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util.c
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util.c
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/* util.c
*
* Copyright (C) 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001,
* 2002, 2003, 2004, 2005, 2006, 2007, 2008 by Larry Wall and others
*
* You may distribute under the terms of either the GNU General Public
* License or the Artistic License, as specified in the README file.
*
*/
/*
* 'Very useful, no doubt, that was to Saruman; yet it seems that he was
* not content.' --Gandalf to Pippin
*
* [p.598 of _The Lord of the Rings_, III/xi: "The Palantír"]
*/
/* This file contains assorted utility routines.
* Which is a polite way of saying any stuff that people couldn't think of
* a better place for. Amongst other things, it includes the warning and
* dieing stuff, plus wrappers for malloc code.
*/
#include "EXTERN.h"
#define PERL_IN_UTIL_C
#include "perl.h"
#include "reentr.h"
#if defined(USE_PERLIO)
#include "perliol.h" /* For PerlIOUnix_refcnt */
#endif
#ifndef PERL_MICRO
#include <signal.h>
#ifndef SIG_ERR
# define SIG_ERR ((Sighandler_t) -1)
#endif
#endif
#include <math.h>
#include <stdlib.h>
#ifdef __Lynx__
/* Missing protos on LynxOS */
int putenv(char *);
#endif
#ifdef __amigaos__
# include "amigaos4/amigaio.h"
#endif
#ifdef HAS_SELECT
# ifdef I_SYS_SELECT
# include <sys/select.h>
# endif
#endif
#ifdef USE_C_BACKTRACE
# ifdef I_BFD
# define USE_BFD
# ifdef PERL_DARWIN
# undef USE_BFD /* BFD is useless in OS X. */
# endif
# ifdef USE_BFD
# include <bfd.h>
# endif
# endif
# ifdef I_DLFCN
# include <dlfcn.h>
# endif
# ifdef I_EXECINFO
# include <execinfo.h>
# endif
#endif
#ifdef PERL_DEBUG_READONLY_COW
# include <sys/mman.h>
#endif
#define FLUSH
/* NOTE: Do not call the next three routines directly. Use the macros
* in handy.h, so that we can easily redefine everything to do tracking of
* allocated hunks back to the original New to track down any memory leaks.
* XXX This advice seems to be widely ignored :-( --AD August 1996.
*/
#if defined (DEBUGGING) || defined(PERL_IMPLICIT_SYS) || defined (PERL_TRACK_MEMPOOL)
# define ALWAYS_NEED_THX
#endif
#if defined(PERL_TRACK_MEMPOOL) && defined(PERL_DEBUG_READONLY_COW)
static void
S_maybe_protect_rw(pTHX_ struct perl_memory_debug_header *header)
{
if (header->readonly
&& mprotect(header, header->size, PROT_READ|PROT_WRITE))
Perl_warn(aTHX_ "mprotect for COW string %p %lu failed with %d",
header, header->size, errno);
}
static void
S_maybe_protect_ro(pTHX_ struct perl_memory_debug_header *header)
{
if (header->readonly
&& mprotect(header, header->size, PROT_READ))
Perl_warn(aTHX_ "mprotect RW for COW string %p %lu failed with %d",
header, header->size, errno);
}
# define maybe_protect_rw(foo) S_maybe_protect_rw(aTHX_ foo)
# define maybe_protect_ro(foo) S_maybe_protect_ro(aTHX_ foo)
#else
# define maybe_protect_rw(foo) NOOP
# define maybe_protect_ro(foo) NOOP
#endif
#if defined(PERL_TRACK_MEMPOOL) || defined(PERL_DEBUG_READONLY_COW)
/* Use memory_debug_header */
# define USE_MDH
# if (defined(PERL_POISON) && defined(PERL_TRACK_MEMPOOL)) \
|| defined(PERL_DEBUG_READONLY_COW)
# define MDH_HAS_SIZE
# endif
#endif
/* paranoid version of system's malloc() */
Malloc_t
Perl_safesysmalloc(MEM_SIZE size)
{
#ifdef ALWAYS_NEED_THX
dTHX;
#endif
Malloc_t ptr;
dSAVEDERRNO;
#ifdef USE_MDH
if (size + PERL_MEMORY_DEBUG_HEADER_SIZE < size)
goto out_of_memory;
size += PERL_MEMORY_DEBUG_HEADER_SIZE;
#endif
#ifdef DEBUGGING
if ((SSize_t)size < 0)
Perl_croak_nocontext("panic: malloc, size=%" UVuf, (UV) size);
#endif
if (!size) size = 1; /* malloc(0) is NASTY on our system */
SAVE_ERRNO;
#ifdef PERL_DEBUG_READONLY_COW
if ((ptr = mmap(0, size, PROT_READ|PROT_WRITE,
MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED) {
perror("mmap failed");
abort();
