Add a merge driver
Sometimes users have text files that they'd like to be able perform merges on that they also want to store in Git LFS. Let's add a custom merge driver that users can use to merge these text files, either with Git, or with a custom merge tool like the one shipped with Unity.
This commit is contained in:
brian m. carlson
parent
aaca22358e
commit
402e958bfa
2
Makefile
2
Makefile
@ -658,6 +658,7 @@ MAN_ROFF_TARGETS = man/man1/git-lfs-checkout.1 \
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man/man1/git-lfs-locks.1 \
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man/man1/git-lfs-logs.1 \
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man/man1/git-lfs-ls-files.1 \
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man/man1/git-lfs-merge-driver.1 \
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man/man1/git-lfs-migrate.1 \
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man/man1/git-lfs-pointer.1 \
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man/man1/git-lfs-post-checkout.1 \
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@ -693,6 +694,7 @@ MAN_HTML_TARGETS = man/html/git-lfs-checkout.1.html \
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man/html/git-lfs-locks.1.html \
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man/html/git-lfs-logs.1.html \
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man/html/git-lfs-ls-files.1.html \
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man/html/git-lfs-merge-driver.1.html \
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man/html/git-lfs-migrate.1.html \
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man/html/git-lfs-pointer.1.html \
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man/html/git-lfs-post-checkout.1.html \
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147
commands/command_merge_driver.go
Normal file
147
commands/command_merge_driver.go
Normal file
@ -0,0 +1,147 @@
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package commands
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import (
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"fmt"
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"os"
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"os/exec"
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"github.com/git-lfs/git-lfs/v3/errors"
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"github.com/git-lfs/git-lfs/v3/lfs"
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"github.com/git-lfs/git-lfs/v3/subprocess"
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"github.com/git-lfs/git-lfs/v3/tr"
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"github.com/spf13/cobra"
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)
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var (
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mergeDriverAncestor string
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mergeDriverCurrent string
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mergeDriverOther string
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mergeDriverOutput string
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mergeDriverProgram string
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mergeDriverMarkerSize int
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)
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func mergeDriverCommand(cmd *cobra.Command, args []string) {
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if len(mergeDriverAncestor) == 0 || len(mergeDriverCurrent) == 0 || len(mergeDriverOther) == 0 || len(mergeDriverOutput) == 0 {
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Exit(tr.Tr.Get("the --ancestor, --current, --other, and --output options are mandatory"))
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}
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fileSpecifiers := make(map[string]string)
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gf := lfs.NewGitFilter(cfg)
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mergeProcessInput(gf, mergeDriverAncestor, fileSpecifiers, "O")
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mergeProcessInput(gf, mergeDriverCurrent, fileSpecifiers, "A")
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mergeProcessInput(gf, mergeDriverOther, fileSpecifiers, "B")
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mergeProcessInput(gf, "", fileSpecifiers, "D")
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fileSpecifiers["L"] = fmt.Sprintf("%d", mergeDriverMarkerSize)
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if len(mergeDriverProgram) == 0 {
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mergeDriverProgram = "git merge-file --stdout --marker-size=%L %A %O %B >%D"
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}
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status, err := processFiles(fileSpecifiers, mergeDriverProgram, mergeDriverOutput)
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if err != nil {
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ExitWithError(err)
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}
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os.Exit(status)
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}
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func processFiles(fileSpecifiers map[string]string, program string, outputFile string) (int, error) {
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defer mergeCleanup(fileSpecifiers)
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var exitStatus int
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formattedMergeProgram := subprocess.FormatPercentSequences(mergeDriverProgram, fileSpecifiers)
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cmd, err := subprocess.ExecCommand("sh", "-c", formattedMergeProgram)
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if err != nil {
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return -1, errors.New(tr.Tr.Get("failed to run merge program %q: %s", formattedMergeProgram, err))
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}
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err = cmd.Run()
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// If it runs but exits nonzero, then that means there's conflicts
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if err != nil {
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if exitError, ok := err.(*exec.ExitError); ok {
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exitStatus = exitError.ProcessState.ExitCode()
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} else {
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return -1, errors.New(tr.Tr.Get("failed to run merge program %q: %s", formattedMergeProgram, err))
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}
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}
