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Bug 16458 reports that the endian-conversion macros in <endian.h> and
<netinet/in.h>, in the case where no endian conversion is needed, just
return their arguments without converting to the expected return type,
so failing to act as expected for a macro version of a function. (The
<netinet/in.h> macros, in particular, are described with prototypes in
POSIX so should act like correspondingly prototyped functions.)
Where previously this was a fairly obscure issue, it now results in
glibc build with GCC mainline breaking for big-endian systems:
nss_hesiod/hesiod-service.c: In function '_nss_hesiod_getservbyport_r':
nss_hesiod/hesiod-service.c:142:39: error: '%d' directive output may be truncated writing between 1 and 11 bytes into a region of size 6 [-Werror=format-truncation=]
snprintf (portstr, sizeof portstr, "%d", ntohs (port));
^~
nss_hesiod/hesiod-service.c:142:38: note: using the range [1, -2147483648] for directive argument
snprintf (portstr, sizeof portstr, "%d", ntohs (port));
^~~~
nss_hesiod/hesiod-service.c:142:3: note: format output between 2 and 12 bytes into a destination of size 6
snprintf (portstr, sizeof portstr, "%d", ntohs (port));
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The port argument is passed as int to this function, so when ntohs
does not convert the compiler cannot tell that the result is within
the range of uint16_t. (I don't know if in fact it's possible for
out-of-range values to reach this function and so get truncated as
strings without this patch or as integers with it.)
This patch arranges for these macros to use identity functions to
ensure appropriate conversions while having warnings for implicit
conversions of function arguments that might not occur with a cast.
Tested for x86_64 and x86; with build-many-glibcs.py with GCC 6; and
with build-many-glibcs.py with GCC mainline for powerpc to test the
build fix.
[BZ #16458]
* bits/uintn-identity.h: New file.
* inet/netinet/in.h: Include <bits/uintn-identity.h>.
[__BYTE_ORDER == __BIG_ENDIAN] (ntohl): Use __uint32_identity.
[__BYTE_ORDER == __BIG_ENDIAN] (ntohs): Use __uint16_identity.
[__BYTE_ORDER == __BIG_ENDIAN] (htonl): Use __uint32_identity.
[__BYTE_ORDER == __BIG_ENDIAN] (htohs): Use __uint16_identity.
* string/endian.h: Include <bits/uintn-identity.h>.
[__BYTE_ORDER == __LITTLE_ENDIAN] (htole16): Use
__uint16_identity.
[__BYTE_ORDER == __LITTLE_ENDIAN] (le16toh): Likewise.
[__BYTE_ORDER == __LITTLE_ENDIAN] (htole32): Use
__uint32_identity.
[__BYTE_ORDER == __LITTLE_ENDIAN] (le32toh): Likewise.
[__BYTE_ORDER == __LITTLE_ENDIAN] (htole64): Use
__uint64_identity.
[__BYTE_ORDER == __LITTLE_ENDIAN] (le64toh): Likewise.
[__BYTE_ORDER != __LITTLE_ENDIAN] (htobe16): Use
__uint16_identity.
[__BYTE_ORDER != __LITTLE_ENDIAN] (be16toh): Likewise.
[__BYTE_ORDER != __LITTLE_ENDIAN] (htobe32): Use
__uint32_identity.
[__BYTE_ORDER != __LITTLE_ENDIAN] (be32toh): Likewise.
[__BYTE_ORDER != __LITTLE_ENDIAN] (htobe64): Use
__uint64_identity.
[__BYTE_ORDER != __LITTLE_ENDIAN] (be64toh): Likewise.
* string/Makefile (headers): Add bits/uintn-identity.h.
(tests): Add test-endian-types.
* string/test-endian-types.c: New file.
* inet/Makefile (tests): Add test-hnto-types.
* inet/test-hnto-types.c: New file.
98 lines
3.1 KiB
C
98 lines
3.1 KiB
C
/* Copyright (C) 1992-2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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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
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License as published by the Free Software Foundation; either
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version 2.1 of the 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; if not, see
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<http://www.gnu.org/licenses/>. */
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#ifndef _ENDIAN_H
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#define _ENDIAN_H 1
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#include <features.h>
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/* Definitions for byte order, according to significance of bytes,
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from low addresses to high addresses. The value is what you get by
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putting '4' in the most significant byte, '3' in the second most
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significant byte, '2' in the second least significant byte, and '1'
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in the least significant byte, and then writing down one digit for
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each byte, starting with the byte at the lowest address at the left,
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and proceeding to the byte with the highest address at the right. */
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#define __LITTLE_ENDIAN 1234
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#define __BIG_ENDIAN 4321
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#define __PDP_ENDIAN 3412
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/* This file defines `__BYTE_ORDER' for the particular machine. */
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#include <bits/endian.h>
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/* Some machines may need to use a different endianness for floating point
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values. */
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#ifndef __FLOAT_WORD_ORDER
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# define __FLOAT_WORD_ORDER __BYTE_ORDER
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#endif
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#ifdef __USE_MISC
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# define LITTLE_ENDIAN __LITTLE_ENDIAN
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# define BIG_ENDIAN __BIG_ENDIAN
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# define PDP_ENDIAN __PDP_ENDIAN
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# define BYTE_ORDER __BYTE_ORDER
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#endif
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#if __BYTE_ORDER == __LITTLE_ENDIAN
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# define __LONG_LONG_PAIR(HI, LO) LO, HI
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#elif __BYTE_ORDER == __BIG_ENDIAN
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# define __LONG_LONG_PAIR(HI, LO) HI, LO
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#endif
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#if defined __USE_MISC && !defined __ASSEMBLER__
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/* Conversion interfaces. */
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# include <bits/byteswap.h>
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# include <bits/uintn-identity.h>
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# if __BYTE_ORDER == __LITTLE_ENDIAN
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# define htobe16(x) __bswap_16 (x)
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# define htole16(x) __uint16_identity (x)
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# define be16toh(x) __bswap_16 (x)
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# define le16toh(x) __uint16_identity (x)
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# define htobe32(x) __bswap_32 (x)
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# define htole32(x) __uint32_identity (x)
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# define be32toh(x) __bswap_32 (x)
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# define le32toh(x) __uint32_identity (x)
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# define htobe64(x) __bswap_64 (x)
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# define htole64(x) __uint64_identity (x)
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# define be64toh(x) __bswap_64 (x)
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# define le64toh(x) __uint64_identity (x)
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# else
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# define htobe16(x) __uint16_identity (x)
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# define htole16(x) __bswap_16 (x)
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# define be16toh(x) __uint16_identity (x)
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# define le16toh(x) __bswap_16 (x)
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# define htobe32(x) __uint32_identity (x)
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# define htole32(x) __bswap_32 (x)
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# define be32toh(x) __uint32_identity (x)
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# define le32toh(x) __bswap_32 (x)
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# define htobe64(x) __uint64_identity (x)
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# define htole64(x) __bswap_64 (x)
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# define be64toh(x) __uint64_identity (x)
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# define le64toh(x) __bswap_64 (x)
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# endif
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#endif
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#endif /* endian.h */
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