Bad DWIM response when git gui cannot start

If git cannot start one of the external commands (at least some of them), the DWIM engine is a bit flaky:

   $ git citool
   /usr/local/libexec/git-core/git-citool: line 10: exec: wish: not found
   git: 'citool' is not a git-command. See 'git --help'.

   Did you mean this?
       citool

   $ git gui
   /usr/local/libexec/git-core/git-gui: line 10: exec: wish: not found
   git: 'gui' is not a git-command. See 'git --help'.

   Did you mean this?
       gui

As reported by Peter Krefting:

  If git cannot start one of the external commands (at least some of them),
  the DWIM engine is a bit flaky:

     $ git citool
     /usr/local/libexec/git-core/git-citool: line 10: exec: wish: not found
     git: 'citool' is not a git-command. See 'git --help'.

     Did you mean this?
         citool

Now we check whether the best bet found by levenshtein() differs from the command line or not before proceeding.

The new error is:

$ git citool /usr/local/libexec/git-core/git-citool: line 10: exec: wish: not found fatal: Failed to run command 'citool': No such file or directory

Signed-off-by: Michele Ballabio <barra_cuda@katamail.com>
---

Is the call to strerror() useless anyway?

 help.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

Michele Ballabio wrote:

[...]

The invocation of help_unknown_cmd comes from

	while (1) {
		// ...
		was_alias = run_argv(&argc, &argv);
		if (errno != ENOENT)
			break;
		// ... side branch with an exit() ...
		if (!done_help) {
			cmd = argv[0] = help_unknown_cmd(cmd);

so errno is always ENOENT when help_unknown_cmd() is called. (Furthermore, the function itself uses git_config() and load_command_list(), both of which _probably_ clobber errno, I don't really have the time for an in-depth check.)

It also seems that the 'errno != ENOENT' check was intended to catch the case where the command failed for any reason other than that it does not exist, but this collides with the kernel reporting ENOENT if the _interpreter_ does not exist. Perhaps run_argv should differentiate the case where a command executable exists but cannot be run?

[I started writing a reply because I wanted to ask for a conversion to die_errno() in the spirit of d824cbb (Convert existing die(..., strerror(errno)) to die_errno(), 2009-06-27). Please keep that in mind if you put in another die() that mentions errno.]

On Mon, Jul 20, 2009 at 04:17:47PM +0200, Thomas Rast wrote:

Yes, I think double-checking the suggested commands list is only half of it; it still says "citool is not a git command" which is wrong. Getting it totally right means differentiating the two ENOENT cases, which I think would require searching the PATH.

Something like the patch below should work, though I didn't think terribly long about it, so there might be a corner case that isn't covered, or some easier helper functions for accomplishing this.

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