GNU/Linux man pages
Livre :
Expressions régulières,
Syntaxe et mise en oeuvre :
GNU/Linux |
CentOS 5.6 |
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getgrouplist(3) |
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getgrouplist − list of groups a user belongs to
#include <grp.h>
int getgrouplist (const char *user, gid_t group,
gid_t *groups, int *ngroups);
The getgrouplist() function scans the group database for all the groups user belongs to. Up to *ngroups group IDs corresponding to these groups are stored in the array groups; the return value from the function is the number of group IDs actually stored. The group group is automatically included in the list of groups returned by getgrouplist().
If *ngroups is smaller than the total number of groups found, then getgrouplist() returns a value of ’−1’. In all cases the actual number of groups is stored in *ngroups.
The glibc 2.3.2 implementation of this function is broken: it overwrites memory when the actual number of groups is larger than *ngroups.
This function is non-standard; it appears on most BSDs.
This function is present since glibc 2.2.4.
/* This crashes
with glibc 2.3.2 */
#include <stdio.h>
#include <stdlib.h>
#include <grp.h>
#include <pwd.h>
int main() {
int i, ng = 0;
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/* username here */ |
gid_t *groups = NULL;
struct passwd *pw = getpwnam(user);
if (pw == NULL)
return 0;
if
(getgrouplist(user, pw->pw_gid, NULL, &ng) < 0) {
groups = (gid_t *) malloc(ng * sizeof (gid_t));
getgrouplist(user, pw->pw_gid, groups, &ng);
}
for(i = 0; i
< ng; i++)
printf("%d\n", groups[i]);
return 0;
}
getgroups(3), setgroups(3)
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getgrouplist(3) | |