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There is only one caller of the dupfdopen() function, so we can simplify

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it a bit:
- We can assert that only ENODEV and ENXIO errors are passed instead of
  handling other errors.
- The caller always call finstall() for indx descriptor, so we can assume
  it is set. Actually the filedesc lock is dropped between finstall() and
  dupfdopen(), so there is a window there for another thread to close the
  indx descriptor, but it will be closed in next commit.

Reviewed by:	mjg
MFC after:	1 month
This commit is contained in:
Pawel Jakub Dawidek 2012-06-13 19:00:29 +00:00
parent 6ae742a549
commit 6195bfebcc
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=237016
1 changed files with 14 additions and 32 deletions
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46
sys/kern/kern_descrip.c
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@ -2593,6 +2593,9 @@ dupfdopen(struct thread *td, struct filedesc *fdp, int indx, int dfd, int mode,
struct file *wfp;
struct file *fp;
KASSERT(error == ENODEV || error == ENXIO,
("unexpected error %d in %s", error, __func__));
/*
* If the to-be-dup'd fd number is greater than the allowed number
* of file descriptors, or the fd to be dup'd has already been
@ -2612,9 +2615,8 @@ dupfdopen(struct thread *td, struct filedesc *fdp, int indx, int dfd, int mode,
*
* For ENXIO steal away the file structure from (dfd) and store it in
* (indx). (dfd) is effectively closed by this operation.
*
* Any other error code is just returned.
*/
fp = fdp->fd_ofiles[indx];
switch (error) {
case ENODEV:
/*
@ -2625,48 +2627,28 @@ dupfdopen(struct thread *td, struct filedesc *fdp, int indx, int dfd, int mode,
FILEDESC_XUNLOCK(fdp);
return (EACCES);
}
fp = fdp->fd_ofiles[indx];
fdp->fd_ofiles[indx] = wfp;
fdp->fd_ofileflags[indx] = fdp->fd_ofileflags[dfd];
if (fp == NULL)
fdused(fdp, indx);
fhold(wfp);
FILEDESC_XUNLOCK(fdp);
if (fp != NULL)
/*
* We now own the reference to fp that the ofiles[]
* array used to own. Release it.
*/
fdrop(fp, td);
return (0);
break;
case ENXIO:
/*
* Steal away the file pointer from dfd and stuff it into indx.
*/
fp = fdp->fd_ofiles[indx];
fdp->fd_ofiles[indx] = fdp->fd_ofiles[dfd];
fdp->fd_ofiles[indx] = wfp;
fdp->fd_ofiles[dfd] = NULL;
fdp->fd_ofileflags[indx] = fdp->fd_ofileflags[dfd];
fdp->fd_ofileflags[dfd] = 0;
fdunused(fdp, dfd);
if (fp == NULL)
fdused(fdp, indx);
FILEDESC_XUNLOCK(fdp);
/*
* We now own the reference to fp that the ofiles[] array
* used to own. Release it.
*/
if (fp != NULL)
fdrop(fp, td);
return (0);
default:
FILEDESC_XUNLOCK(fdp);
return (error);
break;
}
/* NOTREACHED */
FILEDESC_XUNLOCK(fdp);
/*
* We now own the reference to fp that the ofiles[] array used to own.
* Release it.
*/
fdrop(fp, td);
return (0);
}
/*