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-rw-r--r--src/liblzma/api/lzma/stream_flags.h84
-rw-r--r--src/liblzma/common/stream_decoder.c5
-rw-r--r--src/liblzma/common/stream_encoder.c2
-rw-r--r--src/liblzma/common/stream_flags_common.c28
-rw-r--r--src/liblzma/common/stream_flags_common.h9
-rw-r--r--src/liblzma/common/stream_flags_decoder.c3
-rw-r--r--src/liblzma/common/stream_flags_encoder.c10
-rw-r--r--tests/test_stream_flags.c8
8 files changed, 129 insertions, 20 deletions
diff --git a/src/liblzma/api/lzma/stream_flags.h b/src/liblzma/api/lzma/stream_flags.h
index 80c5f00f..bb080ac7 100644
--- a/src/liblzma/api/lzma/stream_flags.h
+++ b/src/liblzma/api/lzma/stream_flags.h
@@ -36,8 +36,37 @@
*/
typedef struct {
/**
+ * \brief Stream Flags format version
+ *
+ * To prevent API and ABI breakages if new features are needed in
+ * Stream Header or Stream Footer, a version number is used to
+ * indicate which fields in this structure are in use. For now,
+ * version must always be zero. With non-zero version, the
+ * lzma_stream_header_encode() and lzma_stream_footer_encode()
+ * will return LZMA_HEADER_ERROR.
+ *
+ * lzma_stream_header_decode() and lzma_stream_footer_decode()
+ * will always set this to the lowest value that supports all the
+ * features indicated by the Stream Flags field. The application
+ * must check that the version number set by the decoding functions
+ * is supported by the application. Otherwise it is possible that
+ * the application will decode the Stream incorrectly.
+ */
+ uint32_t version;
+
+ /**
* Backward Size must be a multiple of four bytes. In this Stream
* format version Backward Size is the size of the Index field.
+ *
+ * Backward Size isn't actually part of the Stream Flags field, but
+ * it is convenient to include in this structure anyway. Backward
+ * Size is present only in the Stream Footer. There is no need to
+ * initialize backward_size when encoding Stream Header.
+ *
+ * lzma_stream_header_decode() always sets backward_size to
+ * LZMA_VLI_VALUE_UNKNOWN so that it is convenient to use
+ * lzma_stream_flags_compare() when both Stream Header and Stream
+ * Footer have been decoded.
*/
lzma_vli backward_size;
# define LZMA_BACKWARD_SIZE_MIN 4
@@ -48,6 +77,34 @@ typedef struct {
*/
lzma_check check;
+ /**
+ * Reserved space to allow possible future extensions without
+ * breaking the ABI. You should not touch these, because the
+ * names of these variables may change.
+ *
+ * (We will never be able to use all of these since Stream Flags
+ * is just two bytes plus Backward Size of four bytes. But it's
+ * nice to have the proper types when they are needed.)
+ */
+ lzma_reserved_enum reserved_enum1;
+ lzma_reserved_enum reserved_enum2;
+ lzma_reserved_enum reserved_enum3;
+ lzma_reserved_enum reserved_enum4;
+ lzma_reserved_enum reserved_enum5;
+ lzma_reserved_enum reserved_enum6;
+ lzma_bool reserved_bool1;
+ lzma_bool reserved_bool2;
+ lzma_bool reserved_bool3;
+ lzma_bool reserved_bool4;
+ lzma_bool reserved_bool5;
+ lzma_bool reserved_bool6;
+ lzma_bool reserved_bool7;
+ lzma_bool reserved_bool8;
+ uint32_t reserved_int1;
+ uint32_t reserved_int2;
+ uint32_t reserved_int3;
+ uint32_t reserved_int4;
+
} lzma_stream_flags;
@@ -61,6 +118,8 @@ typedef struct {
* need to be initialized.
*
* \return - LZMA_OK: Encoding was successful.
+ * - LZMA_HEADER_ERROR: options->version is not supported by
+ * this liblzma version.
* - LZMA_PROG_ERROR: Invalid options.
*/
extern lzma_ret lzma_stream_header_encode(
@@ -76,6 +135,8 @@ extern lzma_ret lzma_stream_header_encode(
* \param options Stream Footer options to be encoded.
*
* \return - LZMA_OK: Encoding was successful.
+ * - LZMA_HEADER_ERROR: options->version is not supported by
+ * this liblzma version.
* - LZMA_PROG_ERROR: Invalid options.
*/
extern lzma_ret lzma_stream_footer_encode(
@@ -92,7 +153,7 @@ extern lzma_ret lzma_stream_footer_encode(
*
* options->index_size is always set to LZMA_VLI_VALUE_UNKNOWN. This is to
* help comparing Stream Flags from Stream Header and Stream Footer with
- * lzma_stream_flags_equal().
+ * lzma_stream_flags_compare().
*
* \return - LZMA_OK: Decoding was successful.
