Deflate: added custom gzip headers support

lib/deflate.js

@@ -86,6 +86,14 @@ var Z_DEFLATED  = 8;
  * - `gzip` (Boolean) - create gzip wrapper
  * - `to` (String) - if equal to 'string', then result will be "binary string"
  *    (each char code [0..255])
+ * - `header` (Object) - custom header for gzip
+ *   - `text` (Boolean) - true if compressed data believed to be text
+ *   - `time` (Number) - modification time, unix timestamp
+ *   - `os` (Number) - operation system code
+ *   - `extra` (Array) - array of bytes with extra data (max 65536)
+ *   - `name` (String) - file name (binary string)
+ *   - `comment` (String) - comment (binary string)
+ *   - `hcrc` (Boolean) - true if header crc should be added
  *
  * ##### Example:
  *
@@ -146,6 +154,10 @@ var Deflate = function(options) {
   if (status !== Z_OK) {
     throw new Error(msg[status]);
   }
+
+  if (opt.header) {
+    zlib_deflate.deflateSetHeader(this.strm, opt.header);
+  }
 };
 
 /**

lib/zlib/deflate.js

@@ -1179,13 +1179,6 @@ function DeflateState() {
   zero(this.dyn_dtree);
   zero(this.bl_tree);
 
-//  struct tree_desc_s l_desc;               /* desc. for literal tree */
-//  struct tree_desc_s d_desc;               /* desc. for distance tree */
-//  struct tree_desc_s bl_desc;              /* desc. for bit length tree */
-
-// Seems to init better from `tree` with direct structures,
-// (?) with separate constructor for bl_desc or not?
-// Make sure objects have the same hidden class if needed
   this.l_desc   = null;         /* desc. for literal tree */
   this.d_desc   = null;         /* desc. for distance tree */
   this.bl_desc  = null;         /* desc. for bit length tree */
@@ -1264,6 +1257,7 @@ function DeflateState() {
    */
 }
 
+
 function deflateResetKeep(strm) {
   var s;
 
@@ -1292,6 +1286,7 @@ function deflateResetKeep(strm) {
   return Z_OK;
 }
 
+
 function deflateReset(strm) {
   var ret = deflateResetKeep(strm);
   if (ret === Z_OK) {
@@ -1300,6 +1295,15 @@ function deflateReset(strm) {
   return ret;
 }
 
+
+function deflateSetHeader(strm, head) {
+  if (!strm || !strm.state) { return Z_STREAM_ERROR; }
+  if (strm.state.wrap !== 2) { return Z_STREAM_ERROR; }
+  strm.state.gzhead = head;
+  return Z_OK;
+}
+
+
 function deflateInit2(strm, level, method, windowBits, memLevel, strategy) {
   if (!strm) { // === Z_NULL
     return err(strm, Z_STREAM_ERROR);
@@ -1378,6 +1382,7 @@ function deflateInit(strm, level) {
 
 function deflate(strm, flush) {
   var old_flush, s;
+  var beg, val; // for gzip header write only
 
   if (!strm || !strm.state ||
     flush > Z_BLOCK || flush < 0) {
@@ -1417,7 +1422,29 @@ function deflate(strm, flush) {
         s.status = BUSY_STATE;
       }
       else {
-        throw new Error('Custom GZIP headers not supported');
+        put_byte(s, (s.gzhead.text ? 1 : 0) +
+                    (s.gzhead.hcrc ? 2 : 0) +
+                    (!s.gzhead.extra ? 0 : 4) +
+                    (!s.gzhead.name ? 0 : 8) +
+                    (!s.gzhead.comment ? 0 : 16)
+                );
+        put_byte(s, s.gzhead.time & 0xff);
+        put_byte(s, (s.gzhead.time >> 8) & 0xff);
+        put_byte(s, (s.gzhead.time >> 16) & 0xff);
+        put_byte(s, (s.gzhead.time >> 24) & 0xff);
+        put_byte(s, s.level === 9 ? 2 :
+                    (s.strategy >= Z_HUFFMAN_ONLY || s.level < 2 ?
+                     4 : 0));
+        put_byte(s, s.gzhead.os & 0xff);
+        if (s.gzhead.extra && s.gzhead.extra.length) {
+          put_byte(s, s.gzhead.extra.length & 0xff);
+          put_byte(s, (s.gzhead.extra.length >> 8) & 0xff);
+        }
+        if (s.gzhead.hcrc) {
+          strm.adler = crc32(strm.adler, s.pending_buf, s.pending, 0);
+        }
+        s.gzindex = 0;
+        s.status = EXTRA_STATE;
       }
     }
     else // DEFLATE header
@@ -1450,6 +1477,130 @@ function deflate(strm, flush) {
     }
   }
 