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outputFp, err := os.OpenFile(outputFile, os.O_WRONLY|os.O_CREATE, 0600)
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if err != nil {
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return -1, err
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}
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defer outputFp.Close()
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filename := fileSpecifiers["D"]
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stat, err := os.Stat(filename)
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if err != nil {
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return -1, err
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}
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inputFp, err := os.OpenFile(filename, os.O_RDONLY|os.O_CREATE, 0600)
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if err != nil {
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return -1, err
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}
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defer inputFp.Close()
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gf := lfs.NewGitFilter(cfg)
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_, err = clean(gf, outputFp, inputFp, filename, stat.Size())
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if err != nil {
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return -1, err
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}
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return exitStatus, nil
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}
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func mergeCleanup(fileSpecifiers map[string]string) {
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ids := []string{"A", "O", "B", "D"}
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for _, id := range ids {
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os.Remove(fileSpecifiers[id])
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}
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}
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func mergeProcessInput(gf *lfs.GitFilter, filename string, fileSpecifiers map[string]string, tag string) {
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file, err := lfs.TempFile(cfg, fmt.Sprintf("merge-driver-%s", tag))
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if err != nil {
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Exit(tr.Tr.Get("could not create temporary file when merging: %s", err))
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}
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defer file.Close()
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fileSpecifiers[tag] = file.Name()
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if len(filename) == 0 {
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return
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}
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pointer, err := lfs.DecodePointerFromFile(filename)
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if err != nil {
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if errors.IsNotAPointerError(err) {
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file.Close()
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if err := lfs.CopyFileContents(cfg, filename, file.Name()); err != nil {
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os.Remove(file.Name())
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Exit(tr.Tr.Get("could not copy non-LFS content when merging: %s", err))
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}
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return
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} else {
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os.Remove(file.Name())
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Exit(tr.Tr.Get("could not decode pointer when merging: %s", err))
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}
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}
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cb, fp, err := gf.CopyCallbackFile("download", file.Name(), 1, 1)
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if err != nil {
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os.Remove(file.Name())
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Exit(tr.Tr.Get("could not create callback: %s", err))
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}
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defer fp.Close()
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_, err = gf.Smudge(file, pointer, file.Name(), true, getTransferManifestOperationRemote("download", cfg.Remote()), cb)
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}
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func init() {
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RegisterCommand("merge-driver", mergeDriverCommand, func(cmd *cobra.Command) {
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cmd.Flags().StringVarP(&mergeDriverAncestor, "ancestor", "", "", "file with the ancestor version")
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cmd.Flags().StringVarP(&mergeDriverCurrent, "current", "", "", "file with the current version")
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cmd.Flags().StringVarP(&mergeDriverOther, "other", "", "", "file with the other version")
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cmd.Flags().StringVarP(&mergeDriverOutput, "output", "", "", "file with the output version")
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cmd.Flags().StringVarP(&mergeDriverProgram, "program", "", "", "program to run to perform the merge")
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cmd.Flags().IntVarP(&mergeDriverMarkerSize, "marker-size", "", 12, "merge marker size")
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})
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}
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91
docs/man/git-lfs-merge-driver.1.ronn
Normal file
91
docs/man/git-lfs-merge-driver.1.ronn
Normal file
@ -0,0 +1,91 @@
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git-lfs-merge-driver(1) -- Merge text-based LFS files
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==============================================================
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## SYNOPSIS
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`git lfs merge-driver` [options]
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## DESCRIPTION
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Merge text files stored in Git LFS using the default Git merge machinery, or a
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custom merge driver if specified. Note that this, in general, does not support
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partial renames or copies because Git does not support them in this case.
