/* The original code is public domain -- Will Hartung 4/9/09 */
/* Modifications, public domain as well, by Antti Haapala, 11/10/17 */

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <stdint.h>

ssize_t _getline(char **lineptr, size_t *n, FILE *stream,
		 int (*fgetc_impl)(FILE*)) {
    size_t pos;
    int c;

    if (lineptr == NULL || stream == NULL || n == NULL) {
        errno = EINVAL;
        return -1;
    }

    c = fgetc_impl(stream);
    if (c == EOF) {
        return -1;
    }

    if (*lineptr == NULL) {
        *lineptr = malloc(128);
        if (*lineptr == NULL) {
            return -1;
        }
        *n = 128;
    }

    pos = 0;
    while(c != EOF) {
        if (pos + 1 >= *n) {
	    char *new_ptr;
            size_t new_size = *n + (*n >> 2);
            if (new_size < 128) {
                new_size = 128;
            }
            new_ptr = realloc(*lineptr, new_size);
            if (new_ptr == NULL) {
                return -1;
            }
            *n = new_size;
            *lineptr = new_ptr;
        }

        ((unsigned char *)(*lineptr))[pos ++] = c;
        if (c == '\n') {
            break;
        }
        c = fgetc_impl(stream);
    }

    (*lineptr)[pos] = '\0';
    return pos;
}