Re: [PATCH updated] Fallback on _NSGetExecutablePath to get the executable path if using argv[0] fails

[Jonathan Nieder <jrnieder@gmail.com>]

Jeremy Huddleston wrote:

> This adds better support for RUNTIME_PREFIX on Mac OS X.  The previous codepath
> would only work if argv[0] contained the full path to the executable or $PATH
> already contained /path/to/libexec/git-core.  We use _NSGetExecutablePath here
> to find the full path (and thus prepend the correct libexec/git-core to $PATH)
> in the case where argv[0] does not contain the full path to the executable.

Closer.  But that is perhaps too much at the level of code rather than
the user:

	Subject: MacOSX: Use _NSGetExecutablePath to get full argv[0] path

	When RUNTIME_PREFIX support is enabled (which is common on Mac OS X)
	the exec-path is derived from the program invocation path.
	Unfortunately, usual Unix semantics are for argv[0] to contain
	the path used to invoke a program rather than the path to the
	executable.  So usual invocations of git would not result in
	helpers from exec-path being found correctly:

		$ git fast-import
		... example output here ...

	So in the spirit of v1.6.0-rc1~21 (Windows: make sure argv[0]
	has a path, 2008-07-21), use _NSGetExecutablePath to find the full
	path to the git binary, avoiding such trouble.

> --- a/exec_cmd.c
> +++ b/exec_cmd.c
[...]
> @@ -53,6 +57,19 @@ const char *git_extract_argv0_path(const char *argv0)
>  	if (slash >= argv0) {
>  		argv0_path = xstrndup(argv0, slash - argv0);
>  		return slash + 1;
> +#if defined(__APPLE__)
> +	} else {
> +		char new_argv0[PATH_MAX];
> +		uint32_t new_argv0_s = PATH_MAX;
> +		if(_NSGetExecutablePath(new_argv0, &new_argv0_s) == 0) {
> +			slash = new_argv0 + strlen(new_argv0);
> +			while (new_argv0 <= slash && !is_dir_sep(*slash))
> +		                slash--;
> +
> +			if (slash >= new_argv0)
> +				argv0_path = xstrndup(new_argv0, slash - new_argv0);
> +		}
> +#endif

Can't this ifdef be avoided?  The ideal is for such code to be
abstracted away into helper functions in git-compat-util.h and compat/*.c.

Jonathan