`git log` or `git show` does not work when setting pager.<cmd> in version 2.11.0(2) or later

[hattya]

• I was not able to find an open or closed issue matching what I'm seeing

Setup

• Which version of Git for Windows are you using? Is it 32-bit or 64-bit?

$ git --version --build-options
git version 2.11.0.windows.1
sizeof-long: 4
machine: x86_64

• Which version of Windows are you running? Vista, 7, 8, 10? Is it 32-bit or 64-bit?

$ cmd.exe /c ver

Microsoft Windows [Version 10.0.14393]

Details

• What commands did you run to trigger this issue? If you can provide a
  Minimal, Complete, and Verifiable example
  this will help us understand the issue.

$ git config --global pager.diff 'diff-highlight | less'
$ git config --global pager.log 'diff-highlight | less'
$ git config --global pager.show 'diff-highlight | less'
$ git diff
$ git log
diff-highlight | less: No such file or directory
$ git show
diff-highlight | less: No such file or directory

The issue is introduced in commit 382b41b, and it seems that it is appeared by commit a9b8a09.

Following patch fixes the issue:

--- a/git.c
+++ b/git.c
@@ -633,10 +633,10 @@ static int run_argv(int *argcp, const char ***argv)
                                argv_array_push(&args, (*argv)[i]);

                        if (get_super_prefix())
-                               die("%s doesn't support --super-prefix", args.argv[0]);
+                               die("%s doesn't support --super-prefix", args.argv[1]);

                        if (use_pager == -1)
-                               use_pager = check_pager_config(args.argv[0]);
+                               use_pager = check_pager_config(args.argv[1]);
                        commit_pager_choice();

                        trace_argv_printf(args.argv, "trace: exec:");

[dscho]

Following patch fixes the issue:

Does it really? Have you verified that args.argv[1] is the command (not the first parameter)?

diff-highlight | less: No such file or directory

This indicates to me that the pager.<cmd> value is interpreted as path, not as command-line. From the documentation, it is not clear that it was ever meant to refer to a command-line instead of a path...

However, from the source code it appears as if the value is actually passed to the shell, so it is a bit puzzling that it is not interpreted correctly.

[dscho]

it is a bit puzzling that it is not interpreted correctly.

The reason is that a special "we have arguments" handling kicks in because in the Windows case apparently not only argv[0] is set to the pager value, but also argv[1]. This is a bug. I am continuing to investigate.

[dscho]

Hah. The problem is that isatty(1) returns non-zero even after the pager was started and stdout redirected.

[hattya]

Thank you for the fix!

I think this patch should also be applied, it is a fix for commit 382b41b.

It seems that commit 382b41b is copied from execv_dashed_external() without updating the index. In this scope, args.argv[0] is git and args.argv[1] (equals argv[0]) is a builtin command. Because get_builtin() returns non-NULL.

[dscho]

@hattya Uh oh. I must have been real tired when I looked at your patch. You are absolutely correct! Thanks!

[dscho]

BTW the code in question should only kick in after an alias was expanded. So I think you would need something like

git -c pager.log 'diff-highlight | less' -c  alias.lg=log lg -1 -p

to trigger that bug.

[dscho]

I chose to apply a slightly different patch, which also made the calls conciser and reordered to allow an early die() without having to initialize the args first.

[hattya]

Sorry, I thought I tested with git log and git show, but their aliases...