On 8/02/2016 9:12 AM, Jilles Tjoelker wrote:
> Author: jilles
> Date: Sun Feb 7 22:12:39 2016
> New Revision: 295385
> URL: https://svnweb.freebsd.org/changeset/base/295385
>
> Log:
> semget(): Check for [EEXIST] error first.
>
> Although POSIX literally permits failing with [EINVAL] if IPC_CREAT and
> IPC_EXCL were both passed, the semaphore set already exists and has fewer
> semaphores than nsems, this does not allow an application to retry safely:
> if the [EINVAL] is actually because of the semmsl limit, an infinite loop
> would result.
>
> PR: 206927
>
> Modified:
> head/sys/kern/sysv_sem.c
> head/tools/regression/sysvsem/semtest.c
+infinity for bugfix & issue reference & regression test.
Thank you Jilles!
> Modified: head/sys/kern/sysv_sem.c
> ==============================================================================
> --- head/sys/kern/sysv_sem.c Sun Feb 7 21:25:08 2016 (r295384)
> +++ head/sys/kern/sysv_sem.c Sun Feb 7 22:12:39 2016 (r295385)
> @@ -867,6 +867,11 @@ sys_semget(struct thread *td, struct sem
> }
> if (semid < seminfo.semmni) {
> DPRINTF(("found public key\n"));
> + if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) {
> + DPRINTF(("not exclusive\n"));
> + error = EEXIST;
> + goto done2;
> + }
> if ((error = ipcperm(td, &sema[semid].u.sem_perm,
> semflg & 0700))) {
> goto done2;
> @@ -876,11 +881,6 @@ sys_semget(struct thread *td, struct sem
> error = EINVAL;
> goto done2;
> }
> - if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) {
> - DPRINTF(("not exclusive\n"));
> - error = EEXIST;
> - goto done2;
> - }
> #ifdef MAC
> error = mac_sysvsem_check_semget(cred, &sema[semid]);
> if (error != 0)
>
> Modified: head/tools/regression/sysvsem/semtest.c
> ==============================================================================
> --- head/tools/regression/sysvsem/semtest.c Sun Feb 7 21:25:08 2016
> (r295384)
> +++ head/tools/regression/sysvsem/semtest.c Sun Feb 7 22:12:39 2016
> (r295385)
> @@ -152,6 +152,15 @@ main(int argc, char *argv[])
>
> print_semid_ds(&s_ds, 0600);
>
> + errno = 0;
> + if (semget(semkey, 1, IPC_CREAT | IPC_EXCL | 0600) != -1 ||
> + errno != EEXIST)
> + err(1, "semget IPC_EXCL 1 did not fail with [EEXIST]");
> + errno = 0;
> + if (semget(semkey, 2, IPC_CREAT | IPC_EXCL | 0600) != -1 ||
> + errno != EEXIST)
> + err(1, "semget IPC_EXCL 2 did not fail with [EEXIST]");
> +
> for (child_count = 0; child_count < 5; child_count++) {
> switch ((child_pid = fork())) {
> case -1:
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