banan-os/libc/stdlib.cpp

546 lines
11 KiB
C++

#include <BAN/Assert.h>
#include <BAN/Limits.h>
#include <BAN/Math.h>
#include <ctype.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <unistd.h>
#include <icxxabi.h>
extern "C" char** environ;
extern "C" void _fini();
static void (*at_exit_funcs[64])();
static uint32_t at_exit_funcs_count = 0;
void abort(void)
{
fflush(nullptr);
fprintf(stderr, "abort()\n");
exit(1);
}
void exit(int status)
{
for (uint32_t i = at_exit_funcs_count; i > 0; i--)
at_exit_funcs[i - 1]();
fflush(nullptr);
__cxa_finalize(nullptr);
_fini();
_exit(status);
ASSERT_NOT_REACHED();
}
int abs(int val)
{
return val < 0 ? -val : val;
}
int atexit(void (*func)(void))
{
if (at_exit_funcs_count > sizeof(at_exit_funcs) / sizeof(*at_exit_funcs))
{
errno = ENOBUFS;
return -1;
}
at_exit_funcs[at_exit_funcs_count++] = func;
return 0;
}
static constexpr int get_base_digit(char c, int base)
{
int digit = -1;
if (isdigit(c))
digit = c - '0';
else if (isalpha(c))
digit = 10 + tolower(c) - 'a';
if (digit < base)
return digit;
return -1;
}
template<BAN::integral T>
static constexpr bool will_multiplication_overflow(T a, T b)
{
if (a == 0 || b == 0)
return false;
if ((a > 0) == (b > 0))
return a > BAN::numeric_limits<T>::max() / b;
else
return a < BAN::numeric_limits<T>::min() / b;
}
template<BAN::integral T>
static constexpr bool will_addition_overflow(T a, T b)
{
if (a > 0 && b > 0)
return a > BAN::numeric_limits<T>::max() - b;
if (a < 0 && b < 0)
return a < BAN::numeric_limits<T>::min() - b;
return false;
}
template<BAN::integral T>
static constexpr bool will_digit_append_overflow(bool negative, T current, int digit, int base)
{
if (BAN::is_unsigned_v<T> && negative && digit)
return true;
if (will_multiplication_overflow<T>(current, base))
return true;
if (will_addition_overflow<T>(current * base, current < 0 ? -digit : digit))
return true;
return false;
}
template<BAN::integral T>
static T strtoT(const char* str, char** endp, int base, int& error)
{
// validate base
if (base != 0 && (base < 2 || base > 36))
{
error = EINVAL;
return 0;
}
// skip whitespace
while (isspace(*str))
str++;
// get sign and skip it
bool negative = (*str == '-');
if (*str == '-' || *str == '+')
str++;
// determine base from prefix
if (base == 0)
{
if (strncasecmp(str, "0x", 2) == 0)
base = 16;
else if (*str == '0')
base = 8;
else if (isdigit(*str))
base = 10;
}
// check for invalid conversion
if (get_base_digit(*str, base) == -1)
{
if (endp)
*endp = const_cast<char*>(str);
error = EINVAL;
return 0;
}
// remove "0x" prefix from hexadecimal
if (base == 16 && strncasecmp(str, "0x", 2) == 0 && get_base_digit(str[2], base) != -1)
str += 2;
bool overflow = false;
T result = 0;
// calculate the value of the number in string
while (!overflow)
{
int digit = get_base_digit(*str, base);
if (digit == -1)
break;
str++;
overflow = will_digit_append_overflow(negative, result, digit, base);
if (!overflow)
result = result * base + (negative ? -digit : digit);
}
// save endp if asked
if (endp)
{
while (get_base_digit(*str, base) != -1)
str++;
*endp = const_cast<char*>(str);
}
// return error on overflow
if (overflow)
{
error = ERANGE;
if constexpr(BAN::is_unsigned_v<T>)
return BAN::numeric_limits<T>::max();
return negative ? BAN::numeric_limits<T>::min() : BAN::numeric_limits<T>::max();
}
return result;
}
template<BAN::floating_point T>
static T strtoT(const char* str, char** endp, int& error)
{