+//#ifdef GZIP
+  if (s.status === EXTRA_STATE) {
+    if (s.gzhead.extra/* != Z_NULL*/) {
+      beg = s.pending;  /* start of bytes to update crc */
+
+      while (s.gzindex < (s.gzhead.extra.length & 0xffff)) {
+        if (s.pending === s.pending_buf_size) {
+          if (s.gzhead.hcrc && s.pending > beg) {
+            strm.adler = crc32(strm.adler, s.pending_buf, s.pending - beg, beg);
+          }
+          flush_pending(strm);
+          beg = s.pending;
+          if (s.pending === s.pending_buf_size) {
+            break;
+          }
+        }
+        put_byte(s, s.gzhead.extra[s.gzindex] & 0xff);
+        s.gzindex++;
+      }
+      if (s.gzhead.hcrc && s.pending > beg) {
+        strm.adler = crc32(strm.adler, s.pending_buf, s.pending - beg, beg);
+      }
+      if (s.gzindex === s.gzhead.extra.length) {
+        s.gzindex = 0;
+        s.status = NAME_STATE;
+      }
+    }
+    else {
+      s.status = NAME_STATE;
+    }
+  }
+  if (s.status === NAME_STATE) {
+    if (s.gzhead.name/* != Z_NULL*/) {
+      beg = s.pending;  /* start of bytes to update crc */
+      //int val;
+
+      do {
+        if (s.pending === s.pending_buf_size) {
+          if (s.gzhead.hcrc && s.pending > beg) {
+            strm.adler = crc32(strm.adler, s.pending_buf, s.pending - beg, beg);
+          }
+          flush_pending(strm);
+          beg = s.pending;
+          if (s.pending === s.pending_buf_size) {
+            val = 1;
+            break;
+          }
+        }
+        // JS specific: little magic to add zero terminator to end of string
+        if (s.gzindex < s.gzhead.name.length) {
+          val = s.gzhead.name.charCodeAt(s.gzindex++) & 0xff;
+        } else {
+          val = 0;
+        }
+        put_byte(s, val);
+      } while (val !== 0);
+
+      if (s.gzhead.hcrc && s.pending > beg){
+        strm.adler = crc32(strm.adler, s.pending_buf, s.pending - beg, beg);
+      }
+      if (val === 0) {
+        s.gzindex = 0;
+        s.status = COMMENT_STATE;
+      }
+    }
+    else {
+      s.status = COMMENT_STATE;
+    }
+  }
+  if (s.status === COMMENT_STATE) {
+    if (s.gzhead.comment/* != Z_NULL*/) {
+      beg = s.pending;  /* start of bytes to update crc */
+      //int val;
+
+      do {
+        if (s.pending === s.pending_buf_size) {
+          if (s.gzhead.hcrc && s.pending > beg) {
+            strm.adler = crc32(strm.adler, s.pending_buf, s.pending - beg, beg);
+          }
+          flush_pending(strm);
+          beg = s.pending;
+          if (s.pending === s.pending_buf_size) {
+            val = 1;
+            break;
+          }
+        }
+        // JS specific: little magic to add zero terminator to end of string
+        if (s.gzindex < s.gzhead.comment.length) {
+          val = s.gzhead.comment.charCodeAt(s.gzindex++) & 0xff;
+        } else {
+          val = 0;
+        }
+        put_byte(s, val);
+      } while (val !== 0);
+
+      if (s.gzhead.hcrc && s.pending > beg) {
+        strm.adler = crc32(strm.adler, s.pending_buf, s.pending - beg, beg);
+      }
+      if (val === 0) {
+        s.status = HCRC_STATE;
+      }
+    }
+    else {
+      s.status = HCRC_STATE;
+    }
+  }
+  if (s.status === HCRC_STATE) {
+    if (s.gzhead.hcrc) {
+      if (s.pending + 2 > s.pending_buf_size) {
+        flush_pending(strm);
+      }
+      if (s.pending + 2 <= s.pending_buf_size) {
+        put_byte(s, strm.adler & 0xff);
+        put_byte(s, (strm.adler >> 8) & 0xff);
+        strm.adler = 0; //crc32(0L, Z_NULL, 0);
+        s.status = BUSY_STATE;
+      }
+    }
+    else {
+      s.status = BUSY_STATE;
+    }
+  }
+//#endif
+
   /* Flush as much pending output as possible */
   if (s.pending !== 0) {
     flush_pending(strm);
@@ -1597,6 +1748,7 @@ function deflateEnd(strm) {
 exports.deflateInit = deflateInit;
 exports.deflateInit2 = deflateInit2;
 exports.deflateReset = deflateReset;
+exports.deflateSetHeader = deflateSetHeader;
 exports.deflate = deflate;
 exports.deflateEnd = deflateEnd;
 exports.deflateInfo = 'pako deflate (from Nodeca project)';
@@ -1604,7 +1756,6 @@ exports.deflateInfo = 'pako deflate (from Nodeca project)';
 /* Not implemented
 exports.deflateSetDictionary = deflateSetDictionary;
 exports.deflateParams = deflateParams;
-exports.deflateSetHeader = deflateSetHeader;
 exports.deflateBound = deflateBound;
 exports.deflatePending = deflatePending;
 */

test/gzip_specials.js

@@ -10,6 +10,7 @@ var assert = require('assert');
 
 var pako_utils = require('../lib/utils/common');
 var pako    = require('../index');
+var cmp     = require('./helpers').cmpBuf;
 
 
 function a2s(array) {
@@ -29,6 +30,36 @@ describe('Gzip special cases', function() {
     assert.equal(a2s(inflator.header.extra), 'test extra');
   });
 
+  it('Write custom headers', function() {
+    var data = '           ';
+
+    var deflator = new pako.Deflate({
+      gzip: true,
+      header: {
+        hcrc: true,
+        time: 1234567,
+        os: 15,
+        name: 'test name',
+        comment: 'test comment',
+        extra: [4,5,6]
+      }
+    });
+    deflator.push(data, true);
+
+    var inflator = new pako.Inflate({ to: 'string' });
+    inflator.push(deflator.result, true);
+
+    assert.equal(inflator.err, 0);
+    assert.equal(inflator.result, data);
+
+    var header = inflator.header;
+    assert.equal(header.time, 1234567);
+    assert.equal(header.os, 15);
+    assert.equal(header.name, 'test name');
+    assert.equal(header.comment, 'test comment');
+    assert(cmp(header.extra, [4,5,6]));
+  });
+
   it('Read stream with SYNC marks', function() {
     var inflator, strm, _in, len, pos = 0, i = 0;
     var data = fs.readFileSync(path.join(__dirname, 'fixtures/gzip-joined.gz'));