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radare2/libr/util/uleb128.c
Pepe Vila 40a33b3a26 Rewrite WASM to fix all oob issues
2017-04-15 19:57:54 +02:00

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/* radare - LGPL - Copyright 2014-2015 - pancake */
#include <r_util.h>
/* dex/dwarf uleb128 implementation */
R_API const ut8 *r_uleb128(const ut8 *data, int datalen, ut64 *v) {
ut8 c;
ut64 s, sum = 0;
const ut8 *data_end;
if (v) *v = 0LL;
if (datalen == ST32_MAX) {
// WARNING; possible overflow
datalen = 0xffff;
}
if (datalen < 0) {
return NULL;
}
data_end = data + datalen;
if (data && datalen > 0) {
if (*data) {
for (s = 0; data < data_end; s += 7) {
c = *(data++) & 0xff;
sum |= ((ut32) (c & 0x7f) << s);
if (!(c & 0x80)) break;
}
} else {
data++;
}
}
if (v) *v = sum;
return data;
}
/* data is the char array containing the uleb number
* datalen will point (if not NULL) to the length of the uleb number
* v (if not NULL) will point to the data's value (if fitting the size of an ut64)
*/
R_API const ut8 *r_uleb128_decode(const ut8 *data, int *datalen, ut64 *v) {
ut8 c = 0xff;
ut64 s = 0, sum = 0, l = 0;
if (data && *data) {
do {
c = *(data++) & 0xff;
sum |= ((ut32) (c&0x7f) << s);
s += 7;
l++;
} while (c & 0x80);
}
if (v) *v = sum;
if (datalen) *datalen = l;
return data;
}
R_API const ut8 *r_uleb128_encode(const ut64 s, int *len) {
ut8 c = 0;
int l = 0;
ut8 *otarget = NULL, *target = NULL;
ut64 source = s;
do {
l++;
if (!(otarget = realloc (otarget, l))) {
l = 0;
break;
}
target = otarget+l-1;
c = 0; //May not be necessary
c = source & 0x7f;
source >>= 7;
if (source) c |= 0x80;
*(target) = c;
} while (source);
if (len) *len = l;
return otarget;
}
R_API const ut8 *r_leb128(const ut8 *data, st64 *v) {
ut8 c = 0;
st64 s = 0, sum = 0;
if (data) {
for (s = 0; *data;) {
c = *(data++) & 0x0ff;
sum |= ((st64) (c & 0x7f) << s);
s += 7;
if (!(c & 0x80)) break;
}
}
if ((s < (8 * sizeof (sum))) && (c & 0x40)) {
sum |= -((st64)1 << s);
}
if (v) *v = sum;
return data;
}
//API borrowed from frida
#define G_GINT64_CONSTANT(val) (val##L)
R_API st64 r_sleb128(const ut8 **data, const ut8 *end) {
const ut8 *p = *data;
st64 result = 0;
int offset = 0;
ut8 value;
do {
st64 chunk;
value = *p;
chunk = value & 0x7f;
result |= (chunk << offset);
offset += 7;
}
while (*p++ & 0x80);
if ((value & 0x40) != 0) {
result |= G_GINT64_CONSTANT (-1) << offset;
}
*data = p;
return result;
}
// API from https://github.com/WebAssembly/wabt/blob/master/src/binary-reader.cc
#define BYTE_AT(type, i, shift) (((type)(p[i]) & 0x7f) << (shift))
#define LEB128_1(type) (BYTE_AT (type, 0, 0))
#define LEB128_2(type) (BYTE_AT (type, 1, 7) | LEB128_1 (type))
#define LEB128_3(type) (BYTE_AT (type, 2, 14) | LEB128_2 (type))
#define LEB128_4(type) (BYTE_AT (type, 3, 21) | LEB128_3 (type))
#define LEB128_5(type) (BYTE_AT (type, 4, 28) | LEB128_4 (type))
#define LEB128_6(type) (BYTE_AT (type, 5, 35) | LEB128_5 (type))
#define LEB128_7(type) (BYTE_AT (type, 6, 42) | LEB128_6 (type))
#define LEB128_8(type) (BYTE_AT (type, 7, 49) | LEB128_7 (type))
#define LEB128_9(type) (BYTE_AT (type, 8, 56) | LEB128_8 (type))
#define LEB128_10(type) (BYTE_AT (type, 9, 63) | LEB128_9 (type))
#define SHIFT_AMOUNT(type, sign_bit) (sizeof(type) * 8 - 1 - (sign_bit))
#define SIGN_EXTEND(type, value, sign_bit) \
((type)((value) << SHIFT_AMOUNT (type, sign_bit)) >> \
SHIFT_AMOUNT (type, sign_bit))
R_API size_t read_u32_leb128 (const ut8* p, const ut8* max, ut32* out_value) {
if (p < max && !(p[0] & 0x80)) {
*out_value = LEB128_1 (ut32);
return 1;
} else if (p + 1 < max && !(p[1] & 0x80)) {
*out_value = LEB128_2 (ut32);
return 2;
} else if (p + 2 < max && !(p[2] & 0x80)) {
*out_value = LEB128_3 (ut32);
return 3;
} else if (p + 3 < max && !(p[3] & 0x80)) {
*out_value = LEB128_4 (ut32);
return 4;
} else if (p + 4 < max && !(p[4] & 0x80)) {
/* the top bits set represent values > 32 bits */
// if (p[4] & 0xf0) {}
*out_value = LEB128_5 (ut32);
return 5;
