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#include <u.h>
#include <libc.h>
#include <diskfs.h>
int nfilereads;
typedef struct DiskFile DiskFile;
struct DiskFile
{
Disk disk;
int fd;
};
static long
preadn(int fd, void *vdata, u32int ulen, u64int offset)
{
long n;
uchar *data;
long len;
nfilereads++;
len = ulen;
data = vdata;
// fprint(2, "readn 0x%llux 0x%ux\n", offset, ulen);
while(len > 0){
n = pread(fd, data, len, offset);
if(n <= 0)
break;
data += n;
offset += n;
len -= n;
}
return data-(uchar*)vdata;
}
static void
diskfileblockput(Block *b)
{
free(b);
}
uvlong nreadx;
static Block*
diskfileread(Disk *dd, u32int len, u64int offset)
{
int n;
Block *b;
DiskFile *d = (DiskFile*)dd;
b = mallocz(sizeof(Block)+len, 1);
if(b == nil)
return nil;
b->data = (uchar*)&b[1];
nreadx += len;
n = preadn(d->fd, b->data, len, offset);
if(n <= 0){
free(b);
return nil;
}
b->_close = diskfileblockput;
b->len = n;
return b;
}
static int
diskfilesync(Disk *dd)
{
USED(dd);
return 0;
}
static void
diskfileclose(Disk *dd)
{
DiskFile *d = (DiskFile*)dd;
close(d->fd);
free(d);
}
Disk*
diskopenfile(char *file)
{
int fd;
DiskFile *d;
if((fd = open(file, OREAD)) < 0)
return nil;
d = mallocz(sizeof(DiskFile), 1);
if(d == nil){
close(fd);
return nil;
}
d->disk._read = diskfileread;
d->disk._sync = diskfilesync;
d->disk._close = diskfileclose;
d->fd = fd;
return &d->disk;
}
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