}
#else
ptr = (Malloc_t)PerlMem_malloc(size?size:1);
#endif
PERL_ALLOC_CHECK(ptr);
if (ptr != NULL) {
#ifdef USE_MDH
struct perl_memory_debug_header *const header
= (struct perl_memory_debug_header *)ptr;
#endif
#ifdef PERL_POISON
PoisonNew(((char *)ptr), size, char);
#endif
#ifdef PERL_TRACK_MEMPOOL
header->interpreter = aTHX;
/* Link us into the list. */
header->prev = &PL_memory_debug_header;
header->next = PL_memory_debug_header.next;
PL_memory_debug_header.next = header;
maybe_protect_rw(header->next);
header->next->prev = header;
maybe_protect_ro(header->next);
# ifdef PERL_DEBUG_READONLY_COW
header->readonly = 0;
# endif
#endif
#ifdef MDH_HAS_SIZE
header->size = size;
#endif
ptr = (Malloc_t)((char*)ptr+PERL_MEMORY_DEBUG_HEADER_SIZE);
DEBUG_m(PerlIO_printf(Perl_debug_log, "0x%" UVxf ": (%05ld) malloc %ld bytes\n",
PTR2UV(ptr),(long)PL_an++,(long)size));
/* malloc() can modify errno() even on success, but since someone
writing perl code doesn't have any control over when perl calls
malloc() we need to hide that.
*/
RESTORE_ERRNO;
}
else {
#ifdef USE_MDH
out_of_memory:
#endif
{
#ifndef ALWAYS_NEED_THX
dTHX;
#endif
if (PL_nomemok)
ptr = NULL;
else
croak_no_mem();
}
}
return ptr;
}
/* paranoid version of system's realloc() */
Malloc_t
Perl_safesysrealloc(Malloc_t where,MEM_SIZE size)
{
#ifdef ALWAYS_NEED_THX
dTHX;
#endif
Malloc_t ptr;
#ifdef PERL_DEBUG_READONLY_COW
const MEM_SIZE oldsize = where
? ((struct perl_memory_debug_header *)((char *)where - PERL_MEMORY_DEBUG_HEADER_SIZE))->size
: 0;
#endif
if (!size) {
safesysfree(where);
ptr = NULL;
}
else if (!where) {
ptr = safesysmalloc(size);
}
else {
dSAVE_ERRNO;
#ifdef USE_MDH
where = (Malloc_t)((char*)where-PERL_MEMORY_DEBUG_HEADER_SIZE);
if (size + PERL_MEMORY_DEBUG_HEADER_SIZE < size)
goto out_of_memory;
size += PERL_MEMORY_DEBUG_HEADER_SIZE;
{
struct perl_memory_debug_header *const header
= (struct perl_memory_debug_header *)where;
# ifdef PERL_TRACK_MEMPOOL
if (header->interpreter != aTHX) {
Perl_croak_nocontext("panic: realloc from wrong pool, %p!=%p",
header->interpreter, aTHX);
}
assert(header->next->prev == header);
assert(header->prev->next == header);
# ifdef PERL_POISON
if (header->size > size) {
const MEM_SIZE freed_up = header->size - size;
char *start_of_freed = ((char *)where) + size;
PoisonFree(start_of_freed, freed_up, char);
}
# endif
# endif
# ifdef MDH_HAS_SIZE
header->size = size;
# endif
}
#endif
#ifdef DEBUGGING
if ((SSize_t)size < 0)
Perl_croak_nocontext("panic: realloc, size=%" UVuf, (UV)size);
#endif
#ifdef PERL_DEBUG_READONLY_COW
if ((ptr = mmap(0, size, PROT_READ|PROT_WRITE,
MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED) {
perror("mmap failed");
abort();
}
Copy(where,ptr,oldsize < size ? oldsize : size,char);
if (munmap(where, oldsize)) {
perror("munmap failed");
abort();
}
#else
ptr = (Malloc_t)PerlMem_realloc(where,size);
#endif
PERL_ALLOC_CHECK(ptr);
/* MUST do this fixup first, before doing ANYTHING else, as anything else
might allocate memory/free/move memory, and until we do the fixup, it
may well be chasing (and writing to) free memory. */
if (ptr != NULL) {
#ifdef PERL_TRACK_MEMPOOL
struct perl_memory_debug_header *const header
= (struct perl_memory_debug_header *)ptr;
# ifdef PERL_POISON
if (header->size < size) {
const MEM_SIZE fresh = size - header->size;
char *start_of_fresh = ((char *)ptr) + size;
PoisonNew(start_of_fresh, fresh, char);
}
# endif
maybe_protect_rw(header->next);
header->next->prev = header;
maybe_protect_ro(header->next);
maybe_protect_rw(header->prev);
header->prev->next = header;
maybe_protect_ro(header->prev);
#endif
ptr = (Malloc_t)((char*)ptr+PERL_MEMORY_DEBUG_HEADER_SIZE);
/* realloc() can modify errno() even on success, but since someone
writing perl code doesn't have any control over when perl calls
realloc() we need to hide that.
