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/* ----------------------------------------------------------------------- *
*
* Copyright 2004-2008 H. Peter Anvin - All Rights Reserved
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom
* the Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall
* be included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* ----------------------------------------------------------------------- */
/*
* read.c
*
* Reading from a file
*/
#include <errno.h>
#include <string.h>
#include <com32.h>
#include <syslinux/pmapi.h>
#include <minmax.h>
#include "file.h"
int __file_get_block(struct file_info *fp)
{
ssize_t bytes_read;
bytes_read = __com32.cs_pm->read_file(&fp->i.fd.handle, fp->i.buf,
MAXBLOCK >> fp->i.fd.blocklg2);
if (!bytes_read) {
errno = EIO;
return -1;
}
fp->i.nbytes = bytes_read;
fp->i.datap = fp->i.buf;
return 0;
}
ssize_t __file_read(struct file_info * fp, void *buf, size_t count)
{
char *bufp = buf;
ssize_t n = 0;
size_t ncopy;
while (count) {
if (fp->i.nbytes == 0) {
if (fp->i.offset >= fp->i.fd.size || !fp->i.fd.handle)
return n; /* As good as it gets... */
if (count > MAXBLOCK) {
/* Large transfer: copy directly, without buffering */
ncopy = __com32.cs_pm->read_file(&fp->i.fd.handle, bufp,
count >> fp->i.fd.blocklg2);
if (!ncopy) {
errno = EIO;
return n ? n : -1;
}
goto got_data;
} else {
if (__file_get_block(fp))
return n ? n : -1;
}
}
ncopy = min(count, fp->i.nbytes);
memcpy(bufp, fp->i.datap, ncopy);
fp->i.datap += ncopy;
fp->i.offset += ncopy;
fp->i.nbytes -= ncopy;
got_data:
n += ncopy;
bufp += ncopy;
count -= ncopy;
}
return n;
}
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