gitk: Unicode file name support

Assumes file names in git tree objects are UTF-8 encoded.

On most unix systems, the system encoding (and thus the TCL system
encoding) will be UTF-8, so file names will be displayed correctly.

On Windows, it is impossible to set the system encoding to UTF-8.
Changing the TCL system encoding (via 'encoding system ...', e.g. in the
startup code) is explicitly discouraged by the TCL docs.

Change gitk functions dealing with file names to always convert
from and to UTF-8.

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

gitk-git/gitk

@@ -7692,7 +7692,7 @@ proc gettreeline {gtf id} {
         if {[string index $fname 0] eq "\""} {
             set fname [lindex $fname 0]
         }
-        set fname [encoding convertfrom $fname]
+        set fname [encoding convertfrom utf-8 $fname]
         lappend treefilelist($id) $fname
     }
     if {![eof $gtf]} {
@@ -7954,7 +7954,7 @@ proc gettreediffline {gdtf ids} {
             if {[string index $file 0] eq "\""} {
                 set file [lindex $file 0]
             }
-            set file [encoding convertfrom $file]
+            set file [encoding convertfrom utf-8 $file]
             if {$file ne [lindex $treediff end]} {
                 lappend treediff $file
                 lappend sublist $file
@@ -8099,7 +8099,7 @@ proc makediffhdr {fname ids} {
     global ctext curdiffstart treediffs diffencoding
     global ctext_file_names jump_to_here targetline diffline
 
-    set fname [encoding convertfrom $fname]
+    set fname [encoding convertfrom utf-8 $fname]
     set diffencoding [get_path_encoding $fname]
     set i [lsearch -exact $treediffs($ids) $fname]
     if {$i >= 0} {
@@ -8161,7 +8161,7 @@ proc parseblobdiffline {ids line} {
 
     if {![string compare -length 5 "diff " $line]} {
         if {![regexp {^diff (--cc|--git) } $line m type]} {
-            set line [encoding convertfrom $line]
+            set line [encoding convertfrom utf-8 $line]
             $ctext insert end "$line\n" hunksep
             continue
         }
@@ -8210,7 +8210,7 @@ proc parseblobdiffline {ids line} {
         makediffhdr $fname $ids
 
     } elseif {![string compare -length 16 "* Unmerged path " $line]} {
-        set fname [encoding convertfrom [string range $line 16 end]]
+        set fname [encoding convertfrom utf-8 [string range $line 16 end]]
         $ctext insert end "\n"
         set curdiffstart [$ctext index "end - 1c"]
         lappend ctext_file_names $fname
@@ -8263,7 +8263,7 @@ proc parseblobdiffline {ids line} {
             if {[string index $fname 0] eq "\""} {
                 set fname [lindex $fname 0]
             }
-            set fname [encoding convertfrom $fname]
+            set fname [encoding convertfrom utf-8 $fname]
             set i [lsearch -exact $treediffs($ids) $fname]
             if {$i >= 0} {
                 setinlist difffilestart $i $curdiffstart
@@ -8282,6 +8282,7 @@ proc parseblobdiffline {ids line} {
             set diffinhdr 0
             return
         }
+        set line [encoding convertfrom utf-8 $line]
         $ctext insert end "$line\n" filesep
 
     } else {
@@ -12244,7 +12245,7 @@ proc cache_gitattr {attr pathlist} {
             foreach row [split $rlist "\n"] {
                 if {[regexp "(.*): $attr: (.*)" $row m path value]} {
                     if {[string index $path 0] eq "\""} {
-                        set path [encoding convertfrom [lindex $path 0]]
+                        set path [encoding convertfrom utf-8 [lindex $path 0]]
                     }
                     set path_attr_cache($attr,$path) $value
                 }