*/
RESTORE_ERRNO;
}
/* In particular, must do that fixup above before logging anything via
*printf(), as it can reallocate memory, which can cause SEGVs. */
DEBUG_m(PerlIO_printf(Perl_debug_log, "0x%" UVxf ": (%05ld) rfree\n",PTR2UV(where),(long)PL_an++));
DEBUG_m(PerlIO_printf(Perl_debug_log, "0x%" UVxf ": (%05ld) realloc %ld bytes\n",PTR2UV(ptr),(long)PL_an++,(long)size));
if (ptr == NULL) {
#ifdef USE_MDH
out_of_memory:
#endif
{
#ifndef ALWAYS_NEED_THX
dTHX;
#endif
if (PL_nomemok)
ptr = NULL;
else
croak_no_mem();
}
}
}
return ptr;
}
/* safe version of system's free() */
Free_t
Perl_safesysfree(Malloc_t where)
{
#ifdef ALWAYS_NEED_THX
dTHX;
#endif
DEBUG_m( PerlIO_printf(Perl_debug_log, "0x%" UVxf ": (%05ld) free\n",PTR2UV(where),(long)PL_an++));
if (where) {
#ifdef USE_MDH
Malloc_t where_intrn = (Malloc_t)((char*)where-PERL_MEMORY_DEBUG_HEADER_SIZE);
{
struct perl_memory_debug_header *const header
= (struct perl_memory_debug_header *)where_intrn;
# ifdef MDH_HAS_SIZE
const MEM_SIZE size = header->size;
# endif
# ifdef PERL_TRACK_MEMPOOL
if (header->interpreter != aTHX) {
Perl_croak_nocontext("panic: free from wrong pool, %p!=%p",
header->interpreter, aTHX);
}
if (!header->prev) {
Perl_croak_nocontext("panic: duplicate free");
}
if (!(header->next))
Perl_croak_nocontext("panic: bad free, header->next==NULL");
if (header->next->prev != header || header->prev->next != header) {
Perl_croak_nocontext("panic: bad free, ->next->prev=%p, "
"header=%p, ->prev->next=%p",
header->next->prev, header,
header->prev->next);
}
/* Unlink us from the chain. */
maybe_protect_rw(header->next);
header->next->prev = header->prev;
maybe_protect_ro(header->next);
maybe_protect_rw(header->prev);
header->prev->next = header->next;
maybe_protect_ro(header->prev);
maybe_protect_rw(header);
# ifdef PERL_POISON
PoisonNew(where_intrn, size, char);
# endif
/* Trigger the duplicate free warning. */
header->next = NULL;
# endif
# ifdef PERL_DEBUG_READONLY_COW
if (munmap(where_intrn, size)) {
perror("munmap failed");
abort();
}
# endif
}
#else
Malloc_t where_intrn = where;
#endif /* USE_MDH */
#ifndef PERL_DEBUG_READONLY_COW
PerlMem_free(where_intrn);
#endif
}
}
/* safe version of system's calloc() */
Malloc_t
Perl_safesyscalloc(MEM_SIZE count, MEM_SIZE size)
{
#ifdef ALWAYS_NEED_THX
dTHX;
#endif
Malloc_t ptr;
#if defined(USE_MDH) || defined(DEBUGGING)
MEM_SIZE total_size = 0;
#endif
/* Even though calloc() for zero bytes is strange, be robust. */
if (size && (count <= MEM_SIZE_MAX / size)) {
#if defined(USE_MDH) || defined(DEBUGGING)
total_size = size * count;
#endif
}
else
croak_memory_wrap();
#ifdef USE_MDH
if (PERL_MEMORY_DEBUG_HEADER_SIZE <= MEM_SIZE_MAX - (MEM_SIZE)total_size)
total_size += PERL_MEMORY_DEBUG_HEADER_SIZE;
