git-p4: add Git LFS backend for large file system

Add example implementation including test cases for the large file
system using Git LFS.

Pushing files to the Git LFS server is not tested.

Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

2 files changed, 360 insertions, 0 deletions

diff --git a/git-p4.py b/git-p4.py
index 02b5e9e362..765ea5f064 100755
--- a/git-p4.py
+++ b/git-p4.py
@@ -1038,6 +1038,78 @@ class MockLFS(LargeFileSystem):
             os.makedirs(remotePath)
         shutil.copyfile(localLargeFile, os.path.join(remotePath, os.path.basename(localLargeFile)))
 
+class GitLFS(LargeFileSystem):
+    """Git LFS as backend for the git-p4 large file system.
+       See https://git-lfs.github.com/ for details."""
+
+    def __init__(self, *args):
+        LargeFileSystem.__init__(self, *args)
+        self.baseGitAttributes = []
+
+    def generatePointer(self, contentFile):
+        """Generate a Git LFS pointer for the content. Return LFS Pointer file
+           mode and content which is stored in the Git repository instead of
+           the actual content. Return also the new location of the actual
+           content.
+           """
+        pointerProcess = subprocess.Popen(
+            ['git', 'lfs', 'pointer', '--file=' + contentFile],
+            stdout=subprocess.PIPE
+        )
+        pointerFile = pointerProcess.stdout.read()
+        if pointerProcess.wait():
+            os.remove(contentFile)
+            die('git-lfs pointer command failed. Did you install the extension?')
+        pointerContents = [i+'\n' for i in pointerFile.split('\n')[2:][:-1]]
+        oid = pointerContents[1].split(' ')[1].split(':')[1][:-1]
+        localLargeFile = os.path.join(
+            os.getcwd(),
+            '.git', 'lfs', 'objects', oid[:2], oid[2:4],
+            oid,
+        )
+        # LFS Spec states that pointer files should not have the executable bit set.
+        gitMode = '100644'
+        return (gitMode, pointerContents, localLargeFile)
+
+    def pushFile(self, localLargeFile):
+        uploadProcess = subprocess.Popen(
+            ['git', 'lfs', 'push', '--object-id', 'origin', os.path.basename(localLargeFile)]
+        )
+        if uploadProcess.wait():
+            die('git-lfs push command failed. Did you define a remote?')
+
+    def generateGitAttributes(self):
+        return (
+            self.baseGitAttributes +
+            [
+                '\n',
+                '#\n',
+                '# Git LFS (see https://git-lfs.github.com/)\n',
+                '#\n',
+            ] +
+            ['*.' + f.replace(' ', '[[:space:]]') + ' filter=lfs -text\n'
+                for f in sorted(gitConfigList('git-p4.largeFileExtensions'))
+            ] +
+            ['/' + f.replace(' ', '[[:space:]]') + ' filter=lfs -text\n'
+                for f in sorted(self.largeFiles) if not self.hasLargeFileExtension(f)
+            ]
+        )
+
+    def addLargeFile(self, relPath):
+        LargeFileSystem.addLargeFile(self, relPath)
+        self.writeToGitStream('100644', '.gitattributes', self.generateGitAttributes())
+
+    def removeLargeFile(self, relPath):
+        LargeFileSystem.removeLargeFile(self, relPath)
+        self.writeToGitStream('100644', '.gitattributes', self.generateGitAttributes())
+
+    def processContent(self, git_mode, relPath, contents):
+        if relPath == '.gitattributes':
+            self.baseGitAttributes = contents
+            return (git_mode, self.generateGitAttributes())
+        else:
+            return LargeFileSystem.processContent(self, git_mode, relPath, contents)
+
 class Command:
     def __init__(self):
         self.usage = "usage: %prog [options]"
diff --git a/t/t9824-git-p4-git-lfs.sh b/t/t9824-git-p4-git-lfs.sh
new file mode 100755
index 0000000000..0b664a377c
--- /dev/null
+++ b/t/t9824-git-p4-git-lfs.sh
@@ -0,0 +1,288 @@
+#!/bin/sh
+
+test_description='Clone repositories and store files in Git LFS'
+
+. ./lib-git-p4.sh
+