* - LZMA_FORMAT_ERROR: Magic bytes don't match, thus the given
@@ -121,6 +182,13 @@ extern lzma_ret lzma_stream_header_decode(
* is corrupt.
* - LZMA_HEADER_ERROR: Unsupported options are present
* in the footer.
+ *
+ * \note If Stream Header was already decoded successfully, but
+ * decoding Stream Footer returns LZMA_FORMAT_ERROR, the
+ * application should probably report some other error message
+ * than "unsupported file format", since the file more likely is
+ * corrupt (possibly truncated). Stream decoder in liblzma uses
+ * LZMA_DATA_ERROR in this situation.
*/
extern lzma_ret lzma_stream_footer_decode(
lzma_stream_flags *options, const uint8_t *in)
@@ -130,10 +198,18 @@ extern lzma_ret lzma_stream_footer_decode(
/**
* \brief Compare two lzma_stream_flags structures
*
- * index_size values are compared only if both are not LZMA_VLI_VALUE_UNKNOWN.
+ * backward_size values are compared only if both are not
+ * LZMA_VLI_VALUE_UNKNOWN.
*
- * \return true if both structures are considered equal; false otherwise.
+ * \return - LZMA_OK: Both are equal. If either had backward_size set
+ * to LZMA_VLI_VALUE_UNKNOWN, backward_size values were not
+ * compared or validated.
+ * - LZMA_DATA_ERROR: The structures differ.
+ * - LZMA_HEADER_ERROR: version in either structure is greater
+ * than the maximum supported version (currently zero).
+ * - LZMA_PROG_ERROR: Invalid value, e.g. invalid check or
+ * backward_size.
*/
-extern lzma_bool lzma_stream_flags_equal(
+extern lzma_ret lzma_stream_flags_compare(
const lzma_stream_flags *a, const lzma_stream_flags *b)
lzma_attr_pure;
diff --git a/src/liblzma/common/stream_decoder.c b/src/liblzma/common/stream_decoder.c
index 884c4e9d..5360d87c 100644
--- a/src/liblzma/common/stream_decoder.c
+++ b/src/liblzma/common/stream_decoder.c
@@ -294,9 +294,8 @@ stream_decode(lzma_coder *coder, lzma_allocator *allocator,
// Compare that the Stream Flags fields are identical in
// both Stream Header and Stream Footer.
- if (!lzma_stream_flags_equal(&coder->stream_flags,
- &footer_flags))
- return LZMA_DATA_ERROR;
+ return_if_error(lzma_stream_flags_compare(
+ &coder->stream_flags, &footer_flags));
if (!coder->concatenated)
return LZMA_STREAM_END;
diff --git a/src/liblzma/common/stream_encoder.c b/src/liblzma/common/stream_encoder.c
index b21ee652..8748f52e 100644
--- a/src/liblzma/common/stream_encoder.c
+++ b/src/liblzma/common/stream_encoder.c
@@ -180,6 +180,7 @@ stream_encode(lzma_coder *coder, lzma_allocator *allocator,
// Encode the Stream Footer into coder->buffer.
const lzma_stream_flags stream_flags = {
+ .version = 0,
.backward_size = lzma_index_size(coder->index),
.check = coder->block_options.check,
};
@@ -247,6 +248,7 @@ lzma_stream_encoder_init(lzma_next_coder *next, lzma_allocator *allocator,
// Encode the Stream Header
lzma_stream_flags stream_flags = {
+ .version = 0,
.check = check,
};
return_if_error(lzma_stream_header_encode(
diff --git a/src/liblzma/common/stream_flags_common.c b/src/liblzma/common/stream_flags_common.c
index c44b3ff2..aaa9fe02 100644
--- a/src/liblzma/common/stream_flags_common.c
+++ b/src/liblzma/common/stream_flags_common.c
@@ -24,17 +24,31 @@ const uint8_t lzma_header_magic[6] = { 0xFF, 0x4C, 0x5A, 0x4D, 0x41, 0x00 };
const uint8_t lzma_footer_magic[2] = { 0x59, 0x5A };
-extern LZMA_API lzma_bool
-lzma_stream_flags_equal(const lzma_stream_flags *a, const lzma_stream_flags *b)
+extern LZMA_API lzma_ret
+lzma_stream_flags_compare(
+ const lzma_stream_flags *a, const lzma_stream_flags *b)
{
+ // We can compare only version 0 structures.
