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[core] Fix UB in frombuf/tobuf #22176

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[core] Fix UB in frombuf/tobuf #22176

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142 changes: 64 additions & 78 deletions core/base/inc/Bytes.h
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Original file line number Diff line number Diff line change
Expand Up @@ -85,7 +85,8 @@ inline void tobuf(char *&buf, UInt_t x)
{
#ifdef R__BYTESWAP
# if defined(R__USEASMSWAP)
*((UInt_t *)buf) = Rbswap_32(x);
x = Rbswap_32(x);
memcpy(buf, &x, sizeof(x));
# else
// To work around a stupid optimization bug in MSVC++ 6.0
const UInt_t *intermediary = &x;
Expand Down Expand Up @@ -197,7 +198,8 @@ inline void tobuf(char *&buf, ULong64_t x)
{
#ifdef R__BYTESWAP
# if defined(R__USEASMSWAP)
*((ULong64_t *)buf) = Rbswap_64(x);
x = Rbswap_64(x);
memcpy(buf, &x, sizeof(x));
# else
// To work around a stupid optimization bug in MSVC++ 6.0
const ULong64_t *intermediary = &x;
Expand All @@ -221,22 +223,17 @@ inline void tobuf(char *&buf, Float_t x)
{
#ifdef R__BYTESWAP
# if defined(R__USEASMSWAP)
union {
volatile UInt_t i;
volatile Float_t f;
} u;
u.f = x;
*((UInt_t *)buf) = Rbswap_32(u.i);
UInt_t i;
memcpy(&i, &x, sizeof(x));
i = Rbswap_32(i);
memcpy(buf, &i, sizeof(i));
# else
union {
volatile char c[4];
volatile Float_t f;
} u;
u.f = x;
buf[0] = u.c[3];
buf[1] = u.c[2];
buf[2] = u.c[1];
buf[3] = u.c[0];
char c[4];
memcpy(c, &x, sizeof(x));
buf[0] = c[3];
buf[1] = c[2];
buf[2] = c[1];
buf[3] = c[0];
# endif
#else
memcpy(buf, &x, sizeof(Float_t));
Expand All @@ -248,26 +245,21 @@ inline void tobuf(char *&buf, Double_t x)
{
#ifdef R__BYTESWAP
# if defined(R__USEASMSWAP)
union {
volatile ULong64_t l;
volatile Double_t d;
} u;
u.d = x;
*((ULong64_t *)buf) = Rbswap_64(u.l);
ULong64_t l;
memcpy(&l, &x, sizeof(x));
l = Rbswap_64(l);
memcpy(buf, &l, sizeof(l));
# else
union {
volatile char c[8];
volatile Double_t d;
} u;
u.d = x;
buf[0] = u.c[7];
buf[1] = u.c[6];
buf[2] = u.c[5];
buf[3] = u.c[4];
buf[4] = u.c[3];
buf[5] = u.c[2];
buf[6] = u.c[1];
buf[7] = u.c[0];
char c[8];
memcpy(c, &x, sizeof(x));
buf[0] = c[7];
buf[1] = c[6];
buf[2] = c[5];
buf[3] = c[4];
buf[4] = c[3];
buf[5] = c[2];
buf[6] = c[1];
buf[7] = c[0];
# endif
#else
memcpy(buf, &x, sizeof(Double_t));
Expand All @@ -291,7 +283,9 @@ inline void frombuf(char *&buf, UShort_t *x)
{
#ifdef R__BYTESWAP
# if defined(R__USEASMSWAP)
*x = Rbswap_16(*((UShort_t *)buf));
Short_t s;
memcpy(&s, buf, sizeof(s));
*x = Rbswap_16(s);
# else
char *sw = (char *)x;
sw[0] = buf[1];
Expand All @@ -307,9 +301,11 @@ inline void frombuf(char *&buf, UInt_t *x)
{
#ifdef R__BYTESWAP
# if defined(R__USEASMSWAP)
*x = Rbswap_32(*((UInt_t *)buf));
UInt_t i;
memcpy(&i, buf, sizeof(i));
*x = Rbswap_32(i);
# else
char *sw = (char *)x;
char *sw = reinterpret_cast<char *>(x);
sw[0] = buf[3];
sw[1] = buf[2];
sw[2] = buf[1];
Expand All @@ -324,7 +320,7 @@ inline void frombuf(char *&buf, UInt_t *x)
inline void frombuf(char *&buf, ULong_t *x)
{
#ifdef R__BYTESWAP
char *sw = (char *)x;
char *sw = reinterpret_cast<char *>(x);
if (sizeof(ULong_t) == 8) {
sw[0] = buf[7];
sw[1] = buf[6];
Expand Down Expand Up @@ -354,9 +350,11 @@ inline void frombuf(char *&buf, ULong64_t *x)
{
#ifdef R__BYTESWAP
# if defined(R__USEASMSWAP)
*x = Rbswap_64(*((ULong64_t *)buf));
ULong64_t l;
memcpy(&l, buf, sizeof(l));
*x = Rbswap_64(l);
# else
char *sw = (char *)x;
char *sw = reinterpret_cast<char *>(x);
sw[0] = buf[7];
sw[1] = buf[6];
sw[2] = buf[5];
Expand All @@ -376,23 +374,17 @@ inline void frombuf(char *&buf, Float_t *x)
{
#ifdef R__BYTESWAP
# if defined(R__USEASMSWAP)
// Use a union to allow strict-aliasing
union {
volatile UInt_t i;
volatile Float_t f;
} u;
u.i = Rbswap_32(*((UInt_t *)buf));
*x = u.f;
UInt_t i;
memcpy(&i, buf, sizeof(i));
i = Rbswap_32(i);
memcpy(x, &i, sizeof(i));
# else
union {
volatile char c[4];
volatile Float_t f;
} u;
u.c[0] = buf[3];
u.c[1] = buf[2];
u.c[2] = buf[1];
u.c[3] = buf[0];
*x = u.f;
char c[4];
c[0] = buf[3];
c[1] = buf[2];
c[2] = buf[1];
c[3] = buf[0];
memcpy(x, c, sizeof(c));
# endif
#else
memcpy(x, buf, sizeof(Float_t));
Expand All @@ -404,27 +396,21 @@ inline void frombuf(char *&buf, Double_t *x)
{
#ifdef R__BYTESWAP
# if defined(R__USEASMSWAP)
// Use a union to allow strict-aliasing
union {
volatile ULong64_t l;
volatile Double_t d;
} u;
u.l = Rbswap_64(*((ULong64_t *)buf));
*x = u.d;
ULong64_t l;
memcpy(&l, buf, sizeof(l));
l = Rbswap_64(l);
memcpy(x, &l, sizeof(l));
# else
union {
volatile char c[8];
volatile Double_t d;
} u;
u.c[0] = buf[7];
u.c[1] = buf[6];
u.c[2] = buf[5];
u.c[3] = buf[4];
u.c[4] = buf[3];
u.c[5] = buf[2];
u.c[6] = buf[1];
u.c[7] = buf[0];
*x = u.d;
char c[8];
c[0] = buf[7];
c[1] = buf[6];
c[2] = buf[5];
c[3] = buf[4];
c[4] = buf[3];
c[5] = buf[2];
c[6] = buf[1];
c[7] = buf[0];
memcpy(x, c, sizeof(c));
# endif
#else
memcpy(x, buf, sizeof(Double_t));
Expand Down
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