else
croak_memory_wrap();
#endif
#ifdef DEBUGGING
if ((SSize_t)size < 0 || (SSize_t)count < 0)
Perl_croak_nocontext("panic: calloc, size=%" UVuf ", count=%" UVuf,
(UV)size, (UV)count);
#endif
#ifdef PERL_DEBUG_READONLY_COW
if ((ptr = mmap(0, total_size ? total_size : 1, PROT_READ|PROT_WRITE,
MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED) {
perror("mmap failed");
abort();
}
#elif defined(PERL_TRACK_MEMPOOL)
/* Have to use malloc() because we've added some space for our tracking
header. */
/* malloc(0) is non-portable. */
ptr = (Malloc_t)PerlMem_malloc(total_size ? total_size : 1);
#else
/* Use calloc() because it might save a memset() if the memory is fresh
and clean from the OS. */
if (count && size)
ptr = (Malloc_t)PerlMem_calloc(count, size);
else /* calloc(0) is non-portable. */
ptr = (Malloc_t)PerlMem_calloc(count ? count : 1, size ? size : 1);
#endif
PERL_ALLOC_CHECK(ptr);
DEBUG_m(PerlIO_printf(Perl_debug_log, "0x%" UVxf ": (%05ld) calloc %zu x %zu = %zu bytes\n",PTR2UV(ptr),(long)PL_an++, count, size, total_size));
if (ptr != NULL) {
#ifdef USE_MDH
{
struct perl_memory_debug_header *const header
= (struct perl_memory_debug_header *)ptr;
# ifndef PERL_DEBUG_READONLY_COW
memset((void*)ptr, 0, total_size);
# endif
# ifdef PERL_TRACK_MEMPOOL
header->interpreter = aTHX;
/* Link us into the list. */
header->prev = &PL_memory_debug_header;
header->next = PL_memory_debug_header.next;
PL_memory_debug_header.next = header;
maybe_protect_rw(header->next);
header->next->prev = header;
maybe_protect_ro(header->next);
# ifdef PERL_DEBUG_READONLY_COW
header->readonly = 0;
# endif
# endif
# ifdef MDH_HAS_SIZE
header->size = total_size;
# endif
ptr = (Malloc_t)((char*)ptr+PERL_MEMORY_DEBUG_HEADER_SIZE);
}
#endif
return ptr;
}
else {
#ifndef ALWAYS_NEED_THX
dTHX;
#endif
if (PL_nomemok)
return NULL;
croak_no_mem();
}
}
/* These must be defined when not using Perl's malloc for binary
* compatibility */
#ifndef MYMALLOC
Malloc_t Perl_malloc (MEM_SIZE nbytes)
{
#ifdef PERL_IMPLICIT_SYS
dTHX;
#endif
return (Malloc_t)PerlMem_malloc(nbytes);
}
Malloc_t Perl_calloc (MEM_SIZE elements, MEM_SIZE size)
{
#ifdef PERL_IMPLICIT_SYS
dTHX;
#endif
return (Malloc_t)PerlMem_calloc(elements, size);
}
Malloc_t Perl_realloc (Malloc_t where, MEM_SIZE nbytes)
{
#ifdef PERL_IMPLICIT_SYS
dTHX;
#endif
return (Malloc_t)PerlMem_realloc(where, nbytes);
}
Free_t Perl_mfree (Malloc_t where)
{
#ifdef PERL_IMPLICIT_SYS
dTHX;
#endif
PerlMem_free(where);
}
#endif
/* copy a string up to some (non-backslashed) delimiter, if any.
* With allow_escape, converts \<delimiter> to <delimiter>, while leaves
* \<non-delimiter> as-is.
* Returns the position in the src string of the closing delimiter, if
* any, or returns fromend otherwise.
