by: Rogan Dawes <rogan@dawes.za.net>
>
> ---
> I am working on a project which has the root directory constructed
> with a leading space. i.e. ./ dir/. "read" skips the leading space
> char, and ends up with an incorrect filename, which can then not be
> found. Setting IFS=\n solves this problem.

Does the project have a file that has letter 'n' (en) in its name?
Have you tested your patch while having a conflict in that file?

Re: [PATCH] Allow git-mergetool to handle paths with a leading space

[Rogan Dawes]

Junio C Hamano wrote:
> Rogan Dawes <rogan@dawes.za.net> writes:
> 
>> Signed-off-by: Rogan Dawes <rogan@dawes.za.net>
>>
>> ---
>> I am working on a project which has the root directory constructed
>> with a leading space. i.e. ./ dir/. "read" skips the leading space
>> char, and ends up with an incorrect filename, which can then not be
>> found. Setting IFS=\n solves this problem.
> 
> Does the project have a file that has letter 'n' (en) in its name?
> Have you tested your patch while having a conflict in that file?
> 

Yes, it works correctly.

$ git mergetool
merge tool candidates: kdiff3 tkdiff xxdiff meld gvimdiff vimdiff 
opendiff emerge vimdiff
Merging the files: 
webgoat/main/project/JavaSource/org/owasp/webgoat/lessons/BackDoors.java 
webgoat/main/project/JavaSource/org/owasp/webgoat/lessons/BlindSqlInjection.java 
webgoat/main/project/JavaSource/org/owasp/webgoat/lessons/Challenge2Screen.java

Normal merge conflict for ' 
webgoat/main/project/JavaSource/org/owasp/webgoat/lessons/BackDoors.java':
   {local}: modified
   {remote}: modified
Hit return to start merge resolution tool (kdiff3):
merge of 
webgoat/main/project/JavaSource/org/owasp/webgoat/lessons/BackDoors.java 
failed

$

My copy and paste does not show the spaces properly, since everything 
gets wrapped. but the "Normal merge conflict for ' webgoat/" line would 
have taken the ' to the next line if the space was not there. :-)

Note that the lines after "Merging the files" don't include the spaces, 
but that is just cosmetic, IMO.

Rogan

Re: [PATCH] Allow git-mergetool to handle paths with a leading space

[Junio C Hamano]

Rogan Dawes <rogan@dawes.za.net> writes:

>>> I am working on a project which has the root directory constructed
>>> with a leading space. i.e. ./ dir/. "read" skips the leading space
>>> char, and ends up with an incorrect filename, which can then not be
>>> found. Setting IFS=\n solves this problem.
>>
>> Does the project have a file that has letter 'n' (en) in its name?
>> Have you tested your patch while having a conflict in that file?
>
> Yes, it works correctly.

I am curious and puzzled...

        $ echo 'ann1' | (IFS=\n read i; echo "<$i>")
        <ann1>
        $ echo 'ann1' | (IFS=\n read i j; echo "<$i>")
	<a>
        $ echo 'n1' | (IFS=\n read i j; echo "<$i>")
	<>

Ok, "\n" is a funny way to say IFS does not matter as long as it
is set to a non whitespace letter.

It is VERY misleading as it looks as if the issue is fixed by
setting IFS to a single LF alone (excluding SP and HT from the
usual set), but that is not the patch is doing.  It is setting
it to a single 'n'.

I think you still will lose backslash by using read, but I guess
you would not care about that too much.

If you really cared, you would do something like this, but you
would also need similar surgery in merge_file function itself
that parses text form of ls-files output that tries to verify
and extract paths, which I did not bother to touch in this
demonstration patch.

 git-mergetool.sh |   33 ++++++++++++++++++++++-----------
 1 files changed, 22 insertions(+), 11 deletions(-)

diff --git a/git-mergetool.sh b/git-mergetool.sh
index 2f31fa2..b7c5098 100755
--- a/git-mergetool.sh
+++ b/git-mergetool.sh
@@ -388,17 +388,28 @@ fi
 
 
 if test $# -eq 0 ; then
-	files=`git ls-files -u | sed -e 's/^[^	]*	//' | sort -u`
-	if test -z "$files" ; then
-		echo "No files need merging"
-		exit 0
-	fi
-	echo Merging the files: $files
-	git ls-files -u | sed -e 's/^[^	]*	//' | sort -u | while read i
-	do
-		printf "\n"
-		merge_file "$i" < /dev/tty > /dev/tty
-	done
+	doit=$(perl -e '
+		$/ = "\0";
+		my (%seen, @file);
+		my $ls_files;
+		open($ls_files, "-|", qw(git ls-files -u -z));
+		while (<$ls_files>) {
+			chomp;
+			s/^[^	]*	//;
+			$seen{$_}++;
+		}
+		@file = sort keys %seen;
+		if (!@file) {
+			print "echo No files need merging\n";
+			print "exit 0\n";
+		}
+		for (@file) {
+			s|'\''|'\''\\'\'''\''|g;
+			print "echo\n";
+			print "merge_file '\''$_'\'' </dev/tty >/dev/tty\n";
+		}
+	')
+	eval "$doit"
 else
 	while test $# -gt 0; do
 		printf "\n"

[PATCH] Allow git-mergetool to handle paths with a leading space

[Rogan Dawes]

