Hi Charlie, It's been some time since my original post, bhowever I recently found some time to look at this properly.
I've attached 2 test scripts, both which processthis XML file: http://gir.deefa.com/bookwise.xml. They contain a thin wrapper around XML::Reader designed to iterate over the nodes of interest in the file. ok.rb runs without a problem, segfault.rb triggers a segfault. The scripts are identical, with the exception of a single uncommented puts line in segfault.rb It's possilbe I'm using expand() incorrectly. If that's the case, it'd be nice to get an error that isn't a segfault. The final attachment is copy of the backtrace from gdb. I'm running libxml-ruby 1.1.3 and libxml2 2.7.3 on Debian. cheers -- James Healy <jimmy-at-deefa-dot-com> Thu, 04 Jun 2009 01:22:12 +1000 Charlie Savage wrote: > Hi James, > > Thanks for the test case and report. > >> require 'rubygems' >> gem "libxml-ruby", "1.1.2" >> require 'libxml' >> >> filename = File.join(File.dirname(__FILE__), "bookwise.xml") >> reader = LibXML::XML::Reader.string(File.read(filename)) >> >> while reader.read >> >> if reader.node_type == LibXML::XML::Reader::TYPE_ELEMENT >> if reader.name == "Header" puts reader.read_outer_xml >> elsif reader.name == "Product" >> puts reader.read_outer_xml >> end >> end >> >> end >> --- >> >> I'm basically attempting to grab the full text of all Header and Product >> nodes in the input file. My actual code doesn't just puts the elements, >> this is simply the simplest script I could make that triggers it. > > You might want to use XPath instead for this. > >> Occasionally, instead of a segfault I get a fatal error, "Opening and >> ending tag mismatch", despite the fact the input file is valid and well >> formed. > > So I tested this with libxml-ruby 1.1.2, ruby 1.8.6 (patch level 287) on > Windows Vista and Fedora 10 and could not reproduce. > >> Am I use the Reader bindings correctly? > > Yes. > >> If I'm not, I'd appreciate a few pointers. > > Since I can't reproduce the problem, can you compile the bindings with > debug information and get a stack trace? > > Charlie
ok.rb
Description: application/ruby
segfault.rb
Description: application/ruby
(gdb) backtrace #0 0xb7dc37f6 in *__GI_raise (sig=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:64 #1 0xb7dc6d38 in *__GI_abort () at abort.c:88 #2 0xb7dfa065 in __libc_message (do_abort=2, fmt=0xb7ebda68 "*** glibc detected *** %s: %s: 0x%s ***\n") at ../sysdeps/unix/sysv/linux/libc_fatal.c:173 #3 0xb7e04215 in malloc_printerr (action=2, str=0xb7ebdb60 "double free or corruption (!prev)", ptr=0xa65d9c8) at malloc.c:5994 #4 0xb7e05aec in *__GI___libc_free (mem=0xa65d9c8) at malloc.c:3625 #5 0xb7874205 in xmlTextReaderFreeNode (reader=0xa658eb8, cur=0xa65d9c8) at xmlreader.c:474 #6 0xb7874f6e in xmlTextReaderRead__internal_alias (reader=0xa658eb8) at xmlreader.c:1400 #7 0xb78e2415 in rxml_reader_read (self=3084323980) at ruby_xml_reader.c:418 #8 0xb7f7cf02 in call_cfunc (func=0xb78e23e0 <rxml_reader_read>, recv=3084323980, len=6, argc=0, argv=0x7ea3) at eval.c:5752 #9 0xb7f88333 in rb_call0 (klass=3082073500, recv=3084323980, id=7657, oid=7657, argc=0, argv=0x0, body=0xb7b4ab38, flags=0) at eval.c:5904 #10 0xb7f88470 in rb_call (klass=3082073500, recv=3084323980, mid=7657, argc=0, argv=0x0, scope=0, self=3084364640) at eval.c:6151 #11 0xb7f82b69 in rb_eval (self=3084364640, n=<value optimized out>) at eval.c:3492 #12 0xb7f8557c in rb_eval (self=3084364640, n=<value optimized out>) at eval.c:3142 #13 0xb7f881fe in rb_call0 (klass=3084462080, recv=3084364640, id=10985, oid=10985, argc=0, argv=0x0, body=0xb7d85150, flags=0) at eval.c:6055 #14 0xb7f88470 in rb_call (klass=3084462080, recv=3084364640, mid=10985, argc=0, argv=0x0, scope=2, self=3084364640) at eval.c:6151 #15 0xb7f82cd8 in rb_eval (self=3084364640, n=<value optimized out>) at eval.c:3513 #16 0xb7f83db4 in rb_eval (self=3084364640, n=<value optimized out>) at eval.c:3677 #17 0xb7f82a82 in rb_eval (self=3084364640, n=<value optimized out>) at eval.c:3486 #18 0xb7f85535 in rb_eval (self=3084364640, n=<value optimized out>) at eval.c:3177 #19 0xb7f881fe in rb_call0 (klass=3084462080, recv=3084364640, id=4001, oid=4001, argc=0, argv=0x0, body=0xb7d85948, flags=0) at eval.c:6055 #20 0xb7f88470 in rb_call (klass=3084462080, recv=3084364640, mid=4001, argc=0, argv=0x0, scope=0, self=3084478800) at eval.c:6151 #21 0xb7f82b69 in rb_eval (self=3084478800, n=<value optimized out>) at eval.c:3492 #22 0xb7f85ff1 in rb_eval (self=3084478800, n=<value optimized out>) at eval.c:3222 #23 0xb7f94817 in ruby_exec_internal () at eval.c:1641 #24 0xb7f94862 in ruby_exec () at eval.c:1661 #25 0xb7f9489f in ruby_run () at eval.c:1671 #26 0x080486ed in main (argc=Cannot access memory at address 0x7ea3) at main.c:48
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