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#include <limits.h>
#include <stdbool.h>
#include <stdarg.h>
#include <stdio.h>
#include <string.h>
static bool print(const char* data, size_t length) {
const unsigned char* bytes = (const unsigned char*) data;
for (size_t i = 0; i < length; i++)
if (putchar(bytes[i]) == EOF)
return false;
return true;
}
int printf(const char* restrict format, ...) {
va_list parameters;
va_start(parameters, format);
int written = 0;
while (*format != '\0') {
size_t maxrem = INT_MAX - written;
if (format[0] != '%' || format[1] == '%') {
if (format[0] == '%')
format++;
size_t amount = 1;
while (format[amount] && format[amount] != '%')
amount++;
if (maxrem < amount) {
// TODO: Set errno to EOVERFLOW.
return -1;
}
if (!print(format, amount))
return -1;
format += amount;
written += amount;
continue;
}
const char* format_begun_at = format++;
if (*format == 'c') {
format++;
char c = (char) va_arg(parameters, int /* char promotes to int */);
if (!maxrem) {
// TODO: Set errno to EOVERFLOW.
return -1;
}
if (!print(&c, sizeof(c)))
return -1;
written++;
} else if (*format == 's') {
format++;
const char* str = va_arg(parameters, const char*);
size_t len = strlen(str);
if (maxrem < len) {
// TODO: Set errno to EOVERFLOW.
return -1;
}
if (!print(str, len))
return -1;
written += len;
} else {
format = format_begun_at;
size_t len = strlen(format);
if (maxrem < len) {
// TODO: Set errno to EOVERFLOW.
return -1;
}
if (!print(format, len))
return -1;
written += len;
format += len;
}
}
va_end(parameters);
return written;
}
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