C++ Code as Seen by a Hypercritical
Reviewer
Phillip Khandeliants
khandeliants@viva64.com

About Me
 A lead C++/C# developer at PVS-
Studio.
 I’ve been developing the C++
analyzer’s core for 3 years.
 I educate on modern C++.
2
Текст слайда

What are you talking about?
3

What are you talking about?
4
 We all do code reviews

What are you talking about?
5
 We all do code reviews
 Who doesn't admit this – does it
twice as often

What are you talking about?
6
 We all do code reviews
 Who doesn't admit this – does it
twice as often
 C++ code reviewers look like a sapper

What are you talking about?
7
 We all do code reviews
 Who doesn't admit this – does it
twice as often
 C++ code reviewers look like a sapper
 ... except that they can make a
mistake more than once 

 We all do code reviews
 Who doesn't admit this – does it
twice as often
 C++ code reviewers look like a sapper
 ... except that they can make a
mistake more than once 
 But sometimes the consequences
are painful 
What are you talking about?
8

Brave code review world
9

1. 'Auto'matic coding
10

void foo(const std::vector<....> &vec)
{
....
for (auto i = 0; i < vec.size(); ++i)
{
// do some magic with vec[i]
....
}
....
}
11

void foo(const std::vector<....> &vec)
{
....
for (int i = 0; i < vec.size(); ++i) // 64-bit problems :)
{
// do some magic with vec[i]
....
}
....
}
12

void foo(const std::vector<....> &vec)
{
....
for (size_t i = 0; i < vec.size(); ++i) // ok
{
// do some magic with vec[i]
....
}
....
}
13

void foo(const std::vector<....> &vec)
{
....
for (std::vector<....>::size_type i = 0; i < vec.size(); ++i)
{
// do some magic with vec[i]
....
}
....
}
14

void foo(const std::vector<....> &vec)
{
....
for (auto i = 0uLL; i < vec.size(); ++i) // don't do that on
// 128-bit processors
{
// do some magic with vec[i]
....
}
....
}
15

void foo(const std::vector<....> &vec)
{
....
for (auto i = 0uLLL; i < vec.size(); ++i) // ok since C++7d
{
// do some magic with vec[i]
....
}
....
}
16

void foo(const std::vector<....> &vec)
{
....
for (auto i = 0uLLL; i < vec.size(); ++i) // ok since C++7d
{
// do some magic with vec[i]
....
}
....
}
17

2. Reference! I said reference! Perfection!
18

19
template <typename T>
int ColumnDecimal<T>::compareAt(size_t n, size_t m,
const IColumn & rhs_, int) const
{
auto other = static_cast<const Self &>(rhs_);
const T &a = data[n];
const T &b = other.data[m];
return decimalLess<T>(b, a, other.scale, scale)
? 1
: (decimalLess<T>(a, b, scale, other.scale) ? -1 : 0);
}

20
template <typename T>
int ColumnDecimal<T>::compareAt(size_t n, size_t m,
const IColumn & rhs_, int) const
{
auto other = static_cast<const Self &>(rhs_);
const T &a = data[n];
const T &b = other.data[m];
return decimalLess<T>(b, a, other.scale, scale)
? 1
: (decimalLess<T>(a, b, scale, other.scale) ? -1 : 0);
}

21
template <typename T>
int ColumnDecimal<T>::compareAt(size_t n, size_t m,
const IColumn & rhs_, int) const
{
auto &other = static_cast<const Self &>(rhs_);
const T &a = data[n];
const T &b = other.data[m];
return decimalLess<T>(b, a, other.scale, scale)
? 1
: (decimalLess<T>(a, b, scale, other.scale) ? -1 : 0);
}

22
template <typename T>
int ColumnDecimal<T>::compareAt(size_t n, size_t m,
const IColumn & rhs_, int) const
{
decltype(auto) other = static_cast<const Self &>(rhs_);
const T &a = data[n];
const T &b = other.data[m];
return decimalLess<T>(b, a, other.scale, scale)
? 1
: (decimalLess<T>(a, b, scale, other.scale) ? -1 : 0);
}

3. Vector-vector, *pChar++
23

void vector32_inc(std::vector<uint32_t> &v)
{
for (size_t i = 0; i < v.size(); i++)
{
v[i]++;
}
}
24

void vector32_inc(std::vector<uint32_t> &v)
{
for (size_t i = 0; i < v.size(); i++)
{
v[i]++;
}
}
void vector8_inc(std::vector<uint8_t> &v)
{
for (size_t i = 0; i < v.size(); i++)
{
v[i]++;
}
}
25

Let's benchmark :)
26
Compiler Element -O1 -O2 -O3
gcc 8 uint8_t 2.0 2.0 2.0
gcc 8 uint32_t 2.3 1.3 0.2
clang 8 uint8_t 9.2 2.0 2.0
clang 8 uint32_t 9.2 0.2 0.2

