github.com/mirantis/virtlet@v1.5.2-0.20191204181327-1659b8a48e9b/tests/gm/git.go (about)

     1  /*
     2  Copyright 2017 Mirantis
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package gm
    18  
    19  import (
    20  	"fmt"
    21  	"io/ioutil"
    22  	"os"
    23  	"os/exec"
    24  	"path/filepath"
    25  
    26  	"github.com/golang/glog"
    27  )
    28  
    29  // GitDiff does 'git diff' on the specified file, first changing
    30  // to its directory. It returns the diff and error, if any
    31  func GitDiff(path string) (string, error) {
    32  	absPath, err := filepath.Abs(path)
    33  	if err != nil {
    34  		return "", fmt.Errorf("can't get abs path for %q: %v", path, err)
    35  	}
    36  	origWd, err := os.Getwd()
    37  	if err != nil {
    38  		return "", fmt.Errorf("can't get current directory: %v", err)
    39  	}
    40  	defer func() {
    41  		if err := os.Chdir(origWd); err != nil {
    42  			glog.Warningf("Can't chdir back to the old work dir: %v", err)
    43  		}
    44  	}()
    45  	fileDir := filepath.Dir(absPath)
    46  	if err := os.Chdir(fileDir); err != nil {
    47  		return "", fmt.Errorf("can't chdir to %q: %v", fileDir, err)
    48  	}
    49  	basePath := filepath.Base(absPath)
    50  
    51  	// https://stackoverflow.com/questions/2405305/how-to-tell-if-a-file-is-git-tracked-by-shell-exit-code
    52  	out, err := exec.Command("git", "ls-files", "--error-unmatch", "--", basePath).CombinedOutput()
    53  	if err != nil {
    54  		if _, ok := err.(*exec.ExitError); ok {
    55  			content, err := ioutil.ReadFile(absPath)
    56  			if err != nil {
    57  				return "", fmt.Errorf("error reading file %q: %v", absPath, err)
    58  			}
    59  			return "<NEW FILE>\n" + string(content), nil
    60  		}
    61  		return "", err
    62  	}
    63  
    64  	out, err = exec.Command("git", "diff", "--", basePath).CombinedOutput()
    65  	if err != nil {
    66  		return "", fmt.Errorf("git diff failed on %q: %v", basePath, err)
    67  	}
    68  	return string(out), nil
    69  }