// find nan end including possible n-char-sequence
auto get_nan_end = [](const char* str) -> const char*
{
ASSERT(strcasecmp(str, "nan") == 0);
if (str[3] != '(')
return str + 3;
for (size_t i = 4; isalnum(str[i]) || str[i] == '_'; i++)
if (str[i] == ')')
return str + i + 1;
return str + 3;
};
// skip whitespace
while (isspace(*str))
str++;
// get sign and skip it
bool negative = (*str == '-');
if (*str == '-' || *str == '+')
str++;
// check for infinity or nan
{
T result = 0;
if (strncasecmp(str, "inf", 3) == 0)
{
result = BAN::numeric_limits<T>::infinity();
str += strncasecmp(str, "infinity", 8) ? 3 : 8;
}
else if (strncasecmp(str, "nan", 3) == 0)
{
result = BAN::numeric_limits<T>::quiet_NaN();
str = get_nan_end(str);
}
if (result != 0)
{
if (endp)
*endp = const_cast<char*>(str);
return negative ? -result : result;
}
}
// no conversion can be performed -- not ([digit] || .[digit])
if (!(isdigit(*str) || (str[0] == '.' && isdigit(str[1]))))
{
error = EINVAL;
return 0;
}
int base = 10;
int exponent = 0;
int exponents_per_digit = 1;
// check whether we have base 16 value -- (0x[xdigit] || 0x.[xdigit])
if (strncasecmp(str, "0x", 2) == 0 && (isxdigit(str[2]) || (str[2] == '.' && isxdigit(str[3]))))
{
base = 16;
exponents_per_digit = 4;
str += 2;
}
// parse whole part
T result = 0;
T multiplier = 1;
while (true)
{
int digit = get_base_digit(*str, base);
if (digit == -1)
break;
str++;
if (result)
exponent += exponents_per_digit;
if (digit)
result += multiplier * digit;
if (result)
multiplier /= base;
}
if (*str == '.')
str++;
while (true)
{
int digit = get_base_digit(*str, base);
if (digit == -1)
break;
str++;
if (result == 0)
exponent -= exponents_per_digit;
if (digit)
result += multiplier * digit;
if (result)
multiplier /= base;
}
if (tolower(*str) == (base == 10 ? 'e' : 'p'))
{
char* maybe_end = nullptr;
int exp_error = 0;
int extra_exponent = strtoT<int>(str + 1, &maybe_end, 10, exp_error);
if (exp_error != EINVAL)
{
if (exp_error == ERANGE || will_addition_overflow(exponent, extra_exponent))
exponent = negative ? BAN::numeric_limits<int>::min() : BAN::numeric_limits<int>::max();
else
exponent += extra_exponent;
str = maybe_end;
}
}
if (endp)
*endp = const_cast<char*>(str);
// no over/underflow can happed with zero
if (result == 0)
return 0;
const int max_exponent = (base == 10) ? BAN::numeric_limits<T>::max_exponent10() : BAN::numeric_limits<T>::max_exponent2();
if (exponent > max_exponent)
{
error = ERANGE;
result = BAN::numeric_limits<T>::infinity();
return negative ? -result : result;
}
const int min_exponent = (base == 10) ? BAN::numeric_limits<T>::min_exponent10() : BAN::numeric_limits<T>::min_exponent2();
if (exponent < min_exponent)
{
error = ERANGE;
result = 0;
return negative ? -result : result;
}
if (exponent)
result *= BAN::Math::pow<T>((base == 10) ? 10 : 2, exponent);
return result;
}
double atof(const char* str)
{
return strtod(str, nullptr);
}
int atoi(const char* str)
{
return strtol(str, nullptr, 10);
}
long atol(const char* str)
{
return strtol(str, nullptr, 10);
}
long long atoll(const char* str)
{
return strtoll(str, nullptr, 10);
}
float strtof(const char* __restrict str, char** __restrict endp)
{
return strtoT<float>(str, endp, errno);
}
double strtod(const char* __restrict str, char** __restrict endp)
{
return strtoT<double>(str, endp, errno);
}
long double strtold(const char* __restrict str, char** __restrict endp)
{
return strtoT<long double>(str, endp, errno);
