commonlib/lz4_wrapper.c: do not use bitfields
Order of bits in bitfields is implementation-defined. This makes them
non-portable, especially across systems using different endianness.
This change removes bitfields and uses masking and shifting instead.
Signed-off-by: Krystian Hebel <krystian.hebel@3mdeb.com>
Change-Id: Ief7d87ddb25c9baa931f27dbd54a4ca730b6ece7
Reviewed-on: https://review.coreboot.org/c/coreboot/+/55040
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
diff --git a/src/commonlib/bsd/lz4_wrapper.c b/src/commonlib/bsd/lz4_wrapper.c
index 73185a5..73a3571 100644
--- a/src/commonlib/bsd/lz4_wrapper.c
+++ b/src/commonlib/bsd/lz4_wrapper.c
@@ -63,39 +63,32 @@
#define LZ4F_MAGICNUMBER 0x184D2204
+/* Bit field endianness is implementation-defined. Use masks instead.
+ * https://stackoverflow.com/a/6044223 */
+#define RESERVED0 0x03
+#define HAS_CONTENT_CHECKSUM 0x04
+#define HAS_CONTENT_SIZE 0x08
+#define HAS_BLOCK_CHECKSUM 0x10
+#define INDEPENDENT_BLOCKS 0x20
+#define VERSION 0xC0
+#define VERSION_SHIFT 6
+
+#define RESERVED1_2 0x8F
+#define MAX_BLOCK_SIZE 0x70
+
struct lz4_frame_header {
uint32_t magic;
- union {
- uint8_t flags;
- struct {
- uint8_t reserved0 : 2;
- uint8_t has_content_checksum : 1;
- uint8_t has_content_size : 1;
- uint8_t has_block_checksum : 1;
- uint8_t independent_blocks : 1;
- uint8_t version : 2;
- };
- };
- union {
- uint8_t block_descriptor;
- struct {
- uint8_t reserved1 : 4;
- uint8_t max_block_size : 3;
- uint8_t reserved2 : 1;
- };
- };
+ uint8_t flags;
+ uint8_t block_descriptor;
/* + uint64_t content_size iff has_content_size is set */
/* + uint8_t header_checksum */
} __packed;
+#define BH_SIZE 0x7FFFFFFF
+#define NOT_COMPRESSED 0x80000000
+
struct lz4_block_header {
- union {
- uint32_t raw;
- struct {
- uint32_t size : 31;
- uint32_t not_compressed : 1;
- };
- };
+ uint32_t raw;
/* + size bytes of data */
/* + uint32_t block_checksum iff has_block_checksum is set */
} __packed;
@@ -114,16 +107,17 @@
return 0; /* input overrun */
/* We assume there's always only a single, standard frame. */
- if (le32toh(h->magic) != LZ4F_MAGICNUMBER || h->version != 1)
+ if (le32toh(h->magic) != LZ4F_MAGICNUMBER
+ || (h->flags & VERSION) != (1 << VERSION_SHIFT))
return 0; /* unknown format */
- if (h->reserved0 || h->reserved1 || h->reserved2)
+ if ((h->flags & RESERVED0) || (h->block_descriptor & RESERVED1_2))
return 0; /* reserved must be zero */
- if (!h->independent_blocks)
+ if (!(h->flags & INDEPENDENT_BLOCKS))
return 0; /* we don't support block dependency */
- has_block_checksum = h->has_block_checksum;
+ has_block_checksum = h->flags & HAS_BLOCK_CHECKSUM;
in += sizeof(*h);
- if (h->has_content_size)
+ if (h->flags & HAS_CONTENT_SIZE)
in += sizeof(uint64_t);
in += sizeof(uint8_t);
}
@@ -133,28 +127,28 @@
break; /* input overrun */
struct lz4_block_header b = {
- { .raw = le32toh(*(const uint32_t *)in) }
+ .raw = le32toh(*(const uint32_t *)in)
};
in += sizeof(struct lz4_block_header);
- if ((size_t)(in - src) + b.size > srcn)
+ if ((size_t)(in - src) + (b.raw & BH_SIZE) > srcn)
break; /* input overrun */
- if (!b.size) {
+ if (!(b.raw & BH_SIZE)) {
out_size = out - dst;
break; /* decompression successful */
}
- if (b.not_compressed) {
- size_t size = MIN((uintptr_t)b.size, (uintptr_t)dst
+ if (b.raw & NOT_COMPRESSED) {
+ size_t size = MIN((uintptr_t)(b.raw & BH_SIZE), (uintptr_t)dst
+ dstn - (uintptr_t)out);
memcpy(out, in, size);
- if (size < b.size)
+ if (size < (b.raw & BH_SIZE))
break; /* output overrun */
out += size;
} else {
/* constant folding essential, do not touch params! */
- int ret = LZ4_decompress_generic(in, out, b.size,
+ int ret = LZ4_decompress_generic(in, out, (b.raw & BH_SIZE),
dst + dstn - out, endOnInputSize,
full, 0, noDict, out, NULL, 0);
if (ret < 0)
@@ -162,7 +156,7 @@
out += ret;
}
- in += b.size;
+ in += (b.raw & BH_SIZE);
if (has_block_checksum)
in += sizeof(uint32_t);
}