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[RFC/PATCH] Teach git mergetool to use custom commands defined at config time

From
Charles Bailey <charles@hashpling.org>
Date
Feb 16, 2008, 18:53 UTC
Message-ID
<20080216185349.GA29177@hashpling.org>

Currently git mergetool is restricted to a set of commands defined in the script. You can subvert the mergetool.<tool>.path to force git mergetool to use a different command, but if you have a command whose invocation syntax does not match one of the current tools then you would have to write a wrapper script for it.

This patch adds three git config variable patterns which allow a more flexible choice of merge tool.

If you run git mergetool with -t/--tool or the merge.tool config variable set to an unrecognized tool then git mergetool will query the mergetool.<tool>.cmd config variable. If this variable exists, then git mergetool will treat the specified tool as a custom command and will use a shell eval to run the command so that the appropriate shell variables can be used to find the merge temporary files.

mergetool.<tool>.trustExitCode can be used to indicate that the exit code of the custom command can be used to determine the success of the merge. mergetool.<tool>.keepBackup can be used to specify whether the original pre-merge file with conflict markers should be kept as a '.orig' file after the merge tool completes. ---

This is a preliminary patch which aims to make it easier to use a.n.other 3-way merge tool with git-mergetool without either hacking the source or writing a wrapper script for the tool.

It follows filter-branch's 'eval a user shell snippet' philosophy to provide the flexibility and here in lies an ugliness. It exposes git-mergetool.sh's private variables to the user script. The variables are BASE, REMOTE, LOCAL and path.

My feeling is that we should give this consistent and documented names, perhaps GIT_BASE, GIT_REMOTE, GIT_LOCAL, GIT_MERGED or similar.

Also, does anyone know of any reason why the temporary files should not be cleaned up after an unsuccessful merge? As it is, every time you abort a mergetool run you end up with another set of .$$.BASE .$$.REMOTE and .$$.LOCAL files.

A further enhancement that I have thought about is providing a config option like mergetool.<tool>.cmdNoBase for the case where there is no base file, as in many cases it might be easier for the user to provide a second command than to have shell conditionals in their config.

Just for reference I've tried this patch in the windows world with things like:

git config --global mergetool.tortoise.cmd 'TortoiseMerge.exe \ /base:"$BASE" /theirs:"$REMOTE" /mine:"$LOCAL" /merged:"$path"'

git config --global mergetool.p4.cmd 'p4merge.exe "$BASE" "$REMOTE" \ "$LOCAL" "$path"'

git config --global mergetool.p4win.cmd 'P4WinMrg "$BASE" "$REMOTE" \ "$LOCAL" "$path"'

 Documentation/config.txt |   30 ++++++++++++++++++++++++++++--
 git-mergetool.sh         |   32 ++++++++++++++++++++++++++++++--
 2 files changed, 58 insertions(+), 4 deletions(-)
diff --git a/Documentation/config.txt b/Documentation/config.txt
index f9bdb16..e26c4b2 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -689,8 +689,10 @@ merge.summary::
 
 merge.tool::
 	Controls which merge resolution program is used by
-	linkgit:git-mergetool[1].  Valid values are: "kdiff3", "tkdiff",
-	"meld", "xxdiff", "emerge", "vimdiff", "gvimdiff", and "opendiff".
+	linkgit:git-mergetool[1].  Valid built-in values are: "kdiff3",
+	"tkdiff", "meld", "xxdiff", "emerge", "vimdiff", "gvimdiff", and
+	"opendiff".  Any other value is treated is custom merge tool
+	and there must be a corresponing mergetool.<tool>.cmd option.
 
 merge.verbosity::
 	Controls the amount of output shown by the recursive merge
@@ -717,6 +719,30 @@ mergetool.<tool>.path::
 	Override the path for the given tool.  This is useful in case
 	your tool is not in the PATH.
 
