| Subject: | File::Map Segmentation Fault |
Hi, Leon.
The attached script (file_map_segfault.pl) reliably causes a segmentation fault. Admittedly, the script takes an approach that File::Map documents as risky, but I wonder if the segfault indicates an unrecognised problem somewhere.
I have run this script on few versions of Perl from 5.18 onwards, including blead, on FreeBSD 9 and 10. I always see the same segfault.
Running the script under valgrind produces the following output:
==34731== Memcheck, a memory error detector
==34731== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==34731== Using Valgrind-3.10.0 and LibVEX; rerun with -h for copyright info
==34731== Command: /home/tom/perl-inst/perl-5.23_debugging_20150713/bin/perl segfault
==34731==
==34731== Invalid write of size 1
==34731== at 0x5096A8: Perl_sv_setpvn (sv.c:4856)
==34731== by 0x68157EA: XS_File__Map__mmap_impl (Map.xs:553)
==34731== by 0x4FDE2D: Perl_pp_entersub (pp_hot.c:3274)
==34731== by 0x4CA229: Perl_runops_debug (dump.c:2224)
==34731== by 0x44AFC8: S_run_body (perl.c:2448)
==34731== by 0x44AFC8: perl_run (perl.c:2371)
==34731== by 0x420075: main (perlmain.c:116)
==34731== Address 0x0 is not stack'd, malloc'd or (recently) free'd
==34731==
==34731==
==34731== Process terminating with default action of signal 11 (SIGSEGV): dumping core
==34731== Access not within mapped region at address 0x0
==34731== at 0x5096A8: Perl_sv_setpvn (sv.c:4856)
==34731== by 0x68157EA: XS_File__Map__mmap_impl (Map.xs:553)
==34731== by 0x4FDE2D: Perl_pp_entersub (pp_hot.c:3274)
==34731== by 0x4CA229: Perl_runops_debug (dump.c:2224)
==34731== by 0x44AFC8: S_run_body (perl.c:2448)
==34731== by 0x44AFC8: perl_run (perl.c:2371)
==34731== by 0x420075: main (perlmain.c:116)
==34731== If you believe this happened as a result of a stack
==34731== overflow in your program's main thread (unlikely but
==34731== possible), you can try to increase the size of the
==34731== main thread stack using the --main-stacksize= flag.
==34731== The main thread stack size used in this run was 16777216.
==34731==
==34731== HEAP SUMMARY:
==34731== in use at exit: 1,263,969 bytes in 4,140 blocks
==34731== total heap usage: 11,287 allocs, 7,147 frees, 2,576,549 bytes allocated
==34731==
==34731== LEAK SUMMARY:
==34731== definitely lost: 0 bytes in 0 blocks
==34731== indirectly lost: 0 bytes in 0 blocks
==34731== possibly lost: 649,220 bytes in 828 blocks
==34731== still reachable: 614,749 bytes in 3,312 blocks
==34731== suppressed: 0 bytes in 0 blocks
==34731== Rerun with --leak-check=full to see details of leaked memory
==34731==
==34731== For counts of detected and suppressed errors, rerun with: -v
==34731== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 11 from 4)
Please let me know if I can provide any more information to help investigate this.
Tom
| Subject: | file_map_segfault.pl |
#!perl
use strict;
use warnings;
use File::Map 'map_file';
foreach my $filename ( 1, 2 ) {
my $output_filename = 'example_' . $filename;
map_file my $output, $output_filename, '+>';
}