erts: Make erlang:halt() accept bignums as Status

Just mask away the high bits to get a more tolerant erlang:halt that behaves the same on 32 and 64 bit architectures.
evnu · Feb 24, 2016 · 1b094d7 · 1b094d7
1 parent 56090db
commit 1b094d7
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Showing 4 changed files with 35 additions and 7 deletions.
diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml
@@ -1794,7 +1794,8 @@ os_prompt% </pre>
 	  </item>
 	</taglist>
         <note><p>On many platforms, the OS supports only status
-        codes 0-255.</p></note>
+        codes 0-255. A too large status code will be truncated by clearing
+	the high bits.</p></note>
 	<p>For integer <c><anno>Status</anno></c>, the Erlang runtime system
           closes all ports and allows async threads to finish their
           operations before exiting. To exit without such flushing, use

diff --git a/erts/emulator/beam/bif.c b/erts/emulator/beam/bif.c
@@ -3938,10 +3938,10 @@ static char halt_msg[HALT_MSG_SIZE];
 /* ARGSUSED */
 BIF_RETTYPE halt_1(BIF_ALIST_1)
 {
-    Sint code;
+    Uint code;
 
-    if (is_small(BIF_ARG_1) && (code = signed_val(BIF_ARG_1)) >= 0) {
-	int pos_int_code = (int)code & INT_MAX;
+    if (term_to_Uint_mask(BIF_ARG_1, &code)) {
+	int pos_int_code = (int) (code & INT_MAX);
 	VERBOSE(DEBUG_SYSTEM,("System halted by BIF halt(%T)\n", BIF_ARG_1));
 	erts_halt(pos_int_code);
 	ERTS_BIF_YIELD1(bif_export[BIF_halt_1], BIF_P, am_undefined);
@@ -3975,7 +3975,7 @@ BIF_RETTYPE halt_1(BIF_ALIST_1)
 /* ARGSUSED */
 BIF_RETTYPE halt_2(BIF_ALIST_2)
 {
-    Sint code;
+    Uint code;
     Eterm optlist = BIF_ARG_2;
     int flush = 1;
 
@@ -4002,8 +4002,8 @@ BIF_RETTYPE halt_2(BIF_ALIST_2)
     if (is_not_nil(optlist))
 	goto error;
 
-    if (is_small(BIF_ARG_1) && (code = signed_val(BIF_ARG_1)) >= 0) {
-	int pos_int_code = (int)code & INT_MAX;
+    if (term_to_Uint_mask(BIF_ARG_1, &code)) {
+	int pos_int_code = (int) (code & INT_MAX);
 	VERBOSE(DEBUG_SYSTEM,
 		("System halted by BIF halt(%T, %T)\n", BIF_ARG_1, BIF_ARG_2));
 	if (flush) {

diff --git a/erts/emulator/beam/big.c b/erts/emulator/beam/big.c
@@ -2028,6 +2028,32 @@ term_to_Uint(Eterm term, Uint *up)
     }
 }
 
+/* same as term_to_Uint()
+   but also accept larger bignums by masking
+ */
+int
+term_to_Uint_mask(Eterm term, Uint *up)
+{
+    if (is_small(term)) {
+	Sint i = signed_val(term);
+	if (i < 0) {
+	    *up = BADARG;
+	    return 0;
+	}
+	*up = (Uint) i;
+	return 1;
+    } else if (is_big(term) && !big_sign(term)) {
+	ErtsDigit* xr = big_v(term);
+
+	ERTS_CT_ASSERT(sizeof(ErtsDigit) == sizeof(Uint));
+	*up = (Uint)*xr;  /* just pick first word */
+	return 1;
+    } else {
+	*up = BADARG;
+	return 0;
+    }
+}
+
 int
 term_to_UWord(Eterm term, UWord *up)
 {

diff --git a/erts/emulator/beam/big.h b/erts/emulator/beam/big.h
@@ -161,6 +161,7 @@ Eterm bytes_to_big(byte*, dsize_t, int, Eterm*);
 byte* big_to_bytes(Eterm, byte*);
 
 int term_to_Uint(Eterm, Uint*);
+int term_to_Uint_mask(Eterm, Uint*);
 int term_to_UWord(Eterm, UWord*);
 int term_to_Sint(Eterm, Sint*);
 #if HAVE_INT64