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libbpf: simplify endianness check

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Rewrite endianness check to use "more canonical" way, using
compiler-defined macros, similar to few other places in libbpf. It also
is more obvious and shorter.

Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Andrii Nakryiko 2019-05-29 10:36:05 -07:00 committed by Daniel Borkmann
parent be5c5d4e9d
commit 12ef5634a8
1 changed files with 11 additions and 24 deletions
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35
tools/lib/bpf/libbpf.c
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@ -607,31 +607,18 @@ errout:
return err;
}
static int
bpf_object__check_endianness(struct bpf_object *obj)
static int bpf_object__check_endianness(struct bpf_object *obj)
{
static unsigned int const endian = 1;
switch (obj->efile.ehdr.e_ident[EI_DATA]) {
case ELFDATA2LSB:
/* We are big endian, BPF obj is little endian. */
if (*(unsigned char const *)&endian != 1)
goto mismatch;
break;
case ELFDATA2MSB:
/* We are little endian, BPF obj is big endian. */
if (*(unsigned char const *)&endian != 0)
goto mismatch;
break;
default:
return -LIBBPF_ERRNO__ENDIAN;
}
return 0;
mismatch:
pr_warning("Error: endianness mismatch.\n");
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
if (obj->efile.ehdr.e_ident[EI_DATA] == ELFDATA2LSB)
return 0;
#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
if (obj->efile.ehdr.e_ident[EI_DATA] == ELFDATA2MSB)
return 0;
#else
# error "Unrecognized __BYTE_ORDER__"
#endif
pr_warning("endianness mismatch.\n");
return -LIBBPF_ERRNO__ENDIAN;
}