erl_interface: Do not generate atoms on old latin1 ext format

Solved by letting ei_encode_atom_as ignore 'to_enc' argument
and always encode in UTF8 format.

10 files changed, 83 insertions, 128 deletions

diff --git a/lib/erl_interface/doc/src/ei.xml b/lib/erl_interface/doc/src/ei.xml
index ddfb4d88a8..c3c776296c 100644
--- a/lib/erl_interface/doc/src/ei.xml
+++ b/lib/erl_interface/doc/src/ei.xml
@@ -421,22 +421,16 @@ typedef enum {
       <name><ret>int</ret><nametext>ei_x_encode_atom_len_as(ei_x_buff* x, const char *p, int len, erlang_char_encoding from_enc, erlang_char_encoding to_enc)</nametext></name>
       <fsummary>Encode an atom.</fsummary>
       <desc>
-        <p>Encodes an atom in the binary format with character encoding
-	  <seealso marker="#erlang_char_encoding"><c>to_enc</c></seealso>
-          (Latin-1 or UTF-8). Parameter <c>p</c> is the name of the atom with
+        <p>Encodes an atom in the binary format. Parameter <c>p</c> is the name of the atom with
           character encoding
           <seealso marker="#erlang_char_encoding"><c>from_enc</c></seealso>
           (ASCII, Latin-1, or UTF-8). The name must either be <c>NULL</c>-terminated or
-          a function variant with a <c>len</c> parameter must be used.
-          If <c>to_enc</c> is set to the bitwise OR'd combination
-	  <c>(ERLANG_LATIN1|ERLANG_UTF8)</c>, UTF-8 encoding is only used if the
-          atom string cannot be represented in Latin-1 encoding.</p>
-	<p>The encoding fails if <c>p</c> is an invalid string in encoding
-          <c>from_enc</c>, if the string is too long, or if it cannot be
-          represented with character encoding <c>to_enc</c>.</p>
-	<p>These functions were introduced in Erlang/OTP R16 as part of a first
-          step to support UTF-8 atoms. Atoms encoded with <c>ERLANG_UTF8</c>
-	  cannot be decoded by earlier releases than R16.</p>
+          a function variant with a <c>len</c> parameter must be used.</p>
+	<p>The encoding fails if <c>p</c> is not a valid string in encoding
+          <c>from_enc</c>.</p>
+
+	<p>Argument <c>to_enc</c> is ignored. As from Erlang/OTP 20 the encoding is always
+	  done in UTF-8 which is readable by nodes as old as Erlang/OTP R16.</p>
       </desc>
     </func>
 
diff --git a/lib/erl_interface/src/encode/encode_atom.c b/lib/erl_interface/src/encode/encode_atom.c
index c1817628e5..1fd7811a0e 100644
--- a/lib/erl_interface/src/encode/encode_atom.c
+++ b/lib/erl_interface/src/encode/encode_atom.c
@@ -26,7 +26,6 @@
 
 static int verify_ascii_atom(const char* src, int slen);
 static int verify_utf8_atom(const char* src, int slen);
-static int is_latin1_as_utf8(const char *p, int len);
 
 int ei_encode_atom(char *buf, int *index, const char *p)
 {
@@ -34,7 +33,7 @@ int ei_encode_atom(char *buf, int *index, const char *p)
 
     if (len >= MAXATOMLEN)
 	len = MAXATOMLEN - 1;
-    return ei_encode_atom_len_as(buf, index, p, len, ERLANG_LATIN1, ERLANG_LATIN1);
+    return ei_encode_atom_len_as(buf, index, p, len, ERLANG_LATIN1, 0);
 }
 
 int ei_encode_atom_len(char *buf, int *index, const char *p, int len)
@@ -42,7 +41,7 @@ int ei_encode_atom_len(char *buf, int *index, const char *p, int len)
     /* This function is documented to truncate at MAXATOMLEN (256) */ 
     if (len >= MAXATOMLEN)
 	len = MAXATOMLEN - 1;
-    return ei_encode_atom_len_as(buf, index, p, len, ERLANG_LATIN1, ERLANG_LATIN1);
+    return ei_encode_atom_len_as(buf, index, p, len, ERLANG_LATIN1, 0);
 }
 
 int ei_encode_atom_as(char *buf, int *index, const char *p,
@@ -64,46 +63,11 @@ int ei_encode_atom_len_as(char *buf, int *index, const char *p, int len,
       return -1;
   }
 