27
vector8_inc(std::vector<uint8_t> &):
mov rdx, QWORD PTR [rdi] ; it = begin()
cmp rdx, QWORD PTR [rdi+8] ; if (it == end())
je .L1 ; return
xor eax, eax ; i = 0
.L3: ; do {
add BYTE PTR [rdx+rax], 1 ; ++(*(it + i))
mov rdx, QWORD PTR [rdi] ; it = begin()
add rax, 1 ; ++i
mov rcx, QWORD PTR [rdi+8] ; end = end()
sub rcx, rdx ; end = end - it
cmp rax, rcx
jb .L3 ; } while (i < end)
.L1:
ret
vector32_inc(std::vector<uint32_t> &):
mov rax, QWORD PTR [rdi] ; it = begin()
mov rdx, QWORD PTR [rdi+8] ; end = end()
sub rdx, rax ; end = end - it
mov rcx, rdx ; size in bytes
shr rcx, 2 ; size in elements
je .L1 ; if (size == 0)
; return
add rdx, rax ; end = end + it
.L3: ; do {
add DWORD PTR [rax], 1 ; ++(*it)
add rax, 4 ; ++it
cmp rax, rdx
jne .L3 ; } while (it != end)
.L1:
ret

28
vector8_inc(std::vector<uint8_t> &):
mov rdx, QWORD PTR [rdi] ; it = begin()
cmp rdx, QWORD PTR [rdi+8] ; if (it == end())
je .L1 ; return
xor eax, eax ; i = 0
.L3: ; do {
add BYTE PTR [rdx+rax], 1 ; ++(*(it + i))
mov rdx, QWORD PTR [rdi] ; it = begin()
add rax, 1 ; ++i
mov rcx, QWORD PTR [rdi+8] ; end = end()
sub rcx, rdx ; end = end - it
cmp rax, rcx
jb .L3 ; } while (i < end)
.L1:
ret
vector32_inc(std::vector<uint32_t> &):
mov rax, QWORD PTR [rdi] ; it = begin()
mov rdx, QWORD PTR [rdi+8] ; end = end()
sub rdx, rax ; end = end - it
mov rcx, rdx ; size in bytes
shr rcx, 2 ; size in elements
je .L1 ; if (size == 0)
; return
add rdx, rax ; end = end + it
.L3: ; do {
add DWORD PTR [rax], 1 ; ++(*it)
add rax, 4 ; ++it
cmp rax, rdx
jne .L3 ; } while (it != end)
.L1:
ret

void vector8_inc(std::vector<uint8_t> &v)
{
for (size_t i = 0; i < v.size(); i++)
{
v[i]++;
}
}
29

void vector8_inc(std::vector<uint8_t> &v)
{
for (size_t i = 0; i < v.size(); i++)
{
v[i]++;
}
}
void vector8_inc(std::vector<uint8_t> &v)
{
auto it = v.begin();
const auto end = v.end();
for (; it != end; ++it)
{
++(*it);
}
}
30

31
vector8_inc(std::vector<uint8_t> &):
mov rax, QWORD PTR [rdi] ; it = begin()
mov rdx, QWORD PTR [rdi+8] ; end = end()
cmp rax, rdx ; if (it == end)
je .L1 ; return
.L3: ; do {
add BYTE PTR [rax], 1 ; ++(*it)
add rax, 1 ; ++it
cmp rax, rdx ; } while (it != end)
.L1:
ret

32
vector8_inc(std::vector<uint8_t> &):
mov rax, QWORD PTR [rdi] ; it = begin()
mov rdx, QWORD PTR [rdi+8] ; end = end()
cmp rax, rdx ; if (it == end)
je .L1 ; return
.L3: ; do {
add BYTE PTR [rax], 1 ; ++(*it)
add rax, 1 ; ++it
cmp rax, rdx ; } while (it != end)
.L1:
ret

Let's make benchmarks great again!
Compiler
uint8_t
-O1 -O2 -O3
gcc 8 (before) 2.0 2.0 2.0
gcc 8 (after) 1.3 1.3 0.06
gcc speedup 1.5x 1.5x 33.4x
Compiler
uint8_t
-O1 -O2 -O3
clang 8 (before) 9.2 2.0 2.0
clang 8 (after) 20.3 0.06 0.06
clang speedup 0.45x 33.4x 33.4x

void vector8_inc(std::vector<uint8_t> &v)
{
auto it = v.begin();
const auto end = v.end();
for (; it != end; ++it)
{
++(*it);
}
}
34

void vector8_inc(std::vector<uint8_t> &v)
{
auto it = v.begin();
const auto end = v.end();
for (; it != end; ++it)
{
++(*it);
}
}
void vector8_inc(std::vector<uint8_t> &v)
{
for (auto &elem : v)
{
++elem;
}
}
35

