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Tidy up fd-related functions called by do_execve

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o assert in each one that fdp is not shared
o remove unnecessary NULL checks - all userspace processes have fdtables
and kernel processes cannot execve
o remove comments about the danger of fd_ofiles getting reallocated - fdtable
is not shared and fd_ofiles could be only reallocated if new fd was about to be
added, but if that was possible the code would already be buggy as setugidsafety
work could be undone

MFC after:	1 week
This commit is contained in:
Mateusz Guzik 2014-06-23 01:28:18 +00:00
parent 8382ec9e6a
commit 450570a55e
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=267760
1 changed files with 2 additions and 18 deletions
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20
sys/kern/kern_descrip.c
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@ -2081,15 +2081,8 @@ setugidsafety(struct thread *td)
struct file *fp;
int i;
/* Certain daemons might not have file descriptors. */
fdp = td->td_proc->p_fd;
if (fdp == NULL)
return;
/*
* Note: fdp->fd_ofiles may be reallocated out from under us while
* we are blocked in a close. Be careful!
*/
KASSERT(fdp->fd_refcnt == 1, ("the fdtable should not be shared"));
FILEDESC_XLOCK(fdp);
for (i = 0; i <= fdp->fd_lastfile; i++) {
if (i > 2)
@ -2141,15 +2134,8 @@ fdcloseexec(struct thread *td)
struct file *fp;
int i;
/* Certain daemons might not have file descriptors. */
fdp = td->td_proc->p_fd;
if (fdp == NULL)
return;
/*
* We cannot cache fd_ofiles since operations
* may block and rip them out from under us.
*/
KASSERT(fdp->fd_refcnt == 1, ("the fdtable should not be shared"));
FILEDESC_XLOCK(fdp);
for (i = 0; i <= fdp->fd_lastfile; i++) {
fde = &fdp->fd_ofiles[i];
@ -2180,8 +2166,6 @@ fdcheckstd(struct thread *td)
int i, error, devnull;
fdp = td->td_proc->p_fd;
if (fdp == NULL)
return (0);
KASSERT(fdp->fd_refcnt == 1, ("the fdtable should not be shared"));
devnull = -1;
error = 0;