+ if (a->version != 0 || b->version != 0)
+ return LZMA_HEADER_ERROR;
+
+ // Check type
+ if ((unsigned int)(a->check) > LZMA_CHECK_ID_MAX
+ || (unsigned int)(b->check) > LZMA_CHECK_ID_MAX)
+ return LZMA_PROG_ERROR;
+
if (a->check != b->check)
- return false;
+ return LZMA_DATA_ERROR;
// Backward Sizes are compared only if they are known in both.
if (a->backward_size != LZMA_VLI_VALUE_UNKNOWN
- && b->backward_size != LZMA_VLI_VALUE_UNKNOWN
- && a->backward_size != b->backward_size)
- return false;
+ && b->backward_size != LZMA_VLI_VALUE_UNKNOWN) {
+ if (!is_backward_size_valid(a) || !is_backward_size_valid(b))
+ return LZMA_PROG_ERROR;
+
+ if (a->backward_size != b->backward_size)
+ return LZMA_DATA_ERROR;
+ }
- return true;
+ return LZMA_OK;
}
diff --git a/src/liblzma/common/stream_flags_common.h b/src/liblzma/common/stream_flags_common.h
index 6e57857b..f422b02a 100644
--- a/src/liblzma/common/stream_flags_common.h
+++ b/src/liblzma/common/stream_flags_common.h
@@ -28,4 +28,13 @@
extern const uint8_t lzma_header_magic[6];
extern const uint8_t lzma_footer_magic[2];
+
+static inline bool
+is_backward_size_valid(const lzma_stream_flags *options)
+{
+ return options->backward_size >= LZMA_BACKWARD_SIZE_MIN
+ && options->backward_size <= LZMA_BACKWARD_SIZE_MAX
+ && (options->backward_size & 3) == 0;
+}
+
#endif
diff --git a/src/liblzma/common/stream_flags_decoder.c b/src/liblzma/common/stream_flags_decoder.c
index ccc1539d..a54ce813 100644
--- a/src/liblzma/common/stream_flags_decoder.c
+++ b/src/liblzma/common/stream_flags_decoder.c
@@ -27,6 +27,7 @@ stream_flags_decode(lzma_stream_flags *options, const uint8_t *in)
if (in[0] != 0x00 || (in[1] & 0xF0))
return true;
+ options->version = 0;
options->check = in[1] & 0x0F;
return false;
@@ -53,7 +54,7 @@ lzma_stream_header_decode(lzma_stream_flags *options, const uint8_t *in)
return LZMA_HEADER_ERROR;
// Set Backward Size to indicate unknown value. That way
- // lzma_stream_flags_equal can be used to compare Stream Header
+ // lzma_stream_flags_compare() can be used to compare Stream Header
// and Stream Footer while keeping it useful also for comparing
// two Stream Footers.
options->backward_size = LZMA_VLI_VALUE_UNKNOWN;
diff --git a/src/liblzma/common/stream_flags_encoder.c b/src/liblzma/common/stream_flags_encoder.c
index 1d736a8a..88ed81e0 100644
--- a/src/liblzma/common/stream_flags_encoder.c
+++ b/src/liblzma/common/stream_flags_encoder.c
@@ -39,6 +39,9 @@ lzma_stream_header_encode(const lzma_stream_flags *options, uint8_t *out)
assert(sizeof(lzma_header_magic) + LZMA_STREAM_FLAGS_SIZE
+ 4 == LZMA_STREAM_HEADER_SIZE);
+ if (options->version != 0)
+ return LZMA_HEADER_ERROR;
+
// Magic
memcpy(out, lzma_header_magic, sizeof(lzma_header_magic));
@@ -63,10 +66,11 @@ lzma_stream_footer_encode(const lzma_stream_flags *options, uint8_t *out)
assert(2 * 4 + LZMA_STREAM_FLAGS_SIZE + sizeof(lzma_footer_magic)
== LZMA_STREAM_HEADER_SIZE);
+ if (options->version != 0)
+ return LZMA_HEADER_ERROR;
+
// Backward Size
- if (options->backward_size < LZMA_BACKWARD_SIZE_MIN
- || options->backward_size > LZMA_BACKWARD_SIZE_MAX
- || (options->backward_size & 3))
+ if (!is_backward_size_valid(options))
return LZMA_PROG_ERROR;
integer_write_32(out + 4, options->backward_size / 4 - 1);
diff --git a/tests/test_stream_flags.c b/tests/test_stream_flags.c
index ead75501..abd0296d 100644
--- a/tests/test_stream_flags.c
+++ b/tests/test_stream_flags.c
@@ -28,7 +28,11 @@ static uint8_t buffer[LZMA_STREAM_HEADER_SIZE];
static bool
validate(void)
{
- return !lzma_stream_flags_equal(&known_flags, &decoded_flags);
+ // TODO: This could require the specific error type as an argument.
+ // We could also test that lzma_stream_flags_compare() gives
+ // the correct return values in different situations.
+ return lzma_stream_flags_compare(&known_flags, &decoded_flags)
+ != LZMA_OK;
}
@@ -44,7 +48,7 @@ test_header_decoder(lzma_ret expected_ret)
return false;
// Header doesn't have Backward Size, so make
- // lzma_stream_flags_equal() ignore it.
+ // lzma_stream_flags_compare() ignore it.
decoded_flags.backward_size = LZMA_VLI_VALUE_UNKNOWN;
return validate();
}
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-10 23:06:36 +0000