36

4. Security? Security!
37

#include <cstring>
#include <memory>
void InputPassword(char *pswd);
void ProcessPassword(const char *pswd);
#define MAX_PASSWORD_LEN ....
void Foo()
{
char password[MAX_PASSWORD_LEN];
InputPassword(password);
ProcessPassword(password);
memset(password, 0, sizeof(password));
}
38

#include <cstring>
#include <memory>
void InputPassword(char *pswd);
void ProcessPassword(const char *pswd);
#define MAX_PASSWORD_LEN ....
void Foo()
{
char password[MAX_PASSWORD_LEN];
InputPassword(password);
ProcessPassword(password);
memset(password, 0, sizeof(password));
}
39

40

#include <cstring>
#include <memory>
void InputPassword(char *pswd);
void ProcessPassword(const char *pswd);
#define MAX_PASSWORD_LEN ....
void Foo()
{
char *password = new char[MAX_PASSWORD_LEN];
InputPassword(password);
ProcessPassword(password);
memset(password, 0, MAX_PASSWORD_LEN);
delete[] password;
} 41

42

void tds_answer_challenge(....)
{
#define MAX_PW_SZ 14
....
if (ntlm_v == 1) {
....
/* with security is best be pedantic */
memset(hash, 0, sizeof(hash));
memset(passwd_buf, 0, sizeof(passwd_buf));
memset(ntlm2_challenge, 0, sizeof(ntlm2_challenge));
} else {
....
}
}
43

typedef struct tds_answer
{
unsigned char lm_resp[24];
unsigned char nt_resp[24];
} TDSANSWER;
static TDSRET tds7_send_auth(....)
{
size_t current_pos;
TDSANSWER answer;
....
/* for security reason clear structure */
memset(&answer, 0, sizeof(TDSANSWER));
return tds_flush_packet(tds);
}
44

char* crypt_md5(const char* pw, const char* salt)
{
unsigned char final[MD5_SIZE];
....
/* Don't leave anything around in vm they could use. */
memset(final, 0, sizeof final);
return passwd;
}
45

void MD4Engine::transform (UInt32 state[4],
const unsigned char block[64])
{
UInt32 a = state[0], b = state[1],
c = state[2], d = state[3], x[16];
decode(x, block, 64);
....
/* Zeroize sensitive information. */
std::memset(x, 0, sizeof(x));
}
46

char* px_crypt_md5(const char *pw, const char *salt,
char *passwd, unsigned dstlen)
{
....
unsigned char final[MD5_SIZE];
....
/* Don't leave anything around in vm they could use. */
memset(final, 0, sizeof final);
....
}
47

48

 Custom safe_memset + disabled LTO/WPO
 Access a non-volatile object through a volatile pointer
 Call memset through a volatile function pointer
 Volatile assembly code
 Memset + memory barrier
 Disable compiler optimizations (-fno-builtin-memset)
 C11: memset_s
 Windows: RtlSecureZeroMemory
 FreeBSD & OpenBSD: explicit_bzero
 Linux Kernel: memzero_explicit
Ways to fix
49

5. Dirty thoughts data
50

static const char* basic_gets(int *cnt)
{
....
int c = getchar();
if (c < 0)
{
if ( fgets(command_buf, sizeof(command_buf) - 1, stdin)
!= command_buf)
{
break;
}
/* remove endline */
command_buf[strlen(command_buf)-1] = '0';
break;
}
....
}
51

static const char* basic_gets(int *cnt)
{
....
int c = getchar();
if (c < 0)
{
if ( fgets(command_buf, sizeof(command_buf) - 1, stdin)
!= command_buf)
{
break;
}
/* remove endline */
command_buf[strlen(command_buf)-1] = '0';
break;
}
....
}
52

int main (int argc, char *argv[])
{
....
else if (fgets(readbuf, BUFSIZ, stdin) == NULL)
{
if (feof (stdin))
break;
error (EXIT_FAILURE, errno, _("input error"));
}
if (readbuf[strlen(readbuf) - 1] == 'n')
readbuf[strlen(readbuf) - 1] = '0';
....
}
53

int main (int argc, char *argv[])
{
....
else if (fgets(readbuf, BUFSIZ, stdin) == NULL)
{
if (feof (stdin))
break;
error (EXIT_FAILURE, errno, _("input error"));
}
if (readbuf[strlen(readbuf) - 1] == 'n')
readbuf[strlen(readbuf) - 1] = '0';
....
}
54
CVE-2015-8948

int main (int argc, char *argv[])
{
....
else if (getline(&line, &linelen, stdin) == -1)
{
if (feof (stdin))
break;
error (EXIT_FAILURE, errno, _("input error"));
}
if (line[strlen(line) - 1] == 'n')
line[strlen(line) - 1] = '0';
....
}
55

int main (int argc, char *argv[])
{
....
else if (getline(&line, &linelen, stdin) == -1)
{
if (feof (stdin))
break;
error (EXIT_FAILURE, errno, _("input error"));
}
if (line[strlen(line) - 1] == 'n')
line[strlen(line) - 1] = '0';
....
}
56
CVE-2016-6262

