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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
#include <signal.h>
#ifndef SIG_ERR
# define SIG_ERR ((Sighandler_t) -1)
#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
/*
=for apidoc_section $memory
=for apidoc safesysmalloc
Paranoid version of system's malloc()
=cut
*/
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);
#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;
}
/*
=for apidoc safesysrealloc
Paranoid version of system's realloc()
=cut
*/
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;
PERL_DEB(UV was_where = PTR2UV(where)); /* used in diags below */
#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 %p from wrong pool, %p!=%p",
where, 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 %p , size=%" UVuf,
where, (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",was_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;
}
/*
=for apidoc safesysfree
Safe version of system's free()
=cut
*/
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 %p from wrong pool, %p!=%p",
where, header->interpreter, aTHX);
}
if (!header->prev) {
Perl_croak_nocontext("panic: duplicate free");
}
if (!(header->next))
Perl_croak_nocontext("panic: bad free of %p, header->next==NULL",
where);
if (header->next->prev != header || header->prev->next != header) {
Perl_croak_nocontext("panic: bad free of %p, ->next->prev=%p, "
"header=%p, ->prev->next=%p",
where, 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
}
}
/*
=for apidoc safesyscalloc
Safe version of system's calloc()
=cut
*/
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
/* This is the value stored in *retlen in the two delimcpy routines below when
* there wasn't enough room in the destination to store everything it was asked
* to. The value is deliberately very large so that hopefully if code uses it
* unquestioningly to access memory, it will likely segfault. And it is small
* enough that if the caller does some arithmetic on it before accessing, it
* won't overflow into a small legal number. */
#define DELIMCPY_OUT_OF_BOUNDS_RET I32_MAX
/*
=for apidoc_section $string
=for apidoc delimcpy_no_escape
Copy a source buffer to a destination buffer, stopping at (but not including)
the first occurrence in the source of the delimiter byte, C<delim>. The source
is the bytes between S<C<from> and C<from_end> - 1>. Similarly, the dest is
C<to> up to C<to_end>.
The number of bytes copied is written to C<*retlen>.
Returns the position of C<delim> in the C<from> buffer, but if there is no
such occurrence before C<from_end>, then C<from_end> is returned, and the entire
buffer S<C<from> .. C<from_end> - 1> is copied.
If there is room in the destination available after the copy, an extra
terminating safety C<NUL> byte is appended (not included in the returned
length).
The error case is if the destination buffer is not large enough to accommodate
everything that should be copied. In this situation, a value larger than
S<C<to_end> - C<to>> is written to C<*retlen>, and as much of the source as
fits will be written to the destination. Not having room for the safety C<NUL>
is not considered an error.
=cut
*/
char *
Perl_delimcpy_no_escape(char *to, const char *to_end,
const char *from, const char *from_end,
const int delim, I32 *retlen)
{
const char * delim_pos;
Ptrdiff_t from_len = from_end - from;
Ptrdiff_t to_len = to_end - to;
SSize_t copy_len;
PERL_ARGS_ASSERT_DELIMCPY_NO_ESCAPE;
assert(from_len >= 0);
assert(to_len >= 0);
/* Look for the first delimiter in the source */
delim_pos = (const char *) memchr(from, delim, from_len);
/* Copy up to where the delimiter was found, or the entire buffer if not
* found */
copy_len = (delim_pos) ? delim_pos - from : from_len;
/* If not enough room, copy as much as can fit, and set error return */
if (copy_len > to_len) {
Copy(from, to, to_len, char);
*retlen = DELIMCPY_OUT_OF_BOUNDS_RET;
}
else {
Copy(from, to, copy_len, char);
/* If there is extra space available, add a trailing NUL */
if (copy_len < to_len) {
to[copy_len] = '\0';
}
*retlen = copy_len;
}
return (char *) from + copy_len;
}
/*
=for apidoc delimcpy
Copy a source buffer to a destination buffer, stopping at (but not including)
the first occurrence in the source of an unescaped (defined below) delimiter
byte, C<delim>. The source is the bytes between S<C<from> and C<from_end> -
1>. Similarly, the dest is C<to> up to C<to_end>.
