Fix array overflow bug in bdiff
I ran into a bug while importing a large repository into mercurial.
The diff algorithm does not allocate a big enough array of hunks
for some test cases. This results in memory corruption, and possibly,
as in my case, a seg fault.
You should be able to reproduce this problem with any case of more
than a few lines that follows this pattern:
a b
= =
1 1
2
2 3
4
3 5
.
4 .
.
5
.
.
.
I.e., "a" has blank lines on every other line that have been removed in
"b". In this case, the number of matching hunks is equal to the number
of lines in "b". This is more than ((an + bn)/4 + 2). I'm not sure what
motivates this formula, but when I changed it to the smaller of an or
bn (+ 1), it works.
[comment added by mpm]
# ui.py - user interface bits for mercurial
#
# Copyright 2005 Matt Mackall <mpm@selenic.com>
#
# This software may be used and distributed according to the terms
# of the GNU General Public License, incorporated herein by reference.
import os, ConfigParser
from demandload import *
demandload(globals(), "re socket sys util")
class ui:
def __init__(self, verbose=False, debug=False, quiet=False,
interactive=True):
self.cdata = ConfigParser.SafeConfigParser()
self.cdata.read(os.path.expanduser("~/.hgrc"))
self.quiet = self.configbool("ui", "quiet")
self.verbose = self.configbool("ui", "verbose")
self.debugflag = self.configbool("ui", "debug")
self.interactive = self.configbool("ui", "interactive", True)
self.quiet = (self.quiet or quiet) and not verbose and not debug
self.verbose = (self.verbose or verbose) or debug
self.debugflag = (self.debugflag or debug)
self.interactive = (self.interactive and interactive)
def readconfig(self, fp):
self.cdata.readfp(fp)
def config(self, section, val, default=None):
if self.cdata.has_option(section, val):
return self.cdata.get(section, val)
return default
def configbool(self, section, val, default=False):
if self.cdata.has_option(section, val):
return self.cdata.getboolean(section, val)
return default
def configitems(self, section):
if self.cdata.has_section(section):
return self.cdata.items(section)
return []
def username(self):
return (os.environ.get("HGUSER") or
self.config("ui", "username") or
os.environ.get("EMAIL") or
(os.environ.get("LOGNAME",
os.environ.get("USERNAME", "unknown"))
+ '@' + socket.getfqdn()))
def expandpath(self, loc):
paths = {}
for name, path in self.configitems("paths"):
paths[name] = path
return paths.get(loc, loc)
def write(self, *args):
for a in args:
sys.stdout.write(str(a))
def write_err(self, *args):
sys.stdout.flush()
for a in args:
sys.stderr.write(str(a))
def readline(self):
return sys.stdin.readline()[:-1]
def prompt(self, msg, pat, default = "y"):
if not self.interactive: return default
while 1:
self.write(msg, " ")
r = self.readline()
if re.match(pat, r):
return r
else:
self.write("unrecognized response\n")
def status(self, *msg):
if not self.quiet: self.write(*msg)
def warn(self, *msg):
self.write_err(*msg)
def note(self, *msg):
if self.verbose: self.write(*msg)
def debug(self, *msg):
if self.debugflag: self.write(*msg)
def edit(self, text):
import tempfile
(fd, name) = tempfile.mkstemp("hg")
f = os.fdopen(fd, "w")
f.write(text)
f.close()
editor = (os.environ.get("HGEDITOR") or
self.config("ui", "editor") or
os.environ.get("EDITOR", "vi"))
os.environ["HGUSER"] = self.username()
util.system("%s %s" % (editor, name), errprefix = "edit failed")
t = open(name).read()
t = re.sub("(?m)^HG:.*\n", "", t)
os.unlink(name)
return t