sys/boot/common/load.c

   1 /*-
   2  * Copyright (c) 1998 Michael Smith <msmith@freebsd.org>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  * $FreeBSD: src/sys/boot/common/load.c,v 1.3 2003/08/25 23:30:41 obrien Exp $
  27  * $DragonFly: src/sys/boot/common/load.c,v 1.3 2003/11/10 06:08:31 dillon Exp $
  28  */
  29 #include <stand.h>
  30
  31 #define LOAD_TINYBUF    2048
  32
  33 /*
  34  * Attempt to load the file at (path) into an allocated
  35  * area on the heap, return a pointer to it or NULL
  36  * on failure.
  37  *
  38  * Because in many cases it is impossible to determine the
  39  * true size of a file without reading it, we do just that.
  40  */
  41 char *
  42 filedup(const char *path, int flags)
  43 {
  44     char        *buf;
  45     int         fd;
  46     size_t      size, result;
  47
  48     if ((fd = open(path, F_READ | flags)) == -1)
  49         return(NULL);
  50
  51     printf("%s open, flags 0x%x\n", path, files[fd].f_flags);
  52     buf = alloc(LOAD_TINYBUF);
  53
  54     /* Read the first buffer-full */
  55     size = read(fd, buf, LOAD_TINYBUF);
  56     if (size < 1) {
  57         free(buf, LOAD_TINYBUF);
  58         close(fd);
  59         return(NULL);
  60     }
  61     /* If it all fitted, then just return the buffer straight out */
  62     if (size < LOAD_TINYBUF) {
  63         close(fd);
  64         buf[size] = 0;
  65         return(buf);
  66     }
  67
  68     printf("tinybuf loaded, size %d\n", size);
  69     getchar();
  70
  71
  72     /* Read everything until we know how big it is */
  73     for (;;) {
  74         result = read(fd, buf, LOAD_TINYBUF);
  75         if (size == -1) {
  76             free(buf, LOAD_TINYBUF);
  77             close(fd);
  78             return(NULL);
  79         }
  80         if (result == 0)
  81             break;
  82         size += result;
  83     }
  84
  85     /* discard the old buffer, close the file */
  86     free(buf, LOAD_TINYBUF);
  87     close(fd);
  88
  89     /* reopen the file, realloc the buffer */
  90     if ((fd = open(path, F_READ | flags)) == -1)
  91         return(NULL);
  92     buf = alloc(size);
  93     result = read(fd, buf, size);
  94     close(fd);
  95     if (result != size) {
  96         free(buf, size);
  97         return(NULL);
  98     }
  99     return(buf);
 100 }
 101