The number of bytes copied is written to C<*retlen>.
Returns the position of the first uncopied C<delim> in the C<from> buffer, but
if there is no such occurrence before C<from_end>, then C<from_end> is returned,
and the entire buffer S<C<from> .. C<from_end> - 1> is copied.
If there is room in the destination available after the copy, an extra
terminating safety C<NUL> byte is appended (not included in the returned
length).
The error case is if the destination buffer is not large enough to accommodate
everything that should be copied. In this situation, a value larger than
S<C<to_end> - C<to>> is written to C<*retlen>, and as much of the source as
fits will be written to the destination. Not having room for the safety C<NUL>
is not considered an error.
In the following examples, let C<x> be the delimiter, and C<0> represent a C<NUL>
byte (B<NOT> the digit C<0>). Then we would have
Source Destination
abcxdef abc0
provided the destination buffer is at least 4 bytes long.
An escaped delimiter is one which is immediately preceded by a single
backslash. Escaped delimiters are copied, and the copy continues past the
delimiter; the backslash is not copied:
Source Destination
abc\xdef abcxdef0
(provided the destination buffer is at least 8 bytes long).
It's actually somewhat more complicated than that. A sequence of any odd number
of backslashes escapes the following delimiter, and the copy continues with
exactly one of the backslashes stripped.
Source Destination
abc\xdef abcxdef0
abc\\\xdef abc\\xdef0
abc\\\\\xdef abc\\\\xdef0
(as always, if the destination is large enough)
An even number of preceding backslashes does not escape the delimiter, so that
the copy stops just before it, and includes all the backslashes (no stripping;
zero is considered even):
Source Destination
abcxdef abc0
abc\\xdef abc\\0
abc\\\\xdef abc\\\\0
=cut
*/
char *
Perl_delimcpy(char *to, const char *to_end,
const char *from, const char *from_end,
const int delim, I32 *retlen)
{
const char * const orig_to = to;
Ptrdiff_t copy_len = 0;
bool stopped_early = FALSE; /* Ran out of room to copy to */
PERL_ARGS_ASSERT_DELIMCPY;
assert(from_end >= from);
assert(to_end >= to);
/* Don't use the loop for the trivial case of the first character being the
* delimiter; otherwise would have to worry inside the loop about backing
* up before the start of 'from' */
if (LIKELY(from_end > from && *from != delim)) {
while ((copy_len = from_end - from) > 0) {
const char * backslash_pos;
const char * delim_pos;
/* Look for the next delimiter in the remaining portion of the
* source. A loop invariant is that we already know that the copy
* should include *from; this comes from the conditional before the
* loop, and how we set things up at the end of each iteration */
delim_pos = (const char *) memchr(from + 1, delim, copy_len - 1);
/* If didn't find it, done looking; set up so copies all of the
* source */
if (! delim_pos) {
copy_len = from_end - from;
break;
}
/* Look for a backslash immediately before the delimiter */
backslash_pos = delim_pos - 1;
/* If the delimiter is not escaped, this ends the copy */
if (*backslash_pos != '\\') {
copy_len = delim_pos - from;
break;
}
/* Here there is a backslash just before the delimiter, but it
* could be the final backslash in a sequence of them. Backup to
* find the first one in it. */
do {
backslash_pos--;
}
while (backslash_pos >= from && *backslash_pos == '\\');
/* If the number of backslashes is even, they just escape one
* another, leaving the delimiter unescaped, and stopping the copy.
