From 59a3998252a8f7b452e8fd60b32f5a5e639b0600 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@suse.de>
Date: Tue, 17 Jun 2025 07:59:54 +0200
Subject: [PATCH] gitk: Add support of SHA256 repositories

This patch adds a basic support of SHA256 Git repository to Gitk, so
that Gitk can show and operate on both SHA1 and SHA256 repos
gracefully.  Since SHA256 has a longer ID length (64 char) than SHA1
(40 char), many field widths are adjusted to fit with it.

A caveat is that the configuration of auto selection length is shared
between SHA1 and SHA256 repos.  That is, once when this value is saved
and read, it's applied to both repo types, which may result in shorter
selection than the full SHA256 ID.  We may introduce another
individual config for sha256 (actually I did write in the first
version), but for simplicity, the common config is used as of writing
this.

Many lines still refer "sha1" although they may point to both SHA1 and
SHA256.  They are left untouched for making the changes simpler.

This patch is based on the early work by Rostislav Krasny:
  https://patchwork.kernel.org/project/git/patch/pull.979.git.1623687519832.gitgitgadget@gmail.com
I refreshed, revised and extended to the latest state.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Johannes Sixt <j6t@kdbg.org>
---
 gitk | 83 ++++++++++++++++++++++++++++++++++++++++++------------------
 1 file changed, 58 insertions(+), 25 deletions(-)

diff --git a/gitk b/gitk
index bc9efa1856..64a074ab02 100755
--- a/gitk
+++ b/gitk
@@ -425,6 +425,7 @@ proc parseviewargs {n arglist} {
 
 proc parseviewrevs {view revs} {
     global vposids vnegids
+    global hashlength
 
     if {$revs eq {}} {
         set revs HEAD
@@ -438,7 +439,7 @@ proc parseviewrevs {view revs} {
         set badrev {}
         for {set l 0} {$l < [llength $errlines]} {incr l} {
             set line [lindex $errlines $l]
-            if {!([string length $line] == 40 && [string is xdigit $line])} {
+            if {!([string length $line] == $hashlength && [string is xdigit $line])} {
                 if {[string match "fatal:*" $line]} {
                     if {[string match "fatal: ambiguous argument*" $line]
                         && $badrev ne {}} {
@@ -655,6 +656,7 @@ proc updatecommits {} {
     global hasworktree
     global varcid vposids vnegids vflags vrevs
     global show_notes
+    global hashlength
 
     set hasworktree [hasworktree]
     rereadrefs
@@ -688,7 +690,7 @@ proc updatecommits {} {
             # take out positive refs that we asked for before or
             # that we have already seen
             foreach rev $revs {
-                if {[string length $rev] == 40} {
+                if {[string length $rev] == $hashlength} {
                     if {[lsearch -exact $oldpos $rev] < 0
                         && ![info exists varcid($view,$rev)]} {
                         lappend newrevs $rev
@@ -1573,6 +1575,7 @@ proc getcommitlines {fd inst view updating}  {
     global parents children curview hlview
     global idpending ordertok
     global varccommits varcid varctok vtokmod vfilelimit vshortids
+    global hashlength
 
     set stuff [read $fd 500000]
     # git log doesn't terminate the last commit with a null...
@@ -1655,7 +1658,7 @@ proc getcommitlines {fd inst view updating}  {
             }
             set ok 1
             foreach id $ids {
-                if {[string length $id] != 40} {
+                if {[string length $id] != $hashlength} {
                     set ok 0
                     break
                 }
@@ -1901,8 +1904,8 @@ proc getcommit {id} {
     return 1
 }
 
