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* crypt/crypt.c: Changed copying permission notice to Lesser GPL from Library GPL. * crypt/crypt_util.c: Likewise. * crypt/ufc.c: Likewise. * elf/dl-conflict.c: Likewise. * elf/dl-iteratephdr.c: Likewise. * iconv/iconvconfig.h: Likewise. * linuxthreads/Examples/ex10.c: Likewise. * linuxthreads/Examples/ex11.c: Likewise. * linuxthreads/Examples/ex13.c: Likewise. * linuxthreads/Examples/ex8.c: Likewise. * linuxthreads/Examples/ex9.c: Likewise. * linuxthreads/barrier.c: Likewise. * linuxthreads/events.c: Likewise. * linuxthreads/lockfile.c: Likewise. * linuxthreads/no-tsd.c: Likewise. * linuxthreads/pt-machine.c: Likewise. * linuxthreads/ptclock_gettime.c: Likewise. * linuxthreads/ptclock_settime.c: Likewise. * linuxthreads/rwlock.c: Likewise. * linuxthreads/sysdeps/alpha/pspinlock.c: Likewise. * linuxthreads/sysdeps/alpha/pt-machine.h: Likewise. * linuxthreads/sysdeps/arm/pspinlock.c: Likewise. * linuxthreads/sysdeps/arm/pt-machine.h: Likewise. * linuxthreads/sysdeps/cris/pspinlock.c: Likewise. * linuxthreads/sysdeps/cris/pt-machine.h: Likewise. * linuxthreads/sysdeps/hppa/pspinlock.c: Likewise. * linuxthreads/sysdeps/hppa/pt-machine.h: Likewise. * linuxthreads/sysdeps/i386/i686/pt-machine.h: Likewise. * linuxthreads/sysdeps/i386/pspinlock.c: Likewise. * linuxthreads/sysdeps/i386/pt-machine.h: Likewise. * linuxthreads/sysdeps/i386/useldt.h: Likewise. * linuxthreads/sysdeps/ia64/pspinlock.c: Likewise. * linuxthreads/sysdeps/ia64/pt-machine.h: Likewise. * linuxthreads/sysdeps/m68k/pspinlock.c: Likewise. * linuxthreads/sysdeps/m68k/pt-machine.h: Likewise. * linuxthreads/sysdeps/mips/pspinlock.c: Likewise. * linuxthreads/sysdeps/mips/pt-machine.h: Likewise. * linuxthreads/sysdeps/powerpc/pspinlock.c: Likewise. * linuxthreads/sysdeps/powerpc/pt-machine.h: Likewise. * linuxthreads/sysdeps/pthread/bits/initspin.h: Likewise. * linuxthreads/sysdeps/pthread/bits/libc-lock.h: Likewise. * linuxthreads/sysdeps/pthread/bits/libc-tsd.h: Likewise. * linuxthreads/sysdeps/pthread/getcpuclockid.c: Likewise. * linuxthreads/sysdeps/pthread/posix-timer.h: Likewise. * linuxthreads/sysdeps/pthread/timer_create.c: Likewise. * linuxthreads/sysdeps/pthread/timer_delete.c: Likewise. * linuxthreads/sysdeps/pthread/timer_getoverr.c: Likewise. * linuxthreads/sysdeps/pthread/timer_gettime.c: Likewise. * linuxthreads/sysdeps/pthread/timer_routines.c: Likewise. * linuxthreads/sysdeps/pthread/timer_settime.c: Likewise. * linuxthreads/sysdeps/pthread/tst-timer.c: Likewise. * linuxthreads/sysdeps/s390/pspinlock.c: Likewise. * linuxthreads/sysdeps/s390/s390-32/pt-machine.h: Likewise. * linuxthreads/sysdeps/s390/s390-64/pt-machine.h: Likewise. * linuxthreads/sysdeps/sh/pspinlock.c: Likewise. * linuxthreads/sysdeps/sh/pt-machine.h: Likewise. * linuxthreads/sysdeps/sparc/sparc32/pspinlock.c: Likewise. * linuxthreads/sysdeps/sparc/sparc32/pt-machine.h: Likewise. * linuxthreads/sysdeps/sparc/sparc32/sparcv9/pspinlock.c: Likewise. * linuxthreads/sysdeps/sparc/sparc64/pspinlock.c: Likewise. * linuxthreads/sysdeps/sparc/sparc64/pt-machine.h: Likewise. * linuxthreads/sysdeps/unix/sysv/linux/bits/local_lim.h: Likewise. * linuxthreads/sysdeps/unix/sysv/linux/bits/posix_opt.h: Likewise. * linuxthreads/sysdeps/unix/sysv/linux/bits/sigthread.h: Likewise. * linuxthreads/sysdeps/unix/sysv/linux/hppa/bits/initspin.h: Likewise. * linuxthreads/sysdeps/unix/sysv/linux/i386/bits/posix_opt.h: Likewise. * linuxthreads/tststack.c: Likewise. * linuxthreads/unload.c: Likewise. * linuxthreads/weaks.c: Likewise. * linuxthreads/wrapsyscall.c: Likewise. * malloc/arena.c: Likewise. * malloc/hooks.c: Likewise. * malloc/malloc.c: Likewise. * posix/glob/Makefile.ami: Likewise. * posix/glob/Makefile.in: Likewise. * stdlib/gmp-impl.h: Likewise. * stdlib/gmp.h: Likewise. * sysdeps/generic/dl-iteratephdr-static.c: Likewise. * sysdeps/generic/strnlen.c: Likewise. * sysdeps/mach/hurd/powerpc/bits/sigcontext.h: Likewise. * sysdeps/mach/hurd/recvmsg.c: Likewise. * sysdeps/mach/hurd/sendmsg.c: Likewise. * sysdeps/mach/hurd/spawni.c: Likewise. * sysdeps/mach/powerpc/machine-sp.h: Likewise. * sysdeps/mach/powerpc/sysdep.h: Likewise. * sysdeps/mach/powerpc/thread_state.h: Likewise. * sysdeps/unix/bsd/bsd4.4/bits/socket.h: Likewise. * sysdeps/unix/sysv/linux/ia64/dl-iteratephdr-static.c: Likewise. * sysdeps/x86_64/gmp-mparam.h: Likewise.