6. Last-ditch effort
57

inline void Init( float ix=0, float iy=0,
float iz=0, float iw = 0 )
{
SetX( ix );
SetY( iy );
SetZ( iz );
SetZ( iw );
}
58

inline void Init( float ix=0, float iy=0,
float iz=0, float iw = 0 )
{
SetX( ix );
SetY( iy );
SetZ( iz );
SetZ( iw );
}
59

60
inline void Init( float ix=0, float iy=0,
float iz=0, float iw = 0 )
{
SetX( ix );
SetY( iy );
SetZ( iz );
SetW( iw );
}

if (access & FILE_WRITE_ATTRIBUTES)
output.append(ASCIIToUTF16("tFILE_WRITE_ATTRIBUTESn"));
if (access & FILE_WRITE_DATA)
output.append(ASCIIToUTF16("tFILE_WRITE_DATAn"));
if (access & FILE_WRITE_EA)
output.append(ASCIIToUTF16("tFILE_WRITE_EAn"));
if (access & FILE_WRITE_EA)
output.append(ASCIIToUTF16("tFILE_WRITE_EAn"));
break;
61

if (access & FILE_WRITE_ATTRIBUTES)
output.append(ASCIIToUTF16("tFILE_WRITE_ATTRIBUTESn"));
if (access & FILE_WRITE_DATA)
output.append(ASCIIToUTF16("tFILE_WRITE_DATAn"));
if (access & FILE_WRITE_EA)
output.append(ASCIIToUTF16("tFILE_WRITE_EAn"));
if (access & FILE_WRITE_EA)
output.append(ASCIIToUTF16("tFILE_WRITE_EAn"));
break;
62

if (protocol.EqualsIgnoreCase("http") ||
protocol.EqualsIgnoreCase("https") ||
protocol.EqualsIgnoreCase("news") ||
protocol.EqualsIgnoreCase("ftp") ||
protocol.EqualsIgnoreCase("file") ||
protocol.EqualsIgnoreCase("javascript") ||
protocol.EqualsIgnoreCase("ftp")) {
63

if (protocol.EqualsIgnoreCase("http") ||
protocol.EqualsIgnoreCase("https") ||
protocol.EqualsIgnoreCase("news") ||
protocol.EqualsIgnoreCase("ftp") ||
protocol.EqualsIgnoreCase("file") ||
protocol.EqualsIgnoreCase("javascript") ||
protocol.EqualsIgnoreCase("ftp")) {
64

7. Zero, one, two,
Freddy's coming for you!
65

Sequence< OUString > FirebirdDriver::
getSupportedServiceNames_Static() throw (RuntimeException)
{
Sequence< OUString > aSNS( 2 );
aSNS[0] = "com.sun.star.sdbc.Driver";
aSNS[0] = "com.sun.star.sdbcx.Driver";
return aSNS;
}
66

Sequence< OUString > FirebirdDriver::
getSupportedServiceNames_Static() throw (RuntimeException)
{
Sequence< OUString > aSNS( 2 );
aSNS[0] = "com.sun.star.sdbc.Driver";
aSNS[0] = "com.sun.star.sdbcx.Driver";
return aSNS;
}
67

struct short2
{
short values[2];
short2(short s1, short s2)
{
values[0] = s1;
values[2] = s2;
}
....
};
68

struct short2
{
short values[2];
short2(short s1, short s2)
{
values[0] = s1;
values[2] = s2;
}
....
};
69

8. Evil within Comparisons!
70

string _server;
....
bool operator<( const ServerAndQuery& other ) const {
if ( ! _orderObject.isEmpty() )
return _orderObject.woCompare( other._orderObject ) < 0;
if ( _server < other._server )
return true;
if ( other._server > _server )
return false;
return _extra.woCompare( other._extra ) < 0;
}
Pattern: A < B, B > A
71

string _server;
....
bool operator<( const ServerAndQuery& other ) const {
if ( ! _orderObject.isEmpty() )
return _orderObject.woCompare( other._orderObject ) < 0;
if ( _server < other._server )
return true;
if ( other._server > _server )
return false;
return _extra.woCompare( other._extra ) < 0;
}
Pattern: A < B, B > A
72

bool
operator==(const SComputePipelineStateDescription &other) const
{
return 0 == memcmp(this, &other, sizeof(this));
}
Pattern: Evaluating the Size of a Pointer Instead of
the Size of the Structure/Class
73

bool
operator==(const SComputePipelineStateDescription &other) const
{
return 0 == memcmp(this, &other, sizeof(this));
}
Pattern: Evaluating the Size of a Pointer Instead of
the Size of the Structure/Class
74