}
long strtol(const char* __restrict str, char** __restrict endp, int base)
{
return strtoT<long>(str, endp, base, errno);
}
long long strtoll(const char* __restrict str, char** __restrict endp, int base)
{
return strtoT<long long>(str, endp, base, errno);
}
unsigned long strtoul(const char* __restrict str, char** __restrict endp, int base)
{
return strtoT<unsigned long>(str, endp, base, errno);
}
unsigned long long strtoull(const char* __restrict str, char** __restrict endp, int base)
{
return strtoT<unsigned long long>(str, endp, base, errno);
}
char* getenv(const char* name)
{
if (environ == nullptr)
return nullptr;
size_t len = strlen(name);
for (int i = 0; environ[i]; i++)
if (strncmp(name, environ[i], len) == 0)
if (environ[i][len] == '=')
return environ[i] + len + 1;
return nullptr;
}
int system(const char* command)
{
// FIXME
if (command == nullptr)
return 1;
int pid = fork();
if (pid == 0)
{
execl("/bin/Shell", "Shell", "-c", command, (char*)0);
exit(1);
}
if (pid == -1)
return -1;
int stat_val;
waitpid(pid, &stat_val, 0);
return stat_val;
}
int setenv(const char* name, const char* val, int overwrite)
{
if (name == nullptr || !name[0] || strchr(name, '='))
{
errno = EINVAL;
return -1;
}
if (!overwrite && getenv(name))
return 0;
size_t namelen = strlen(name);
size_t vallen = strlen(val);
char* string = (char*)malloc(namelen + vallen + 2);
memcpy(string, name, namelen);
string[namelen] = '=';
memcpy(string + namelen + 1, val, vallen);
string[namelen + vallen + 1] = '\0';
return putenv(string);
}
int unsetenv(const char* name)
{
if (name == nullptr || !name[0] || strchr(name, '='))
{
errno = EINVAL;
return -1;
}
size_t len = strlen(name);
bool found = false;
for (int i = 0; environ[i]; i++)
{
if (!found && strncmp(environ[i], name, len) == 0 && environ[i][len] == '=')
{
free(environ[i]);
found = true;
}
if (found)
environ[i] = environ[i + 1];
}
return 0;
}
int putenv(char* string)
{
if (string == nullptr || !string[0])
{
errno = EINVAL;
return -1;
}
if (!environ)
{
environ = (char**)malloc(sizeof(char*) * 2);
if (!environ)
return -1;
environ[0] = string;
environ[1] = nullptr;
return 0;
}
int cnt = 0;
for (int i = 0; string[i]; i++)
if (string[i] == '=')
cnt++;
if (cnt != 1)
{
errno = EINVAL;
return -1;
}
int namelen = strchr(string, '=') - string;
for (int i = 0; environ[i]; i++)
{
if (strncmp(environ[i], string, namelen + 1) == 0)
{
free(environ[i]);
environ[i] = string;
return 0;
}
}
int env_count = 0;
while (environ[env_count])
env_count++;
char** new_envp = (char**)malloc(sizeof(char*) * (env_count + 2));
if (new_envp == nullptr)
return -1;
for (int i = 0; i < env_count; i++)
new_envp[i] = environ[i];
new_envp[env_count] = string;
new_envp[env_count + 1] = nullptr;
free(environ);
environ = new_envp;
return 0;
}
// Constants and algorithm from https://en.wikipedia.org/wiki/Permuted_congruential_generator
static uint64_t s_rand_state = 0x4d595df4d0f33173;
static constexpr uint64_t s_rand_multiplier = 6364136223846793005;
static constexpr uint64_t s_rand_increment = 1442695040888963407;
static constexpr uint32_t rotr32(uint32_t x, unsigned r)
{
return x >> r | x << (-r & 31);
}
int rand(void)
{
uint64_t x = s_rand_state;
unsigned count = (unsigned)(x >> 59);
s_rand_state = x * s_rand_multiplier + s_rand_increment;
x ^= x >> 18;
return rotr32(x >> 27, count) % RAND_MAX;
}
void srand(unsigned int seed)
{
s_rand_state = seed + s_rand_increment;
(void)rand();
}