-# Expand an abbreviated commit ID to a list of full 40-char IDs that match
-# and are present in the current view.
+# Expand an abbreviated commit ID to a list of full 40-char (or 64-char
+# for SHA256 repo) IDs that match and are present in the current view.
 # This is fairly slow...
 proc longid {prefix} {
     global varcid curview vshortids
@@ -1935,6 +1938,7 @@ proc readrefs {} {
     global selecthead selectheadid
     global hideremotes
     global tclencoding
+    global hashlength
 
     foreach v {tagids idtags headids idheads otherrefids idotherrefs} {
         unset -nocomplain $v
@@ -1944,9 +1948,9 @@ proc readrefs {} {
         fconfigure $refd -encoding $tclencoding
     }
     while {[gets $refd line] >= 0} {
-        if {[string index $line 40] ne " "} continue
-        set id [string range $line 0 39]
-        set ref [string range $line 41 end]
+        if {[string index $line $hashlength] ne " "} continue
+        set id [string range $line 0 [expr {$hashlength - 1}]]
+        set ref [string range $line [expr {$hashlength + 1}] end]
         if {![string match "refs/*" $ref]} continue
         set name [string range $ref 5 end]
         if {[string match "remotes/*" $name]} {
@@ -2241,6 +2245,7 @@ proc makewindow {} {
     global have_tk85 have_tk86 use_ttk NS
     global git_version
     global worddiff
+    global hashlength
 
     # The "mc" arguments here are purely so that xgettext
     # sees the following string as needing to be translated
@@ -2366,7 +2371,7 @@ proc makewindow {} {
         -command gotocommit -width 8
     $sha1but conf -disabledforeground [$sha1but cget -foreground]
     pack .tf.bar.sha1label -side left
-    ${NS}::entry $sha1entry -width 40 -font textfont -textvariable sha1string
+    ${NS}::entry $sha1entry -width $hashlength -font textfont -textvariable sha1string
     trace add variable sha1string write sha1change
     pack $sha1entry -side left -pady 2
 
@@ -4093,6 +4098,7 @@ proc stopblaming {} {
 
 proc read_line_source {fd inst} {
     global blamestuff curview commfd blameinst nullid nullid2
+    global hashlength
 
     while {[gets $fd line] >= 0} {
         lappend blamestuff($inst) $line
@@ -4113,7 +4119,7 @@ proc read_line_source {fd inst} {
     set line [split [lindex $blamestuff($inst) 0] " "]
     set id [lindex $line 0]
     set lnum [lindex $line 1]
-    if {[string length $id] == 40 && [string is xdigit $id] &&
+    if {[string length $id] == $hashlength && [string is xdigit $id] &&
         [string is digit -strict $lnum]} {
         # look for "filename" line
         foreach l $blamestuff($inst) {
@@ -5257,11 +5263,13 @@ proc askrelhighlight {row id} {
 # Graph layout functions
 
 proc shortids {ids} {
+    global hashlength
+
     set res {}
     foreach id $ids {
         if {[llength $id] > 1} {
             lappend res [shortids $id]
-        } elseif {[regexp {^[0-9a-f]{40}$} $id]} {
+        } elseif {[regexp [string map "@@ $hashlength" {^[0-9a-f]{@@}$}] $id]} {
             lappend res [string range $id 0 7]
         } else {
             lappend res $id
@@ -5436,13 +5444,14 @@ proc get_viewmainhead {view} {
 # git rev-list should give us just 1 line to use as viewmainheadid($view)
 proc getviewhead {fd inst view} {
     global viewmainheadid commfd curview viewinstances showlocalchanges
+    global hashlength
 
     set id {}
     if {[gets $fd line] < 0} {
         if {![eof $fd]} {
             return 1
         }
-    } elseif {[string length $line] == 40 && [string is xdigit $line]} {
+    } elseif {[string length $line] == $hashlength && [string is xdigit $line]} {
         set id $line
     }
     set viewmainheadid($view) $id
@@ -7206,10 +7215,11 @@ proc commit_descriptor {p} {
 # Also look for URLs of the form "http[s]://..." and make them web links.
 proc appendwithlinks {text tags} {
     global ctext linknum curview
+    global hashlength
 
