130 lines
2.1 KiB
C
130 lines
2.1 KiB
C
#include <limits.h>
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#include <stdarg.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <string.h>
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static bool print(const char* data, size_t len)
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{
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const unsigned char* bytes = (const unsigned char*)data;
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for(size_t i = 0; i < len; i++)
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if (putchar(bytes[i]) == EOF)
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return false;
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return true;
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}
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static bool print_int(int value, int* out_len)
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{
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if (value == -2147483648)
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{
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if (!print("-2147483648", 11))
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return false;
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*out_len = 11;
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return true;
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}
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// Enough for any (32-bit) integer value
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char buffer[11];
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char* ptr = buffer + sizeof(buffer);
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int len = 0;
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bool sign = false;
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if (value < 0)
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{
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sign = true;
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value = -value;
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}
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while (value)
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{
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*(--ptr) = (value % 10) + '0';
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value /= 10;
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len++;
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}
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if (sign)
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{
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*(--ptr) = '-';
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len++;
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}
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if (!print(ptr, len))
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return false;
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*out_len = len;
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return true;
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}
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int printf(const char* restrict format, ...)
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{
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va_list args;
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va_start(args, format);
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int written = 0;
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while (*format)
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{
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size_t max_rem = INT_MAX - written;
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if (format[0] != '%' || format[1] == '%')
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{
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if (format[0] == '%')
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format++;
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size_t len = 1;
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while (format[len] && format[len] != '%')
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len++;
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if (!print(format, len))
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return -1;
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format += len;
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written += len;
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continue;
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}
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const char* format_start = format++;
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if (*format == 'c')
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{
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format++;
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char c = (char)va_arg(args, int);
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if (!max_rem) // FIXME: EOVERFLOW
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return -1;
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if (!print(&c, sizeof(c)))
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return -1;
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written++;
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}
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else if (*format == 's')
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{
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format++;
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const char* str = va_arg(args, const char*);
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size_t len = strlen(str);
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if (max_rem < len) // FIXME: EOVERFLOW
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return -1;
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if (!print(str, len))
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return -1;
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written += len;
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}
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else if (*format == 'd' || *format == 'i')
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{
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format++;
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int value = va_arg(args, int);
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int len;
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if (!print_int(value, &len))
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return -1;
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written += len;
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}
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else
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{
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format = format_start;
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size_t len = strlen(format);
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if (max_rem < len) // FIXME: EOVERFLOW
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return -1;
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if (!print(format, len))
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return -1;
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written += len;
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format += len;
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}
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}
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va_end(args);
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return written;
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} |