-  if (to_enc == (ERLANG_LATIN1 | ERLANG_UTF8)) {
-    if (from_enc == ERLANG_UTF8) {
-      to_enc = is_latin1_as_utf8(p, len) ? ERLANG_LATIN1 : ERLANG_UTF8;
-    }
-    else {
-      to_enc = from_enc;
-    }
-  }
-  switch(to_enc) {
-  case ERLANG_LATIN1:
-      if (buf) {
-	  put8(s,ERL_ATOM_EXT);
-	  switch (from_enc) {
-	  case ERLANG_UTF8:
-	      len = utf8_to_latin1(s+2, p, len, MAXATOMLEN-1, NULL);
-	      if (len < 0) return -1;
-	      break;
-	  case ERLANG_ASCII:
-	      if (verify_ascii_atom(p, len) < 0) return -1;
-	      memcpy(s+2, p, len);
-	      break;
-	  case ERLANG_LATIN1:
-	      memcpy(s+2, p, len);
-	      break;
-	  default:
-	      return -1;
-	  }
-	  put16be(s,len);
-      }
-      else {
-	  s += 3;
-	  if (from_enc == ERLANG_UTF8) {
-	      len = utf8_to_latin1(NULL, p, len, MAXATOMLEN-1, NULL);
-	      if (len < 0) return -1;
-	  } else if (from_enc == ERLANG_ASCII)
-	    if (verify_ascii_atom(p, len) < 0) return -1;
-      }
-      break;
-      
-  case ERLANG_UTF8:
+  /*
+   * Since OTP 20 we totally ignore 'to_enc'
+   * and alway encode as UTF8.
+   */
+  {
       offs =  1 + 1;
       switch (from_enc) {
       case ERLANG_LATIN1:
@@ -133,10 +97,6 @@ int ei_encode_atom_len_as(char *buf, int *index, const char *p, int len,
 	  }
       }
       else s+= offs;
-      break;
-
-  default:
-      return -1;
   }
   s += len;
 
@@ -197,13 +157,3 @@ static int verify_utf8_atom(const char* src, int slen)
     return 0;
 }
 
-/* Only latin1 code points in utf8 string?
- */
-static int is_latin1_as_utf8(const char *p, int len)
-{
-  int i;
-  for (i=0; i<len; i++) {
-    if ((unsigned char)p[i] > 0xC3) return 0;
-  }
-  return 1;
-}
diff --git a/lib/erl_interface/src/encode/encode_boolean.c b/lib/erl_interface/src/encode/encode_boolean.c
index 61e7e5e6e7..053029af05 100644
--- a/lib/erl_interface/src/encode/encode_boolean.c
+++ b/lib/erl_interface/src/encode/encode_boolean.c
@@ -32,12 +32,12 @@ int ei_encode_boolean(char *buf, int *index, int p)
   val = p ? "true" : "false";
   len = strlen(val);
 
-  if (!buf) s += 3;
+  if (!buf) s += 2;
   else {
-    put8(s,ERL_ATOM_EXT);
-    put16be(s,len);
+      put8(s, ERL_SMALL_ATOM_UTF8_EXT);
+      put8(s, len);
 
