getline.c

/*
    Replace getline() with BSD specific fgetln().

    Copyright (C) 2015 JianXiong Zhou <zhoujianxiong2@gmail.com>
    Copyright (C) 2015 Jonathan Pelletier <funmungus(a)gmail.com>

    This file is part of libscanmem.

    This library is free software: you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published
    by the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with this library.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "getline.h"

#if !defined(HAVE_GETLINE) && defined(HAVE_FGETLN)
#include <stdlib.h>
#include <string.h>
#include <errno.h>

/*
 * Avoid frequent malloc()/free() calls
 * (determined by getline() test on Linux)
 */
#define BUF_MIN 120

ssize_t getline(char **lineptr, size_t *n, FILE *stream)
{
    char *lptr;
    size_t len = 0;

    /* check for invalid arguments */
    if (lineptr == NULL || n == NULL) {
        errno = EINVAL;
        return -1;
    }

    lptr = fgetln(stream, &len);
    if (lptr == NULL) {
        /* invalid stream */
        errno = EINVAL;
        return -1;
    }

    /*
     * getline() returns a null byte ('\0') terminated C string,
     * but fgetln() returns characters without '\0' termination
     */
    if (*lineptr == NULL) {
        *n = BUF_MIN;
        goto alloc_buf;
    }

    /* realloc the original pointer */
    if (*n < len + 1) {
        free(*lineptr);

        *n = len + 1;
alloc_buf:
        *lineptr = malloc(*n);
        if (*lineptr == NULL) {
            *n = 0;
            return -1;
        }
    }

    /* copy over the string */
    memcpy(*lineptr, lptr, len);
    (*lineptr)[len] = '\0';

    /*
     * getline() and fgetln() both return len including the
     * delimiter but without the null byte at the end
     */
    return len;
}

#endif