buckets/apr_buckets_file.c

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2000-2001 The Apache Software Foundation.  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, 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
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 *    distribution.
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 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
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 *    not be used to endorse or promote products derived from this
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 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

#include "apr.h"
#include "apr_general.h"
#include "apr_file_io.h"
#include "apr_buckets.h"
#include <stdlib.h>

/* Allow Apache to use ap_mmap */
#if APR_HAS_MMAP
#include "apr_mmap.h"

/* mmap support for static files based on ideas from John Heidemann's
 * patch against 1.0.5.  See
 * <http://www.isi.edu/~johnh/SOFTWARE/APACHE/index.html>.
 */

/* Files have to be at least this big before they're mmap()d.  This is to deal
 * with systems where the expense of doing an mmap() and an munmap() outweighs
 * the benefit for small files.  It shouldn't be set lower than 1.
 */
#ifndef MMAP_THRESHOLD
#  ifdef SUNOS4
#  define MMAP_THRESHOLD                (8*1024)
#  else
#  define MMAP_THRESHOLD                1
#  endif /* SUNOS4 */
#endif /* MMAP_THRESHOLD */
#ifndef MMAP_LIMIT
#define MMAP_LIMIT              (4*1024*1024)
#endif
#endif /* APR_HAS_MMAP */


static void file_destroy(void *data)
{
    if (apr_bucket_shared_destroy(data)) {
        /* no need to close the file here; it will get
         * done automatically when the pool gets cleaned up */
        free(data);
    }
}

static apr_status_t file_read(apr_bucket *e, const char **str,
			      apr_size_t *len, apr_read_type_e block)
{
    apr_bucket_file *a = e->data;
    apr_file_t *f = a->fd;
    apr_bucket *b = NULL;
    char *buf;
    apr_status_t rv;
    apr_off_t filelength = e->length;  /* bytes remaining in file past offset */
    apr_off_t fileoffset = e->start;
#if APR_HAS_MMAP
    apr_mmap_t *mm = NULL;
#endif

#if APR_HAS_MMAP
    if ((filelength >= MMAP_THRESHOLD)
        && (filelength < MMAP_LIMIT)) {
        /* we need to protect ourselves in case we die while we've got the
         * file mmapped */
        apr_status_t status;
        apr_pool_t *p = apr_file_pool_get(f);
        if ((status = apr_mmap_create(&mm, f, fileoffset, filelength, 
                                      APR_MMAP_READ, p)) != APR_SUCCESS) {
            mm = NULL;
        }
    }
    else {
        mm = NULL;
    }
    if (mm) {
        apr_bucket_mmap_make(e, mm, 0, filelength); /*XXX: check for failure? */
        file_destroy(a);
        return apr_bucket_read(e, str, len, block);
    }
#endif

    *len = (filelength > APR_BUCKET_BUFF_SIZE)
               ? APR_BUCKET_BUFF_SIZE
               : filelength;
    *str = NULL;  /* in case we die prematurely */
    buf = malloc(*len);

    /* Handle offset ... */
    if (fileoffset) {
        rv = apr_file_seek(f, APR_SET, &fileoffset);
        if (rv != APR_SUCCESS) {
            free(buf);
            return rv;
        }
    }
    rv = apr_file_read(f, buf, len);
    if (rv != APR_SUCCESS && rv != APR_EOF) {
        free(buf);
        return rv;
    }
    filelength -= *len;
    /*
     * Change the current bucket to refer to what we read,
     * even if we read nothing because we hit EOF.
     */
    apr_bucket_heap_make(e, buf, *len, 0, NULL); /*XXX: check for failure? */

    /* If we have more to read from the file, then create another bucket */
    if (filelength > 0) {
        /* for efficiency, we can just build a new apr_bucket struct
         * to wrap around the existing file bucket */
        b = malloc(sizeof(*b));
        b->start  = fileoffset + (*len);
        b->length = filelength;
        b->data   = a;
        b->type   = &apr_bucket_type_file;
        APR_BUCKET_INSERT_AFTER(e, b);
    }
    else {
        file_destroy(a);
    }

    *str = buf;
    return APR_SUCCESS;
}

APU_DECLARE(apr_bucket *) apr_bucket_file_make(apr_bucket *b, apr_file_t *fd,
                                            apr_off_t offset, apr_size_t len)
{
    apr_bucket_file *f;

    f = malloc(sizeof(*f));
    if (f == NULL) {
        return NULL;
    }
    f->fd = fd;

    b = apr_bucket_shared_make(b, f, offset, len);
    b->type = &apr_bucket_type_file;

    return b;
}

APU_DECLARE(apr_bucket *) apr_bucket_file_create(apr_file_t *fd,
                                              apr_off_t offset, apr_size_t len)
{
    apr_bucket *b = (apr_bucket *)calloc(1, sizeof(*b));

    APR_BUCKET_INIT(b);
    return apr_bucket_file_make(b, fd, offset, len);
}

APU_DECLARE_DATA const apr_bucket_type_t apr_bucket_type_file = {
    "FILE", 5,
    file_destroy,
    file_read,
    apr_bucket_setaside_notimpl,
    apr_bucket_shared_split,
    apr_bucket_shared_copy
};