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This program is intended to be invoked automatically by Git and not by users
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manually. See [CONFIGURATION] for details on the configuration required for
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that.
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## OPTIONS
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* `--ancestor` <path>
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Specify the file containing the ancestor revision.
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* `--current` <path>
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Specify the file containing the current revision.
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* `--marker-size` <num>
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Specify the conflict marker size as an integer.
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* `--other` <path>
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Specify the file containing the other revision.
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* `--program` <program>
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Specify a command, which is passed to the shell after substitution, that
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performs the actual merge. If this is not specified, `git merge-file` is
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invoked with appropriate arguments to perform the merge of the file.
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See [CONFIGURATION] for the sequences which are substituted here.
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## CONFIGURATION
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Git allows the use of a custom merge driver for files based on the `merge`
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attribute set in `.gitattributes`. By default, when using `git lfs track`, this
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value is set to `lfs`.
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Because Git LFS can be used to store both text and binary files and it isn't
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always clear which behavior should be used, Git LFS does not enable this merge
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driver by default. However, if you know that some or all of your files are text
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files, then you can set the `merge` attribute for those files to `lfs-text` and
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use `git config` to set the merge driver like so:
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```console
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$ git config merge.lfs-text.driver 'git lfs merge-driver --ancestor %O --current %A --other %B --marker-size %L --output %A'
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```
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This tells Git to invoke the custom Git LFS merge driver, which in turn uses
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Git's merge machinery, to merge files where the `merge` attribute is set to
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`lfs-text`. Note that `lfs-text` here is an example and any syntactically valid
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value can be used.
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If you are using a special type of file that needs rules different from Git's
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standard merge machinery, you can also specify the `--program` option, which
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is passed to `sh` after substituting its own percent-encoded escapes:
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* `%A`: the current version
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* `%B`: the other version
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* `%D`: the destination version
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* `%O`: the ancestor version
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* `%L`: the conflict marker size
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Note that the percent sign must typically be doubled to prevent Git from
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substituting its own values here. Therefore, specifying the default behavior
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explicitly looks like this:
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```console
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$ git config merge.lfs-text.driver \
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'git lfs merge-driver --ancestor %O --current %A --other %B --marker-size %L --output %A --program '\''git merge-file --stdout --marker-size=%%L %%A %%O %%B >%%D'\'''
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```
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The exit status from the custom command should be zero on success or non-zero on
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conflicts or other failure.
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Note that if no merge driver is specified for the value of the `merge` attribute
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(as is the case by default with `merge=lfs`), then the default Git merge
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strategy is used. For LFS files, this means that Git will try to merge the
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pointer files, which usually is not useful.
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## SEE ALSO
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git-merge(1), git-merge-file(1), gitattributes(5)
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Part of the git-lfs(1) suite.
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@ -81,6 +81,8 @@ commands and low level ("plumbing") commands.
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Git clean filter that converts large files to pointers.
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* git-lfs-filter-process(1):
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Git process filter that converts between large files and pointers.
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* git-lfs-merge-driver(1):
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Merge text-based LFS files
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* git-lfs-pointer(1):
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Build and compare pointers.
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* git-lfs-post-checkout(1):
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286
t/t-merge-driver.sh
Executable file
286
t/t-merge-driver.sh
Executable file
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#!/usr/bin/env bash
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. "$(dirname "$0")/testlib.sh"
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setup_successful_repo () {
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if [ "$1" != "--track-later" ]
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then
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git lfs track '*.dat'
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else
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touch .gitattributes
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fi
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seq 1 10 > a.dat
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git add .gitattributes *.dat
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git commit -m 'Initial import'
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git checkout -b other
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# sed -i isn't portable.
