add option for bare stream

Author: ryancdotorg

src/bin/brotli.rs

@@ -528,6 +528,10 @@ fn main() {
           params.byte_align = true;
           continue;
       }
+      if (argument == "-bare" || argument == "--bare") && !double_dash {
+          params.bare_stream = true;
+          continue;
+      }
       if (argument == "-appendable" || argument == "--appendable") && !double_dash {
           params.appendable = true;
           continue;

src/enc/backward_references/mod.rs

@@ -94,6 +94,8 @@ pub struct BrotliEncoderParams {
   // insert empty metadata blocks before and after the compressed data
   // this allows for concatonation by byte copying with catable/appendable
   pub byte_align: bool,
+  // do not emit a stream header or empty last block at end of data
+  pub bare_stream: bool,
   // construct brotli in such a way that it may be concatenated with another brotli file using appropriate bit ops
   pub catable: bool,
   // can use the dictionary (default yes unless catable is set)

src/enc/encode.rs

@@ -345,6 +345,13 @@ value: u32) -> i32 {
     params.byte_align = value != 0;
     return 1i32;
   }
+  if p as (i32) == BrotliEncoderParameter::BROTLI_PARAM_BARE_STREAM as (i32) {
+    params.bare_stream = value != 0;
+    if !params.byte_align {
+      params.byte_align = value != 0;
+    }
+    return 1i32;
+  }
   0i32  
 }
 
@@ -403,6 +410,7 @@ pub fn BrotliEncoderInitParams() -> BrotliEncoderParams {
            prior_bitmask_detection: 0,
            literal_adaptation: [(0,0);4],
            byte_align: false,
+           bare_stream: false,
            catable: false,
            use_dictionary: true,
            appendable: false,
@@ -627,7 +635,10 @@ pub fn SanitizeParams(params: &mut BrotliEncoderParams) {
     }
   }
   if params.catable {
-      params.appendable = true;
+    params.appendable = true;
+  }
+  if params.bare_stream {
+    params.byte_align = true;
   }
 }
 
@@ -727,7 +738,9 @@ fn EnsureInitialized<Alloc: BrotliAlloc>
     if (*s).params.quality == 0i32 || (*s).params.quality == 1i32 {
       lgwin = brotli_max_int(lgwin, 18i32);
     }
-    EncodeWindowBits(lgwin, s.params.large_window, &mut (*s).last_bytes_, &mut (*s).last_bytes_bits_);
+    if !(*s).params.bare_stream {
+      EncodeWindowBits(lgwin, s.params.large_window, &mut (*s).last_bytes_, &mut (*s).last_bytes_bits_);
+    }
   }
   if (*s).params.quality == 0i32 {
     InitCommandPrefixCodes(&mut (*s).cmd_depths_[..],
@@ -2024,7 +2037,9 @@ fn WriteMetaBlockInternal<Alloc: BrotliAlloc,
       if params.byte_align && ((*storage_ix & 7u32 as (usize)) != 0) {
         BrotliStoreSyncMetaBlock(storage_ix, storage);
       }
-      BrotliWriteEmptyLastMetaBlock(storage_ix, storage)
+      if !params.bare_stream {
+        BrotliWriteEmptyLastMetaBlock(storage_ix, storage)
+      }
     }
     return;
   }
@@ -2168,7 +2183,9 @@ fn WriteMetaBlockInternal<Alloc: BrotliAlloc,
     if params.byte_align && ((*storage_ix & 7u32 as (usize)) != 0) {
       BrotliStoreSyncMetaBlock(storage_ix, storage);
     }
-    BrotliWriteEmptyLastMetaBlock(storage_ix, storage)
+    if !params.bare_stream {
+      BrotliWriteEmptyLastMetaBlock(storage_ix, storage)
+    }
   }
 }
 
@@ -2255,7 +2272,7 @@ fn EncodeData<Alloc: BrotliAlloc,
   }
   let mut catable_header_size = 0;
   if let IsFirst::NothingWritten = s.is_first_mb {
-    if s.params.magic_number || (s.params.byte_align && !s.params.catable && !s.params.appendable) {
+    if s.params.magic_number || (s.params.byte_align && !s.params.catable && !s.params.appendable && !s.params.bare_stream) {
       if s.params.magic_number {
         BrotliWriteMetadataMetaBlock(&s.params, &mut storage_ix, (*s).storage_.slice_mut());
       } else {

src/enc/parameters.rs

@@ -31,6 +31,7 @@ pub enum BrotliEncoderParameter {
   BROTLI_PARAM_NO_DICTIONARY = 170,
   BROTLI_PARAM_FAVOR_EFFICIENCY = 171,
   BROTLI_PARAM_BYTE_ALIGN = 172,
+  BROTLI_PARAM_BARE_STREAM = 173,
   UNUSED7=7,
   UNUSED8=8,
   UNUSED9=9,
@@ -174,7 +175,6 @@ pub enum BrotliEncoderParameter {
   UNUSED147=147,
   UNUSED148=148,
   UNUSED149=149,
-  UNUSED173=173,
   UNUSED174=174,
   UNUSED175=175,
   UNUSED176=176,