SSHORT TextType::compare(ULONG len1, const UCHAR* str1,
ULONG len2, const UCHAR* str2)
{
....
SSHORT cmp = memcmp(str1, str2, MIN(len1, len2));
if (cmp == 0)
cmp = (len1 < len2 ? -1 : (len1 > len2 ? 1 : 0));
return cmp;
}
Pattern: Incorrect Use of the memcmp result
75

SSHORT TextType::compare(ULONG len1, const UCHAR* str1,
ULONG len2, const UCHAR* str2)
{
....
SSHORT cmp = memcmp(str1, str2, MIN(len1, len2));
if (cmp == 0)
cmp = (len1 < len2 ? -1 : (len1 > len2 ? 1 : 0));
return cmp;
}
Pattern: Incorrect Use of the memcmp result
76

if (cmp == 0)
cmp = (len1 < len2 ? -1 : (len1 > len2 ? 1 : 0));
Pattern: Incorrect Use of the memcmp result
77

bool Peptide::operator==(Peptide& p) {
....
for (i = 0, j = 0;
i < this->stripped.length(), j < p.stripped.length();
i++, j++) {
....
}
Pattern: Incorrect Loops
78

bool Peptide::operator==(Peptide& p) {
....
for (i = 0, j = 0;
i < this->stripped.length(), j < p.stripped.length();
i++, j++) {
....
}
Pattern: Incorrect Loops
79

bool equals( class1* val1, class2* val2 ) const
{
...
size_t size = val1->size();
...
while ( --size >= 0 )
{
if ( !comp(*itr1,*itr2) )
return false;
itr1++;
itr2++;
}
...
}
Pattern: Incorrect Loops
80

bool equals( class1* val1, class2* val2 ) const
{
...
size_t size = val1->size();
...
while ( --size >= 0 )
{
if ( !comp(*itr1,*itr2) )
return false;
itr1++;
itr2++;
}
...
}
Pattern: Incorrect Loops
81

9. Use <=>, Luke!
82

Base equality comparison
83
struct Foo
{
int a, b;
};

Base equality comparison
84
struct Foo
{
int a, b;
};
bool operator==(Foo lhs, Foo rhs)
{
return lhs.a == rhs.a && lhs.b == rhs.b;
}

Base equality comparison
85
struct Foo
{
int a, b;
};
bool operator==(Foo lhs, Foo rhs)
{
return lhs.a == rhs.a && lhs.b == rhs.b;
}
bool operator!=(Foo lhs, Foo rhs)
{
return !(lhs == rhs);
}

Base 'less' comparison
86
struct Foo
{
int a, b;
};
bool operator<(Foo lhs, Foo rhs)
{
return lhs.a < rhs.a && lhs.b < rhs.b;
}

Base 'less' comparison
87
struct Foo
{
int a, b;
};
bool operator<(Foo lhs, Foo rhs)
{
return lhs.a < rhs.a && lhs.b < rhs.b;
}
Foo { 1, 2 } < Foo { 2, 1 }; // <= false
Foo { 2, 1 } < Foo { 1, 2 }; // <= false

Base 'less' comparison
88
struct Foo
{
int a, b;
};
bool operator<(Foo lhs, Foo rhs)
{
if (lhs.a < rhs.a) return true;
if (rhs.a < lhs.a) return false;
return lhs.b < rhs.b;
}
Foo { 1, 2 } < Foo { 2, 1 }; // <= true
Foo { 2, 1 } < Foo { 1, 2 }; // <= false

Base 'less' comparison
89
struct Foo
{
double a;
};
bool operator<(Foo lhs, Foo rhs)
{
return lhs.a < rhs.a;
}

Base 'less' comparison
90
struct Foo
{
double a;
};
bool operator<(Foo lhs, Foo rhs)
{
return lhs.a < rhs.a;
}
bool operator>=(Foo lhs, Foo rhs)
{
return !(lhs < rhs);
}

Base 'less' comparison
91
struct Foo
{
double a;
};
bool operator<(Foo lhs, Foo rhs)
{
return lhs.a < rhs.a;
}
bool operator>=(Foo lhs, Foo rhs)
{
return !(lhs < rhs);
}
Foo { 1.0 } < Foo { 2.0 }; // <= true
Foo { 1.0 } < Foo { NaN }; // <= false
Foo { 1.0 } >= Foo { NaN }; // <= true