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Signed-off-by: Rogan Dawes <rogan@dawes.za.net>
---
Junio C Hamano wrote:
> Rogan Dawes <rogan@dawes.za.net> writes:
> 
>>>> I am working on a project which has the root directory constructed
>>>> with a leading space. i.e. ./ dir/. "read" skips the leading space
>>>> char, and ends up with an incorrect filename, which can then not be
>>>> found. Setting IFS=\n solves this problem.
>>> Does the project have a file that has letter 'n' (en) in its name?
>>> Have you tested your patch while having a conflict in that file?
>> Yes, it works correctly.
> 
> I am curious and puzzled...
> 
>         $ echo 'ann1' | (IFS=\n read i; echo "<$i>")
>         <ann1>
>         $ echo 'ann1' | (IFS=\n read i j; echo "<$i>")
> 	<a>
>         $ echo 'n1' | (IFS=\n read i j; echo "<$i>")
> 	<>
> 
> Ok, "\n" is a funny way to say IFS does not matter as long as it
> is set to a non whitespace letter.
> 
> It is VERY misleading as it looks as if the issue is fixed by
> setting IFS to a single LF alone (excluding SP and HT from the
> usual set), but that is not the patch is doing.  It is setting
> it to a single 'n'.

Yes, you are right. Maybe setting IFS to the empty string is better?

$ printf " ann 1\n ann 2\n" | while IFS="" read i j k ; do echo "<$i> 
<$j> <$k>"; done
< ann 1> <> <>
< ann 2> <> <>
$

Admittedly, there are still problems with my version, as you say, 
backslashes and newlines will not be handled correctly. My Perl-fu is 
weak, however, and my revised solution (IFS="") works for me :-)

Rogan

P.S. Quoting "$files" stops the spaces from being eaten in the preceding 
echo line.

diff --git a/git-mergetool.sh b/git-mergetool.sh
index 2f31fa2..facfbc8 100755
--- a/git-mergetool.sh
+++ b/git-mergetool.sh
@@ -393,8 +393,8 @@ if test $# -eq 0 ; then
                 echo "No files need merging"
                 exit 0
         fi
-       echo Merging the files: $files
-       git ls-files -u | sed -e 's/^[^ ]*      //' | sort -u | while read i
+       echo Merging the files: "$files"
+       git ls-files -u | sed -e 's/^[^ ]*      //' | sort -u | while 
IFS="" read i
         do
                 printf "\n"
                 merge_file "$i" < /dev/tty > /dev/tty

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diff --git a/git-mergetool.sh b/git-mergetool.sh
index 2f31fa2..facfbc8 100755
--- a/git-mergetool.sh
+++ b/git-mergetool.sh
@@ -393,8 +393,8 @@ if test $# -eq 0 ; then
 		echo "No files need merging"
 		exit 0
 	fi
-	echo Merging the files: $files
-	git ls-files -u | sed -e 's/^[^	]*	//' | sort -u | while read i
+	echo Merging the files: "$files"
+	git ls-files -u | sed -e 's/^[^	]*	//' | sort -u | while IFS="" read i
 	do
 		printf "\n"
 		merge_file "$i" < /dev/tty > /dev/tty

Re: [PATCH] Allow git-mergetool to handle paths with a leading space

[Junio C Hamano]

Rogan Dawes <rogan@dawes.za.net> writes:

> Yes, you are right. Maybe setting IFS to the empty string is better?

Yes.  POSIX XCU "2.6.5 Field Splitting" is quite clear about
this.  Empty IFS tells read not to split the fields, and such an
IFS does not have IFS white space in it so the SP at the
beginning of the input will not be stripped.

My limited test indicates that bash, dash and ksh do behave as
specified, so I think it is a reasonably safe thing to do.
Although I usually would say "I do not care about Solaris
default /bin/sh", I know even that shell at least gets this
right.

I think the patch is Ok as long as the user does not care any
character outside the portable filename character set (POSIX XBD
3.276) other than SP.  Because the rest of the mergetool is
written in such a way that it does not handle many characters
outside the portable filename character set well anyway, I think
the filename limitation that still remains after your patch may
be acceptable.

I did not however apply your patch to my tree tonight, as Ted as
the original and the primary author of the script may have
better ideas, and/or future directions for the patch.  He can
simply just Ack your patch if he chooses to.

I'd however write that overly long pipeline indented a bit more
sanely, like this, though:

	git ls-files -u |
        sed -e 's/^[^	]*	//' |
        sort -u |
        while IFS="" read i
	do
        	printf "\n"
                merge_file "$i" </dev/tty >/dev/tty
                ...

In the longer term, I'd probably suggest redoing the entire
command in a NUL safe scripting language (or even C, especially
if pressed by mingw or msys folks) to eliminate the issue
altogether, though.  But that would definitely be a post 1.5.4
item.


[Reference]

http://www.opengroup.org/onlinepubs/000095399/toc.htm

Re: [PATCH] Allow git-mergetool to handle paths with a leading space

[Theodore Tso]

On Mon, Jan 07, 2008 at 01:09:45AM -0800, Junio C Hamano wrote:
> Rogan Dawes <rogan@dawes.za.net> writes:
> 
> I did not however apply your patch to my tree tonight, as Ted as
> the original and the primary author of the script may have
> better ideas, and/or future directions for the patch.  He can
> simply just Ack your patch if he chooses to.

Acked-by: "Theodore Ts'o" <tytso@mit.edu>

> In the longer term, I'd probably suggest redoing the entire
> command in a NUL safe scripting language (or even C, especially
> if pressed by mingw or msys folks) to eliminate the issue
> altogether, though.  But that would definitely be a post 1.5.4
> item.

Yeah, we eventually need to redo "git mergetool" in C.  One of the
reasons for that is at the moment it can't take advantage of the
rename detection machinery, so in the case where there is a merge
conflict involving a file that has been renamed in one of the two
branches, "git mergetool" doesn't do the right thing.

Even if it would be possible to expose the rename machinery in a form
that would be convenient for a shell script, it's past time to rewrite
it in C, I think....

						- Ted