+git lfs help >/dev/null 2>&1 || {
+	skip_all='skipping git p4 Git LFS tests; Git LFS not found'
+	test_done
+}
+
+test_file_in_lfs () {
+	FILE="$1" &&
+	SIZE="$2" &&
+	EXPECTED_CONTENT="$3" &&
+	cat "$FILE" | grep "size $SIZE" &&
+	HASH=$(cat "$FILE" | grep "oid sha256:" | sed -e "s/oid sha256://g") &&
+	LFS_FILE=".git/lfs/objects/$(echo "$HASH" | cut -c1-2)/$(echo "$HASH" | cut -c3-4)/$HASH" &&
+	echo $EXPECTED_CONTENT >expect &&
+	test_path_is_file "$FILE" &&
+	test_path_is_file "$LFS_FILE" &&
+	test_cmp expect "$LFS_FILE"
+}
+
+test_file_count_in_dir () {
+	DIR="$1" &&
+	EXPECTED_COUNT="$2" &&
+	find "$DIR" -type f >actual &&
+	test_line_count = $EXPECTED_COUNT actual
+}
+
+test_expect_success 'start p4d' '
+	start_p4d
+'
+
+test_expect_success 'Create repo with binary files' '
+	client_view "//depot/... //client/..." &&
+	(
+		cd "$cli" &&
+
+		echo "content 1 txt 23 bytes" >file1.txt &&
+		p4 add file1.txt &&
+		echo "content 2-3 bin 25 bytes" >file2.dat &&
+		p4 add file2.dat &&
+		p4 submit -d "Add text and binary file" &&
+
+		mkdir "path with spaces" &&
+		echo "content 2-3 bin 25 bytes" >"path with spaces/file3.bin" &&
+		p4 add "path with spaces/file3.bin" &&
+		p4 submit -d "Add another binary file with same content and spaces in path" &&
+
+		echo "content 4 bin 26 bytes XX" >file4.bin &&
+		p4 add file4.bin &&
+		p4 submit -d "Add another binary file with different content"
+	)
+'
+
+test_expect_success 'Store files in LFS based on size (>24 bytes)' '
+	client_view "//depot/... //client/..." &&
+	test_when_finished cleanup_git &&
+	(
+		cd "$git" &&
+		git init . &&
+		git config git-p4.useClientSpec true &&
+		git config git-p4.largeFileSystem GitLFS &&
+		git config git-p4.largeFileThreshold 24 &&
+		git p4 clone --destination="$git" //depot@all &&
+
+		test_file_in_lfs file2.dat 25 "content 2-3 bin 25 bytes" &&
+		test_file_in_lfs "path with spaces/file3.bin" 25 "content 2-3 bin 25 bytes" &&
+		test_file_in_lfs file4.bin 26 "content 4 bin 26 bytes XX" &&
+
+		test_file_count_in_dir ".git/lfs/objects" 2 &&
+
+		cat >expect <<-\EOF &&
+
+		#
+		# Git LFS (see https://git-lfs.github.com/)
+		#
+		/file2.dat filter=lfs -text
+		/file4.bin filter=lfs -text
+		/path[[:space:]]with[[:space:]]spaces/file3.bin filter=lfs -text
+		EOF
+		test_path_is_file .gitattributes &&
+		test_cmp expect .gitattributes
+	)
+'
+
+test_expect_success 'Store files in LFS based on size (>25 bytes)' '
+	client_view "//depot/... //client/..." &&
+	test_when_finished cleanup_git &&
+	(
+		cd "$git" &&
+		git init . &&
+		git config git-p4.useClientSpec true &&
+		git config git-p4.largeFileSystem GitLFS &&
+		git config git-p4.largeFileThreshold 25 &&
+		git p4 clone --destination="$git" //depot@all &&
+
+		test_file_in_lfs file4.bin 26 "content 4 bin 26 bytes XX" &&
+		test_file_count_in_dir ".git/lfs/objects" 1 &&
+
+		cat >expect <<-\EOF &&
+
+		#
+		# Git LFS (see https://git-lfs.github.com/)
+		#
+		/file4.bin filter=lfs -text
+		EOF
+		test_path_is_file .gitattributes &&
+		test_cmp expect .gitattributes
+	)
+'
+
+test_expect_success 'Store files in LFS based on extension (dat)' '
+	client_view "//depot/... //client/..." &&
+	test_when_finished cleanup_git &&
+	(
+		cd "$git" &&
+		git init . &&
+		git config git-p4.useClientSpec true &&
+		git config git-p4.largeFileSystem GitLFS &&
+		git config git-p4.largeFileExtensions dat &&
+		git p4 clone --destination="$git" //depot@all &&
+
+		test_file_in_lfs file2.dat 25 "content 2-3 bin 25 bytes" &&
+		test_file_count_in_dir ".git/lfs/objects" 1 &&
+
+		cat >expect <<-\EOF &&
+
+		#
+		# Git LFS (see https://git-lfs.github.com/)
+		#
+		*.dat filter=lfs -text
+		EOF
+		test_path_is_file .gitattributes &&
+		test_cmp expect .gitattributes
+	)
+'
+
+test_expect_success 'Store files in LFS based on size (>25 bytes) and extension (dat)' '
+	client_view "//depot/... //client/..." &&
+	test_when_finished cleanup_git &&
+	(
+		cd "$git" &&
+		git init . &&
+		git config git-p4.useClientSpec true &&