Comparisons in C++20
92
#include <compare>
struct Foo
{
double a;
auto operator<=>(const Foo &rhs) const = default;
};
Foo { 1.0 } < Foo { 2.0 }; // <= true
Foo { 1.0 } < Foo { NaN }; // <= false
Foo { 1.0 } >= Foo { NaN }; // <= false

10. Payne, I can't feel my legs pointer
93

void Item_Paint(itemDef_t *item) {
vec4_t red;
menuDef_t *parent = (menuDef_t*)item->parent;
red[0] = red[3] = 1;
red[1] = red[2] = 0;
if (item == NULL) {
return;
}
....
}
94

void Item_Paint(itemDef_t *item) {
vec4_t red;
menuDef_t *parent = (menuDef_t*)item->parent;
red[0] = red[3] = 1;
red[1] = red[2] = 0;
if (item == NULL) {
return;
}
....
}
95

void Item_Paint(std::unique_ptr<itemDef_t> &item) {
vec4_t red;
menuDef_t *parent = (menuDef_t*)item->parent;
red[0] = red[3] = 1;
red[1] = red[2] = 0;
if (item == NULL) {
return;
}
....
}
96

void Item_Paint(std::shared_ptr<itemDef_t> &item) {
vec4_t red;
menuDef_t *parent = (menuDef_t*)item->parent;
red[0] = red[3] = 1;
red[1] = red[2] = 0;
if (item == NULL) {
return;
}
....
}
97

void Item_Paint(std::optional<itemDef_t> &item) {
vec4_t red;
menuDef_t *parent = (menuDef_t*)item->parent;
red[0] = red[3] = 1;
red[1] = red[2] = 0;
if (!item) {
return;
}
....
}
98

static struct DerivedMesh *dynamicPaint_Modifier_apply(....)
{
....
for (; surface; surface = surface->next) {
PaintSurfaceData *sData = surface->data;
if (surface &&
surface->format !=
MOD_DPAINT_SURFACE_F_IMAGESEQ &&
sData)
{
....
}
99

static struct DerivedMesh *dynamicPaint_Modifier_apply(....)
{
....
for (; surface; surface = surface->next) {
PaintSurfaceData *sData = surface->data;
if (surface &&
surface->format !=
MOD_DPAINT_SURFACE_F_IMAGESEQ &&
sData)
{
....
}
100

11. Push me and then emplace me!
101

struct G584_Info
{
G584_Info(const Ptree *p, bool add, bool mul, bool sub, bool div)
{
....
}
....
const Ptree *m_p;
bool m_add;
bool m_mul;
bool m_sub;
bool m_div;
};
102

static void G584_CollectExprInfo(const Ptree *p,
vector<G584_Info> &infs)
{
....
auto what = p->What();
if (what == ntParenExpr)
{
// Remember the expression in parentheses and continue
infs.push_back(G584_Info(p, true, true, false, false));
p = SafeSkipParentesis(p);
}
....
}
103

static void G584_CollectExprInfo(const Ptree *p,
vector<G584_Info> &infs)
{
....
auto what = p->What();
if (what == ntParenExpr)
{
// Remember the expression in parentheses and continue
infs.push_back(G584_Info(p, true, true, false, false));
p = SafeSkipParentesis(p);
}
....
}
104

static void G584_CollectExprInfo(const Ptree *p,
vector<G584_Info> &infs)
{
....
auto what = p->What();
if (what == ntParenExpr)
{
// Remember the expression in parentheses and continue
infs.emplace_back(p, true, true, false, false);
p = SafeSkipParentesis(p);
}
....
}
105

struct G584_Info
{
G584_Info(const Ptree *p, bool add, bool mul, bool sub, bool div)
{
....
}
....
const Ptree *m_p;
bool m_add;
bool m_mul;
bool m_sub;
bool m_div;
};
106

struct G584_Info
{
G584_Info(const Ptree *p, bool add, bool mul, bool sub, bool div)
{
....
}
....
const Ptree *m_p;
bool m_add;
bool m_mul;
bool m_sub;
bool m_div;
};
107

static void G584_CollectExprInfo(const Ptree *p,
vector<G584_Info> &infs)
{
....
auto what = p->What();
if (what == ntParenExpr)
{
// Remember the expression in parentheses and continue
infs.emplace_back(p, true, true, false, false); // ok since C++20
p = SafeSkipParentesis(p);
}
....
}
108

