Merge branch 'sverk/large-list_to_integer-bug/OTP-12624' into maint

* sverk/large-list_to_integer-bug/OTP-12624: erts: Fix bug in list_to_integer for very large strings
jackric · Mar 27, 2015 · cbceea6 · cbceea6
2 parents d477e59 + 59ec304
commit cbceea6
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Showing 2 changed files with 9 additions and 3 deletions.
diff --git a/erts/emulator/beam/bif.c b/erts/emulator/beam/bif.c
@@ -2775,7 +2775,7 @@ static int do_list_to_integer(Process *p, Eterm orig_list,
      Uint ui = 0;
      int skip = 0;
      int neg = 0;
-     int n = 0;
+     Sint n = 0;
      int m;
      int lg2;
      Eterm res;
@@ -2855,7 +2855,9 @@ static int do_list_to_integer(Process *p, Eterm orig_list,
          else i = (Sint)ui;
 	 res = make_small(i);
      } else {
-	 lg2 =  (n+1)*230/69+1;
+	 /* Convert from log10 to log2 by multiplying with 1/log10(2)=3.3219
+	    which we round up to (3 + 1/3) */
+	 lg2 = (n+1)*3 + (n+1)/3 + 1;
 	 m  = (lg2+D_EXP-1)/D_EXP; /* number of digits */
 	 m  = BIG_NEED_SIZE(m);    /* number of words + thing */
 

diff --git a/erts/emulator/test/num_bif_SUITE.erl b/erts/emulator/test/num_bif_SUITE.erl
@@ -441,7 +441,11 @@ t_string_to_integer(Config) when is_list(Config) ->
 		       {"1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111z",16},
 		       {"1z111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111",16},
 		       {"111z11111111",16}]),
-
+
+    %% log2 calculation overflow bug in do_integer_to_list (OTP-12624)
+    %% Would crash with segv
+    0 = list_to_integer(lists:duplicate(10000000,$0)),
+
     ok.
 
 test_sti(Num) ->