     set start [$ctext index "end - 1c"]
     $ctext insert end $text $tags
-    set links [regexp -indices -all -inline {(?:\m|-g)[0-9a-f]{6,40}\M} $text]
+    set links [regexp -indices -all -inline [string map "@@ $hashlength" {(?:\m|-g)[0-9a-f]{6,@@}\M}] $text]
     foreach l $links {
         set s [lindex $l 0]
         set e [lindex $l 1]
@@ -7237,13 +7247,14 @@ proc appendwithlinks {text tags} {
 proc setlink {id lk} {
     global curview ctext pendinglinks
     global linkfgcolor
+    global hashlength
 
     if {[string range $id 0 1] eq "-g"} {
       set id [string range $id 2 end]
     }
 
     set known 0
-    if {[string length $id] < 40} {
+    if {[string length $id] < $hashlength} {
         set matches [longid $id]
         if {[llength $matches] > 0} {
             if {[llength $matches] > 1} return
@@ -8888,13 +8899,16 @@ proc incrfont {inc} {
 
 proc clearsha1 {} {
     global sha1entry sha1string
-    if {[string length $sha1string] == 40} {
+    global hashlength
+
+    if {[string length $sha1string] == $hashlength} {
         $sha1entry delete 0 end
     }
 }
 
 proc sha1change {n1 n2 op} {
     global sha1string currentid sha1but
+
     if {$sha1string == {}
         || ([info exists currentid] && $sha1string == $currentid)} {
         set state disabled
@@ -8911,6 +8925,7 @@ proc sha1change {n1 n2 op} {
 
 proc gotocommit {} {
     global sha1string tagids headids curview varcid
+    global hashlength
 
     if {$sha1string == {}
         || ([info exists currentid] && $sha1string == $currentid)} return
@@ -8920,7 +8935,7 @@ proc gotocommit {} {
         set id $headids($sha1string)
     } else {
         set id [string tolower $sha1string]
-        if {[regexp {^[0-9a-f]{4,39}$} $id]} {
+        if {[regexp {^[0-9a-f]{4,63}$} $id]} {
             set matches [longid $id]
             if {$matches ne {}} {
                 if {[llength $matches] > 1} {
@@ -9409,6 +9424,7 @@ proc doseldiff {oldid newid} {
 
 proc mkpatch {} {
     global rowmenuid currentid commitinfo patchtop patchnum NS
+    global hashlength
 
     if {![info exists currentid]} return
     set oldid $currentid
@@ -9423,7 +9439,7 @@ proc mkpatch {} {
     ${NS}::label $top.title -text [mc "Generate patch"]
     grid $top.title - -pady 10
     ${NS}::label $top.from -text [mc "From:"]
-    ${NS}::entry $top.fromsha1 -width 40
+    ${NS}::entry $top.fromsha1 -width $hashlength
     $top.fromsha1 insert 0 $oldid
     $top.fromsha1 conf -state readonly
     grid $top.from $top.fromsha1 -sticky w
@@ -9432,7 +9448,7 @@ proc mkpatch {} {
     $top.fromhead conf -state readonly
     grid x $top.fromhead -sticky w
     ${NS}::label $top.to -text [mc "To:"]
-    ${NS}::entry $top.tosha1 -width 40
+    ${NS}::entry $top.tosha1 -width $hashlength
     $top.tosha1 insert 0 $newid
     $top.tosha1 conf -state readonly
     grid $top.to $top.tosha1 -sticky w
@@ -9501,6 +9517,7 @@ proc mkpatchcan {} {
 
 proc mktag {} {
     global rowmenuid mktagtop commitinfo NS
+    global hashlength
 
     set top .maketag
     set mktagtop $top
@@ -9510,7 +9527,7 @@ proc mktag {} {
     ${NS}::label $top.title -text [mc "Create tag"]
     grid $top.title - -pady 10
     ${NS}::label $top.id -text [mc "ID:"]
-    ${NS}::entry $top.sha1 -width 40
+    ${NS}::entry $top.sha1 -width $hashlength
     $top.sha1 insert 0 $rowmenuid
     $top.sha1 conf -state readonly
     grid $top.id $top.sha1 -sticky w
@@ -9618,10 +9635,11 @@ proc mktaggo {} {
 
