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#include <u.h>
#include <libc.h>
#include <thread.h>
#include "dat.h"
#include "fns.h"
int
fcopy(int dfd, int sfd, vlong len)
{
uchar buf[BUFSZ];
int n;
while(len > 0){
if((n = BUFSZ) > len)
n = len;
if((n = read(sfd, buf, n)) < 0)
return -1;
if(write(dfd, buf, n) != n)
return -1;
len -= n;
}
return 0;
}
static uchar patchmark[12] = {
0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff,
};
int
fpatchmark(int pfd, char *)
{
if(write(pfd, patchmark, 12) != 12)
return -1;
return 0;
}
typedef struct Frag Frag;
struct Frag
{
Frag *next;
int fd;
vlong len;
vlong off;
};
int
fpatch(int ofd, int bfd, int pfd)
{
vlong off, fstart, fend, start, end, len;
int err, front, back;
Frag *h, *f, *p;
uchar buf[12];
h = nil;
err = -1;
if(bfd >= 0){
h = malloc(sizeof(Frag));
h->next = nil;
h->off = 0;
h->fd = bfd;
h->len = seek(h->fd, 0, 2);
if(h->len < 0)
goto errout;
}
off = 0;
while(pfd >= 0){
if(readn(pfd, buf, 12) != 12)
break;
if(memcmp(buf, patchmark, 12) == 0){
off = 0;
continue;
}
start = buf[0]<<24 | buf[1]<<16 | buf[2]<<8 | buf[3];
end = buf[4]<<24 | buf[5]<<16 | buf[6]<<8 | buf[7];
len = buf[8]<<24 | buf[9]<<16 | buf[10]<<8 | buf[11];
if(start > end){
werrstr("bad patch: start > end");
goto errout;
}
start += off;
end += off;
off += start + len - end;
fstart = 0;
for(f = h; f; f = f->next, fstart = fend){
fend = fstart + f->len;
if(fend <= start)
continue;
if(fstart >= end)
break;
front = start > fstart;
back = end < fend;
if(front && back){
p = malloc(sizeof(Frag));
*p = *f;
f->next = p;
f->len = start - fstart;
p->off += end - fstart;
p->len -= end - fstart;
break;
} else if(back){
f->off += end - fstart;
f->len -= end - fstart;
break;
} else if(front){
f->len = start - fstart;
} else {
f->len = 0;
}
}
fstart = 0;
for(p = nil, f = h; f && fstart < start; p = f, f = f->next)
fstart += f->len;
f = malloc(sizeof(Frag));
f->fd = pfd;
f->len = len;
f->off = seek(f->fd, 0, 1);
if(p){
f->next = p->next;
p->next = f;
} else {
f->next = h;
h = f;
}
if(f->off < 0)
goto errout;
if(seek(pfd, f->len, 1) < 0)
goto errout;
}
for(f = h; f; f = f->next){
if(seek(f->fd, f->off, 0) < 0)
goto errout;
if(fcopy(ofd, f->fd, f->len) < 0)
goto errout;
}
err = 0;
errout:
while(f = h){
h = f->next;
free(f);
}
return err;
}
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