-    memmove(s,val,len); /* unterminated string */
+      memcpy(s,val,len); /* unterminated string */
   }
   s += len;
 
diff --git a/lib/erl_interface/src/legacy/erl_eterm.c b/lib/erl_interface/src/legacy/erl_eterm.c
index e4b3b49c7d..5153d0f2e7 100644
--- a/lib/erl_interface/src/legacy/erl_eterm.c
+++ b/lib/erl_interface/src/legacy/erl_eterm.c
@@ -188,14 +188,20 @@ char* erl_atom_ptr_latin1(Erl_Atom_data* a)
 char* erl_atom_ptr_utf8(Erl_Atom_data* a)
 {
     if (a->utf8 == NULL) {
-	int dlen = a->lenL * 2; /* over estimation */
-	a->utf8 = malloc(dlen + 1); 
-	a->lenU = latin1_to_utf8(a->utf8, a->latin1, a->lenL, dlen, NULL);
-	a->utf8[a->lenU] = '\0';
+        erlang_char_encoding enc;
+        a->lenU = latin1_to_utf8(NULL, a->latin1, a->lenL, a->lenL*2, &enc);
+        if (enc == ERLANG_ASCII) {
+            a->utf8 = a->latin1;
+        }
+        else {
+            a->utf8 = malloc(a->lenU + 1);
+            latin1_to_utf8(a->utf8, a->latin1, a->lenL, a->lenU, NULL);
+            a->utf8[a->lenU] = '\0';
+        }
     }
     return a->utf8;
-
 }
+
 int erl_atom_size_latin1(Erl_Atom_data* a)
 {
     if (a->latin1 == NULL) {
diff --git a/lib/erl_interface/src/legacy/erl_marshal.c b/lib/erl_interface/src/legacy/erl_marshal.c
index 527ae0ef8f..b7a8455313 100644
--- a/lib/erl_interface/src/legacy/erl_marshal.c
+++ b/lib/erl_interface/src/legacy/erl_marshal.c
@@ -175,10 +175,9 @@ static void encode_atom(Erl_Atom_data* a, unsigned char **ext)
     int ix = 0;
     if (a->latin1) {
 	ei_encode_atom_len_as((char*)*ext, &ix, a->latin1, a->lenL,
-			      ERLANG_LATIN1, ERLANG_LATIN1);
+			      ERLANG_LATIN1, ERLANG_UTF8);
     }
-    else if (ei_encode_atom_len_as((char*)*ext, &ix, a->utf8, a->lenU,
-				   ERLANG_UTF8, ERLANG_LATIN1) < 0) {
+    else {
 	ei_encode_atom_len_as((char*)*ext, &ix, a->utf8, a->lenU,
 			      ERLANG_UTF8, ERLANG_UTF8);
     }
@@ -542,12 +541,8 @@ int erl_term_len(ETERM *ep)
 
 static int atom_len_helper(Erl_Atom_data* a)
 {
-    if (erl_atom_ptr_latin1(a)) {
-	return 1 + 2 + a->lenL; /* ERL_ATOM_EXT */
-    }
-    else {
-	return 1 + 1 + (a->lenU > 255) + a->lenU;
-    }
+    (void) erl_atom_ptr_utf8(a);
+    return 1 + 1 + (a->lenU > 255) + a->lenU;
 }
 
 static int erl_term_len_helper(ETERM *ep, int dist)
diff --git a/lib/erl_interface/test/ei_decode_SUITE.erl b/lib/erl_interface/test/ei_decode_SUITE.erl
index 10e90685c8..8612450692 100644
--- a/lib/erl_interface/test/ei_decode_SUITE.erl
+++ b/lib/erl_interface/test/ei_decode_SUITE.erl
@@ -179,7 +179,8 @@ test_ei_decode_misc(Config) when is_list(Config) ->
 
     send_term_as_binary(P,foo),
     send_term_as_binary(P,''),
-    send_term_as_binary(P,'ÅÄÖåäö'),
+    %%send_term_as_binary(P,'ÅÄÖåäö'),
+    send_latin1_atom_as_binary(P, "ÅÄÖåäö"),
 
     send_term_as_binary(P,"foo"),
     send_term_as_binary(P,""),
@@ -200,18 +201,19 @@ test_ei_decode_misc(Config) when is_list(Config) ->
 test_ei_decode_utf8_atom(Config) ->
     P = runner:start(?test_ei_decode_utf8_atom),
 
