source: bootcd/isolinux/syslinux-6.03/com32/lib/fgets.c

/*
 * fgets.c
 *
 * This will be very slow due to the implementation of getc(),
 * but we can't afford to drain characters we don't need from
 * the input.
 */

#include <stdio.h>

char *fgets(char *s, int n, FILE * f)
{
    int ch;
    char *p = s;

    while (n > 1) {
        ch = getc(f);
        if (ch == EOF) {
            *p = '\0';
            return (p == s) ? NULL : s;
        }
        *p++ = ch;
        if (ch == '\n')
            break;
        n--;
    }
    if (n)
        *p = '\0';

    return s;
}