posix_getline.c

/* posix_getline.c
 * RT-Thread POSIX
 * getdelim(), getline() - read a delimited record from stream, ersatz implementation
 * This code is unlicensed -- free and released into the public domain.
 * https://man7.org/linux/man-pages/man3/getline.3.html
 * Authors:
 *     https://github.com/ivanrad/getline
 *
 * Meco Man    2020-09-03    porting to RT-Thread
 */

#include "posix_getline.h"
#include <stdlib.h>
#include <limits.h>
#include <sys/errno.h>

ssize_t getdelim(char **lineptr, size_t *n, int delim, FILE *stream) {
    char *cur_pos, *new_lineptr;
    size_t new_lineptr_len;
    int c;

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

    if (*lineptr == NULL) {
        *n = 128; /* init len */
        if ((*lineptr = (char *)malloc(*n)) == NULL) {
            errno = ENOMEM;
            return -1;
        }
    }

    cur_pos = *lineptr;
    for (;;) {
        c = getc(stream);

        if (ferror(stream) || (c == EOF && cur_pos == *lineptr))
            return -1;

        if (c == EOF)
            break;

        if ((*lineptr + *n - cur_pos) < 2) {
            if (LONG_MAX / 2 < *n) {
#ifdef EOVERFLOW
                errno = EOVERFLOW;
#else
                errno = ERANGE; /* no EOVERFLOW defined */
#endif
                return -1;
            }
            new_lineptr_len = *n * 2;

            if ((new_lineptr = (char *)realloc(*lineptr, new_lineptr_len)) == NULL) {
                errno = ENOMEM;
                return -1;
            }
            cur_pos = new_lineptr + (cur_pos - *lineptr);
            *lineptr = new_lineptr;
            *n = new_lineptr_len;
        }

        *cur_pos++ = (char)c;

        if (c == delim)
            break;
    }

    *cur_pos = '\0';
    return (ssize_t)(cur_pos - *lineptr);
}

ssize_t getline(char **lineptr, size_t *n, FILE *stream) {
    return getdelim(lineptr, n, '\n', stream);
}