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Merge pull request #82 from t8m/ingroup

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newgrp: avoid unnecessary group lookups
This commit is contained in:
Serge Hallyn 2017-10-06 17:45:31 -05:00 committed by GitHub
commit 0c2939b331
1 changed files with 34 additions and 24 deletions
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58
src/newgrp.c
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@ -83,16 +83,30 @@ static void usage (void)
} }
} }
/* static bool ingroup(const char *name, struct group *gr)
* find_matching_group - search all groups of a given group id for
* membership of a given username
*/
static /*@null@*/struct group *find_matching_group (const char *name, gid_t gid)
{ {
struct group *gr;
char **look; char **look;
bool notfound = true; bool notfound = true;
look = gr->gr_mem;
while (*look && notfound)
notfound = strcmp (*look++, name);
return !notfound;
}
/*
* find_matching_group - search all groups of a gr's group id for
* membership of a given username
* but check gr itself first
*/
static /*@null@*/struct group *find_matching_group (const char *name, struct group *gr)
{
gid_t gid = gr->gr_gid;
if (ingroup(name, gr))
return gr;
setgrent (); setgrent ();
while ((gr = getgrent ()) != NULL) { while ((gr = getgrent ()) != NULL) {
if (gr->gr_gid != gid) { if (gr->gr_gid != gid) {
@ -103,14 +117,8 @@ static /*@null@*/struct group *find_matching_group (const char *name, gid_t gid)
* A group with matching GID was found. * A group with matching GID was found.
* Test for membership of 'name'. * Test for membership of 'name'.
*/ */
look = gr->gr_mem; if (ingroup(name, gr))
while ((NULL != *look) && notfound) {
notfound = (strcmp (*look, name) != 0);
look++;
}
if (!notfound) {
break; break;
}
} }
endgrent (); endgrent ();
return gr; return gr;
@ -643,17 +651,19 @@ int main (int argc, char **argv)
* groups of the same GID like the requested group for * groups of the same GID like the requested group for
* membership of the current user. * membership of the current user.
*/ */
grp = find_matching_group (name, grp->gr_gid); if (!is_member) {
if (NULL == grp) { grp = find_matching_group (name, grp);
/* if (NULL == grp) {
* No matching group found. As we already know that /*
* the group exists, this happens only in the case * No matching group found. As we already know that
* of a requested group where the user is not member. * the group exists, this happens only in the case
* * of a requested group where the user is not member.
* Re-read the group entry for further processing. *
*/ * Re-read the group entry for further processing.
grp = xgetgrnam (group); */
assert (NULL != grp); grp = xgetgrnam (group);
assert (NULL != grp);
}
} }
#ifdef SHADOWGRP #ifdef SHADOWGRP
sgrp = getsgnam (group); sgrp = getsgnam (group);