erl_interface: Tweak bit string encode/decode API

to support zero copy decoding
and bit offset arguments for future unaligned bit strings.

2 files changed, 32 insertions, 39 deletions

diff --git a/lib/erl_interface/src/decode/decode_binary.c b/lib/erl_interface/src/decode/decode_binary.c
index 2799438bef..0d28c67230 100644
--- a/lib/erl_interface/src/decode/decode_binary.c
+++ b/lib/erl_interface/src/decode/decode_binary.c
@@ -40,40 +40,41 @@ int ei_decode_binary(const char *buf, int *index, void *p, long *lenp)
   return 0; 
 }
 
-int ei_decode_bitstring(const char *buf, int *index, void *p, size_t plen,
-                        size_t *bitsp)
+int ei_decode_bitstring(const char *buf, int *index,
+                        const char** pp,
+                        unsigned int* bitoffsp,
+                        size_t *nbitsp)
 {
-  const char *s = buf + *index;
-  const char *s0 = s;
-  unsigned long len;
-  unsigned char last_bits;
-  const unsigned char tag = get8(s);
+    const char *s = buf + *index;
+    const char *s0 = s;
+    unsigned char last_bits;
+    const unsigned char tag = get8(s);
+    size_t len = get32be(s);
 
-  if (tag == ERL_BINARY_EXT) {
-      long bytes;
-      int ret = ei_decode_binary(buf, index, p, &bytes);
-      if (bitsp)
-          *bitsp = (size_t)bytes * 8;
-      return ret;
-  }
+    switch(tag) {
+    case ERL_BINARY_EXT:
+        if (nbitsp)
+            *nbitsp = len * 8;
+        break;
+    case ERL_BIT_BINARY_EXT:
+        last_bits = get8(s);
+        if (((last_bits==0) != (len==0)) || last_bits > 8)
+            return -1;
 
-  if (tag != ERL_BIT_BINARY_EXT)
-      return -1;
-
-  len = get32be(s);
-  last_bits = get8(s);
-
-  if (len > plen || ((last_bits==0) != (len==0)) || last_bits > 8)
-      return -1;
-
-  if (p)
-      memcpy(p, s, len);
-  s += len;
+        if (nbitsp)
+            *nbitsp = (len == 0) ? 0 : ((len-1) * 8) + last_bits;
+        break;
+    default:
+        return -1;
+    }
 
-  if (bitsp)
-      *bitsp = (len == 0) ? 0 : ((len-1) * 8) + last_bits;
+    if (pp)
+        *pp = s;
+    if (bitoffsp)
+        *bitoffsp = 0;
 
-  *index += s-s0;
-  return 0;
+    s += len;
+    *index += s-s0;
+    return 0;
 }
 
diff --git a/lib/erl_interface/src/decode/decode_skip.c b/lib/erl_interface/src/decode/decode_skip.c
index 11d3bc1786..736c00e074 100644
--- a/lib/erl_interface/src/decode/decode_skip.c
+++ b/lib/erl_interface/src/decode/decode_skip.c
@@ -21,14 +21,6 @@
 #include "eiext.h"
 #include "decode_skip.h"
 
-#ifdef HAVE_STDINT_H
-#  include <stdint.h>
-#endif
-
-#ifndef SIZE_MAX
-#  define SIZE_MAX (~((size_t)0))
-#endif
-
 int ei_skip_term(const char* buf, int* index)
 {
     int i, n, ty;
@@ -88,7 +80,7 @@ int ei_skip_term(const char* buf, int* index)
 	    return -1;
 	break;
     case ERL_BIT_BINARY_EXT:
-        if (ei_decode_bitstring(buf, index, NULL, SIZE_MAX, NULL) < 0)
+        if (ei_decode_bitstring(buf, index, NULL, NULL, NULL) < 0)
             return -1;
         break;
     case ERL_SMALL_INTEGER_EXT: