From 01aa8b82dd0f8229355ffd2bb2bc8e8f496d2df6 Mon Sep 17 00:00:00 2001
From: Sverker Eriksson <sverker@erlang.org>
Date: Fri, 26 Apr 2019 19:43:53 +0200
Subject: erl_interface: Tweak bit string encode/decode API

to support zero copy decoding
and bit offset arguments for future unaligned bit strings.
---
 lib/erl_interface/src/misc/ei_printterm.c | 14 +++++++-------
 lib/erl_interface/src/misc/ei_x_encode.c  |  6 +++---
 lib/erl_interface/src/misc/show_msg.c     |  9 +--------
 3 files changed, 11 insertions(+), 18 deletions(-)

(limited to 'lib/erl_interface/src/misc')

diff --git a/lib/erl_interface/src/misc/ei_printterm.c b/lib/erl_interface/src/misc/ei_printterm.c
index a89b990ac1..5c40fb7747 100644
--- a/lib/erl_interface/src/misc/ei_printterm.c
+++ b/lib/erl_interface/src/misc/ei_printterm.c
@@ -250,12 +250,13 @@ static int print_term(FILE* fp, ei_x_buff* x,
 	ei_free(p);
 	break;
     case ERL_BIT_BINARY_EXT: {
+        const char* cp;
         size_t bits;
+        unsigned int bitoffs;
         int trunc = 0;
-        p = ei_malloc(n);
-        if (p == NULL) goto err;
-        if (ei_decode_bitstring(buf, index, p, n, &bits) < 0) {
-            ei_free(p);
+
+        if (ei_decode_bitstring(buf, index, &cp, &bitoffs, &bits) < 0
+            || bitoffs != 0) {
             goto err;
         }
         ch_written += xprintf(fp, x, "#Bits<");
@@ -266,15 +267,14 @@ static int print_term(FILE* fp, ei_x_buff* x,
         }
         --m;
         for (i = 0; i < m; ++i) {
-            ch_written += xprintf(fp, x, "%d,", p[i]);
+            ch_written += xprintf(fp, x, "%d,", cp[i]);
         }
-        ch_written += xprintf(fp, x, "%d", p[i]);
+        ch_written += xprintf(fp, x, "%d", cp[i]);
         if (trunc)
             ch_written += xprintf(fp, x, ",...");
         else if (bits % 8 != 0)
             ch_written += xprintf(fp, x, ":%u", (unsigned)(bits % 8));
         xputc('>', fp, x); ++ch_written;
-        ei_free(p);
         break;
     }
     case ERL_SMALL_INTEGER_EXT:
diff --git a/lib/erl_interface/src/misc/ei_x_encode.c b/lib/erl_interface/src/misc/ei_x_encode.c
index 2da271795f..8e77679d2a 100644
--- a/lib/erl_interface/src/misc/ei_x_encode.c
+++ b/lib/erl_interface/src/misc/ei_x_encode.c
@@ -117,14 +117,14 @@ int ei_x_encode_binary(ei_x_buff* x, const void* p, int len)
     return ei_encode_binary(x->buff, &x->index, p, len);
 }
 
-int ei_x_encode_bitstring(ei_x_buff* x, const void* p, size_t bits)
+int ei_x_encode_bitstring(ei_x_buff* x, const char* p, size_t bitoffs, size_t bits)
 {
     int i = x->index;
-    if (ei_encode_bitstring(NULL, &i, p, bits) == -1)
+    if (ei_encode_bitstring(NULL, &i, p, bitoffs, bits) == -1)
       return -1;
     if (!x_fix_buff(x, i))
 	return -1;
-    return ei_encode_bitstring(x->buff, &x->index, p, bits);
+    return ei_encode_bitstring(x->buff, &x->index, p, bitoffs, bits);
 }
 
 int ei_x_encode_long(ei_x_buff* x, long n)
diff --git a/lib/erl_interface/src/misc/show_msg.c b/lib/erl_interface/src/misc/show_msg.c
index 2d49eb6449..805d69e9b3 100644
--- a/lib/erl_interface/src/misc/show_msg.c
+++ b/lib/erl_interface/src/misc/show_msg.c
@@ -24,13 +24,6 @@
 #include <stdlib.h>
 #include <stdarg.h>
 #include <string.h>
-#ifdef HAVE_STDINT_H
-#  include <stdint.h>
-#endif
-
-#ifndef SIZE_MAX
-#  define SIZE_MAX (~((size_t)0))
-#endif
 
 #include <sys/types.h>
 
@@ -464,7 +457,7 @@ static void show_term(const char *termbuf, int *index, FILE *stream)
     
     case ERL_BIT_BINARY_EXT: {
         size_t bits;
-        ei_decode_bitstring(termbuf, index, NULL, SIZE_MAX, &bits);
+        ei_decode_bitstring(termbuf, index, NULL, NULL, &bits);
         fprintf(stream, "#Bits<%lu>", (unsigned long)bits);
         break;
     }
-- 
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