`mruby-pack` should not rely on `MRB_ENDIAN_BIG` macro; fix
The `MRB_ENDIAN_BIG` macro is originally used for `NaN` boxing.
We cannot assume it is defined on every big endian platform
is the case). So instead of relying on untrusted `MRB_ENDIAN_BIG`, we
use `BYTE_ORDER` macro with a fallback function to check endian in
runtime.
MODIFY
mrbgems/mruby-pack/src/pack.c
mrbgems/mruby-pack/src/pack.c
@@ -60,19 +60,28 @@ enum {
#define PACK_BASE64_IGNORE 0xff
#define PACK_BASE64_PADDING 0xfe
-static int littleendian = 0;
-
const static unsigned char base64chars[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
static unsigned char base64_dec_tab[128];
-
-static int
+#ifdef BYTE_ORDER
+# if BYTE_ORDER == BIG_ENDIAN
+# define littleendian 0
+# define check_little_endian() (void)0
+# elif BYTE_ORDER == LITTLE_ENDIAN
+# define littleendian 1
+# define check_little_endian() (void)0
+# else
+/* can't distinguish endian in compile time */
+static int littleendian = 0;
+static void
check_little_endian(void)
{
unsigned int n = 1;
- return (*(unsigned char *)&n == 1);
+ littleendian = (*(unsigned char *)&n == 1);
}
+# endif
+#endif
static unsigned int
hex2int(unsigned char ch)
@@ -313,21 +322,23 @@ pack_double(mrb_state *mrb, mrb_value o, mrb_value str, mrb_int sidx, unsigned i
d = mrb_float(o);
if (flags & PACK_FLAG_LITTLEENDIAN) {
-#ifdef MRB_ENDIAN_BIG
+ if (littleendian) {
+ memcpy(RSTRING_PTR(str) + sidx, buffer, 8);
+ }
+ else {
for (i = 0; i < 8; ++i) {
RSTRING_PTR(str)[sidx + i] = buffer[8 - i - 1];
}
-#else
- memcpy(RSTRING_PTR(str) + sidx, buffer, 8);
-#endif
+ }
} else {
-#ifdef MRB_ENDIAN_BIG
- memcpy(RSTRING_PTR(str) + sidx, buffer, 8);
-#else
+ if (littleendian) {
for (i = 0; i < 8; ++i) {
RSTRING_PTR(str)[sidx + i] = buffer[8 - i - 1];
}
-#endif
+ }
+ else {
+ memcpy(RSTRING_PTR(str) + sidx, buffer, 8);
+ }
}
return 8;
@@ -341,21 +352,23 @@ unpack_double(mrb_state *mrb, const unsigned char * src, int srclen, mrb_value a
uint8_t *buffer = (uint8_t *)&d;
if (flags & PACK_FLAG_LITTLEENDIAN) {
-#ifdef MRB_ENDIAN_BIG
+ if (littleendian) {
+ memcpy(buffer, src, 8);
+ }
+ else {
for (i = 0; i < 8; ++i) {
buffer[8 - i - 1] = src[i];
}
-#else
- memcpy(buffer, src, 8);
-#endif
+ }
} else {
-#ifdef MRB_ENDIAN_BIG
- memcpy(buffer, src, 8);
-#else
+ if (littleendian) {
for (i = 0; i < 8; ++i) {
buffer[8 - i - 1] = src[i];
}
-#endif
+ }
+ else {
+ memcpy(buffer, src, 8);
+ }
}
mrb_ary_push(mrb, ary, mrb_float_value(mrb, d));
@@ -372,21 +385,23 @@ pack_float(mrb_state *mrb, mrb_value o, mrb_value str, mrb_int sidx, unsigned in
f = (float)mrb_float(o);
if (flags & PACK_FLAG_LITTLEENDIAN) {
-#ifdef MRB_ENDIAN_BIG
+ if (littleendian) {
+ memcpy(RSTRING_PTR(str) + sidx, buffer, 4);
+ }
+ else {
for (i = 0; i < 4; ++i) {
RSTRING_PTR(str)[sidx + i] = buffer[4 - i - 1];
}
-#else
- memcpy(RSTRING_PTR(str) + sidx, buffer, 4);
-#endif
+ }
} else {
-#ifdef MRB_ENDIAN_BIG
- memcpy(RSTRING_PTR(str) + sidx, buffer, 4);
-#else
+ if (littleendian) {
for (i = 0; i < 4; ++i) {
RSTRING_PTR(str)[sidx + i] = buffer[4 - i - 1];
}
-#endif
+ }
+ else {
+ memcpy(RSTRING_PTR(str) + sidx, buffer, 4);
+ }
}
return 4;
@@ -400,21 +415,23 @@ unpack_float(mrb_state *mrb, const unsigned char * src, int srclen, mrb_value ar
uint8_t *buffer = (uint8_t *)&f;
if (flags & PACK_FLAG_LITTLEENDIAN) {
-#ifdef MRB_ENDIAN_BIG
+ if (littleendian) {
+ memcpy(buffer, src, 4);
+ }
+ else {
for (i = 0; i < 4; ++i) {
buffer[4 - i - 1] = src[i];
}
-#else
- memcpy(buffer, src, 4);
-#endif
+ }
} else {
-#ifdef MRB_ENDIAN_BIG
- memcpy(buffer, src, 4);
-#else
+ if (littleendian) {
for (i = 0; i < 4; ++i) {
buffer[4 - i - 1] = src[i];
}
-#endif
+ }
+ else {
+ memcpy(buffer, src, 4);
+ }
}
mrb_ary_push(mrb, ary, mrb_float_value(mrb, f));
@@ -1297,7 +1314,7 @@ mrb_pack_unpack1(mrb_state *mrb, mrb_value str)
void
mrb_mruby_pack_gem_init(mrb_state *mrb)
{
- littleendian = check_little_endian();
+ check_little_endian();
make_base64_dec_tab();
mrb_define_method(mrb, mrb->array_class, "pack", mrb_pack_pack, MRB_ARGS_REQ(1));

`mruby-pack` should not rely on `MRB_ENDIAN_BIG` macro; fix #4190

The `MRB_ENDIAN_BIG` macro is originally used for `NaN` boxing.
We cannot assume it is defined on every big endian platform (#4190
is the case). So instead of relying on untrusted `MRB_ENDIAN_BIG`, we
use `BYTE_ORDER` macro with a fallback function to check endian in
runtime.