Add a svnrdump-simulator replaying a dump file for testing

To ease testing without depending on a reachable svn server, this
compact python script mimics parts of svnrdumps behaviour.  It
requires the remote url to start with sim://.

Start and end revisions are evaluated.  If the requested revision
doesn't exist, as it is the case with incremental imports, if no new
commit was added, it returns 1 (like svnrdump).

To allow using the same dump file for simulating multiple incremental
imports, the highest revision can be limited by setting the environment
variable SVNRMAX to that value. This simulates the situation where
higher revs don't exist yet.

Signed-off-by: Florian Achleitner <florian.achleitner.2.6.31@gmail.com>
Acked-by: David Michael Barr <b@rr-dav.id.au>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/contrib/svn-fe/svnrdump_sim.py b/contrib/svn-fe/svnrdump_sim.py
new file mode 100755 (executable)
index 0000000..1cfac4a
--- /dev/null
+++ b/contrib/svn-fe/svnrdump_sim.py
@@ -0,0 +1,53 @@
+#!/usr/bin/python
+"""
+Simulates svnrdump by replaying an existing dump from a file, taking care
+of the specified revision range.
+To simulate incremental imports the environment variable SVNRMAX can be set
+to the highest revision that should be available.
+"""
+import sys, os
+
+
+def getrevlimit():
+        var = 'SVNRMAX'
+        if os.environ.has_key(var):
+                return os.environ[var]
+        return None
+
+def writedump(url, lower, upper):
+        if url.startswith('sim://'):
+                filename = url[6:]
+                if filename[-1] == '/': filename = filename[:-1] #remove terminating slash
+        else:
+                raise ValueError('sim:// url required')
+        f = open(filename, 'r');
+        state = 'header'
+        wroterev = False
+        while(True):
+                l = f.readline()
+                if l == '': break
+                if state == 'header' and l.startswith('Revision-number: '):
+                        state = 'prefix'
+                if state == 'prefix' and l == 'Revision-number: %s\n' % lower:
+                        state = 'selection'
+                if not upper == 'HEAD' and state == 'selection' and l == 'Revision-number: %s\n' % upper:
+                        break;
+
+                if state == 'header' or state == 'selection':
+                        if state == 'selection': wroterev = True
+                        sys.stdout.write(l)
+        return wroterev
+
+if __name__ == "__main__":
+        if not (len(sys.argv) in (3, 4, 5)):
+                print "usage: %s dump URL -rLOWER:UPPER"
+                sys.exit(1)
+        if not sys.argv[1] == 'dump': raise NotImplementedError('only "dump" is suppported.')
+        url = sys.argv[2]
+        r = ('0', 'HEAD')
+        if len(sys.argv) == 4 and sys.argv[3][0:2] == '-r':
+                r = sys.argv[3][2:].lstrip().split(':')
+        if not getrevlimit() is None: r[1] = getrevlimit()
+        if writedump(url, r[0], r[1]): ret = 0
+        else: ret = 1
+        sys.exit(ret)