-    send_utf8_atom_as_binary(P,"å"),
-    send_utf8_atom_as_binary(P,"ä"),
-    send_term_as_binary(P,'ö'),
-    send_term_as_binary(P,'õ'),
+    send_latin1_atom_as_binary(P,"å"),
+    send_latin1_atom_as_binary(P,"ä"),
+    send_latin1_atom_as_binary(P,"ö"),
+    send_latin1_atom_as_binary(P,"õ"),
 
     send_utf8_atom_as_binary(P,[1758]),
     send_utf8_atom_as_binary(P,[1758,1758]),
     send_utf8_atom_as_binary(P,[1758,1758,1758]),
     send_utf8_atom_as_binary(P,[1758,1758,1758,1758]),
 
-    send_utf8_atom_as_binary(P,"a"),
-    send_utf8_atom_as_binary(P,"b"),
+    send_latin1_atom_as_binary(P,"a"),
+    send_latin1_atom_as_binary(P,"b"),
+
     send_term_as_binary(P,'c'),
     send_term_as_binary(P,'d'),
 
@@ -230,6 +232,9 @@ send_raw(Port, Bin) when is_port(Port) ->
 send_utf8_atom_as_binary(Port, String) ->
     Port ! {self(), {command, term_to_binary(uc_atup(String))}}.
 
+send_latin1_atom_as_binary(Port, String) ->
+    Port ! {self(), {command, encode_latin1_atom(String)}}.
+
 send_integers(P) ->
     send_term_as_binary(P,0),		% SMALL_INTEGER_EXT smallest
     send_term_as_binary(P,255),		% SMALL_INTEGER_EXT largest
@@ -304,6 +309,12 @@ send_integers2(P) ->
     send_term_as_binary(P, []), % illegal type
     ok.
 
+encode_latin1_atom(String) ->
+    Len = length(String),
+    %% Use ATOM_EXT (not SMALL_*) to simulate old term_to_binary
+    TagLen = [$d, Len bsr 8, Len band 16#ff],
+    list_to_binary([131, TagLen, String]).
+
 uc_atup(ATxt) ->
     string_to_atom(ATxt).
 
diff --git a/lib/erl_interface/test/ei_decode_SUITE_data/ei_decode_test.c b/lib/erl_interface/test/ei_decode_SUITE_data/ei_decode_test.c
index cfe9083065..649dc9a677 100644
--- a/lib/erl_interface/test/ei_decode_SUITE_data/ei_decode_test.c
+++ b/lib/erl_interface/test/ei_decode_SUITE_data/ei_decode_test.c
@@ -102,7 +102,7 @@ int ei_decode_my_string(const char *buf, int *index, char *to,
     } \
 \
     if (size1 != SIZE) { \
-      fail("size of encoded data is incorrect"); \
+        fail1("size of encoded data (%d) is incorrect", size1);    \
       return; \
     } \
   } \
@@ -614,11 +614,11 @@ TESTCASE(test_ei_decode_misc)
     EI_DECODE_2(decode_double, 9, double, -1.0);
     EI_DECODE_2(decode_double, 9, double, 1.0);
 
-    EI_DECODE_2(decode_boolean, 8, int, 0);
-    EI_DECODE_2(decode_boolean, 7, int, 1);
+    EI_DECODE_2(decode_boolean, 7, int, 0);
+    EI_DECODE_2(decode_boolean, 6, int, 1);
 
-    EI_DECODE_STRING(decode_my_atom, 6, "foo");
-    EI_DECODE_STRING(decode_my_atom, 3, "");
+    EI_DECODE_STRING(decode_my_atom, 5, "foo");
+    EI_DECODE_STRING(decode_my_atom, 2, "");
     EI_DECODE_STRING(decode_my_atom, 9, "������");
 
