1 files changed, 77 insertions, 0 deletions
diff --git a/src/lib/compress/compress_buf.c b/src/lib/compress/compress_buf.c
new file mode 100644
index 0000000000..4b88772382
--- /dev/null
+++ b/src/lib/compress/compress_buf.c
@@ -0,0 +1,77 @@
+/* Copyright (c) 2003, Roger Dingledine
+ * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
+ * Copyright (c) 2007-2018, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+#define BUFFERS_PRIVATE
+#include "lib/cc/compat_compiler.h"
+#include "lib/container/buffers.h"
+#include "lib/compress/compress.h"
+#include "lib/log/util_bug.h"
+
+#ifdef PARANOIA
+/** Helper: If PARANOIA is defined, assert that the buffer in local variable
+ * <b>buf</b> is well-formed. */
+#define check() STMT_BEGIN buf_assert_ok(buf); STMT_END
+#else
+#define check() STMT_NIL
+#endif /* defined(PARANOIA) */
+
+/** Compress or uncompress the <b>data_len</b> bytes in <b>data</b> using the
+ * compression state <b>state</b>, appending the result to <b>buf</b>.  If
+ * <b>done</b> is true, flush the data in the state and finish the
+ * compression/uncompression.  Return -1 on failure, 0 on success. */
+int
+buf_add_compress(buf_t *buf, tor_compress_state_t *state,
+                 const char *data, size_t data_len,
+                 const int done)
+{
+  char *next;
+  size_t old_avail, avail;
+  int over = 0;
+
+  do {
+    int need_new_chunk = 0;
+    if (!buf->tail || ! CHUNK_REMAINING_CAPACITY(buf->tail)) {
+      size_t cap = data_len / 4;
+      buf_add_chunk_with_capacity(buf, cap, 1);
+    }
+    next = CHUNK_WRITE_PTR(buf->tail);
+    avail = old_avail = CHUNK_REMAINING_CAPACITY(buf->tail);
+    switch (tor_compress_process(state, &next, &avail,
+                                 &data, &data_len, done)) {
+      case TOR_COMPRESS_DONE:
+        over = 1;
+        break;
+      case TOR_COMPRESS_ERROR:
+        return -1;
+      case TOR_COMPRESS_OK:
+        if (data_len == 0) {
+          tor_assert_nonfatal(!done);
+          over = 1;
+        }
+        break;
+      case TOR_COMPRESS_BUFFER_FULL:
+        if (avail) {
+          /* The compression module says we need more room
+           * (TOR_COMPRESS_BUFFER_FULL).  Start a new chunk automatically,
+           * whether were going to or not. */
+          need_new_chunk = 1;
+        }
+        if (data_len == 0 && !done) {
+          /* We've consumed all the input data, though, so there's no
+           * point in forging ahead right now. */
+          over = 1;
+        }
+        break;
+    }
+    buf->datalen += old_avail - avail;
+    buf->tail->datalen += old_avail - avail;
+    if (need_new_chunk) {
+      buf_add_chunk_with_capacity(buf, data_len/4, 1);
+    }
+
+  } while (!over);
+  check();
+  return 0;
+}