parseindex: implement context manager method on the wrapper

This is needed for incoming cleanups.

tests/test-parseindex.t

@@ -1,185 +1,192 b''
 revlog.parseindex must be able to parse the index file even if
 an index entry is split between two 64k blocks.  The ideal test
 would be to create an index file with inline data where
 64k < size < 64k + 64 (64k is the size of the read buffer, 64 is
 the size of an index entry) and with an index entry starting right
 before the 64k block boundary, and try to read it.
 We approximate that by reducing the read buffer to 1 byte.
 
   $ hg init a
   $ cd a
   $ echo abc > foo
   $ hg add foo
   $ hg commit -m 'add foo'
   $ echo >> foo
   $ hg commit -m 'change foo'
   $ hg log -r 0:
   changeset:   0:7c31755bf9b5
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     add foo
   
   changeset:   1:26333235a41c
   tag:         tip
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     change foo
   
   $ cat >> test.py << EOF
   > from mercurial import changelog, vfs
   > from mercurial.node import *
   > 
   > class singlebyteread(object):
   >     def __init__(self, real):
   >         self.real = real
   > 
   >     def read(self, size=-1):
   >         if size == 65536:
   >             size = 1
   >         return self.real.read(size)
   > 
   >     def __getattr__(self, key):
   >         return getattr(self.real, key)
   > 
+  >     def __enter__(self):
+  >         self.real.__enter__()
+  >         return self
+  > 
+  >     def __exit__(self, *args, **kwargs):
+  >         return self.real.__exit__(*args, **kwargs)
+  > 
   > def opener(*args):
   >     o = vfs.vfs(*args)
   >     def wrapper(*a, **kwargs):
   >         f = o(*a, **kwargs)
   >         return singlebyteread(f)
   >     return wrapper
   > 
   > cl = changelog.changelog(opener('.hg/store'))
   > print len(cl), 'revisions:'
   > for r in cl:
   >     print short(cl.node(r))
   > EOF
   $ $PYTHON test.py
   2 revisions:
   7c31755bf9b5
   26333235a41c
 
   $ cd ..
 
 #if no-pure
 
 Test SEGV caused by bad revision passed to reachableroots() (issue4775):
 
   $ cd a
 
   $ $PYTHON <<EOF
   > from mercurial import changelog, vfs
   > cl = changelog.changelog(vfs.vfs('.hg/store'))
   > print 'good heads:'
   > for head in [0, len(cl) - 1, -1]:
   >     print'%s: %r' % (head, cl.reachableroots(0, [head], [0]))
   > print 'bad heads:'
   > for head in [len(cl), 10000, -2, -10000, None]:
   >     print '%s:' % head,
   >     try:
   >         cl.reachableroots(0, [head], [0])
   >         print 'uncaught buffer overflow?'
   >     except (IndexError, TypeError) as inst:
   >         print inst
   > print 'good roots:'
   > for root in [0, len(cl) - 1, -1]:
   >     print '%s: %r' % (root, cl.reachableroots(root, [len(cl) - 1], [root]))
   > print 'out-of-range roots are ignored:'
   > for root in [len(cl), 10000, -2, -10000]:
   >     print '%s: %r' % (root, cl.reachableroots(root, [len(cl) - 1], [root]))
   > print 'bad roots:'
   > for root in [None]:
   >     print '%s:' % root,
   >     try:
   >         cl.reachableroots(root, [len(cl) - 1], [root])
   >         print 'uncaught error?'
   >     except TypeError as inst:
   >         print inst
   > EOF
   good heads:
   0: [0]
   1: [0]
   -1: []
   bad heads:
   2: head out of range
   10000: head out of range
   -2: head out of range
   -10000: head out of range
   None: an integer is required
   good roots:
   0: [0]
   1: [1]
   -1: [-1]
   out-of-range roots are ignored:
   2: []
   10000: []
   -2: []
   -10000: []
   bad roots:
   None: an integer is required
 
   $ cd ..
 
 Test corrupted p1/p2 fields that could cause SEGV at parsers.c:
 
   $ mkdir invalidparent
   $ cd invalidparent
 
   $ hg clone --pull -q --config phases.publish=False ../a limit
   $ hg clone --pull -q --config phases.publish=False ../a segv
   $ rm -R limit/.hg/cache segv/.hg/cache
 
   $ $PYTHON <<EOF
   > data = open("limit/.hg/store/00changelog.i", "rb").read()
   > for n, p in [('limit', '\0\0\0\x02'), ('segv', '\0\x01\0\0')]:
   >     # corrupt p1 at rev0 and p2 at rev1
   >     d = data[:24] + p + data[28:127 + 28] + p + data[127 + 32:]
   >     open(n + "/.hg/store/00changelog.i", "wb").write(d)
   > EOF
 
   $ hg debugindex -f1 limit/.hg/store/00changelog.i
      rev flag   offset   length     size   base   link     p1     p2       nodeid
        0 0000        0       63       62      0      0      2     -1 7c31755bf9b5
        1 0000       63       66       65      1      1      0      2 26333235a41c
   $ hg debugindex -f1 segv/.hg/store/00changelog.i
      rev flag   offset   length     size   base   link     p1     p2       nodeid
        0 0000        0       63       62      0      0  65536     -1 7c31755bf9b5
        1 0000       63       66       65      1      1      0  65536 26333235a41c
 
   $ cat <<EOF > test.py
   > import sys
   > from mercurial import changelog, vfs
   > cl = changelog.changelog(vfs.vfs(sys.argv[1]))
   > n0, n1 = cl.node(0), cl.node(1)
   > ops = [
   >     ('reachableroots',
   >      lambda: cl.index.reachableroots2(0, [1], [0], False)),
   >     ('compute_phases_map_sets', lambda: cl.computephases([[0], []])),
   >     ('index_headrevs', lambda: cl.headrevs()),
   >     ('find_gca_candidates', lambda: cl.commonancestorsheads(n0, n1)),
   >     ('find_deepest', lambda: cl.ancestor(n0, n1)),
   >     ]
   > for l, f in ops:
   >     print l + ':',
   >     try:
   >         f()
   >         print 'uncaught buffer overflow?'
   >     except ValueError, inst:
   >         print inst
   > EOF
 
   $ $PYTHON test.py limit/.hg/store
   reachableroots: parent out of range
   compute_phases_map_sets: parent out of range
   index_headrevs: parent out of range
   find_gca_candidates: parent out of range
   find_deepest: parent out of range
   $ $PYTHON test.py segv/.hg/store
   reachableroots: parent out of range
   compute_phases_map_sets: parent out of range
   index_headrevs: parent out of range
   find_gca_candidates: parent out of range
   find_deepest: parent out of range
 
   $ cd ..
 
 #endif