[Rd] memory leak in sub("[range]", ...) when #ifndef _LIBC (PR#11946)

From: <bill_at_insightful.com>
Date: Thu, 07 Aug 2008 11:24:42 +0200 (CEST)


Full_Name: Bill Dunlap
Version: R version 2.8.0 Under development (unstable) (2008-07-05 r46037) OS: Linux
Submission from: (NULL) (76.28.245.14)

valgrind finds some memory leaks in R when I use sub() with a range in the regular expression:

% R --debugger=valgrind --debugger-args=--leak-check=full --quiet --vanilla
==28643== Memcheck, a memory error detector.
==28643== Copyright (C) 2002-2006, and GNU GPL'd, by Julian Seward et al.
==28643== Using LibVEX rev 1658, a library for dynamic binary translation.
==28643== Copyright (C) 2004-2006, and GNU GPL'd, by OpenWorks LLP.
==28643== Using valgrind-3.2.1, a dynamic binary instrumentation framework.
==28643== Copyright (C) 2000-2006, and GNU GPL'd, by Julian Seward et al.
==28643== For more details, rerun with: -v
==28643==
> for(i in 1:1000)sub("[0-9]","*","17")
> q()
==28643==
==28643== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 38 from 2)
==28643== malloc/free: in use at exit: 12,607,663 bytes in 7,918 blocks.
==28643== malloc/free: 61,907 allocs, 53,989 frees, 54,692,481 bytes allocated.
==28643== For counts of detected errors, rerun with: -v
==28643== searching for pointers to 7,918 not-freed blocks.
==28643== checked 12,620,188 bytes.
==28643==
==28643== 82 bytes in 4 blocks are definitely lost in loss record 15 of 44
==28643== at 0x40046EE: malloc (vg_replace_malloc.c:149)
==28643== by 0x3200FF9: xmalloc (in
/a/devlnx3206.insightful.com/opt/builds/R/devel/LX/46036/dist/lib/R/lib/libreadline.so.4)
==28643== by 0x31EC0D5: readline_internal_teardown (in
/a/devlnx3206.insightful.com/opt/builds/R/devel/LX/46036/dist/lib/R/lib/libreadline.so.4)
==28643== by 0x31FD992: rl_callback_read_char (in
/a/devlnx3206.insightful.com/opt/builds/R/devel/LX/46036/dist/lib/R/lib/libreadline.so.4)
==28643== by 0x80E7634: Rstd_ReadConsole (sys-std.c:905)
==28643== by 0x8057EA9: Rf_ReplIteration (main.c:205)
==28643== by 0x80581C6: R_ReplConsole (main.c:306)
==28643== by 0x805845C: run_Rmainloop (main.c:966)
==28643== by 0x80566B5: main (Rmain.c:33)
==28643==
==28643==
==28643== 7,996 bytes in 1,999 blocks are definitely lost in loss record 35 of
44
==28643== at 0x40046EE: malloc (vg_replace_malloc.c:149)
==28643== by 0x4005B9A: realloc (vg_replace_malloc.c:306)
==28643== by 0x80A5E22: parse_expression (regex.c:5202)
==28643== by 0x80A5FDF: parse_branch (regex.c:4707)
==28643== by 0x80A60AA: parse_reg_exp (regex.c:4666)
==28643== by 0x80A64A8: Rf_regcomp (regex.c:4635)
==28643== by 0x8110AE0: do_gsub (character.c:1355)
==28643== by 0x80653BC: do_internal (names.c:1129)
==28643== by 0x815EF17: Rf_eval (eval.c:461)
==28643== by 0x8160BD3: do_begin (eval.c:1174)
==28643== by 0x815EF17: Rf_eval (eval.c:461)
==28643== by 0x816203C: Rf_applyClosure (eval.c:667)
==28643==
==28643== LEAK SUMMARY:
==28643== definitely lost: 8,078 bytes in 2,003 blocks.
==28643== possibly lost: 0 bytes in 0 blocks.
==28643== still reachable: 12,599,585 bytes in 5,915 blocks.
==28643== suppressed: 0 bytes in 0 blocks.
==28643== Reachable blocks (those to which a pointer was found) are not shown.
==28643== To see them, rerun with: --show-reachable=yes

The flagged memory block is the range_ends component of mbcset. I think that range_starts was also being leaked, but valgrind was combining the two.  

It looks like the cpp macro _LIBC is not defined when I compile R in this Linux box. regex.c defines range_ends and range_starts as different types, depending on the value of _LIBC, and it allocates space for them in either case. However, free_charset() was only freeing these things if _LIBC was defined. The following change to regex.c:free_charset() seems to take care of the problem.

% svn diff regex.c
Index: regex.c


> version

               _
platform       i686-pc-linux-gnu
arch           i686
os             linux-gnu
system         i686, linux-gnu
status         Under development (unstable)
major          2
minor          8.0
year           2008
month          07
day            05
svn rev        46037
language       R

version.string R version 2.8.0 Under development (unstable) (2008-07-05 r46037)

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