} else {
/* past the end */
*out_value = 0;
return 0;
}
}
R_API size_t read_i32_leb128 (const ut8* p, const ut8* max, st32* out_value) {
if (p < max && !(p[0] & 0x80)) {
ut32 result = LEB128_1 (ut32);
*out_value = SIGN_EXTEND (ut32, result, 6);
return 1;
} else if (p + 1 < max && !(p[1] & 0x80)) {
ut32 result = LEB128_2 (ut32);
*out_value = SIGN_EXTEND (ut32, result, 13);
return 2;
} else if (p + 2 < max && !(p[2] & 0x80)) {
ut32 result = LEB128_3 (ut32);
*out_value = SIGN_EXTEND (ut32, result, 20);
return 3;
} else if (p + 3 < max && !(p[3] & 0x80)) {
ut32 result = LEB128_4 (ut32);
*out_value = SIGN_EXTEND (ut32, result, 27);
return 4;
} else if (p+4 < max && !(p[4] & 0x80)) {
/* the top bits should be a sign-extension of the sign bit */
bool sign_bit_set = (p[4] & 0x8);
int top_bits = p[4] & 0xf0;
if ((sign_bit_set && top_bits != 0x70) || (!sign_bit_set && top_bits != 0)) {
return 0;
}
ut32 result = LEB128_5 (ut32);
*out_value = result;
return 5;
} else {
/* past the end */
return 0;
}
}
R_API size_t read_u64_leb128 (const ut8* p, const ut8* max, ut64* out_value) {
if (p < max && !(p[0] & 0x80)) {
*out_value = LEB128_1 (ut64);
return 1;
} else if (p + 1 < max && !(p[1] & 0x80)) {
*out_value = LEB128_2 (ut64);
return 2;
} else if (p + 2 < max && !(p[2] & 0x80)) {
*out_value = LEB128_3 (ut64);
return 3;
} else if (p + 3 < max && !(p[3] & 0x80)) {
*out_value = LEB128_4 (ut64);
return 4;
} else if (p + 4 < max && !(p[4] & 0x80)) {
*out_value = LEB128_5 (ut64);
return 5;
} else if (p + 5 < max && !(p[5] & 0x80)) {
*out_value = LEB128_6 (ut64);
return 6;
} else if (p + 6 < max && !(p[6] & 0x80)) {
*out_value = LEB128_7 (ut64);
return 7;
} else if (p + 7 < max && !(p[7] & 0x80)) {
*out_value = LEB128_8 (ut64);
return 8;
} else if (p + 8 < max && !(p[8] & 0x80)) {
*out_value = LEB128_9 (ut64);
return 9;
} else if (p + 9 < max && !(p[9] & 0x80)) {
*out_value = LEB128_10 (ut64);
return 10;
} else {
/* past the end */
*out_value = 0;
return 0;
}
}
R_API size_t read_i64_leb128 (const ut8* p, const ut8* max, st64* out_value) {
if (p < max && !(p[0] & 0x80)) {
ut64 result = LEB128_1 (ut64);
*out_value = SIGN_EXTEND (ut64, result, 6);
return 1;
} else if (p + 1 < max && !(p[1] & 0x80)) {
ut64 result = LEB128_2(ut64);
*out_value = SIGN_EXTEND (ut64, result, 13);
return 2;
} else if (p + 2 < max && !(p[2] & 0x80)) {
ut64 result = LEB128_3 (ut64);
*out_value = SIGN_EXTEND (ut64, result, 20);
return 3;
} else if (p + 3 < max && !(p[3] & 0x80)) {
ut64 result = LEB128_4 (ut64);
*out_value = SIGN_EXTEND (ut64, result, 27);
return 4;
} else if (p + 4 < max && !(p[4] & 0x80)) {
ut64 result = LEB128_5 (ut64);
*out_value = SIGN_EXTEND (ut64, result, 34);
return 5;
} else if (p + 5 < max && !(p[5] & 0x80)) {
ut64 result = LEB128_6 (ut64);
*out_value = SIGN_EXTEND (ut64, result, 41);
return 6;
} else if (p + 6 < max && !(p[6] & 0x80)) {
ut64 result = LEB128_7 (ut64);
*out_value = SIGN_EXTEND (ut64, result, 48);
return 7;
} else if (p + 7 < max && !(p[7] & 0x80)) {
ut64 result = LEB128_8 (ut64);
*out_value = SIGN_EXTEND (ut64, result, 55);
return 8;
} else if (p + 8 < max && !(p[8] & 0x80)) {
ut64 result = LEB128_9 (ut64);
*out_value = SIGN_EXTEND (ut64, result, 62);
return 9;
} else if (p + 9 < max && !(p[9] & 0x80)) {
/* the top bits should be a sign-extension of the sign bit */
bool sign_bit_set = (p[9] & 0x1);
int top_bits = p[9] & 0xfe;
if ((sign_bit_set && top_bits != 0x7e) || (!sign_bit_set && top_bits != 0)) {
return 0;
}
ut64 result = LEB128_10 (ut64);
*out_value = result;
return 10;
} else {
/* past the end */
return 0;
}
}
#undef BYTE_AT
#undef LEB128_1
#undef LEB128_2
#undef LEB128_3
#undef LEB128_4
#undef LEB128_5
#undef LEB128_6
#undef LEB128_7
#undef LEB128_8
#undef LEB128_9
#undef LEB128_10
#undef SHIFT_AMOUNT
#undef SIGN_EXTEND
#if 0
main() {
ut32 n;
ut8 *buf = "\x10\x02\x90\x88";
r_uleb128 (buf, &n);
printf ("n = %d\n", n);
}
#endif
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