git-gui: Add a --trace command line option

Often new Git users want to know what commands git-gui uses to make
changes, so they can learn the command line interface by mimicking
what git-gui does in response to GUI actions.  Showing the direct
commands being executed is easy enough to implement but this is of
little value to end-users because git-gui frequently directly calls
plumbing, not porcelain.

Since the code is already written and tested, its fairly harmless
to include.  It may not help a new end-user, but it can help with
debugging git-gui or reverse-engineering its logic to further make
changes to it or implement another GUI for Git.

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

diff --git a/git-gui.sh b/git-gui.sh
index 9df49710e1b378af1f49c5ce3c8c8c48731d7d38..6a8831a99e4014c53211920b817354e4412ef3b3 100755 (executable)
--- a/git-gui.sh
+++ b/git-gui.sh
@@ -122,6 +122,14 @@ set _reponame {}
 set _iscygwin {}
 set _search_path {}
 
+set _trace [lsearch -exact $argv --trace]
+if {$_trace >= 0} {
+       set argv [lreplace $argv $_trace $_trace]
+       set _trace 1
+} else {
+       set _trace 0
+}
+
 proc appname {} {
        global _appname
        return $_appname
@@ -245,6 +253,21 @@ proc get_config {name} {
 ##
 ## handy utils
 
+proc _trace_exec {cmd} {
+       if {!$::_trace} return
+       set d {}
+       foreach v $cmd {
+               if {$d ne {}} {
+                       append d { }
+               }
+               if {[regexp {[ \t\r\n'"$?*]} $v]} {
+                       set v [sq $v]
+               }
+               append d $v
+       }
+       puts stderr $d
+}
+
 proc _git_cmd {name} {
        global _git_cmd_path
 
@@ -339,7 +362,7 @@ proc _lappend_nice {cmd_var} {
 }
 
 proc git {args} {
-       set opt [list exec]
+       set opt [list]
 
        while {1} {
                switch -- [lindex $args 0] {
@@ -359,12 +382,18 @@ proc git {args} {
        set cmdp [_git_cmd [lindex $args 0]]
        set args [lrange $args 1 end]
 
-       return [eval $opt $cmdp $args]
+       _trace_exec [concat $opt $cmdp $args]
+       set result [eval exec $opt $cmdp $args]
+       if {$::_trace} {
+               puts stderr "< $result"
+       }
+       return $result
 }
 
 proc _open_stdout_stderr {cmd} {
+       _trace_exec $cmd
        if {[catch {
-                       set fd [open $cmd r]
+                       set fd [open [concat [list | ] $cmd] r]
                } err]} {
                if {   [lindex $cmd end] eq {2>@1}
                    && $err eq {can not find channel named "1"}
@@ -375,6 +404,7 @@ proc _open_stdout_stderr {cmd} {
                        # to try to start it a second time.
                        #
                        set fd [open [concat \
+                               [list | ] \
                                [lrange $cmd 0 end-1] \
                                [list |& cat] \
                                ] r]
@@ -387,7 +417,7 @@ proc _open_stdout_stderr {cmd} {
 }
 
 proc git_read {args} {
-       set opt [list |]
+       set opt [list]
 
        while {1} {
                switch -- [lindex $args 0] {
@@ -415,7 +445,7 @@ proc git_read {args} {
 }
 
 proc git_write {args} {
-       set opt [list |]
+       set opt [list]
 
        while {1} {
                switch -- [lindex $args 0] {
@@ -435,7 +465,8 @@ proc git_write {args} {
        set cmdp [_git_cmd [lindex $args 0]]
        set args [lrange $args 1 end]
 
-       return [open [concat $opt $cmdp $args] w]
+       _trace_exec [concat $opt $cmdp $args]
+       return [open [concat [list | ] $opt $cmdp $args] w]
 }
 
 proc githook_read {hook_name args} {
@@ -455,12 +486,12 @@ proc githook_read {hook_name args} {
                }
 
                set scr {if test -x "$1";then exec "$@";fi}
-               set sh_c [list | $interp -c $scr $interp $pchook]
+               set sh_c [list $interp -c $scr $interp $pchook]
                return [_open_stdout_stderr [concat $sh_c $args]]
        }
 
        if {[file executable $pchook]} {
-               return [_open_stdout_stderr [concat [list | $pchook] $args]]
+               return [_open_stdout_stderr [concat [list $pchook] $args]]
        }
 
        return {}