From ffd9a7ea27d82b96ec51ee6016fb85dccda51ef5 Mon Sep 17 00:00:00 2001 From: shyouhei Date: Fri, 16 Nov 2018 09:04:34 +0000 Subject: pack.c: cast from double to float can be undefined Generally speaking, a value of double is not always representable when demoted to a float. ISO C defines what to do when such conversion loses precision, but leaves it undefined when the value is completely out of range. (cf: ISO/IEC 9899:1990 section 6.2.1.4). Because ruby do not have half-precision floating-point types this is not a frequent headache but for pack / unpack, there are specifiers that has something to do with C float types. We have to explicitly care these situations. git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65768 b2dd03c8-39d4-4d8f-98ff-823fe69b080e --- pack.c | 27 ++++++++++++++++++++++++--- 1 file changed, 24 insertions(+), 3 deletions(-) (limited to 'pack.c') diff --git a/pack.c b/pack.c index 7a1a425cee..b1efef54f1 100644 --- a/pack.c +++ b/pack.c @@ -14,6 +14,7 @@ #include #include #include +#include /* * It is intentional that the condition for natstr is HAVE_TRUE_LONG_LONG @@ -148,6 +149,26 @@ unknown_directive(const char *mode, char type, VALUE fmt) mode, unknown, fmt); } +static float +VALUE_to_float(VALUE obj) +{ + VALUE v = rb_to_float(obj); + double d = RFLOAT_VALUE(v); + + if (isnan(d)) { + return NAN; + } + else if (d < -FLT_MAX) { + return -INFINITY; + } + else if (d <= FLT_MAX) { + return d; + } + else { + return INFINITY; + } +} + /* * call-seq: * arr.pack( aTemplateString ) -> aBinaryString @@ -663,7 +684,7 @@ pack_pack(int argc, VALUE *argv, VALUE ary) float f; from = NEXTFROM; - f = (float)RFLOAT_VALUE(rb_to_float(from)); + f = VALUE_to_float(from); rb_str_buf_cat(res, (char*)&f, sizeof(float)); } break; @@ -673,7 +694,7 @@ pack_pack(int argc, VALUE *argv, VALUE ary) FLOAT_CONVWITH(tmp); from = NEXTFROM; - tmp.f = (float)RFLOAT_VALUE(rb_to_float(from)); + tmp.f = VALUE_to_float(from); HTOVF(tmp); rb_str_buf_cat(res, tmp.buf, sizeof(float)); } @@ -704,7 +725,7 @@ pack_pack(int argc, VALUE *argv, VALUE ary) while (len-- > 0) { FLOAT_CONVWITH(tmp); from = NEXTFROM; - tmp.f = (float)RFLOAT_VALUE(rb_to_float(from)); + tmp.f = VALUE_to_float(from); HTONF(tmp); rb_str_buf_cat(res, tmp.buf, sizeof(float)); } -- cgit v1.2.3