tests/svn/svndump-branches.sh

lock: block signal interrupt while making a lock file

On Windows where symlink isn't supported, util.makelock() could leave an empty
file if interrupted immediately after os.open(). This empty lock never dies
as it has no process id recorded.

    ld = os.open(pathname, os.O_CREAT | os.O_WRONLY | os.O_EXCL)
    # an interrupt may occur here
    os.write(ld, info)
    os.close(ld)

This was a long-standing bug of TortoiseHg which runs a command-server and
kills it by CTRL_C_EVENT, reported by random Windows users.

https://bitbucket.org/tortoisehg/thg/issues/4873/#comment-43591129

At first, I tried to fix makelock() to clean up a stale lock file, which
turned out to be hard because any instructions may be interrupted by a
signal.

    ld = None
    try:
        # CALL_FUNCTION  # os.open(...)
        # an interrupt may occur here
        # STORE_FAST     # ld = ...
        ld = os.open(pathname, os.O_CREAT | os.O_WRONLY | os.O_EXCL)
        os.write(ld, info)
        ...
        return True
    except:
        if ld:
            ...
            os.unlink(pathname)
        return False

So I decided to block signals by temporarily replacing the signal handlers
so makelcok() and held = 1 will never be interrupted.

Many thanks to Fernando Najera for investigating the issue.

#!/bin/sh
#
# Use this script to generate branches.svndump
#

mkdir temp
cd temp

mkdir project-orig
cd project-orig
mkdir trunk
mkdir branches
cd ..

svnadmin create svn-repo
svnurl=file://`pwd`/svn-repo
svn import project-orig $svnurl -m "init projA"

svn co $svnurl project
cd project
echo a > trunk/a
echo b > trunk/b
echo c > trunk/c
mkdir trunk/dir
echo e > trunk/dir/e
# Add a file within branches, used to confuse branch detection
echo d > branches/notinbranch
svn add trunk/a trunk/b trunk/c trunk/dir branches/notinbranch
svn ci -m hello
svn up

# Branch to old
svn copy trunk branches/old
svn rm branches/old/c
svn rm branches/old/dir
svn ci -m "branch trunk, remove c and dir"
svn up

# Update trunk
echo a >> trunk/a
svn ci -m "change a"

# Update old branch
echo b >> branches/old/b
svn ci -m "change b"

# Create a cross-branch revision
svn move trunk/b branches/old/c
echo c >> branches/old/c
svn ci -m "move and update c"

# Update old branch again
echo b >> branches/old/b
svn ci -m "change b again"

# Move back and forth between branch of similar names
# This used to generate fake copy records
svn up
svn move branches/old branches/old2
svn ci -m "move to old2"
svn move branches/old2 branches/old
svn ci -m "move back to old"

# Update trunk again
echo a > trunk/a
svn ci -m "last change to a"

# Branch again from a converted revision
svn copy -r 1 $svnurl/trunk branches/old3
svn ci -m "branch trunk@1 into old3"
cd ..

svnadmin dump svn-repo > ../branches.svndump