[PATCH] fix sv_usepvn_flags's docs

[p5pRT]

Migrated from rt.perl.org#121869 (status was 'resolved')

Searchable as RT121869$

[p5pRT]

From @bulk88

Created by @bulk88

See attached patch. I'd like this in for 5.20 since #116925
"document/publicize THINKFIRST" is stalled/bikeshedding and probably
won't correct this big mistake in the docs for sv_usepvn_flags.

Perl Info

Flags:
               category=core
               severity=low

Site configuration information for perl 5.19.7:

Configured by Owner at Thu Nov 28 02:32:44 2013.

Summary of my perl5 (revision 5 version 19 subversion 7) configuration:
             Derived from: 8f47723e28b75530b743941cdd8b07f849ec48e2
             Ancestor: 1061065f7a09399eefb50e9a035502621722bcc0
             Platform:
               osname=MSWin32, osvers=5.1, archname=MSWin32-x86-multi-thread
               uname=''
               config_args='undef'
               hint=recommended, useposix=true, d_sigaction=undef
               useithreads=define, usemultiplicity=define
               useperlio=define, d_sfio=undef, uselargefiles=define,
usesocks=undef
               use64bitint=undef, use64bitall=undef, uselongdouble=undef
               usemymalloc=n, bincompat5005=undef
             Compiler:
               cc='cl', ccflags ='-nologo -GF -W3 -O1 -MD -Zi -DNDEBUG
-G7 -GL
-DWIN32 -D_CONSOLE -DNO_STRICT  -DPERL_TEXTMODE_SCRIPTS
-DPERL_HASH_FUNC_ONE_AT_A_TIME -DPERL_IMPLICIT_CONTEXT
-DPERL_IMPLICIT_SYS -DUSE_PERLIO -D_USE_32BIT_TIME_T',
               optimize='-O1 -MD -Zi -DNDEBUG -G7 -GL',
               cppflags='-DWIN32'
               ccversion='13.10.6030', gccversion='', gccosandvers=''
               intsize=4, longsize=4, ptrsize=4, doublesize=8, 
byteorder=1234
               d_longlong=undef, longlongsize=8, d_longdbl=define,
longdblsize=8
               ivtype='long', ivsize=4, nvtype='double', nvsize=8,
Off_t='__int64',
lseeksize=8
               alignbytes=8, prototype=define
             Linker and Libraries:
               ld='link', ldflags ='-nologo -nodefaultlib -debug 
-opt:ref,icf
-ltcg  -libpath:"c:\perl519\lib\CORE"  -machine:x86'
               libpth="C:\Program Files\Microsoft Visual Studio .NET
2003\VC7\lib"
               libs=oldnames.lib kernel32.lib user32.lib gdi32.lib
winspool.lib
comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib
netapi32.lib uuid.lib ws2_32.lib mpr.lib winmm.lib  version.lib
odbc32.lib odbccp32.lib comctl32.lib msvcrt.lib
               perllibs=oldnames.lib kernel32.lib user32.lib gdi32.lib
winspool.lib  comdlg32.lib advapi32.lib shell32.lib ole32.lib
oleaut32.lib  netapi32.lib uuid.lib ws2_32.lib mpr.lib winmm.lib
version.lib odbc32.lib odbccp32.lib comctl32.lib msvcrt.lib
               libc=msvcrt.lib, so=dll, useshrplib=true, libperl=perl519.lib
               gnulibc_version=''
             Dynamic Linking:
               dlsrc=dl_win32.xs, dlext=dll, d_dlsymun=undef, ccdlflags=' '
               cccdlflags=' ', lddlflags='-dll -nologo -nodefaultlib -debug
-opt:ref,icf -ltcg  -libpath:"c:\perl519\lib\CORE"  -machine:x86'

Locally applied patches:
               uncommitted-changes
               8f47723e28b75530b743941cdd8b07f849ec48e2


@INC for perl 5.19.7:
               C:/perl519/site/lib
               C:/perl519/lib
               .


Environment for perl 5.19.7:
               HOME (unset)
               LANG (unset)
               LANGUAGE (unset)
               LD_LIBRARY_PATH (unset)
               LOGDIR (unset)
               PATH=C:\perl519\bin;C:\Program Files\Microsoft Visual Studio
.NET
2003\Common7\IDE;C:\Program Files\Microsoft Visual Studio .NET
2003\VC7\BIN;C:\Program Files\Microsoft Visual Studio .NET
2003\Common7\Tools;C:\Program Files\Microsoft Visual Studio .NET
2003\Common7\Tools\bin\prerelease;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\system32\wbem;
               PERL_BADLANG (unset)
               SHELL (unset)

[p5pRT]

From @bulk88

0001-fix-sv_usepvn_flags-s-docs.patch

From 6a80a09ff167581a49ad3d65db8030fe03bcd823 Mon Sep 17 00:00:00 2001
From: Daniel Dragan <bulk88@hotmail.com>
Date: Wed, 14 May 2014 04:08:13 -0400
Subject: [PATCH 1/2] fix sv_usepvn_flags's docs

Newx != malloc, mixing Newx and malloc leads to heap corruption on some
builds like Win32, use the official Perl API for allocating memory.
---
 sv.c |   10 ++++++----
 1 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/sv.c b/sv.c
index 1005313..b43fadf 100644
--- a/sv.c
+++ b/sv.c
@@ -4846,10 +4846,12 @@ Perl_sv_sethek(pTHX_ SV *const sv, const HEK *const hek)
 Tells an SV to use C<ptr> to find its string value.  Normally the
 string is stored inside the SV but sv_usepvn allows the SV to use an
 outside string.  The C<ptr> should point to memory that was allocated
-by C<malloc>.  It must be the start of a mallocked block
-of memory, and not a pointer to the middle of it.  The
-string length, C<len>, must be supplied.  By default
-this function will realloc (i.e. move) the memory pointed to by C<ptr>,
+by L<Newx|perlclib/Memory Management and String Handling>. It must be
+the start of a Newx-ed block of memory, and not a pointer to the
+middle of it (beware of L<OOK|perlguts/Offsets> and copy-on-write),
+and not be from a non-Newx memory allocator like C<malloc>. The
+string length, C<len>, must be supplied.  By default this function
+will C<Renew> (i.e. realloc, move) the memory pointed to by C<ptr>,
 so that pointer should not be freed or used by the programmer after
 giving it to sv_usepvn, and neither should any pointers from "behind"
 that pointer (e.g. ptr + 1) be used.
-- 
1.7.9.msysgit.0

[p5pRT]

From @tonycoz

On Wed May 14 01​:30​:51 2014, bulk88 wrote​:

This is a bug report for perl from bulk88@​hotmail.com,
generated with the help of perlbug 1.39 running under perl 5.19.7.

-----------------------------------------------------------------
[Please describe your issue here]

See attached patch. I'd like this in for 5.20 since #116925
"document/publicize THINKFIRST" is stalled/bikeshedding and probably
won't correct this big mistake in the docs for sv_usepvn_flags.

Added as a 5.21.1 blocker.

Tony

[p5pRT]

The RT System itself - Status changed from 'new' to 'open'

[p5pRT]

From @tsee

Thank you, applied as 461a975.

[p5pRT]

@tsee - Status changed from 'open' to 'resolved'