freebsd-nq/sys/boot/common/load.c
1999-08-28 01:08:13 +00:00

102 lines
2.9 KiB
C

/*-
* Copyright (c) 1998 Michael Smith <msmith@freebsd.org>
* 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 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.
*
* $FreeBSD$
*/
#include <stand.h>
#define LOAD_TINYBUF 2048
/*
* Attempt to load the file at (path) into an allocated
* area on the heap, return a pointer to it or NULL
* on failure.
*
* Because in many cases it is impossible to determine the
* true size of a file without reading it, we do just that.
*/
char *
filedup(const char *path, int flags)
{
char *buf;
int fd;
size_t size, result;
if ((fd = open(path, F_READ | flags)) == -1)
return(NULL);
printf("%s open, flags 0x%x\n", path, files[fd].f_flags);
buf = alloc(LOAD_TINYBUF);
/* Read the first buffer-full */
size = read(fd, buf, LOAD_TINYBUF);
if (size < 1) {
free(buf, LOAD_TINYBUF);
close(fd);
return(NULL);
}
/* If it all fitted, then just return the buffer straight out */
if (size < LOAD_TINYBUF) {
close(fd);
buf[size] = 0;
return(buf);
}
printf("tinybuf loaded, size %d\n", size);
getchar();
/* Read everything until we know how big it is */
for (;;) {
result = read(fd, buf, LOAD_TINYBUF);
if (size == -1) {
free(buf, LOAD_TINYBUF);
close(fd);
return(NULL);
}
if (result == 0)
break;
size += result;
}
/* discard the old buffer, close the file */
free(buf, LOAD_TINYBUF);
close(fd);
/* reopen the file, realloc the buffer */
if ((fd = open(path, F_READ | flags)) == -1)
return(NULL);
buf = alloc(size);
result = read(fd, buf, size);
close(fd);
if (result != size) {
free(buf, size);
return(NULL);
}
return(buf);
}