161 lines
5.3 KiB
C
161 lines
5.3 KiB
C
/* Find the length of STRING, but scan at most MAXLEN characters.
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Copyright (C) 1991, 1993, 1997, 2000, 2001 Free Software Foundation, Inc.
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Contributed by Jakub Jelinek <jakub@redhat.com>.
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Based on strlen written by Torbjorn Granlund (tege@sics.se),
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with help from Dan Sahlin (dan@sics.se);
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commentary by Jim Blandy (jimb@ai.mit.edu).
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; see the file COPYING.LIB. If not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include <string.h>
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#include <stdlib.h>
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/* Find the length of S, but scan at most MAXLEN characters. If no
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'\0' terminator is found in that many characters, return MAXLEN. */
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size_t
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__strnlen (const char *str, size_t maxlen)
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{
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const char *char_ptr, *end_ptr = str + maxlen;
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const unsigned long int *longword_ptr;
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unsigned long int longword, magic_bits, himagic, lomagic;
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if (maxlen == 0)
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return 0;
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if (__builtin_expect (end_ptr < str, 0))
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end_ptr = (const char *) ~0UL;
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/* Handle the first few characters by reading one character at a time.
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Do this until CHAR_PTR is aligned on a longword boundary. */
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for (char_ptr = str; ((unsigned long int) char_ptr
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& (sizeof (longword) - 1)) != 0;
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++char_ptr)
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if (*char_ptr == '\0')
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{
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if (char_ptr > end_ptr)
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char_ptr = end_ptr;
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return char_ptr - str;
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}
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/* All these elucidatory comments refer to 4-byte longwords,
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but the theory applies equally well to 8-byte longwords. */
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longword_ptr = (unsigned long int *) char_ptr;
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/* Bits 31, 24, 16, and 8 of this number are zero. Call these bits
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the "holes." Note that there is a hole just to the left of
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each byte, with an extra at the end:
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bits: 01111110 11111110 11111110 11111111
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bytes: AAAAAAAA BBBBBBBB CCCCCCCC DDDDDDDD
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The 1-bits make sure that carries propagate to the next 0-bit.
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The 0-bits provide holes for carries to fall into. */
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magic_bits = 0x7efefeffL;
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himagic = 0x80808080L;
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lomagic = 0x01010101L;
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if (sizeof (longword) > 4)
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{
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/* 64-bit version of the magic. */
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/* Do the shift in two steps to avoid a warning if long has 32 bits. */
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magic_bits = ((0x7efefefeL << 16) << 16) | 0xfefefeffL;
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himagic = ((himagic << 16) << 16) | himagic;
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lomagic = ((lomagic << 16) << 16) | lomagic;
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}
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if (sizeof (longword) > 8)
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abort ();
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/* Instead of the traditional loop which tests each character,
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we will test a longword at a time. The tricky part is testing
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if *any of the four* bytes in the longword in question are zero. */
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while (longword_ptr < (unsigned long int *) end_ptr)
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{
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/* We tentatively exit the loop if adding MAGIC_BITS to
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LONGWORD fails to change any of the hole bits of LONGWORD.
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1) Is this safe? Will it catch all the zero bytes?
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Suppose there is a byte with all zeros. Any carry bits
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propagating from its left will fall into the hole at its
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least significant bit and stop. Since there will be no
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carry from its most significant bit, the LSB of the
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byte to the left will be unchanged, and the zero will be
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detected.
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2) Is this worthwhile? Will it ignore everything except
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zero bytes? Suppose every byte of LONGWORD has a bit set
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somewhere. There will be a carry into bit 8. If bit 8
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is set, this will carry into bit 16. If bit 8 is clear,
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one of bits 9-15 must be set, so there will be a carry
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into bit 16. Similarly, there will be a carry into bit
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24. If one of bits 24-30 is set, there will be a carry
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into bit 31, so all of the hole bits will be changed.
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The one misfire occurs when bits 24-30 are clear and bit
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31 is set; in this case, the hole at bit 31 is not
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changed. If we had access to the processor carry flag,
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we could close this loophole by putting the fourth hole
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at bit 32!
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So it ignores everything except 128's, when they're aligned
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properly. */
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longword = *longword_ptr++;
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if ((longword - lomagic) & himagic)
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{
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/* Which of the bytes was the zero? If none of them were, it was
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a misfire; continue the search. */
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const char *cp = (const char *) (longword_ptr - 1);
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char_ptr = cp;
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if (cp[0] == 0)
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break;
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char_ptr = cp + 1;
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if (cp[1] == 0)
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break;
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char_ptr = cp + 2;
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if (cp[2] == 0)
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break;
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char_ptr = cp + 3;
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if (cp[3] == 0)
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break;
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if (sizeof (longword) > 4)
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{
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char_ptr = cp + 4;
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if (cp[4] == 0)
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break;
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char_ptr = cp + 5;
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if (cp[5] == 0)
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break;
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char_ptr = cp + 6;
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if (cp[6] == 0)
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break;
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char_ptr = cp + 7;
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if (cp[7] == 0)
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break;
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}
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}
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char_ptr = end_ptr;
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}
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if (char_ptr > end_ptr)
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char_ptr = end_ptr;
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return char_ptr - str;
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}
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weak_alias (__strnlen, strnlen)
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