109

12. I will find you and insert you!
110

void AddFunctionDangerousInfo(const vstring &strFunctionInfo,
const FunctionDangerousInfo &info)
{
FunctionDangerousInfoMap &infoMap = GetFunctionDangerousInfoMap();
DangerousInfoIterator it = infoMap.find(strFunctionInfo);
if (it == infoMap.end())
{
infoMap.insert(make_pair(strFunctionInfo, dangerousInfo));
}
else
{
FunctionDangerousInfo &a = it->second;
// some works with 'a'
}
}
111

void AddFunctionDangerousInfo(const vstring &strFunctionInfo,
const FunctionDangerousInfo &info)
{
FunctionDangerousInfoMap &infoMap = GetFunctionDangerousInfoMap();
DangerousInfoIterator it = infoMap.find(strFunctionInfo);
if (it == infoMap.end())
{
infoMap.insert(make_pair(strFunctionInfo, dangerousInfo));
}
else
{
FunctionDangerousInfo &a = it->second;
// some works with 'a'
}
}
112

void AddFunctionDangerousInfo(....)
{
auto &infoMap = GetFunctionDangerousInfoMap();
if (auto it = infoMap.find(strFunctionInfo); it == infoMap.end())
{
infoMap.emplace(strFunctionInfo, dangerousInfo);
}
else
{
FunctionDangerousInfo &a = it->second;
// some works with 'a'
}
}
113

void AddFunctionDangerousInfo(....)
{
auto &infoMap = GetFunctionDangerousInfoMap();
if (auto it = infoMap.find(strFunctionInfo); it == infoMap.end())
{
infoMap.emplace(strFunctionInfo, dangerousInfo);
}
else
{
FunctionDangerousInfo &a = it->second;
// some works with 'a'
}
}
114

void AddFunctionDangerousInfo(....)
{
auto &infoMap = GetFunctionDangerousInfoMap();
if (auto it = infoMap.lower_bound(strFunctionInfo);
it != infoMap.end())
{
auto &a = it->second;
// some works with 'a'
}
else
{
infoMap.emplace_hint(it,
strFunctionInfo,
dangerousInfo);
}
}
115

void AddFunctionDangerousInfo(....)
{
auto &infoMap = GetFunctionDangerousInfoMap();
if (auto it = infoMap.lower_bound(strFunctionInfo);
it != infoMap.end() && it->first == strFunctionInfo)
{
auto &a = it->second;
// some works with 'a'
}
else
{
infoMap.emplace_hint(it,
strFunctionInfo,
dangerousInfo);
}
}
116

13. Is it alive?
117

struct Foo
{
int i;
double d;
};
Foo* bar()
{
Foo *ptr = (Foo *) malloc(sizeof(Foo));
if (ptr == NULL)
return NULL;
ptr->i = 0;
ptr->d = 0.0;
return ptr;
}
118

struct Foo
{
int i;
double d;
};
Foo* bar()
{
Foo *ptr = (Foo *) malloc(sizeof(Foo));
if (ptr == NULL)
return NULL;
ptr->i = 0; // ok in C, UB in C++
ptr->d = 0.0; // ok in C, UB in C++
return ptr;
}
119

struct Foo
{
int i;
double d;
};
Foo* bar()
{
Foo *ptr = (Foo *) malloc(sizeof(Foo));
if (ptr == NULL)
return NULL;
new (ptr) Foo;
ptr->i = 0; // ok in C++
ptr->d = 0.0; // ok in C++
return ptr;
}
120

struct Foo
{
int i;
double d;
};
Foo* bar()
{
Foo *ptr = (Foo *) malloc(sizeof(Foo));
if (ptr == NULL)
return NULL;
ptr->i = 0; // ok in C, UB in C++ until C++20
ptr->d = 0.0; // ok in C, UB in C++ until C++20
return ptr;
}
121

14. Mind the sign
122

int foo(const char *s)
{
int r = 0;
while (*s)
{
r += ((r * 20891 + *s * 200) | *s ^ 4 | *s ^ 3 ) ^ (r >> 1);
s++;
}
return r & 0x7fffffff;
}
124

int foo(const char *s)
{
int r = 0;
while (*s)
{
r += ((r * 20891 + *s * 200) | *s ^ 4 | *s ^ 3 ) ^ (r >> 1);
s++;
}
return r & 0x7fffffff;
}
gcc-8 -O2 -std=c++17 -funsigned-char source.cpp
125

int foo(const char *s)
{
int r = 0;
while (*s)
{
r += ((r * 20891 + *s * 200) | *s ^ 4 | *s ^ 3 ) ^ (r >> 1);
s++;
}
return r & 0x7fffffff;
}
gcc-8 -O2 -std=c++17 -funsigned-char source.cpp
126

15. No exceptions, except...
129

BOOL WINAPI DllMain(HANDLE hModule, ULONG nReason, LPVOID /*pSituation*/)
{
BOOL br = TRUE;
if (nReason == DLL_PROCESS_ATTACH)
{
// Remember our hModule.
g_hModule = hModule;
g_hInstance = (HINSTANCE)g_hModule;
// Make sure we're properly registered.
if (FAILED(DllRegisterServer()))
br = FALSE;
}
else if (nReason == DLL_PROCESS_DETACH)
{
// Nothing to do.
}
return br;
}
130