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sed -e 's/9/B/' a.dat > b.dat
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mv b.dat a.dat
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git add -u
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git commit -m 'B'
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if [ "$1" = "--track-later" ]
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then
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git lfs track '*.dat'
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git add .gitattributes
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git commit -m 'B2'
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fi
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git checkout --force main
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sed -e 's/2/A/' a.dat > b.dat
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mv b.dat a.dat
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git add -u
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git commit -m 'A'
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if [ "$1" = "--track-later" ]
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then
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git lfs track '*.dat'
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git add -u
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git commit -m 'A2'
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fi
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}
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setup_custom_repo () {
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git lfs track '*.dat'
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seq 1 10 > a.dat
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git add .gitattributes *.dat
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git commit -m 'Initial import'
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git checkout -b other
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# sed -i isn't portable.
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sed -e 's/2/B/' -e 's/9/B/' a.dat > b.dat
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mv b.dat a.dat
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git add -u
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git commit -m 'B'
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git checkout main
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sed -e 's/2/A/' -e 's/9/A/' a.dat > b.dat
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mv b.dat a.dat
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git add -u
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git commit -m 'A'
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}
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setup_conflicting_repo () {
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if [ "$1" != "--track-later" ]
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then
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git lfs track '*.dat'
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else
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touch .gitattributes
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fi
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seq 1 10 > a.dat
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git add .gitattributes *.dat
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git commit -m 'Initial import'
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git checkout -b other
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# sed -i isn't portable.
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sed -e 's/3/B/' a.dat > b.dat
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mv b.dat a.dat
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git add -u
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git commit -m 'B'
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if [ "$1" = "--track-later" ]
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then
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git lfs track '*.dat'
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git add .gitattributes
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git commit -m 'B2'
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fi
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git checkout --force main
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sed -e 's/2/A/' a.dat > b.dat
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mv b.dat a.dat
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git add -u
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git commit -m 'A'
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if [ "$1" = "--track-later" ]
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then
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git lfs track '*.dat'
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git add -u
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git commit -m 'A2'
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fi
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}
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begin_test "merge-driver uses Git merge by default"
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(
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set -e
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reponame="merge-driver-basic"
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git init "$reponame"
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cd "$reponame"
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result="07b26d7b3123467282635a68fdf9b59e81269cf9faf12282cedf30f393a55e5b"
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git config merge.lfs.driver 'git lfs merge-driver --ancestor %O --current %A --other %B --marker-size %L --output %A'
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setup_successful_repo
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git merge other
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(
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set -
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echo 1
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echo A
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seq 3 8
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echo B
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echo 10
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) > expected.dat
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diff -u a.dat expected.dat
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assert_pointer "main" "a.dat" "$result" 21
