From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=5.0 tests=MAILING_LIST_MULTI, RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 18516 invoked from network); 4 May 2023 17:52:24 -0000 Received: from second.openwall.net (193.110.157.125) by inbox.vuxu.org with ESMTPUTF8; 4 May 2023 17:52:24 -0000 Received: (qmail 3652 invoked by uid 550); 4 May 2023 17:52:21 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Reply-To: musl@lists.openwall.com Received: (qmail 3617 invoked from network); 4 May 2023 17:52:20 -0000 Date: Thu, 4 May 2023 13:52:08 -0400 From: Rich Felker To: Markus Wichmann Cc: musl@lists.openwall.com Message-ID: <20230504175208.GF4163@brightrain.aerifal.cx> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Subject: Re: [musl] Namespace violation in system()? On Thu, May 04, 2023 at 06:33:27PM +0200, Markus Wichmann wrote: > Hi all, > > I stumbled upon the source code of system() today. It is this at the > moment: > > |int system(const char *cmd) > |{ > | pid_t pid; > | sigset_t old, reset; > | struct sigaction sa = { .sa_handler = SIG_IGN }, oldint, oldquit; > | int status = -1, ret; > | posix_spawnattr_t attr; > | > | pthread_testcancel(); > | > | if (!cmd) return 1; > | > | sigaction(SIGINT, &sa, &oldint); > | sigaction(SIGQUIT, &sa, &oldquit); > | sigaddset(&sa.sa_mask, SIGCHLD); > | sigprocmask(SIG_BLOCK, &sa.sa_mask, &old); > | > | sigemptyset(&reset); > | if (oldint.sa_handler != SIG_IGN) sigaddset(&reset, SIGINT); > | if (oldquit.sa_handler != SIG_IGN) sigaddset(&reset, SIGQUIT); > | posix_spawnattr_init(&attr); > | posix_spawnattr_setsigmask(&attr, &old); > | posix_spawnattr_setsigdefault(&attr, &reset); > | posix_spawnattr_setflags(&attr, POSIX_SPAWN_SETSIGDEF|POSIX_SPAWN_SETSIGMASK); > | ret = posix_spawn(&pid, "/bin/sh", 0, &attr, > | (char *[]){"sh", "-c", (char *)cmd, 0}, __environ); > | posix_spawnattr_destroy(&attr); > | > | if (!ret) while (waitpid(pid, &status, 0)<0 && errno == EINTR); > | sigaction(SIGINT, &oldint, NULL); > | sigaction(SIGQUIT, &oldquit, NULL); > | sigprocmask(SIG_SETMASK, &old, NULL); > | > | if (ret) errno = ret; > | return status; > |} > > Aren't all of those calls namespace violations? system() is an ISO-C > function, so the only symbols it is allowed to pull into the link are > other ISO-C functions or hidden double-underscore symbols, right? But > all the functions called here POSIX functions. And while POSIX contains > the rule that posix_* functions are reserved, that is in POSIX, not > ISO-C. And even with that rule, there are all the other calls. > > Does someone need to pour out a bucket of underscores over this > function? The behavior of system() is implementation-defined, so we define it as calling those functions. :-) Rich