+mergetool.<tool>.cmd::
+	Specify the command to invoke the specified merge tool.  The
+	specified command is evaluated in shell with the following
+	variables available: 'BASE' is the name of a temporary file
+	containing the common base of the files to be merged, if available;
+	'LOCAL' is the name of a temporary file containing the contents of
+	the file on the current branch; 'REMOTE' is the name of a temporary
+	file containing the contents of the file from the branch being
+	merged; 'path' contains the name of the file to which the merge
+	tool should write the results of a successful merge.
+
+mergetool.<tool>.trustExitCode::
+	For a custom merge command, specify whether the exit code of
+	the merge command can be used to determine whether the merge was
+	successful.  If this is not set to true then the merge target file
+	timestamp is checked and the merge assumed to have been successful
+	if the file has been updated, otherwise the user is prompted to
+	indicate the success of the merge.
+
+mergetool.<tool>.keepBackup::
+	After performing a merge, the original file with conflict markers
+	can be saved as a file with a `.orig` extension.  If this variable
+	is set to `false` then this file is not preserved.
+
 pack.window::
 	The size of the window used by linkgit:git-pack-objects[1] when no
 	window size is given on the command line. Defaults to 10.
diff --git a/git-mergetool.sh b/git-mergetool.sh
index cbbb707..78c73ca 100755
--- a/git-mergetool.sh
+++ b/git-mergetool.sh
@@ -271,6 +271,21 @@ merge_file () {
 	    status=$?
 	    save_backup
 	    ;;
+	*)
+	    if test -n "$merge_tool_cmd"; then
+		touch "$BACKUP"
+		eval "$merge_tool_cmd"
+		status=$?
+		if test "$merge_tool_trust_exit_code" = "false"; then
+		    check_unchanged
+		fi
+		if test "$merge_tool_keep_backup" = "true"; then
+		    save_backup
+		else
+		    remove_backup
+		fi
+	    fi
+	    ;;
     esac
     if test "$status" -ne 0; then
 	echo "merge of $path failed" 1>&2
@@ -309,12 +324,20 @@ do
     shift
 done
 
+valid_custom_tool()
+{
+    merge_tool_cmd="$(git config mergetool.$1.cmd)"
+    test -n "$merge_tool_cmd"
+}
+
 valid_tool() {
 	case "$1" in
 		kdiff3 | tkdiff | xxdiff | meld | opendiff | emerge | vimdiff | gvimdiff | ecmerge)
 			;; # happy
 		*)
-			return 1
+			if ! valid_custom_tool "$1"; then
+				return 1
+			fi
 			;;
 	esac
 }
@@ -380,10 +403,15 @@ else
 
     init_merge_tool_path "$merge_tool"
 
-    if ! type "$merge_tool_path" > /dev/null 2>&1; then
+    if test -z "$merge_tool_cmd" && ! type "$merge_tool_path" > /dev/null 2>&1; then
         echo "The merge tool $merge_tool is not available as '$merge_tool_path'"
         exit 1
     fi
+
+    if ! test -z "$merge_tool_cmd"; then
+        merge_tool_trust_exit_code="$(git config --bool merge.$merge_tool.trustExitCode || echo false)"
+        merge_tool_keep_backup="$(git config --bool merge.$merge_tool.keepBackup || echo true)"
+    fi
 fi
 
 

-- 
1.5.4.1.144.gb4758f
Next: Junio C Hamano
Message 1 of 16 in “Teach git mergetool to use custom commands defined at config time”
  1. Teach git mergetool to use custom commands defined at config timeCharles Bailey, Feb 16, 2008
  2. Junio C HamanoFeb 16, 2008
  3. Charles BaileyFeb 16, 2008
  4. Jakub NarebskiFeb 16, 2008
  5. Steffen ProhaskaFeb 16, 2008
  6. Charles BaileyFeb 17, 2008
  7. Johannes SchindelinFeb 17, 2008
  8. Charles BaileyFeb 17, 2008
  9. Junio C HamanoFeb 17, 2008
  10. Steffen ProhaskaFeb 17, 2008
  11. Charles BaileyFeb 17, 2008
  12. Theodore TsoFeb 17, 2008
  13. Charles BaileyFeb 17, 2008
  14. Charles BaileyFeb 17, 2008
  15. Junio C HamanoFeb 18, 2008
  16. Charles BaileyFeb 18, 2008

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