[zlib] Re-sync with zlib 1.2.12, patch 7 of N

Ported:
- Fix deflateEnd() to not report an error at start of raw deflate
- Emphasize the need to continue decompressing gzip members
- Correct the initialization requirements for deflateInit2()
- Assure that the number of bits for deflatePrime() is valid

Bug: 1032721
Change-Id: I6c1cbf67b8c983ddc4481a445982f226bc97ceb6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3573054


Reviewed-by: Noel Gordon <noel@chromium.org>
Commit-Queue: Adenilson Cavalcanti <cavalcantii@chromium.org>
Cr-Commit-Position: refs/heads/main@{#989437}
NOKEYCHECK=True
GitOrigin-RevId: eb8415cd3f004003fbadc5152d52b22ad0b843b4

deflate.c

@@ -539,7 +539,7 @@ int ZEXPORT deflateResetKeep (strm)
 #ifdef GZIP
         s->wrap == 2 ? GZIP_STATE :
 #endif
-        s->wrap ? INIT_STATE : BUSY_STATE;
+        INIT_STATE;
     strm->adler =
 #ifdef GZIP
         s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
@@ -600,7 +600,8 @@ int ZEXPORT deflatePrime (strm, bits, value)
 
     if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
     s = strm->state;
-    if (s->sym_buf < s->pending_out + ((Buf_size + 7) >> 3))
+    if (bits < 0 || bits > 16 ||
+        s->sym_buf < s->pending_out + ((Buf_size + 7) >> 3))
         return Z_BUF_ERROR;
     do {
         put = Buf_size - s->bi_valid;
@@ -862,6 +863,8 @@ int ZEXPORT deflate (strm, flush)
     }
 
     /* Write the header */
+    if (s->status == INIT_STATE && s->wrap == 0)
+        s->status = BUSY_STATE;
     if (s->status == INIT_STATE) {
         /* zlib header */
         uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;

zlib.h

@@ -543,8 +543,7 @@ ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
                                      int  strategy));
 
      This is another version of deflateInit with more compression options.  The
-   fields next_in, zalloc, zfree and opaque must be initialized before by the
-   caller.
+   fields zalloc, zfree and opaque must be initialized before by the caller.
 
      The method parameter is the compression method.  It must be Z_DEFLATED in
    this version of the library.
@@ -866,9 +865,11 @@ ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
    detection, or add 16 to decode only the gzip format (the zlib format will
    return a Z_DATA_ERROR).  If a gzip stream is being decoded, strm->adler is a
    CRC-32 instead of an Adler-32.  Unlike the gunzip utility and gzread() (see
-   below), inflate() will not automatically decode concatenated gzip streams.
-   inflate() will return Z_STREAM_END at the end of the gzip stream.  The state
-   would need to be reset to continue decoding a subsequent gzip stream.
+   below), inflate() will *not* automatically decode concatenated gzip members.
+   inflate() will return Z_STREAM_END at the end of the gzip member.  The state
+   would need to be reset to continue decoding a subsequent gzip member.  This
+   *must* be done if there is more data after a gzip member, in order for the
+   decompression to be compliant with the gzip standard (RFC 1952).
 
      inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
    memory, Z_VERSION_ERROR if the zlib library version is incompatible with the