* This is the internal implementation for Perl_delimcpy and
* Perl_delimcpy_no_escape.
*/
static char *
S_delimcpy_intern(char *to, const char *toend, const char *from,
const char *fromend, int delim, I32 *retlen,
const bool allow_escape)
{
I32 tolen;
PERL_ARGS_ASSERT_DELIMCPY;
for (tolen = 0; from < fromend; from++, tolen++) {
if (allow_escape && *from == '\\' && from + 1 < fromend) {
if (from[1] != delim) {
if (to < toend)
*to++ = *from;
tolen++;
}
from++;
}
else if (*from == delim)
break;
if (to < toend)
*to++ = *from;
}
if (to < toend)
*to = '\0';
*retlen = tolen;
return (char *)from;
}
char *
Perl_delimcpy(char *to, const char *toend, const char *from, const char *fromend, int delim, I32 *retlen)
{
PERL_ARGS_ASSERT_DELIMCPY;
return S_delimcpy_intern(to, toend, from, fromend, delim, retlen, 1);
}
char *
Perl_delimcpy_no_escape(char *to, const char *toend, const char *from,
const char *fromend, int delim, I32 *retlen)
{
PERL_ARGS_ASSERT_DELIMCPY_NO_ESCAPE;
return S_delimcpy_intern(to, toend, from, fromend, delim, retlen, 0);
}
/*
=head1 Miscellaneous Functions
=for apidoc Am|char *|ninstr|char * big|char * bigend|char * little|char * little_end
Find the first (leftmost) occurrence of a sequence of bytes within another
sequence. This is the Perl version of C<strstr()>, extended to handle
arbitrary sequences, potentially containing embedded C<NUL> characters (C<NUL>
is what the initial C<n> in the function name stands for; some systems have an
equivalent, C<memmem()>, but with a somewhat different API).
Another way of thinking about this function is finding a needle in a haystack.
C<big> points to the first byte in the haystack. C<big_end> points to one byte
beyond the final byte in the haystack. C<little> points to the first byte in
the needle. C<little_end> points to one byte beyond the final byte in the
needle. All the parameters must be non-C<NULL>.
The function returns C<NULL> if there is no occurrence of C<little> within
C<big>. If C<little> is the empty string, C<big> is returned.
Because this function operates at the byte level, and because of the inherent
characteristics of UTF-8 (or UTF-EBCDIC), it will work properly if both the
needle and the haystack are strings with the same UTF-8ness, but not if the
UTF-8ness differs.
=cut
*/
char *
Perl_ninstr(const char *big, const char *bigend, const char *little, const char *lend)
{
PERL_ARGS_ASSERT_NINSTR;
#ifdef HAS_MEMMEM
return ninstr(big, bigend, little, lend);
#else
if (little >= lend)
return (char*)big;
{
const char first = *little;
bigend -= lend - little++;
OUTER:
while (big <= bigend) {
if (*big++ == first) {
const char *s, *x;
for (x=big,s=little; s < lend; x++,s++) {
if (*s != *x)
goto OUTER;
}
return (char*)(big-1);
}
}
}
return NULL;
#endif
}
/*
=head1 Miscellaneous Functions
=for apidoc Am|char *|rninstr|char * big|char * bigend|char * little|char * little_end
Like C<L</ninstr>>, but instead finds the final (rightmost) occurrence of a
sequence of bytes within another sequence, returning C<NULL> if there is no
such occurrence.
=cut
*/
char *
Perl_rninstr(const char *big, const char *bigend, const char *little, const char *lend)
{
const char *bigbeg;
const I32 first = *little;
const char * const littleend = lend;
PERL_ARGS_ASSERT_RNINSTR;
if (little >= littleend)
return (char*)bigend;
bigbeg = big;
big = bigend - (littleend - little++);
while (big >= bigbeg) {
const char *s, *x;
if (*big-- != first)
continue;
for (x=big+2,s=little; s < littleend; /**/ ) {
if (*s != *x)
break;
else {
x++;
s++;
}
}
if (s >= littleend)
return (char*)(big+1);
}
return NULL;
}
/* As a space optimization, we do not compile tables for strings of length
0 and 1, and for strings of length 2 unless FBMcf_TAIL. These are
special-cased in fbm_instr().
If FBMcf_TAIL, the table is created as if the string has a trailing \n. */
/*
=head1 Miscellaneous Functions
=for apidoc fbm_compile
Analyzes the string in order to make fast searches on it using C<fbm_instr()>
-- the Boyer-Moore algorithm.
