patches/glibc/2_9/210-2.9-strlen-hack.patch
author "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>
Mon Feb 02 22:00:18 2009 +0000 (2009-02-02)
changeset 1201 c9967a6e3b25
permissions -rw-r--r--
Add a patchset for glibc 2_9. Vampirised from the gentoo repository.

/trunk/patches/glibc/2_9/500-ppc-glibc-2.9-atomic.patch | 414 414 0 0 ++++++++++
/trunk/patches/glibc/2_9/140-regex-BZ9697.patch | 111 111 0 0 +++
/trunk/patches/glibc/2_9/190-queue-header-updates.patch | 89 89 0 0 ++
/trunk/patches/glibc/2_9/370-hppa_glibc-2.7-hppa-nptl-carlos.patch | 249 249 0 0 ++++++
/trunk/patches/glibc/2_9/450-alpha-glibc-2.5-no-page-header.patch | 32 32 0 0 +
/trunk/patches/glibc/2_9/270-ldbl-nexttowardf.patch | 68 68 0 0 ++
/trunk/patches/glibc/2_9/330-2.3.3-china.patch | 35 35 0 0 +
/trunk/patches/glibc/2_9/340-new-valencian-locale.patch | 120 120 0 0 +++
/trunk/patches/glibc/2_9/410-2.9-fnmatch.patch | 64 64 0 0 ++
/trunk/patches/glibc/2_9/350-2.4-undefine-__i686.patch | 47 47 0 0 +
/trunk/patches/glibc/2_9/160-i386-x86_64-revert-clone-cfi.patch | 53 53 0 0 +
/trunk/patches/glibc/2_9/420-dont-build-timezone.patch | 19 19 0 0 +
/trunk/patches/glibc/2_9/150-regex-BZ697.patch | 28 28 0 0 +
/trunk/patches/glibc/2_9/290-no-inline-gmon.patch | 38 38 0 0 +
/trunk/patches/glibc/2_9/280-section-comments.patch | 29 29 0 0 +
/trunk/patches/glibc/2_9/180-math-tests.patch | 72 72 0 0 ++
/trunk/patches/glibc/2_9/120-_nss_dns_gethostbyaddr2_r-check-and-adjust-the-buffer-alignment.patch | 35 35 0 0 +
/trunk/patches/glibc/2_9/250-resolv-dynamic.patch | 44 44 0 0 +
/trunk/patches/glibc/2_9/300-2.9-check_native-headers.patch | 22 22 0 0 +
/trunk/patches/glibc/2_9/310-2.3.6-fix-pr631.patch | 50 50 0 0 +
/trunk/patches/glibc/2_9/130-add_prio-macros.patch | 26 26 0 0 +
/trunk/patches/glibc/2_9/260-fadvise64_64.patch | 30 30 0 0 +
/trunk/patches/glibc/2_9/440-alpha-glibc-2.4-xstat.patch | 249 249 0 0 ++++++
/trunk/patches/glibc/2_9/170-2.10-dns-no-gethostbyname4.patch | 35 35 0 0 +
/trunk/patches/glibc/2_9/230-2.3.3-localedef-fix-trampoline.patch | 74 74 0 0 ++
/trunk/patches/glibc/2_9/360-2.8-nscd-one-fork.patch | 45 45 0 0 +
/trunk/patches/glibc/2_9/480-alpha-glibc-2.8-cache-shape.patch | 18 18 0 0 +
/trunk/patches/glibc/2_9/210-2.9-strlen-hack.patch | 109 109 0 0 +++
/trunk/patches/glibc/2_9/320-2.9-assume-pipe2.patch | 59 59 0 0 +
/trunk/patches/glibc/2_9/100-ssp-compat.patch | 193 193 0 0 +++++
/trunk/patches/glibc/2_9/110-respect-env-CPPFLAGS.patch | 30 30 0 0 +
/trunk/patches/glibc/2_9/220-manual-no-perl.patch | 29 29 0 0 +
/trunk/patches/glibc/2_9/390-2.3.3_pre20040117-pt_pax.patch | 35 35 0 0 +
/trunk/patches/glibc/2_9/460-alpha-glibc-2.5-no-asm-elf-header.patch | 38 38 0 0 +
/trunk/patches/glibc/2_9/400-tests-sandbox-libdl-paths.patch | 198 198 0 0 +++++
/trunk/patches/glibc/2_9/240-i386-LOAD_PIC_REG.patch | 23 23 0 0 +
/trunk/patches/glibc/2_9/200-awk-in-C-locale.patch | 23 23 0 0 +
/trunk/patches/glibc/2_9/430-2.7-cross-compile-nptl.patch | 57 57 0 0 +
/trunk/patches/glibc/2_9/380-2.3.6-dl_execstack-PaX-support.patch | 71 71 0 0 ++
/trunk/patches/glibc/2_9/490-ptr-mangling.patch | 114 114 0 0 +++
/trunk/patches/glibc/2_9/470-alpha-glibc-2.8-creat.patch | 19 19 0 0 +
41 files changed, 3094 insertions(+)
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Original patch from: gentoo/src/patchsets/glibc/2.9/1020_all_glibc-2.9-strlen-hack.patch
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-= BEGIN original header =-
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http://sourceware.org/bugzilla/show_bug.cgi?id=5807
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http://www.cl.cam.ac.uk/~am21/progtricks.html
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-= END original header =-
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diff -durN glibc-2_9.orig/string/strlen.c glibc-2_9/string/strlen.c
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--- glibc-2_9.orig/string/strlen.c	2005-12-14 12:09:07.000000000 +0100
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+++ glibc-2_9/string/strlen.c	2009-02-02 22:00:51.000000000 +0100
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@@ -32,7 +32,7 @@
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 {
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   const char *char_ptr;
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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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+  unsigned long int longword, himagic, lomagic;
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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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@@ -42,28 +42,14 @@
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     if (*char_ptr == '\0')
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       return char_ptr - str;
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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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-
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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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-
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-     bits:  01111110 11111110 11111110 11111111
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-     bytes: AAAAAAAA BBBBBBBB CCCCCCCC DDDDDDDD
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-
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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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@@ -75,56 +61,12 @@
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      if *any of the four* bytes in the longword in question are zero.  */
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   for (;;)
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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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-
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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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-
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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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-
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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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-
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-	 So it ignores everything except 128's, when they're aligned
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-	 properly.  */
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-
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       longword = *longword_ptr++;
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-      if (
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-#if 0
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-	  /* Add MAGIC_BITS to LONGWORD.  */
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-	  (((longword + magic_bits)
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-
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-	    /* Set those bits that were unchanged by the addition.  */
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-	    ^ ~longword)
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-
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-	   /* Look at only the hole bits.  If any of the hole bits
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-	      are unchanged, most likely one of the bytes was a
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-	      zero.  */
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-	   & ~magic_bits)
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-#else
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-	  ((longword - lomagic) & himagic)
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-#endif
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-	  != 0)
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+      /* This hack taken from Alan Mycroft's HAKMEMC postings.
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+         See: http://www.cl.cam.ac.uk/~am21/progtricks.html */
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+      if (((longword - lomagic) & ~longword & himagic) != 0)
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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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