BOOL WINAPI DllMain(HANDLE hModule, ULONG nReason, LPVOID /*pSituation*/)
{
BOOL br = TRUE;
if (nReason == DLL_PROCESS_ATTACH)
{
// Remember our hModule.
g_hModule = hModule;
g_hInstance = (HINSTANCE)g_hModule;
// Make sure we're properly registered.
if (FAILED(DllRegisterServer()))
br = FALSE;
}
else if (nReason == DLL_PROCESS_DETACH)
{
// Nothing to do.
}
return br;
}
131

HRESULT WINAPI DllRegisterServer(VOID)
{
....
hr = ::RegOpenKeyEx(HKEY_CURRENT_USER, "SoftwaregeOgeOShellPlugins",
NULL, KEY_WRITE, &hk);
if ( SUCCEEDED(hr = HRESULT_FROM_WIN32(hr)) )
{
strcpy(szValue, "geOCommandTime.dll,0");
DllGetObjectInfo(0, GI_Name, szName, MAX_PATH);
hr = ::RegSetValueEx(hk, szName, 0, REG_SZ, (LPBYTE)szValue, strlen(szValue));
hr = HRESULT_FROM_WIN32(hr);
RegCloseKey(hk);
}
....
return hr;
}
132

HRESULT WINAPI DllGetObjectInfo(DWORD dwPluginId, DWORD dwInfo,
VOID *pBuffer, DWORD dwBuffer)
{
....
// Get the specified plugin:
hr = DllGetObject(dwPluginId, &pPlugin);
if (SUCCEEDED(hr))
{
// We got it, so get some info:
hr = pPlugin->GetInfo(dwInfo, pBuffer, dwBuffer);
// And delete the plugin:
delete pPlugin;
}
....
return hr;
}
133

HRESULT WINAPI DllGetObjectInfo(DWORD dwPluginId, DWORD dwInfo,
VOID *pBuffer, DWORD dwBuffer)
{
....
// Get the specified plugin:
hr = DllGetObject(dwPluginId, &pPlugin);
if (SUCCEEDED(hr))
{
// We got it, so get some info:
hr = pPlugin->GetInfo(dwInfo, pBuffer, dwBuffer);
// And delete the plugin:
delete pPlugin;
}
....
return hr;
}
134

HRESULT WINAPI DllGetObject(DWORD dwPluginId, IShellPlugin **ppPlugin)
{
....
{
// We need to create a new command plugin:
switch (dwPluginId)
{
case 0:
*ppPlugin = new CCommandPlugin;
break;
default:
*ppPlugin = NULL;
};
....
}
....
return hr;
}
135

HRESULT WINAPI DllGetObject(DWORD dwPluginId, IShellPlugin **ppPlugin)
{
....
{
// We need to create a new command plugin:
switch (dwPluginId)
{
case 0:
*ppPlugin = new CCommandPlugin;
break;
default:
*ppPlugin = NULL;
};
....
}
....
return hr;
}
136

10 commandments
137

 Thou shalt not auto, unless thy faith is strong and pure
138

 Thou shalt not auto, unless thy faith is strong and pure
 Thou shalt not write indexed loops for they are abominations before the Code
139

 Thou shalt not auto, unless thy faith is strong and pure
 Thou shalt not write indexed loops for they are abominations before the Code
 Thou shalt wash thy data thoroughly before releasing it
140

 Thou shalt not auto, unless thy faith is strong and pure
 Thou shalt not write indexed loops for they are abominations before the Code
 Thou shalt wash thy data thoroughly before releasing it
 Thou shalt not accept data from strangers for they might be sinful
141

 Thou shalt not auto, unless thy faith is strong and pure
 Thou shalt not write indexed loops for they are abominations before the Code
 Thou shalt wash thy data thoroughly before releasing it
 Thou shalt not accept data from strangers for they might be sinful
 Thou shalt not copy-paste thy code blocks
142

 Thy comparison routines shall be correct or else the Wrath of Code will get thee
143

 Thy comparison routines shall be correct or else the Wrath of Code will get thee
 Thou shalt check thy nullables for they are sinful
144

 Thy comparison routines shall be correct or else the Wrath of Code will get thee
 Thou shalt check thy nullables for they are sinful
 Thou shalt not push that which can be emplaced
145

 Thy comparison routines shall be correct or else the Wrath of Code will get thee
 Thou shalt check thy nullables for they are sinful
 Thou shalt not push that which can be emplaced
 Thou shalt not cook signed values with overflow semantics
146

 Thy comparison routines shall be correct or else the Wrath of Code will get thee
 Thou shalt check thy nullables for they are sinful
 Thou shalt not push that which can be emplaced
 Thou shalt not cook signed values with overflow semantics
 He who is without noexcept shall throw, and none other
147

END
Q&A148