tests/svn/svndump-move.sh

worker: rewrite error handling so os._exit covers all cases

Previously the worker error handling is like:

    pid = os.fork()   --+
    if pid == 0:        |
        ....            | problematic
        ....          --+
        try:          --+
            ....        | worker error handling
                      --+

If a signal arrives when Python is executing the "problematic" lines, an
external error handling (dispatch.py) will take over the control flow and
it's no longer guaranteed "os._exit" is called (see 86cd09bc13ba for why it
is necessary).

This patch rewrites the error handling so it covers all possible code paths
for a worker even during fork.

Note: "os.getpid() == parentpid" is used to test if the process is parent or
not intentionally, instead of checking "pid", because "pid = os.fork()" may
be not atomic - it's possible that that a signal hits the worker before the
assignment completes [1].  The newly added test replaces "os.fork" to
exercise that extreme case.

[1]: CPython compiles "pid = os.fork()" to 2 byte codes: "CALL_FUNCTION" and
"STORE_FAST", so it's probably not atomic:

    def f():
        pid = os.fork()

    dis.dis(f)
      2           0 LOAD_GLOBAL              0 (os)
                  3 LOAD_ATTR                1 (fork)
                  6 CALL_FUNCTION            0
                  9 STORE_FAST               0 (pid)
                 12 LOAD_CONST               0 (None)
                 15 RETURN_VALUE

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

mkdir temp
cd temp

mkdir project-orig
cd project-orig
mkdir trunk
echo a > trunk/a
mkdir trunk/d1
mkdir trunk/d2
echo b > trunk/d1/b
echo c > trunk/d1/c
echo d > trunk/d2/d
cd ..

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

svn co $svnurl project
cd project
# Build a module renaming chain which used to confuse the converter.
# Update svn repository
echo a >> trunk/a
echo c >> trunk/d1/c
svn ci -m commitbeforemove
svn mv $svnurl/trunk $svnurl/subproject -m movedtrunk
svn up
mkdir subproject/trunk
svn add subproject/trunk
svn ci -m createtrunk
mkdir subproject/branches
svn add subproject/branches
svn ci -m createbranches
svn mv $svnurl/subproject/d1 $svnurl/subproject/trunk/d1 -m moved1
svn mv $svnurl/subproject/d2 $svnurl/subproject/trunk/d2 -m moved2
svn up
echo b >> subproject/trunk/d1/b

svn rm subproject/trunk/d2
svn ci -m "changeb and rm d2"
svn mv $svnurl/subproject/trunk/d1 $svnurl/subproject/branches/d1 -m moved1again

if svn help copy | grep 'SRC\[@REV\]' > /dev/null 2>&1; then
    # SVN >= 1.5 replaced the -r REV syntax with @REV
    # Copy a file from a past revision
    svn copy $svnurl/subproject/trunk/d2/d@7 $svnurl/subproject/trunk -m copyfilefrompast
    # Copy a directory from a past revision
    svn copy $svnurl/subproject/trunk/d2@7 $svnurl/subproject/trunk -m copydirfrompast
else
    # Copy a file from a past revision
    svn copy -r 7 $svnurl/subproject/trunk/d2/d $svnurl/subproject/trunk -m copyfilefrompast
    # Copy a directory from a past revision
    svn copy -r 7 $svnurl/subproject/trunk/d2 $svnurl/subproject/trunk -m copydirfrompast
fi

# Copy a directory while removing a subdirectory
svn up
mkdir -p subproject/trunk/d3/d31
echo e > subproject/trunk/d3/d31/e
echo f > subproject/trunk/d3/f
svn add subproject/trunk/d3
svn ci -m "add d3"
svn copy subproject/trunk/d3 subproject/trunk/d4
svn rm subproject/trunk/d3/d31
svn ci -m "copy dir and remove subdir"

# Test directory moves
svn up
mkdir -p subproject/trunk/d4old
echo g > subproject/trunk/d4old/g
svn add subproject/trunk/d4old
svn ci -m "add d4old"
svn mv subproject/trunk/d4old subproject/trunk/d4new
svn ci -m "rename d4old into d4new"

cd ..

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