buffer.c

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/*
 * Copyright (c) Christos Zoulas 2017.
 * All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice immediately at the beginning of the file, without modification,
 *    this list of conditions, and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
#include "file.h"
 
#ifndef lint
FILE_RCSID("@(#)$File: buffer.c,v 1.13 2023/07/02 12:48:39 christos Exp $")
#endif  /* lint */
 
#include "magic.h"
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <string.h>
#include <stdlib.h>
#include <sys/stat.h>
 
void
buffer_init(struct buffer *b, int fd, const zend_stat_t *st, const void *data,
    size_t len)
{
    b->fd = fd;
    if (st)
        memcpy(&b->st, st, sizeof(b->st));
    else if (b->fd == -1 || zend_fstat(b->fd, &b->st) == -1)
        memset(&b->st, 0, sizeof(b->st));
    b->fbuf = data;
    b->flen = len;
    b->eoff = 0;
    b->ebuf = NULL;
    b->elen = 0;
}
 
void
buffer_fini(struct buffer *b)
{
    efree(b->ebuf);
    b->ebuf = NULL;
    b->elen = 0;
}
 
int
buffer_fill(const struct buffer *bb)
{
    struct buffer *b = CCAST(struct buffer *, bb);
 
    if (b->elen != 0)
        return b->elen == FILE_BADSIZE ? -1 : 0;
 
    if (!S_ISREG(b->st.st_mode))
        goto out;
 
    b->elen = CAST(size_t, b->st.st_size) < b->flen ?
        CAST(size_t, b->st.st_size) : b->flen;
    if (b->elen == 0) {
        efree(b->ebuf);
        b->ebuf = NULL;
        return 0;
    }
    if ((b->ebuf = emalloc(b->elen)) == NULL)
        goto out;
 
    b->eoff = b->st.st_size - b->elen;
    if (FINFO_LSEEK_FUNC(b->fd, b->eoff, SEEK_SET) == (zend_off_t)-1 ||
        FINFO_READ_FUNC(b->fd, b->ebuf, b->elen) != (ssize_t)b->elen)
    {
        efree(b->ebuf);
        b->ebuf = NULL;
        goto out;
    }
 
    return 0;
out:
    b->elen = FILE_BADSIZE;
    return -1;
}