108 lines
1.9 KiB
C
Executable File
108 lines
1.9 KiB
C
Executable File
#include <limits.h>
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#include <stdbool.h>
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#include <stdarg.h>
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#include <stdio.h>
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#include <string.h>
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static bool print(const char * str, size_t len) {
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const unsigned char * bytes = (const unsigned char *) str;
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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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}
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}
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return true;
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}
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int printf(const char * restrict format, ...) {
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va_list parameters;
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va_start(parameters, format);
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int written = 0;
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while(*format != '\0') {
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size_t maxrem = INT_MAX - written;
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if(format[0] != '%' || format[1] == '%') {
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if(format[0] == '%') {
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format++;
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}
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size_t amount = 1;
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while(format[amount] && format[amount] != '%') {
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amount++;
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}
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if(maxrem < amount) {
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/* TODO: Set errno to EOVERFLOW after implementing errno.h */
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return -1;
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}
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if(!print(format, amount)) {
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return -1;
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}
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format += amount;
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written += amount;
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continue;
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}
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const char * format_begun_at = format++;
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/* TODO: Implement all format specifiers (%g, %o, &c.) */
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if(*format == 'c') {
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format++;
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char c = (char) va_arg(parameters, int);
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if(!maxrem) {
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/* TODO: Set errno to EOVERFLOW after implementing errno.h */
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return -1;
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}
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if(!print(&c, sizeof(c))) {
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return -1;
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}
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written++;
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}
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else if(*format == 's') {
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format++;
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const char * str = va_arg(parameters, const char *);
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size_t len = strlen(str);
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if(maxrem < len) {
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/* TODO: Set errno to EOVERFLOW after implementing errno.h */
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return -1;
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}
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if(!print(str, len)) {
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return -1;
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}
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written += len;
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}
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else {
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format = format_begun_at;
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size_t len = strlen(format);
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if(maxrem < len) {
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/* TODO: Set errno to EOVERFLOW after implementing errno.h */
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return -1;
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}
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if(!print(format, len)) {
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return -1;
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}
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format += len;
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}
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}
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va_end(parameters);
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return(written);
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}
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