+		git config git-p4.largeFileSystem GitLFS &&
+		git config git-p4.largeFileExtensions dat &&
+		git config git-p4.largeFileThreshold 25 &&
+		git p4 clone --destination="$git" //depot@all &&
+
+		test_file_in_lfs file2.dat 25 "content 2-3 bin 25 bytes" &&
+		test_file_in_lfs file4.bin 26 "content 4 bin 26 bytes XX" &&
+		test_file_count_in_dir ".git/lfs/objects" 2 &&
+
+		cat >expect <<-\EOF &&
+
+		#
+		# Git LFS (see https://git-lfs.github.com/)
+		#
+		*.dat filter=lfs -text
+		/file4.bin filter=lfs -text
+		EOF
+		test_path_is_file .gitattributes &&
+		test_cmp expect .gitattributes
+	)
+'
+
+test_expect_success 'Remove file from repo and store files in LFS based on size (>24 bytes)' '
+	client_view "//depot/... //client/..." &&
+	(
+		cd "$cli" &&
+		p4 delete file4.bin &&
+		p4 submit -d "Remove file"
+	) &&
+
+	client_view "//depot/... //client/..." &&
+	test_when_finished cleanup_git &&
+	(
+		cd "$git" &&
+		git init . &&
+		git config git-p4.useClientSpec true &&
+		git config git-p4.largeFileSystem GitLFS &&
+		git config git-p4.largeFileThreshold 24 &&
+		git p4 clone --destination="$git" //depot@all &&
+
+		test_file_in_lfs file2.dat 25 "content 2-3 bin 25 bytes" &&
+		test_file_in_lfs "path with spaces/file3.bin" 25 "content 2-3 bin 25 bytes" &&
+		test_path_is_missing file4.bin &&
+		test_file_count_in_dir ".git/lfs/objects" 2 &&
+
+		cat >expect <<-\EOF &&
+
+		#
+		# Git LFS (see https://git-lfs.github.com/)
+		#
+		/file2.dat filter=lfs -text
+		/path[[:space:]]with[[:space:]]spaces/file3.bin filter=lfs -text
+		EOF
+		test_path_is_file .gitattributes &&
+		test_cmp expect .gitattributes
+	)
+'
+
+test_expect_success 'Add .gitattributes and store files in LFS based on size (>24 bytes)' '
+	client_view "//depot/... //client/..." &&
+	(
+		cd "$cli" &&
+		echo "*.txt text" >.gitattributes &&
+		p4 add .gitattributes &&
+		p4 submit -d "Add .gitattributes"
+	) &&
+
+	client_view "//depot/... //client/..." &&
+	test_when_finished cleanup_git &&
+	(
+		cd "$git" &&
+		git init . &&
+		git config git-p4.useClientSpec true &&
+		git config git-p4.largeFileSystem GitLFS &&
+		git config git-p4.largeFileThreshold 24 &&
+		git p4 clone --destination="$git" //depot@all &&
+
+		test_file_in_lfs file2.dat 25 "content 2-3 bin 25 bytes" &&
+		test_file_in_lfs "path with spaces/file3.bin" 25 "content 2-3 bin 25 bytes" &&
+		test_path_is_missing file4.bin &&
+		test_file_count_in_dir ".git/lfs/objects" 2 &&
+
+		cat >expect <<-\EOF &&
+		*.txt text
+
+		#
+		# Git LFS (see https://git-lfs.github.com/)
+		#
+		/file2.dat filter=lfs -text
+		/path[[:space:]]with[[:space:]]spaces/file3.bin filter=lfs -text
+		EOF
+		test_path_is_file .gitattributes &&
+		test_cmp expect .gitattributes
+	)
+'
+
+test_expect_success 'Add big files to repo and store files in LFS based on compressed size (>28 bytes)' '
+	client_view "//depot/... //client/..." &&
+	(
+		cd "$cli" &&
+		echo "content 5 bin 40 bytes XXXXXXXXXXXXXXXX" >file5.bin &&
+		p4 add file5.bin &&
+		p4 submit -d "Add file with small footprint after compression" &&
+
+		echo "content 6 bin 39 bytes XXXXXYYYYYZZZZZ" >file6.bin &&
+		p4 add file6.bin &&
+		p4 submit -d "Add file with large footprint after compression"
+	) &&
+
+	client_view "//depot/... //client/..." &&
+	test_when_finished cleanup_git &&
+	(
+		cd "$git" &&
+		git init . &&
+		git config git-p4.useClientSpec true &&
+		git config git-p4.largeFileSystem GitLFS &&
+		git config git-p4.largeFileCompressedThreshold 28 &&
+		# We only import HEAD here ("@all" is missing!)
+		git p4 clone --destination="$git" //depot &&
+
+		test_file_in_lfs file6.bin 13 "content 6 bin 39 bytes XXXXXYYYYYZZZZZ"
+		test_file_count_in_dir ".git/lfs/objects" 1 &&
+
+		cat >expect <<-\EOF &&
+		*.txt text
+
+		#
+		# Git LFS (see https://git-lfs.github.com/)
+		#
+		/file6.bin filter=lfs -text
+		EOF
+		test_path_is_file .gitattributes &&
+		test_cmp expect .gitattributes
+	)
+'
+
+test_expect_success 'kill p4d' '
+	kill_p4d
+'
+
+test_done