git-gui: Ensure .git/info/exclude is honored in Cygwin workdirs

If we are using Cygwin and the git repository is actually a
workdir (by way of git-new-workdir) but this Tcl process is
a native Tcl/Tk and not the Cygwin Tcl/Tk then we are unable
to traverse the .git/info path as it is a Cygwin symlink and
not a standard Windows directory.

So we actually need to start a Cygwin process that can do the
path translation for us and let it test for .git/info/exclude
so we know if we can include that file in our git-ls-files or
not.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

diff --git a/git-gui.sh b/git-gui.sh
index 62e1652..c837502 100755 (executable)
--- a/git-gui.sh
+++ b/git-gui.sh
@@ -907,6 +907,35 @@ proc rescan {after {honor_trustmtime 1}} {
        }
 }
 
+if {[is_Cygwin]} {
+       set is_git_info_link {}
+       set is_git_info_exclude {}
+       proc have_info_exclude {} {
+               global is_git_info_link is_git_info_exclude
+
+               if {$is_git_info_link eq {}} {
+                       set is_git_info_link [file isfile [gitdir info.lnk]]
+               }
+
+               if {$is_git_info_link} {
+                       if {$is_git_info_exclude eq {}} {
+                               if {[catch {exec test -f [gitdir info exclude]}]} {
+                                       set is_git_info_exclude 0
+                               } else {
+                                       set is_git_info_exclude 1
+                               }
+                       }
+                       return $is_git_info_exclude
+               } else {
+                       return [file readable [gitdir info exclude]]
+               }
+       }
+} else {
+       proc have_info_exclude {} {
+               return [file readable [gitdir info exclude]]
+       }
+}
+
 proc rescan_stage2 {fd after} {
        global rescan_active buf_rdi buf_rdf buf_rlo
 
@@ -917,9 +946,8 @@ proc rescan_stage2 {fd after} {
        }
 
        set ls_others [list --exclude-per-directory=.gitignore]
-       set info_exclude [gitdir info exclude]
-       if {[file readable $info_exclude]} {
-               lappend ls_others "--exclude-from=$info_exclude"
+       if {[have_info_exclude]} {
+               lappend ls_others "--exclude-from=[gitdir info exclude]"
        }
        set user_exclude [get_config core.excludesfile]
        if {$user_exclude ne {} && [file readable $user_exclude]} {