=cut
*/
void
Perl_fbm_compile(pTHX_ SV *sv, U32 flags)
{
const U8 *s;
MAGIC *mg;
STRLEN i;
STRLEN len;
U32 frequency = 256;
PERL_DEB( STRLEN rarest = 0 );
PERL_ARGS_ASSERT_FBM_COMPILE;
if (isGV_with_GP(sv) || SvROK(sv))
return;
if (SvVALID(sv))
return;
if (flags & FBMcf_TAIL) {
MAGIC * const mg = SvUTF8(sv) && SvMAGICAL(sv) ? mg_find(sv, PERL_MAGIC_utf8) : NULL;
sv_catpvs(sv, "\n"); /* Taken into account in fbm_instr() */
if (mg && mg->mg_len >= 0)
mg->mg_len++;
}
if (!SvPOK(sv) || SvNIOKp(sv))
s = (U8*)SvPV_force_mutable(sv, len);
else s = (U8 *)SvPV_mutable(sv, len);
if (len == 0) /* TAIL might be on a zero-length string. */
return;
SvUPGRADE(sv, SVt_PVMG);
SvIOK_off(sv);
SvNOK_off(sv);
/* add PERL_MAGIC_bm magic holding the FBM lookup table */
assert(!mg_find(sv, PERL_MAGIC_bm));
mg = sv_magicext(sv, NULL, PERL_MAGIC_bm, &PL_vtbl_bm, NULL, 0);
assert(mg);
if (len > 2) {
/* Shorter strings are special-cased in Perl_fbm_instr(), and don't use
the BM table. */
const U8 mlen = (len>255) ? 255 : (U8)len;
const unsigned char *const sb = s + len - mlen; /* first char (maybe) */
U8 *table;
Newx(table, 256, U8);
memset((void*)table, mlen, 256);
mg->mg_ptr = (char *)table;
mg->mg_len = 256;
s += len - 1; /* last char */
i = 0;
while (s >= sb) {
if (table[*s] == mlen)
table[*s] = (U8)i;
s--, i++;
}
}
s = (const unsigned char*)(SvPVX_const(sv)); /* deeper magic */
for (i = 0; i < len; i++) {
if (PL_freq[s[i]] < frequency) {
PERL_DEB( rarest = i );
frequency = PL_freq[s[i]];
}
}
BmUSEFUL(sv) = 100; /* Initial value */
((XPVNV*)SvANY(sv))->xnv_u.xnv_bm_tail = cBOOL(flags & FBMcf_TAIL);
DEBUG_r(PerlIO_printf(Perl_debug_log, "rarest char %c at %" UVuf "\n",
s[rarest], (UV)rarest));
}
/* If SvTAIL(littlestr), it has a fake '\n' at end. */
/* If SvTAIL is actually due to \Z or \z, this gives false positives
if multiline */
/*
=for apidoc fbm_instr
Returns the location of the SV in the string delimited by C<big> and
C<bigend>. It returns C<NULL> if the string can't be found. The C<sv>
does not have to be C<fbm_compiled>, but the search will not be as fast
then.
=cut
*/
char *
Perl_fbm_instr(pTHX_ unsigned char *big, unsigned char *bigend, SV *littlestr, U32 flags)
{
STRLEN l;
unsigned char *s;
const unsigned char *little = (const unsigned char *)SvPV_const(littlestr,l);
STRLEN littlelen = l;
const I32 multiline = flags & FBMrf_MULTILINE;
bool valid = SvVALID(littlestr);
bool tail = valid ? cBOOL(SvTAIL(littlestr)) : FALSE;
PERL_ARGS_ASSERT_FBM_INSTR;
assert(bigend >= big);
if ((STRLEN)(bigend - big) < littlelen) {
if ( tail
&& ((STRLEN)(bigend - big) == littlelen - 1)
&& (littlelen == 1
|| (*big == *little &&
memEQ((char *)big, (char *)little, littlelen - 1))))
return (char*)big;
return NULL;
}
switch (littlelen) { /* Special cases for 0, 1 and 2 */
case 0:
return (char*)big; /* Cannot be SvTAIL! */
case 1:
if (tail && !multiline) /* Anchor only! */
/* [-1] is safe because we know that bigend != big. */
return (char *) (bigend - (bigend[-1] == '\n'));
s = (unsigned char *)memchr((void*)big, *little, bigend-big);
if (s)
return (char *)s;
if (tail)
return (char *) bigend;
return NULL;
case 2:
if (tail && !multiline) {
/* a littlestr with SvTAIL must be of the form "X\n" (where X
* is a single char). It is anchored, and can only match
* "....X\n" or "....X" */
if (bigend[-2] == *little && bigend[-1] == '\n')
return (char*)bigend - 2;
if (bigend[-1] == *little)
return (char*)bigend - 1;
return NULL;
}
{
/* memchr() is likely to be very fast, possibly using whatever
* hardware support is available, such as checking a whole
* cache line in one instruction.