 proc copyreference {} {
     global rowmenuid autosellen
+    global hashlength
 
     set format "%h (\"%s\", %ad)"
     set cmd [list git show -s --pretty=format:$format --date=short]
-    if {$autosellen < 40} {
+    if {$autosellen < $hashlength} {
         lappend cmd --abbrev=$autosellen
     }
     set reference [eval exec $cmd $rowmenuid]
@@ -9632,6 +9650,7 @@ proc copyreference {} {
 
 proc writecommit {} {
     global rowmenuid wrcomtop commitinfo wrcomcmd NS
+    global hashlength
 
     set top .writecommit
     set wrcomtop $top
@@ -9641,7 +9660,7 @@ proc writecommit {} {
     ${NS}::label $top.title -text [mc "Write commit to file"]
     grid $top.title - -pady 10
     ${NS}::label $top.id -text [mc "ID:"]
-    ${NS}::entry $top.sha1 -width 40
+    ${NS}::entry $top.sha1 -width $hashlength
     $top.sha1 insert 0 $rowmenuid
     $top.sha1 conf -state readonly
     grid $top.id $top.sha1 -sticky w
@@ -9721,6 +9740,7 @@ proc mvbranch {} {
 
 proc branchdia {top valvar uivar} {
     global NS commitinfo
+    global hashlength
     upvar $valvar val $uivar ui
 
     catch {destroy $top}
@@ -9729,7 +9749,7 @@ proc branchdia {top valvar uivar} {
     ${NS}::label $top.title -text $ui(title)
     grid $top.title - -pady 10
     ${NS}::label $top.id -text [mc "ID:"]
-    ${NS}::entry $top.sha1 -width 40
+    ${NS}::entry $top.sha1 -width $hashlength
     $top.sha1 insert 0 $val(id)
     $top.sha1 conf -state readonly
     grid $top.id $top.sha1 -sticky w
@@ -9739,7 +9759,7 @@ proc branchdia {top valvar uivar} {
     grid x $top.head -sticky ew
     grid columnconfigure $top 1 -weight 1
     ${NS}::label $top.nlab -text [mc "Name:"]
-    ${NS}::entry $top.name -width 40
+    ${NS}::entry $top.name -width $hashlength
     $top.name insert 0 $val(name)
     grid $top.nlab $top.name -sticky w
     ${NS}::frame $top.buts
@@ -11728,6 +11748,7 @@ proc prefspage_general {notebook} {
     global tabstop wrapcomment wrapdefault limitdiffs
     global autocopy autoselect autosellen extdifftool perfile_attrs
     global hideremotes want_ttk have_ttk maxrefs web_browser
+    global hashlength
 
     set page [create_prefs_page $notebook.general]
 
@@ -11756,7 +11777,8 @@ proc prefspage_general {notebook} {
             -variable autoselect
         grid x $page.autoselect -sticky w
     }
-    spinbox $page.autosellen -from 1 -to 40 -width 4 -textvariable autosellen
+
+    spinbox $page.autosellen -from 1 -to $hashlength -width 4 -textvariable autosellen
     ${NS}::label $page.autosellenl -text [mc "Length of commit ID to copy"]
     grid x $page.autosellenl $page.autosellen -sticky w
 
@@ -12537,6 +12559,17 @@ catch {
     }
 }
 
+# Use object format as hash algorightm (either "sha1" or "sha256")
+set hashalgorithm [exec git rev-parse --show-object-format]
+if {$hashalgorithm eq "sha1"} {
+    set hashlength 40
+} elseif {$hashalgorithm eq "sha256"} {
+    set hashlength 64
+} else {
+    puts stderr "Unknown hash algorithm: $hashalgorithm"
+    exit 1
+}
+
 set log_showroot true
 catch {
     set log_showroot [exec git config --bool --get log.showroot]
@@ -12578,7 +12611,7 @@ set limitdiffs 1
 set datetimeformat "%Y-%m-%d %H:%M:%S"
 set autocopy 0
 set autoselect 1
-set autosellen 40
+set autosellen $hashlength
 set perfile_attrs 0
 set want_ttk 1
 
-- 
2.47.2