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Change crsetgroups_locked() (called by crsetgroups()) to sort the

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supplemental groups using insertion sort.  Use this property in
groupmember() to let us use a binary search instead of the previous
linear search.
This commit is contained in:
brooks 2009-06-20 20:29:21 +00:00
parent a2017ad896
commit 03ed423a4a
1 changed files with 45 additions and 10 deletions
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55
sys/kern/kern_prot.c
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@ -86,7 +86,6 @@ static void crextend(struct ucred *cr, int n);
static void crsetgroups_locked(struct ucred *cr, int ngrp,
gid_t *groups);
#ifndef _SYS_SYSPROTO_H_
struct getpid_args {
int dummy;
@ -1248,13 +1247,30 @@ __setugid(struct thread *td, struct __setugid_args *uap)
int
groupmember(gid_t gid, struct ucred *cred)
{
register gid_t *gp;
gid_t *egp;
int l;
int h;
int m;
if (cred->cr_groups[0] == gid)
return(1);
/*
* If gid was not our primary group, perform a binary search
* of the supplemental groups. This is possible because we
* sort the groups in crsetgroups().
*/
l = 1;
h = cred->cr_ngroups;
while (l < h) {
m = l + ((h - l) / 2);
if (cred->cr_groups[m] < gid)
l = m + 1;
else
h = m;
}
if ((l < cred->cr_ngroups) && (cred->cr_groups[l] == gid))
return (1);
egp = &(cred->cr_groups[cred->cr_ngroups]);
for (gp = cred->cr_groups; gp < egp; gp++)
if (*gp == gid)
return (1);
return (0);
}
@ -1986,18 +2002,37 @@ crextend(struct ucred *cr, int n)
}
/*
* Copy groups in to a credential, preserving any necessicary invariants
* (i.e. sorting in the future). crextend() must have been called
* before hand to ensure sufficient space is available. If
* Copy groups in to a credential, preserving any necessary invariants.
* Currently this includes the sorting of all supplemental gids.
* crextend() must have been called before hand to ensure sufficient
* space is available.
*/
static void
crsetgroups_locked(struct ucred *cr, int ngrp, gid_t *groups)
{
int i;
int j;
gid_t g;
KASSERT(cr->cr_agroups >= ngrp, ("cr_ngroups is too small"));
bcopy(groups, cr->cr_groups, ngrp * sizeof(gid_t));
cr->cr_ngroups = ngrp;
/*
* Sort all groups except cr_groups[0] to allow groupmember to
* perform a binary search.
*
* XXX: If large numbers of groups become common this should
* be replaced with shell sort like linux uses or possibly
* heap sort.
*/
for (i = 2; i < ngrp; i++) {
g = cr->cr_groups[i];
for (j = i-1; j >= 1 && g < cr->cr_groups[j]; j--)
cr->cr_groups[j + 1] = cr->cr_groups[j];
cr->cr_groups[j + 1] = g;
}
}
/*