A question about ipcperm() call?

[李尚杰]

The code for ipcperm() call :
 78 ipcperm(td, perm, mode)
 79         struct thread *td;
 80         struct ipc_perm *perm;
 81         int mode;
 82 {
 83         struct ucred *cred = td->td_ucred;
 84         int error;
 85
 86         if (cred->cr_uid != perm->cuid && cred->cr_uid != perm->uid) {
 87                 /*
 88                  * For a non-create/owner, we require privilege to
 89                  * modify the object protections.  Note: some other
 90                  * implementations permit IPC_M to be delegated to
 91                  * unprivileged non-creator/owner uids/gids.
 92                  */
 93                 if (mode & IPC_M) {
 94                         error = suser(td);
 95                         if (error)
 96                                 return (error);
 97                 }
 98                 /*
 99                  * Try to match against creator/owner group; if not, fall
100                  * back on other.
101                  */
102                 mode >>= 3;
103                 if (!groupmember(perm->gid, cred) &&
104                     !groupmember(perm->cgid, cred))
105                         mode >>= 3;
106         } else {
107                 /*
108                  * Always permit the creator/owner to update the object
109                  * protections regardless of whether the object mode
110                  * permits it.
111                  */
112                 if (mode & IPC_M)
113                         return (0);
114         }
115
116         if ((mode & perm->mode) != mode) {
117                 if (suser(td) != 0)
118                         return (EACCES);
119         }
120         return (0);
121 }

why not directly return the error in line 94?


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