* So for a 2 char pattern, calling memchr() is likely to be
* faster than running FBM, or rolling our own. The previous
* version of this code was roll-your-own which typically
* only needed to read every 2nd char, which was good back in
* the day, but no longer.
*/
unsigned char c1 = little[0];
unsigned char c2 = little[1];
/* *** for all this case, bigend points to the last char,
* not the trailing \0: this makes the conditions slightly
* simpler */
bigend--;
s = big;
if (c1 != c2) {
while (s < bigend) {
/* do a quick test for c1 before calling memchr();
* this avoids the expensive fn call overhead when
* there are lots of c1's */
if (LIKELY(*s != c1)) {
s++;
s = (unsigned char *)memchr((void*)s, c1, bigend - s);
if (!s)
break;
}
if (s[1] == c2)
return (char*)s;
/* failed; try searching for c2 this time; that way
* we don't go pathologically slow when the string
* consists mostly of c1's or vice versa.
*/
s += 2;
if (s > bigend)
break;
s = (unsigned char *)memchr((void*)s, c2, bigend - s + 1);
if (!s)
break;
if (s[-1] == c1)
return (char*)s - 1;
}
}
else {
/* c1, c2 the same */
while (s < bigend) {
if (s[0] == c1) {
got_1char:
if (s[1] == c1)
return (char*)s;
s += 2;
}
else {
s++;
s = (unsigned char *)memchr((void*)s, c1, bigend - s);
if (!s || s >= bigend)
break;
goto got_1char;
}
}
}
/* failed to find 2 chars; try anchored match at end without
* the \n */
if (tail && bigend[0] == little[0])
return (char *)bigend;
return NULL;
}
default:
break; /* Only lengths 0 1 and 2 have special-case code. */
}
if (tail && !multiline) { /* tail anchored? */
s = bigend - littlelen;
if (s >= big && bigend[-1] == '\n' && *s == *little
/* Automatically of length > 2 */
&& memEQ((char*)s + 1, (char*)little + 1, littlelen - 2))
{
return (char*)s; /* how sweet it is */
}
if (s[1] == *little
&& memEQ((char*)s + 2, (char*)little + 1, littlelen - 2))
{
return (char*)s + 1; /* how sweet it is */
}
return NULL;
}
if (!valid) {
/* not compiled; use Perl_ninstr() instead */
char * const b = ninstr((char*)big,(char*)bigend,
(char*)little, (char*)little + littlelen);
assert(!tail); /* valid => FBM; tail only set on SvVALID SVs */
return b;
}
/* Do actual FBM. */
if (littlelen > (STRLEN)(bigend - big))
return NULL;
{
const MAGIC *const mg = mg_find(littlestr, PERL_MAGIC_bm);
const unsigned char *oldlittle;
if (UNLIKELY(!mg))
return NULL;
--littlelen; /* Last char found by table lookup */
s = big + littlelen;
little += littlelen; /* last char */
oldlittle = little;
if (s < bigend) {
const unsigned char * const table = (const unsigned char *) mg->mg_ptr;
const unsigned char lastc = *little;
I32 tmp;
top2:
if ((tmp = table[*s])) {
/* *s != lastc; earliest position it could match now is
* tmp slots further on */
if ((s += tmp) >= bigend)
goto check_end;
if (LIKELY(*s != lastc)) {
s++;
s = (unsigned char *)memchr((void*)s, lastc, bigend - s);
if (!s) {
s = bigend;
goto check_end;
}
goto top2;
}
}
/* hand-rolled strncmp(): less expensive than calling the
* real function (maybe???) */
{
unsigned char * const olds = s;
tmp = littlelen;
while (tmp--) {