     EI_DECODE_STRING(decode_my_string, 6, "foo");
@@ -665,10 +665,10 @@ TESTCASE(test_ei_decode_utf8_atom)
 		   P99({ERLANG_ANY,ERLANG_LATIN1,ERLANG_ASCII}));
   EI_DECODE_STRING_4(decode_my_atom_as, 4, "b",
 		     P99({ERLANG_UTF8,ERLANG_LATIN1,ERLANG_ASCII}));
-  EI_DECODE_STRING_4(decode_my_atom_as, 4, "c",
-		     P99({ERLANG_LATIN1,ERLANG_LATIN1,ERLANG_ASCII}));
-  EI_DECODE_STRING_4(decode_my_atom_as, 4, "d",
-		     P99({ERLANG_ASCII,ERLANG_LATIN1,ERLANG_ASCII}));
+  EI_DECODE_STRING_4(decode_my_atom_as, 3, "c",
+		     P99({ERLANG_LATIN1,ERLANG_UTF8,ERLANG_ASCII}));
+  EI_DECODE_STRING_4(decode_my_atom_as, 3, "d",
+		     P99({ERLANG_ASCII,ERLANG_UTF8,ERLANG_ASCII}));
 
   report(1);
 }
diff --git a/lib/erl_interface/test/ei_decode_encode_SUITE.erl b/lib/erl_interface/test/ei_decode_encode_SUITE.erl
index 570a91e2da..108a1f5142 100644
--- a/lib/erl_interface/test/ei_decode_encode_SUITE.erl
+++ b/lib/erl_interface/test/ei_decode_encode_SUITE.erl
@@ -170,7 +170,6 @@ get_binary(P) ->
 
 -define(VERSION_MAGIC,       131).
 
--define(ATOM_EXT,            100).
 -define(REFERENCE_EXT,       101).
 -define(PORT_EXT,            102).
 -define(PID_EXT,             103).
diff --git a/lib/erl_interface/test/ei_encode_SUITE.erl b/lib/erl_interface/test/ei_encode_SUITE.erl
index ac6ec9cf4e..43484a1319 100644
--- a/lib/erl_interface/test/ei_encode_SUITE.erl
+++ b/lib/erl_interface/test/ei_encode_SUITE.erl
@@ -184,17 +184,17 @@ test_ei_encode_misc(Config) when is_list(Config) ->
     {<<70,_:8/binary>>,Fp1} = get_buf_and_term(P),
     true = match_float(Fp1, 1.0),
 
-    {<<100,0,5,"false">>,false}  = get_buf_and_term(P),
-    {<<100,0,4,"true">> ,true}   = get_buf_and_term(P),
-    {<<100,0,4,"true">> ,true}   = get_buf_and_term(P),
-    {<<100,0,4,"true">> ,true}   = get_buf_and_term(P),
-
-    {<<100,0,3,"foo">>,foo}         = get_buf_and_term(P),
-    {<<100,0,3,"foo">>,foo}         = get_buf_and_term(P),
-    {<<100,0,0,"">>,''}             = get_buf_and_term(P),
-    {<<100,0,0,"">>,''}             = get_buf_and_term(P),
-    {<<100,0,6,"ÅÄÖåäö">>,'ÅÄÖåäö'} = get_buf_and_term(P),
-    {<<100,0,6,"ÅÄÖåäö">>,'ÅÄÖåäö'} = get_buf_and_term(P),
+    {<<$w,5,"false">>,false}  = get_buf_and_term(P),
+    {<<$w,4,"true">> ,true}   = get_buf_and_term(P),
+    {<<$w,4,"true">> ,true}   = get_buf_and_term(P),
+    {<<$w,4,"true">> ,true}   = get_buf_and_term(P),
+
+    {<<$w,3,"foo">>,foo}         = get_buf_and_term(P),
+    {<<$w,3,"foo">>,foo}         = get_buf_and_term(P),
+    {<<$w,0,"">>,''}             = get_buf_and_term(P),
+    {<<$w,0,"">>,''}             = get_buf_and_term(P),
+    {<<$w,12,"ÅÄÖåäö"/utf8>>,'ÅÄÖåäö'} = get_buf_and_term(P),
+    {<<$w,12,"ÅÄÖåäö"/utf8>>,'ÅÄÖåäö'} = get_buf_and_term(P),
 
