Mercurial > hg > mercurial-crew-with-dirclash
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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]
| author | "Wallace, Eric S" <eric.s.wallace@intel.com> |
|---|---|
| date | Thu, 04 Aug 2005 13:25:59 -0800 |
| parents | d2422f10c136 |
| children | c333dfa8fa1a c2e77581bc84 |
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header = header.tmpl footer = footer.tmpl search = search.tmpl changelog = changelog.tmpl naventry = "<a href="?cmd=changelog;rev=#rev#">#label#</a> " filedifflink = "<a href="?cmd=filediff;node=#node#;file=#file#">#file#</a> " filenodelink = "<a href="?cmd=file;filenode=#filenode#;file=#file#">#file#</a> " fileellipses = "..." changelogentry = changelogentry.tmpl searchentry = changelogentry.tmpl changeset = changeset.tmpl manifest = manifest.tmpl manifestdirentry = "<tr class="parity#parity#"><td><tt>drwxr-xr-x</tt> <td><a href="?cmd=manifest;manifest=#manifest#;path=#path#">#basename#/</a>" manifestfileentry = "<tr class="parity#parity#"><td><tt>#permissions|permissions#</tt> <td><a href="?cmd=file;filenode=#filenode#;file=#file#">#basename#</a>" filerevision = filerevision.tmpl fileannotate = fileannotate.tmpl filediff = filediff.tmpl filelog = filelog.tmpl fileline = "<div class="parity#parity#"><span class="lineno">#linenumber# </span>#line|escape#</div>" filelogentry = filelogentry.tmpl annotateline = "<tr class="parity#parity#"><td class="annotate"><a href="?cmd=changeset;node=#node#">#author|obfuscate#@#rev#</a></td><td><pre>#line|escape#</pre></td></tr>" difflineplus = "<span class="plusline">#line|escape#</span>" difflineminus = "<span class="minusline">#line|escape#</span>" difflineat = "<span class="atline">#line|escape#</span>" diffline = "#line|escape#" changelogparent = "<tr><th class="parent">parent #rev#:</th><td class="parent"><a href="?cmd=changeset;node=#node#">#node|short#</a></td></tr>" changesetparent = "<tr><th class="parent">parent #rev#:</th><td class="parent"><a href="?cmd=changeset;node=#node#">#node|short#</a></td></tr>" filerevparent = "<tr><td class="metatag">parent:</td><td><a href="?cmd=file;file=#file#;filenode=#node#">#node|short#</a></td></tr>" fileannotateparent = "<tr><td class="metatag">parent:</td><td><a href="?cmd=annotate;file=#file#;filenode=#node#">#node|short#</a></td></tr>" tags = tags.tmpl tagentry = "<li class="tagEntry parity#parity#"><span class="node">#node#</span> <a href="?cmd=changeset;node=#node#">#tag#</a></li>" diffblock = "<pre class="parity#parity#">#lines#</pre>" changelogtag = "<tr><th class="tag">tag:</th><td class="tag">#tag#</td></tr>" changesettag = "<tr><th class="tag">tag:</th><td class="tag">#tag#</td></tr>" filediffparent = "<tr><th class="parent">parent #rev#:</th><td class="parent"><a href="?cmd=changeset;node=#node#">#node|short#</a></td></tr>" filelogparent = "<tr><td align="right">parent #rev#: </td><td><a href="?cmd=file;file=#file#;filenode=#node#">#node|short#</a></td></tr>"