107 lines
1.9 KiB
C
Executable file
107 lines
1.9 KiB
C
Executable file
#include <limits.h>
|
|
#include <stdbool.h>
|
|
#include <stdarg.h>
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
|
|
static bool print(const char * str, size_t len) {
|
|
const unsigned char * bytes = (const unsigned char *) str;
|
|
|
|
for(size_t i = 0; i < len; 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 after implementing errno.h */
|
|
return -1;
|
|
}
|
|
|
|
if(!print(format, amount)) {
|
|
return -1;
|
|
}
|
|
|
|
format += amount;
|
|
written += amount;
|
|
continue;
|
|
}
|
|
|
|
const char * format_begun_at = format++;
|
|
|
|
/* TODO: Implement all format specifiers (%g, %o, &c.) */
|
|
if(*format == 'c') {
|
|
format++;
|
|
char c = (char) va_arg(parameters, int);
|
|
|
|
if(!maxrem) {
|
|
/* TODO: Set errno to EOVERFLOW after implementing errno.h */
|
|
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 after implementing errno.h */
|
|
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 after implementing errno.h */
|
|
return -1;
|
|
}
|
|
|
|
if(!print(format, len)) {
|
|
return -1;
|
|
}
|
|
|
|
format += len;
|
|
}
|
|
}
|
|
|
|
va_end(parameters);
|
|
|
|
return(written);
|
|
}
|