* */
if (! ((delim_pos - (backslash_pos + 1)) & 1)) {
copy_len = delim_pos - from; /* even, copy up to delimiter */
break;
}
/* Here is odd, so the delimiter is escaped. We will try to copy
* all but the final backslash in the sequence */
copy_len = delim_pos - 1 - from;
/* Do the copy, but not beyond the end of the destination */
if (copy_len >= to_end - to) {
Copy(from, to, to_end - to, char);
stopped_early = TRUE;
to = (char *) to_end;
}
else {
Copy(from, to, copy_len, char);
to += copy_len;
}
/* Set up so next iteration will include the delimiter */
from = delim_pos;
}
}
/* Here, have found the final segment to copy. Copy that, but not beyond
* the size of the destination. If not enough room, copy as much as can
* fit, and set error return */
if (stopped_early || copy_len > to_end - to) {
Copy(from, to, to_end - to, char);
*retlen = DELIMCPY_OUT_OF_BOUNDS_RET;
}
else {
Copy(from, to, copy_len, char);
to += copy_len;
/* If there is extra space available, add a trailing NUL */
if (to < to_end) {
*to = '\0';
}
*retlen = to - orig_to;
}
return (char *) from + copy_len;
}
/*
=for apidoc ninstr
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;
}
else {
const U8 first = *little;
Size_t lsize;
/* No match can start closer to the end of the haystack than the length
* of the needle. */
bigend -= lend - little;
little++; /* Look for 'first', then the remainder is in here */
lsize = lend - little;
while (big <= bigend) {
big = (char *) memchr((U8 *) big, first, bigend - big + 1);
if (big == NULL || big > bigend) {
return NULL;
}
if (memEQ(big + 1, little, lsize)) {
return (char*) big;
}
big++;
}
}
return NULL;
#endif
}
/*
=for apidoc rninstr
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 Ptrdiff_t little_len = lend - little;
const Ptrdiff_t big_len = bigend - big;
PERL_ARGS_ASSERT_RNINSTR;
/* A non-existent needle trivially matches the rightmost possible position
* in the haystack */
if (UNLIKELY(little_len <= 0)) {
return (char*)bigend;
}
/* If the needle is larger than the haystack, the needle can't possibly fit
* inside the haystack. */
if (UNLIKELY(little_len > big_len)) {
return NULL;
}
/* Special case length 1 needles. It's trivial if we have memrchr();
* and otherwise we just do a per-byte search backwards.
*
* XXX When we don't have memrchr, we could use something like
* S_find_next_masked( or S_find_span_end() to do per-word searches */
if (little_len == 1) {
const char final = *little;
#ifdef HAS_MEMRCHR
return (char *) memrchr(big, final, big_len);
#else
const char * cur = bigend - 1;
do {
if (*cur == final) {
return (char *) cur;
}
} while (--cur >= big);
return NULL;
#endif
}
else { /* Below, the needle is longer than a single byte */
/* We search backwards in the haystack for the final character of the
* needle. Each time one is found, we see if the characters just
* before it in the haystack match the rest of the needle. */
const char final = *(lend - 1);
/* What matches consists of 'little_len'-1 characters, then the final
* one */
const Size_t prefix_len = little_len - 1;
/* If the final character in the needle is any closer than this to the
* left edge, there wouldn't be enough room for all of it to fit in the
* haystack */
const char * const left_fence = big + prefix_len;
/* Start at the right edge */
char * cur = (char *) bigend;
/* memrchr() makes the search easy (and fast); otherwise, look
* backwards byte-by-byte. */
do {
#ifdef HAS_MEMRCHR
cur = (char *) memrchr(left_fence, final, cur - left_fence);
if (cur == NULL) {
return NULL;
}
#else
do {
cur--;
if (cur < left_fence) {
return NULL;
}
}
while (*cur != final);
#endif
/* Here, we know that *cur is 'final'; see if the preceding bytes
* of the needle also match the corresponding haystack bytes */
if memEQ(cur - prefix_len, little, prefix_len) {
return cur - prefix_len;
}
} while (cur > left_fence);
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. */
/*
=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;
STRLEN i;
STRLEN len;
MAGIC *mg;
PERL_ARGS_ASSERT_FBM_COMPILE;
if (isGV_with_GP(sv) || SvROK(sv))
return;