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assert_local_object "$result" 21
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)
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end_test
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begin_test "merge-driver uses Git merge when explicit"
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(
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set -e
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reponame="merge-driver-explicit"
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git init "$reponame"
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cd "$reponame"
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result="07b26d7b3123467282635a68fdf9b59e81269cf9faf12282cedf30f393a55e5b"
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git config merge.lfs.driver 'git lfs merge-driver --ancestor %O --current %A --other %B --marker-size %L --output %A --program '\''git merge-file --stdout --marker-size=%%L %%A %%O %%B >%%D'\'''
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git lfs track '*.dat'
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setup_successful_repo
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git merge other
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(
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set -e
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echo 1
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echo A
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seq 3 8
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echo B
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echo 10
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) > expected.dat
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diff -u a.dat expected.dat
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assert_pointer "main" "a.dat" "$result" 21
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assert_local_object "$result" 21
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)
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end_test
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begin_test "merge-driver uses custom driver when explicit"
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(
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set -e
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reponame="merge-driver-custom"
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git init "$reponame"
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cd "$reponame"
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result="07b26d7b3123467282635a68fdf9b59e81269cf9faf12282cedf30f393a55e5b"
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git config merge.lfs.driver 'git lfs merge-driver --ancestor %O --current %A --other %B --marker-size %L --output %A --program '\''(sed -n 1,5p %%A; sed -n 6,10p %%B) >%%D'\'''
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git lfs track '*.dat'
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setup_custom_repo
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git merge other
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(
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set -e
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echo 1
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echo A
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seq 3 8
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echo B
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echo 10
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) > expected.dat
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diff -u a.dat expected.dat
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assert_pointer "main" "a.dat" "$result" 21
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assert_local_object "$result" 21
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)
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end_test
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begin_test "merge-driver reports conflicts"
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(
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set -e
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reponame="merge-driver-conflicts"
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git init "$reponame"
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cd "$reponame"
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|
||||
git config merge.lfs.driver 'git lfs merge-driver --ancestor %O --current %A --other %B --marker-size %L --output %A --program '\''git merge-file --stdout --marker-size=%%L %%A %%O %%B >%%D'\'''
|
||||
git lfs track '*.dat'
|
||||
|
||||
setup_conflicting_repo
|
||||
|
||||
git merge other && exit 1
|
||||
sed -e 's/<<<<<<<.*/<<<<<<</' -e 's/>>>>>>>.*/>>>>>>>/' a.dat > actual.dat
|
||||
(
|
||||
set -e
|
||||
echo 1
|
||||
echo "<<<<<<<"
|
||||
echo A
|
||||
echo 3
|
||||
echo "======="
|
||||
echo 2
|
||||
echo B
|
||||
echo ">>>>>>>"
|
||||
seq 4 10
|
||||
) > expected.dat
|
||||
diff -u actual.dat expected.dat
|
||||
)
|
||||
end_test
|
||||
|
||||
begin_test "merge-driver gracefully handles non-pointer"
|
||||
(
|
||||
set -e
|
||||
|
||||
reponame="merge-driver-non-pointer"
|
||||
git init "$reponame"
|
||||
cd "$reponame"
|
||||
|
||||
result="07b26d7b3123467282635a68fdf9b59e81269cf9faf12282cedf30f393a55e5b"
|
||||
git config merge.lfs.driver 'git lfs merge-driver --ancestor %O --current %A --other %B --marker-size %L --output %A'
|
||||
|
||||
setup_successful_repo --track-later
|
||||
|
||||
git merge other
|
||||
|
||||
(
|
||||
set -
|
||||
echo 1
|
||||
echo A
|
||||
seq 3 8
|
||||
echo B
|
||||
echo 10
|
||||
) > expected.dat
|
||||
diff -u a.dat expected.dat
|
||||
assert_pointer "main" "a.dat" "$result" 21
|
||||
assert_local_object "$result" 21
|
||||
)
|
||||
end_test
|
||||
|
||||
begin_test "merge-driver reports conflicts with non-pointer"
|
||||
(
|
||||
set -e
|
||||
|
||||
reponame="conflicts-non-pointer"
|
||||
git init "$reponame"
|
||||
cd "$reponame"
|
||||
|
||||
git config merge.lfs.driver 'git lfs merge-driver --ancestor %O --current %A --other %B --marker-size %L --output %A --program '\''git merge-file --stdout --marker-size=%%L %%A %%O %%B >%%D'\'''
|
||||
|
||||
setup_conflicting_repo --track-later
|
||||
|
||||
git merge other && exit 1
|
||||
sed -e 's/<<<<<<<.*/<<<<<<</' -e 's/>>>>>>>.*/>>>>>>>/' a.dat > actual.dat
|
||||
(
|
||||
set -e
|
||||
echo 1
|
||||
echo "<<<<<<<"
|
||||
echo A
|
||||
echo 3
|
||||
echo "======="
|
||||
echo 2
|
||||
echo B
|
||||
echo ">>>>>>>"
|
||||
seq 4 10
|
||||
) > expected.dat
|
||||
diff -u actual.dat expected.dat
|
||||
)
|
||||
end_test
|
||||
Loading…
Reference in New Issue
Block a user