Author: jilles
Date: Sat Feb 12 23:44:05 2011
New Revision: 218626
URL: http://svn.freebsd.org/changeset/base/218626
Log:
sh: Detect dividing the smallest integer by -1.
This overflows and on some architectures such as amd64 it generates SIGFPE.
Generate an error on all architectures.
Added:
head/tools/regression/bin/sh/expansion/arith11.0 (contents, props changed)
Modified:
head/bin/sh/arith_yacc.c
head/bin/sh/shell.h
Modified: head/bin/sh/arith_yacc.c
==============================================================================
--- head/bin/sh/arith_yacc.c Sat Feb 12 21:30:46 2011 (r218625)
+++ head/bin/sh/arith_yacc.c Sat Feb 12 23:44:05 2011 (r218626)
@@ -125,6 +125,8 @@ static arith_t do_binop(int op, arith_t
case ARITH_DIV:
if (!b)
yyerror("division by zero");
+ if (a == ARITH_MIN && b == -1)
+ yyerror("divide error");
return op == ARITH_REM ? a % b : a / b;
case ARITH_MUL:
return a * b;
Modified: head/bin/sh/shell.h
==============================================================================
--- head/bin/sh/shell.h Sat Feb 12 21:30:46 2011 (r218625)
+++ head/bin/sh/shell.h Sat Feb 12 23:44:05 2011 (r218626)
@@ -59,6 +59,8 @@ typedef intmax_t arith_t;
#define ARITH_FORMAT_STR "%" PRIdMAX
#define atoarith_t(arg) strtoimax(arg, NULL, 0)
#define strtoarith_t(nptr, endptr, base) strtoimax(nptr, endptr, base)
+#define ARITH_MIN INTMAX_MIN
+#define ARITH_MAX INTMAX_MAX
typedef void *pointer;
#define MKINIT /* empty */
Added: head/tools/regression/bin/sh/expansion/arith11.0
==============================================================================
--- /dev/null 00:00:00 1970 (empty, because file is newly added)
+++ head/tools/regression/bin/sh/expansion/arith11.0 Sat Feb 12 23:44:05
2011 (r218626)
@@ -0,0 +1,12 @@
+# $FreeBSD$
+# Try to divide the smallest integer by -1.
+# On amd64 this causes SIGFPE, so make sure the shell checks.
+
+# Calculate the minimum possible value, assuming two's complement and
+# a certain interpretation of overflow when shifting left.
+minint=1
+while [ $((minint <<= 1)) -gt 0 ]; do
+ :
+done
+v=$( eval ': $((minint / -1))' 2>&1 >/dev/null)
+[ $? -ne 0 ] && [ -n "$v" ]
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