     {<<107,0,3,"foo">>,"foo"}       = get_buf_and_term(P),
     {<<107,0,3,"foo">>,"foo"}       = get_buf_and_term(P),
@@ -239,12 +239,12 @@ test_ei_encode_utf8_atom(Config) ->
     P = runner:start(?test_ei_encode_utf8_atom),
 
     {<<119,2,195,133>>,'Å'} = get_buf_and_term(P),
-    {<<100,0,1,197>>,'Å'} = get_buf_and_term(P),
-    {<<100,0,1,197>>,'Å'} = get_buf_and_term(P),
+    {<<119,2,195,133>>,'Å'} = get_buf_and_term(P),
+    {<<119,2,195,133>>,'Å'} = get_buf_and_term(P),
     {<<119,2,195,133>>,'Å'} = get_buf_and_term(P),
 
     {<<119,1,$A>>,'A'} = get_buf_and_term(P),
-    {<<100,0,1,$A>>,'A'} = get_buf_and_term(P),
+    {<<119,1,$A>>,'A'} = get_buf_and_term(P),
 
     runner:recv_eot(P),
     ok.
@@ -254,13 +254,13 @@ test_ei_encode_utf8_atom_len(Config) ->
     P = runner:start(?test_ei_encode_utf8_atom_len),
 
     {<<119,2,195,133>>,'Å'} = get_buf_and_term(P),
-    {<<100,0,2,197,196>>,'ÅÄ'} = get_buf_and_term(P),
-    {<<100,0,1,197>>,'Å'} = get_buf_and_term(P),
+    {<<119,4,195,133,195,132>>,'ÅÄ'} = get_buf_and_term(P),
+    {<<119,2,195,133>>,'Å'} = get_buf_and_term(P),
     {<<119,4,195,133,195,132>>,'ÅÄ'} = get_buf_and_term(P),
 
     {<<119,1,$A>>,'A'} = get_buf_and_term(P),
-    {<<100,0,2,$A,$B>>,'AB'} = get_buf_and_term(P),
-    {<<100,0,255,_:(255*8)>>,_} = get_buf_and_term(P),
+    {<<119,2,$A,$B>>,'AB'} = get_buf_and_term(P),
+    {<<119,255,_:(255*8)>>,_} = get_buf_and_term(P),
 
     runner:recv_eot(P),
     ok.
diff --git a/lib/erl_interface/test/erl_ext_SUITE_data/ext_test.c b/lib/erl_interface/test/erl_ext_SUITE_data/ext_test.c
index 36cf086ed2..afac5485e8 100644
--- a/lib/erl_interface/test/erl_ext_SUITE_data/ext_test.c
+++ b/lib/erl_interface/test/erl_ext_SUITE_data/ext_test.c
@@ -407,7 +407,7 @@ test_compare_ext(char *test_desc,
 }
 
 
-#define ATOM_EXT          (100)
+#define SMALL_ATOM_UTF8_EXT (119)
 #define REFERENCE_EXT     (101)
 #define PORT_EXT          (102)
 #define PID_EXT           (103)
@@ -429,13 +429,13 @@ write_atom(unsigned char *buf, char *atom)
 
     len = 0;
     while(atom[len]) {
-	buf[len + 3] = atom[len];
+	buf[len + 2] = atom[len];
 	len++;
     }
-    buf[0] = ATOM_EXT;
-    PUT_UINT16(&buf[1], len);
+    buf[0] = SMALL_ATOM_UTF8_EXT;
+    buf[1] = len;
 
-    return buf + 3 + len;
+    return buf + 2 + len;
 }
 
 static unsigned char *