riot-ci/RIOT
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

cbor: Packed struct to bypass unaligned stack

Browse Source 
This can happen due to cast using buggy GCC on ARMv7

Credit to our shy french pal
This commit is contained in:
Matias Devenuta 2015-11-06 19:12:12 -03:00 committed by Oleg Hahm
parent 5f26b7686f
commit 63bcccf43d
1 changed files with 18 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
sys/cbor/cbor.c
View File

@ -95,7 +95,20 @@
#define NAN (0.0/0.0) #define NAN (0.0/0.0)
#endif #endif
/* pack to force aligned access on ARMv7 (buggy GCC) */
#pragma GCC diagnostic error "-Wcast-align"
typedef struct __attribute__((packed)) {
unsigned char u8;
union {
uint16_t u16;
uint32_t u32;
uint64_t u64;
} u;
} cast_align_u8_t;
#ifndef CBOR_NO_FLOAT #ifndef CBOR_NO_FLOAT
/** /**
* Convert float @p x to network format * Convert float @p x to network format
*/ */
@ -345,15 +358,15 @@ static size_t decode_int(const cbor_stream_t *s, size_t offset, uint64_t *val)
break; break;
case 2: case 2:
*val = HTONS(*((uint16_t *)&in[1])); *val = HTONS(((cast_align_u8_t *)in)->u.u16);
break; break;
case 4: case 4:
*val = HTONL(*((uint32_t *)&in[1])); *val = HTONL(((cast_align_u8_t *)in)->u.u32);
break; break;
default: default:
*val = HTONLL(*((uint64_t *)&in[1])); *val = HTONLL(((cast_align_u8_t *)in)->u.u64);
break; break;
} }
@ -565,7 +578,7 @@ size_t cbor_deserialize_float(const cbor_stream_t *stream, size_t offset, float
unsigned char *data = &stream->data[offset]; unsigned char *data = &stream->data[offset];
if (*data == CBOR_FLOAT32) { if (*data == CBOR_FLOAT32) {
*val = ntohf(*(uint32_t *)(data + 1)); *val = ntohf(((cast_align_u8_t *)data)->u.u32);
return 5; return 5;
} }
@ -594,7 +607,7 @@ size_t cbor_deserialize_double(const cbor_stream_t *stream, size_t offset, doubl
if (*data == CBOR_FLOAT64) { if (*data == CBOR_FLOAT64) {
CBOR_ENSURE_SIZE_READ(stream, offset + 9); CBOR_ENSURE_SIZE_READ(stream, offset + 9);
*val = ntohd(*(uint64_t *)(data + 1)); *val = ntohd(((cast_align_u8_t *)data)->u.u64);
return 9; return 9;
} }