[PATCH 1/2] DRAFT *** lib/xz: Use size_t instead of uint32_t in a few places

[Lasse Collin]

Now both arguments to min() have the same type. This is required to for
compatibility with PowerPC boot code[1] whose min() is strict like
include/linux/minmax.h was before commit d03eba99f5bf ("minmax: allow
min()/max()/clamp() if the arguments have the same signedness.").

Since "uncompressed" was changed to size_t, change also "compressed"
and its uses for consistency.

Swap the order of the "state" and "len" in struct lzma_dec to avoid
padding in the middle of the struct when size_t is 64 bits. The size of
the struct doesn't change; the padding just appears at the end instead.

Link: https://lore.kernel.org/lkml/20260610232323.GA1071374@ax162/ [1]
---
 lib/xz/xz_dec_lzma2.c | 36 +++++++++++++++++-------------------
 lib/xz/xz_lzma2.h     |  2 +-
 2 files changed, 18 insertions(+), 20 deletions(-)

diff --git a/lib/xz/xz_dec_lzma2.c b/lib/xz/xz_dec_lzma2.c
index 9d80342b9c6b..087385e5d9a7 100644
--- a/lib/xz/xz_dec_lzma2.c
+++ b/lib/xz/xz_dec_lzma2.c
@@ -135,14 +135,14 @@ struct lzma_dec {
 	uint32_t rep2;
 	uint32_t rep3;
 
-	/* Types of the most recently seen LZMA symbols */
-	enum lzma_state state;
-
 	/*
 	 * Length of a match. This is updated so that dict_repeat can
 	 * be called again to finish repeating the whole match.
 	 */
-	uint32_t len;
+	size_t len;
+
+	/* Types of the most recently seen LZMA symbols */
+	enum lzma_state state;
 
 	/*
 	 * LZMA properties or related bit masks (number of literal
@@ -228,13 +228,13 @@ struct lzma2_dec {
 	enum lzma2_seq next_sequence;
 
 	/* Uncompressed size of LZMA chunk (2 MiB at maximum) */
-	uint32_t uncompressed;
+	size_t uncompressed;
 
 	/*
 	 * Compressed size of LZMA chunk or compressed/uncompressed
 	 * size of uncompressed chunk (64 KiB at maximum)
 	 */
-	uint32_t compressed;
+	size_t compressed;
 
 	/*
 	 * True if dictionary reset is needed. This is false before
@@ -273,7 +273,7 @@ struct xz_dec_lzma2 {
 	 * decoder calls. See lzma2_lzma() for details.
 	 */
 	struct {
-		uint32_t size;
+		size_t size;
 		uint8_t buf[3 * LZMA_IN_REQUIRED];
 	} temp;
 };
@@ -320,7 +320,7 @@ static inline bool dict_has_space(const struct dictionary *dict)
  * still empty. This special case is needed for single-call decoding to
  * avoid writing a '\0' to the end of the destination buffer.
  */
-static inline uint32_t dict_get(const struct dictionary *dict, uint32_t dist)
+static inline uint32_t dict_get(const struct dictionary *dict, size_t dist)
 {
 	size_t offset = dict->pos - dist - 1;
 
@@ -346,10 +346,10 @@ static inline void dict_put(struct dictionary *dict, uint8_t byte)
  * invalid, false is returned. On success, true is returned and *len is
  * updated to indicate how many bytes were left to be repeated.
  */
-static bool dict_repeat(struct dictionary *dict, uint32_t *len, uint32_t dist)
+static bool dict_repeat(struct dictionary *dict, size_t *len, size_t dist)
 {
 	size_t back;
-	uint32_t left;
+	size_t left;
 
 	if (dist >= dict->full || dist >= dict->size)
 		return false;
@@ -375,7 +375,7 @@ static bool dict_repeat(struct dictionary *dict, uint32_t *len, uint32_t dist)
 
 /* Copy uncompressed data as is from input to dictionary and output buffers. */
 static void dict_uncompressed(struct dictionary *dict, struct xz_buf *b,
-			      uint32_t *left)
+			      size_t *left)
 {
 	size_t copy_size;
 
@@ -433,7 +433,7 @@ static void dict_uncompressed(struct dictionary *dict, struct xz_buf *b,
  * enough space in b->out. This is guaranteed because caller uses dict_limit()
  * before decoding data into the dictionary.
  */
-static uint32_t dict_flush(struct dictionary *dict, struct xz_buf *b)
+static size_t dict_flush(struct dictionary *dict, struct xz_buf *b)
 {
 	size_t copy_size = dict->pos - dict->start;
 
@@ -878,7 +878,7 @@ static bool lzma_props(struct xz_dec_lzma2 *s, uint8_t props)
 static bool lzma2_lzma(struct xz_dec_lzma2 *s, struct xz_buf *b)
 {
 	size_t in_avail;
-	uint32_t tmp;
+	size_t tmp;
 
 	in_avail = b->in_size - b->in_pos;
 	if (s->temp.size > 0 || s->lzma2.compressed == 0) {
@@ -1046,25 +1046,23 @@ enum xz_ret xz_dec_lzma2_run(struct xz_dec_lzma2 *s, struct xz_buf *b)
 
 		case SEQ_UNCOMPRESSED_1:
 			s->lzma2.uncompressed
-					+= (uint32_t)b->in[b->in_pos++] << 8;
+					+= (size_t)b->in[b->in_pos++] << 8;
 			s->lzma2.sequence = SEQ_UNCOMPRESSED_2;
 			break;
 
 		case SEQ_UNCOMPRESSED_2:
 			s->lzma2.uncompressed
-					+= (uint32_t)b->in[b->in_pos++] + 1;
+					+= (size_t)b->in[b->in_pos++] + 1;
 			s->lzma2.sequence = SEQ_COMPRESSED_0;
 			break;
 
 		case SEQ_COMPRESSED_0:
-			s->lzma2.compressed
-					= (uint32_t)b->in[b->in_pos++] << 8;
+			s->lzma2.compressed = (size_t)b->in[b->in_pos++] << 8;
 			s->lzma2.sequence = SEQ_COMPRESSED_1;
 			break;
 
 		case SEQ_COMPRESSED_1:
-			s->lzma2.compressed
-					+= (uint32_t)b->in[b->in_pos++] + 1;
+			s->lzma2.compressed += (size_t)b->in[b->in_pos++] + 1;
 			s->lzma2.sequence = s->lzma2.next_sequence;
 			break;
 
diff --git a/lib/xz/xz_lzma2.h b/lib/xz/xz_lzma2.h
index d2632b7dfb9c..a612ce4fd450 100644
--- a/lib/xz/xz_lzma2.h
+++ b/lib/xz/xz_lzma2.h
@@ -143,7 +143,7 @@ static inline bool lzma_state_is_literal(enum lzma_state state)
  * Get the index of the appropriate probability array for decoding
  * the distance slot.
  */
-static inline uint32_t lzma_get_dist_state(uint32_t len)
+static inline size_t lzma_get_dist_state(size_t len)
 {
 	return len < DIST_STATES + MATCH_LEN_MIN
 			? len - MATCH_LEN_MIN : DIST_STATES - 1;
-- 
2.54.0


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