Don't bother computing check value after successful inflateSync().

madler/zlib@0d36ec4
nodeca · Jun 10, 2022 · 77f1c17 · 77f1c17
1 parent a194382
commit 77f1c17
Showing 1 changed file with 5 additions and 3 deletions.
diff --git a/lib/zlib/inflate.js b/lib/zlib/inflate.js
@@ -104,7 +104,8 @@ function InflateState() {
   this.wrap = 0;              /* bit 0 true for zlib, bit 1 true for gzip,
                                  bit 2 true to validate check value */
   this.havedict = false;      /* true if dictionary provided */
-  this.flags = 0;             /* gzip header method and flags (0 if zlib) */
+  this.flags = 0;             /* gzip header method and flags (0 if zlib), or
+                                 -1 if raw or no header yet */
   this.dmax = 0;              /* zlib header max distance (INFLATE_STRICT) */
   this.check = 0;             /* protected copy of check value */
   this.total = 0;             /* protected copy of output count */
@@ -184,6 +185,7 @@ const inflateResetKeep = (strm) => {
   state.mode = HEAD;
   state.last = 0;
   state.havedict = 0;
+  state.flags = -1;
   state.dmax = 32768;
   state.head = null/*Z_NULL*/;
   state.hold = 0;
@@ -464,7 +466,6 @@ const inflate = (strm, flush) => {
           state.mode = FLAGS;
           break;
         }
-        state.flags = 0;           /* expect zlib header */
         if (state.head) {
           state.head.done = false;
         }
@@ -498,6 +499,7 @@ const inflate = (strm, flush) => {
         state.dmax = 1 << state.wbits;
         //state.dmax = 1 << len;
 
+        state.flags = 0;               /* indicate zlib header */
         //Tracev((stderr, "inflate:   zlib header ok\n"));
         strm.adler = state.check = 1/*adler32(0L, Z_NULL, 0)*/;
         state.mode = hold & 0x200 ? DICTID : TYPE;
@@ -1408,7 +1410,7 @@ const inflate = (strm, flush) => {
             bits += 8;
           }
           //===//
-          if (hold !== (state.total & 0xffffffff)) {
+          if ((state.wrap & 4) && hold !== (state.total & 0xffffffff)) {
             strm.msg = 'incorrect length check';
             state.mode = BAD;
             break;