Rebasing in SVN

Suppose you are creating a branch from a trunk and you need to merge the commits from the trunk to the branch. Unlike Git, SVN does not really have a concept of rebasing. To do that in SVN, it requires quite a bit of work. To simplify the tasks of rebasing in SVN, I created small tools, one in Go and the other one in Python.

svnrebase.go

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package main   import (     "bufio"     "bytes"     "errors"     "fmt"     "io"     "os"     "os/exec"     "strings" )   const BaseRevFile = "base_rev.txt"   func getLatestBaseSVNRev(svnBaseURL string) (string, error) {     out, e1 := exec.Command("svn", "info", svnBaseURL).Output()     if e1 != nil {         return "", errors.New("Unable to execute svn info " +             svnBaseURL)     }     r := bufio.NewReader(bytes.NewReader(out))     for {         l, _, e2 := r.ReadLine()         if e2 == io.EOF {             break         }         s := string(l)         if strings.Contains(s, "Revision:") {             svnRev := strings.TrimSpace(strings.Split(s, ":")[1])             return svnRev, nil         }     }     return "", errors.New("Unable to get the SVN revision number") }   func getOldBaseSVNRev() (string, error) {     f, e := os.Open(BaseRevFile)     if e != nil {         return "", errors.New(BaseRevFile + " does not exist. " +             "You need to create this file initially!")     }     defer f.Close()     r := bufio.NewReader(f)     l, _, _ := r.ReadLine()     return strings.TrimSpace(string(l)), nil }   func updateBaseSVNFile(newBaseRev string) error {     f, e := os.OpenFile(BaseRevFile, os.O_WRONLY, 0666)     if e != nil {         return e     }     defer f.Close()     f.Write([]byte(newBaseRev))     return nil }   func SVNRebase(svnBaseURL string, dryRun bool) error {     oldBaseRev, e1 := getOldBaseSVNRev()     if e1 != nil {         return e1     }     newBaseRev, e2 := getLatestBaseSVNRev(svnBaseURL)     if e2 != nil {         return e2     }     if oldBaseRev == newBaseRev {         fmt.Println("Your repo has already had the latest revision")         return nil     }     cmd := "svn"     args := []string{"merge"}     if dryRun {         args = append(args, "--dry-run")     }     args = append(args, svnBaseURL + "@" + oldBaseRev)     args = append(args, svnBaseURL + "@" + newBaseRev)     fmt.Println("Command:", cmd + " " + strings.Join(args, " "))     c := exec.Command(cmd, args...)     c.Stdout = os.Stdout     c.Stdin = os.Stdout     c.Stderr = os.Stderr     e3 := c.Run()     if e3 != nil {         return e3     }     if !dryRun {         updateBaseSVNFile(newBaseRev)     }     return nil }   func printUsage() {     fmt.Println("Usage:", os.Args[0], "<svn_base_url> [--dry-run]") }   func validateArgs() {     if len(os.Args) == 1 || len(os.Args) > 3 {         printUsage()         os.Exit(1)     }     if len(os.Args) == 3 {         if os.Args[2] != "--dry-run" {             fmt.Println("Error: Invalid option:", os.Args[2])             os.Exit(1)         }     } }   func main() {     validateArgs()     baseSVNURL := os.Args[1]     dryRun := false     if len(os.Args) == 3 {         dryRun = true     }     if e := SVNRebase(baseSVNURL, dryRun); e != nil {         fmt.Println("Error:", e)     } }

Usage: ./svnrebase  [--dry-run]

svnrebase.py

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#!/usr/bin/env python import sys, subprocess, os   BASE_REV_FILE = 'base_rev.txt'   def get_latest_base_svn_rev(svn_base_url):     p = subprocess.Popen(['svn', 'info', svn_base_url], stdout=subprocess.PIPE)     for line in p.communicate()[0].split(os.linesep):         if line.startswith('Revision:'):             return line.split(":")[1].strip()     return None   def get_old_base_svn_rev():     if not os.path.exists(BASE_REV_FILE):         raise Exception(BASE_REV_FILE + ' does not exist. ' +                         'You need to create this file initially!')     f = open(BASE_REV_FILE, 'r')     return f.read().strip()   def update_base_svn_file(new_base_rev):      f = open(BASE_REV_FILE, 'w')      f.write(new_base_rev)      f.close()   def svn_rebase(svn_base_url, dry_run):     old_base_rev = get_old_base_svn_rev()     new_base_rev = get_latest_base_svn_rev(svn_base_url)     if old_base_rev == new_base_rev:         print 'Your repo has already had the latest revision'         return     cmd = ['svn', 'merge']     if dry_run:         cmd.append('--dry-run')     cmd.append(svn_base_url + '@' + old_base_rev)     cmd.append(svn_base_url + '@' + new_base_rev)     print 'Command:', ' '.join(cmd)     subprocess.call(cmd)     if not dry_run:        update_base_svn_file(new_base_rev)   def print_usage():     print 'Usage:', sys.argv[0], '<svn_base_url> [--dry-run]'   def validate_args():     if len(sys.argv) == 1 or len(sys.argv) > 3:         print_usage()         sys.exit(1)     if len(sys.argv) == 3:         if sys.argv[2] != '--dry-run':             print 'Error: Invalid option:', sys.argv[2]             sys.exit(1)   if __name__ == '__main__':     validate_args()     base_svn_url = sys.argv[1]     dry_run = True if len(sys.argv) == 3 else False     try:         svn_rebase(base_svn_url, dry_run)     except Exception, e:         print 'Error:', e

Usage: ./svnrebase.py  [--dry-run]

Initially, you need to create base_rev.txt that specifies which revision your branch was created. Subsequently, the base_rev.txt will be automatically updated by the tool.