1 files changed, 36 insertions, 2 deletions

diff --git a/libbb/update_passwd.c b/libbb/update_passwd.c
index a30af6f72..dc26ebd1d 100644
--- a/libbb/update_passwd.c
+++ b/libbb/update_passwd.c
@@ -62,6 +62,8 @@ static void check_selinux_update_passwd(const char *username)
     only if CONFIG_PASSWD=y and applet_name[0] == 'p' like in passwd
     or if CONFIG_CHPASSWD=y and applet_name[0] == 'c' like in chpasswd
 
+ 8) delete a user from all groups: update_passwd(FILE, NULL, NULL, MEMBER)
+
  This function does not validate the arguments fed to it
  so the calling program should take care of that.
 
@@ -99,12 +101,13 @@ int FAST_FUNC update_passwd(const char *filename,
         if (filename == NULL)
                 return ret;
 
-        check_selinux_update_passwd(name);
+        if (name)
+                check_selinux_update_passwd(name);
 
         /* New passwd file, "/etc/passwd+" for now */
         fnamesfx = xasprintf("%s+", filename);
         sfx_char = &fnamesfx[strlen(fnamesfx)-1];
-        name_colon = xasprintf("%s:", name);
+        name_colon = xasprintf("%s:", name ? name : "");
         user_len = strlen(name_colon);
 
         if (shadow)
@@ -167,6 +170,37 @@ int FAST_FUNC update_passwd(const char *filename,
                 line = xmalloc_fgetline(old_fp);
                 if (!line) /* EOF/error */
                         break;
+
+                if (!name && member) {
+                        /* Delete member from all groups */
+                        /* line is "GROUP:PASSWD:[member1[,member2]...]" */
+                        unsigned member_len = strlen(member);
+                        char *list = strrchr(line, ':');
+                        while (list) {
+                                list++;
+ next_list_element:
+                                if (strncmp(list, member, member_len) == 0) {
+                                        char c;
+                                        changed_lines++;
+                                        c = list[member_len];
+                                        if (c == '\0') {
+                                                if (list[-1] == ',')
+                                                        list--;
+                                                *list = '\0';
+                                                break;
+                                        }
+                                        if (c == ',') {
+                                                overlapping_strcpy(list, list + member_len + 1);
+                                                goto next_list_element;
+                                        }
+                                        changed_lines--;
+                                }
+                                list = strchr(list, ',');
+                        }
+                        fprintf(new_fp, "%s\n", line);
+                        goto next;
+                }
+
                 if (strncmp(name_colon, line, user_len) != 0) {
                         fprintf(new_fp, "%s\n", line);
                         goto next;