update id to be SUS compliant

 * add -n and -G flag
 * allow a username to be given as argument
 * display complete list of groups
 * include it in default build

diff --git a/toys/id.c b/toys/id.c
index 6f0d12f..6ae3efe 100644 (file)
--- a/toys/id.c
+++ b/toys/id.c
@@ -8,49 +8,165 @@
  *
  * See http://www.opengroup.org/onlinepubs/009695399/utilities/id.html
 
-USE_ID(NEWTOY(id, "gru", TOYFLAG_BIN))
+USE_ID(NEWTOY(id, "nGgru", TOYFLAG_BIN))
 
 config ID
        bool "id"
-       default n
+       default y
        help
-         usage: id [-gru]
+         usage: id [-nGgru]
 
          Print user and group ID.
 
+         -n    print names instead of numeric IDs (to be used with -Ggu)
+         -G    Show only the group IDs
          -g    Show only the effective group ID
          -r    Show real ID instead of effective ID
          -u    Show only the effective user ID
 */
 
+#include <sys/types.h>
+#include <pwd.h>
+#include <grp.h>
 #include "toys.h"
 
+#define FLAG_n (1<<4)
+#define FLAG_G (1<<3)
 #define FLAG_g (1<<2)
 #define FLAG_r (1<<1)
 #define FLAG_u 1
 
+void
+pretty_print(struct passwd *pw, struct group *grp, struct group **grps, int n)
+{
+       int i;
+       printf("uid= %d(%s) gid= %d(%s)", pw->pw_uid, pw->pw_name,
+                                                                         grp->gr_gid, grp->gr_name);
+       if (n) {
+               printf(" groups= ");
+       }
+       for (i = 0; i < n; i++) {
+               printf("%d(%s)%s", grps[i]->gr_gid, grps[i]->gr_name,
+                                                  (i < n-1) ? ",": "");
+       }
+       printf("\n");
+}
+
 void id_main(void)
 {
        int flags = toys.optflags;
 
+       struct passwd *pw;
+       struct group *grp;
+       struct group **grps;
        uid_t uid;
        gid_t gid;
+       gid_t *groups;
+       int i;
+       int ngroups;
+       char *username;
 
-       /* show effective, unless user specifies real */
-       uid = geteuid();
-       gid = getegid();
+       /* check if a username is given */
+       if (*toys.optargs) {
+               username = *(toys.optargs);
+               pw = getpwnam(username);
+               if (!pw) {
+                       printf("id: %s: no such user\n", username);
+                       toys.exitval = 1;
+                       return;
+               }
+               uid = pw->pw_uid;
+               gid = pw->pw_gid;
+       } else {
+               /* show effective, unless user specifies real */
+               if (flags & FLAG_r) {
+                       uid = getuid();
+                       gid = getgid();
+               } else {
+                       uid = geteuid();
+                       gid = getegid();
+               }
+       }
 
-       if (flags & FLAG_r) {
-               uid = getuid();
-               gid = getgid();
+       pw = getpwuid(uid);
+       if (!pw) {
+               perror("id");
+               toys.exitval = 1;
+               return;
+       }
+       
+       grp = getgrgid(pw->pw_gid);
+       if (!grp) {
+               perror("id");
+               toys.exitval = 1;
+               return;
        }
+       
        if (flags & FLAG_u) {
-           printf("%d\n", uid);
+               if (flags & FLAG_n)
+                   printf("%s\n", pw->pw_name);
+               else
+                   printf("%d\n", pw->pw_uid);
                return;
        }
        if (flags & FLAG_g) {
-               printf("%d\n", gid);
+               if (flags & FLAG_n)
+                       printf("%s\n", grp->gr_name);
+               else
+                       printf("%d\n", grp->gr_gid);
                return;
        }
-       printf("%d %d\n", uid, gid);
+       
+
+       if (flags & FLAG_r) {
+               printf("-r can only be used in combination with -u or -g\n");
+               toys.exitval = 1;
+               return;
+       }
+       ngroups = sysconf(_SC_NGROUPS_MAX);
+       /* fallback for number of groups to 32 */
+       if (ngroups < 0)
+               ngroups = 32;
+       groups = malloc(ngroups * sizeof(gid_t));
+       if (!groups) {
+               perror("id");
+               toys.exitval = 1;
+               return;
+       }
+       if (getgrouplist(pw->pw_name, pw->pw_gid, groups, &ngroups) < 0) {
+               perror("id");
+               toys.exitval = 1;
+               return;
+       }
+       grps = malloc(ngroups * sizeof(struct group *));
+       for (i = 0; i < ngroups; i++) {
+               struct group *tmp;
+               grps[i] = malloc(sizeof(struct group));
+               size_t f = sysconf(_SC_GETGR_R_SIZE_MAX);
+               char *buf = malloc(f);
+               if (getgrgid_r(groups[i], grps[i], buf, f, &tmp) < 0) {
+                       perror("id");
+                       continue;
+               }
+               if (tmp == NULL) {
+                       perror("id");
+                       continue;
+               }
+       }
+       
+       if (flags & FLAG_G) {
+               for (i = 0; i < ngroups; i++) {
+                       if (flags & FLAG_n)
+                               printf("%s%s", !i ? "" : " ", grps[i]->gr_name);
+                       else
+                               printf("%s%d", !i ? "" : " ", grps[i]->gr_gid);
+               }
+               printf("\n");
+               return;
+       }
+
+       pretty_print(pw, grp, grps, ngroups);
+       for (i=0; i < ngroups; i++)
+               free(grps[i]);
+
 }