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authorJoseph Myers <joseph@codesourcery.com>2017-01-11 15:28:08 +0000
committerJoseph Myers <joseph@codesourcery.com>2017-01-11 15:28:08 +0000
commit6a1cefac196f45d766027c97a6c8c44459c9cccd (patch)
treebbb56dea2158d008c1bfa2d12f30d0cabbbda55e /string/endian.h
parentbb440151433f0298e7a6786ccd30cd084812f897 (diff)
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Make endian-conversion macros always return correct types (bug 16458).
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.
Diffstat (limited to 'string/endian.h')
-rw-r--r--string/endian.h25
1 files changed, 13 insertions, 12 deletions
diff --git a/string/endian.h b/string/endian.h
index 18e67085b4..dcc9a65df7 100644
--- a/string/endian.h
+++ b/string/endian.h
@@ -58,37 +58,38 @@
#if defined __USE_MISC && !defined __ASSEMBLER__
/* Conversion interfaces. */
# include <bits/byteswap.h>
+# include <bits/uintn-identity.h>
# if __BYTE_ORDER == __LITTLE_ENDIAN
# define htobe16(x) __bswap_16 (x)
-# define htole16(x) (x)
+# define htole16(x) __uint16_identity (x)
# define be16toh(x) __bswap_16 (x)
-# define le16toh(x) (x)
+# define le16toh(x) __uint16_identity (x)
# define htobe32(x) __bswap_32 (x)
-# define htole32(x) (x)
+# define htole32(x) __uint32_identity (x)
# define be32toh(x) __bswap_32 (x)
-# define le32toh(x) (x)
+# define le32toh(x) __uint32_identity (x)
# define htobe64(x) __bswap_64 (x)
-# define htole64(x) (x)
+# define htole64(x) __uint64_identity (x)
# define be64toh(x) __bswap_64 (x)
-# define le64toh(x) (x)
+# define le64toh(x) __uint64_identity (x)
# else
-# define htobe16(x) (x)
+# define htobe16(x) __uint16_identity (x)
# define htole16(x) __bswap_16 (x)
-# define be16toh(x) (x)
+# define be16toh(x) __uint16_identity (x)
# define le16toh(x) __bswap_16 (x)
-# define htobe32(x) (x)
+# define htobe32(x) __uint32_identity (x)
# define htole32(x) __bswap_32 (x)
-# define be32toh(x) (x)
+# define be32toh(x) __uint32_identity (x)
# define le32toh(x) __bswap_32 (x)
-# define htobe64(x) (x)
+# define htobe64(x) __uint64_identity (x)
# define htole64(x) __bswap_64 (x)
-# define be64toh(x) (x)
+# define be64toh(x) __uint64_identity (x)
# define le64toh(x) __bswap_64 (x)
# endif
#endif