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-rw-r--r--src/master/master_status.c198
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diff --git a/src/master/master_status.c b/src/master/master_status.c
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+/*++
+/* NAME
+/* master_status 3
+/* SUMMARY
+/* Postfix master - process child status reports
+/* SYNOPSIS
+/* #include "master.h"
+/*
+/* void master_status_init(serv)
+/* MASTER_SERV *serv;
+/*
+/* void master_status_cleanup(serv)
+/* MASTER_SERV *serv;
+/* DESCRIPTION
+/* This module reads and processes status reports from child processes.
+/*
+/* master_status_init() enables the processing of child status updates
+/* for the specified service. Child process status updates (process
+/* available, process taken) are passed on to the master_avail_XXX()
+/* routines.
+/*
+/* master_status_cleanup() disables child status update processing
+/* for the specified service.
+/* DIAGNOSTICS
+/* Panic: internal inconsistency. Warnings: a child process sends
+/* incomplete or incorrect information.
+/* BUGS
+/* SEE ALSO
+/* master_avail(3)
+/* LICENSE
+/* .ad
+/* .fi
+/* The Secure Mailer license must be distributed with this software.
+/* AUTHOR(S)
+/* Wietse Venema
+/* IBM T.J. Watson Research
+/* P.O. Box 704
+/* Yorktown Heights, NY 10598, USA
+/*--*/
+
+/* System libraries. */
+
+#include <sys_defs.h>
+#include <unistd.h>
+
+/* Utility library. */
+
+#include <msg.h>
+#include <events.h>
+#include <binhash.h>
+#include <iostuff.h>
+
+/* Application-specific. */
+
+#include "master_proto.h"
+#include "master.h"
+
+/* master_status_event - status read event handler */
+
+static void master_status_event(int event, void *context)
+{
+ const char *myname = "master_status_event";
+ MASTER_SERV *serv = (MASTER_SERV *) context;
+ MASTER_STATUS stat;
+ MASTER_PROC *proc;
+ MASTER_PID pid;
+ int n;
+
+ if (event == 0) /* XXX Can this happen? */
+ return;
+
+ /*
+ * We always keep the child end of the status pipe open, so an EOF read
+ * condition means that we're seriously confused. We use non-blocking
+ * reads so that we don't get stuck when someone sends a partial message.
+ * Messages are short, so a partial read means someone wrote less than a
+ * whole status message. Hopefully the next read will be in sync again...
+ * We use a global child process status table because when a child dies
+ * only its pid is known - we do not know what service it came from.
+ */
+ switch (n = read(serv->status_fd[0], (void *) &stat, sizeof(stat))) {
+
+ case -1:
+ msg_warn("%s: read: %m", myname);
+ return;
+
+ case 0:
+ msg_panic("%s: read EOF status", myname);
+ /* NOTREACHED */
+
+ default:
+ msg_warn("service %s(%s): child (pid %d) sent partial status update (%d bytes)",
+ serv->ext_name, serv->name, stat.pid, n);
+ return;
+
+ case sizeof(stat):
+ pid = stat.pid;
+ if (msg_verbose)
+ msg_info("%s: pid %d gen %u avail %d",
+ myname, stat.pid, stat.gen, stat.avail);
+ }
+
+ /*
+ * Sanity checks. Do not freak out when the child sends garbage because
+ * it is confused or for other reasons. However, be sure to freak out
+ * when our own data structures are inconsistent. A process not found
+ * condition can happen when we reap a process before receiving its
+ * status update, so this is not an error.
+ */
+ if ((proc = (MASTER_PROC *) binhash_find(master_child_table,
+ (void *) &pid, sizeof(pid))) == 0) {
+ if (msg_verbose)
+ msg_info("%s: process id not found: %d", myname, stat.pid);
+ return;
+ }
+ if (proc->gen != stat.gen) {
+ msg_info("ignoring status update from child pid %d generation %u",
+ pid, stat.gen);
+ return;
+ }
+ if (proc->serv != serv)
+ msg_panic("%s: pointer corruption: %p != %p",
+ myname, (void *) proc->serv, (void *) serv);
+
+ /*
+ * Update our idea of the child process status. Allow redundant status
+ * updates, because different types of events may be processed out of
+ * order. Otherwise, warn about weird status updates but do not take
+ * action. It's all gossip after all.
+ */
+ if (proc->avail == stat.avail)
+ return;
+ switch (stat.avail) {
+ case MASTER_STAT_AVAIL:
+ proc->use_count++;
+ master_avail_more(serv, proc);
+ break;
+ case MASTER_STAT_TAKEN:
+ master_avail_less(serv, proc);
+ break;
+ default:
+ msg_warn("%s: ignoring unknown status: %d allegedly from pid: %d",
+ myname, stat.pid, stat.avail);
+ break;
+ }
+}
+
+/* master_status_init - start status event processing for this service */
+
+void master_status_init(MASTER_SERV *serv)
+{
+ const char *myname = "master_status_init";
+
+ /*
+ * Sanity checks.
+ */
+ if (serv->status_fd[0] >= 0 || serv->status_fd[1] >= 0)
+ msg_panic("%s: status events already enabled", myname);
+ if (msg_verbose)
+ msg_info("%s: %s", myname, serv->name);
+
+ /*
+ * Make the read end of this service's status pipe non-blocking so that
+ * we can detect partial writes on the child side. We use a duplex pipe
+ * so that the child side becomes readable when the master goes away.
+ */
+ if (duplex_pipe(serv->status_fd) < 0)
+ msg_fatal("pipe: %m");
+ non_blocking(serv->status_fd[0], BLOCKING);
+ close_on_exec(serv->status_fd[0], CLOSE_ON_EXEC);
+ close_on_exec(serv->status_fd[1], CLOSE_ON_EXEC);
+ event_enable_read(serv->status_fd[0], master_status_event, (void *) serv);
+}
+
+/* master_status_cleanup - stop status event processing for this service */
+
+void master_status_cleanup(MASTER_SERV *serv)
+{
+ const char *myname = "master_status_cleanup";
+
+ /*
+ * Sanity checks.
+ */
+ if (serv->status_fd[0] < 0 || serv->status_fd[1] < 0)
+ msg_panic("%s: status events not enabled", myname);
+ if (msg_verbose)
+ msg_info("%s: %s", myname, serv->name);
+
+ /*
+ * Dispose of this service's status pipe after disabling read events.
+ */
+ event_disable_readwrite(serv->status_fd[0]);
+ if (close(serv->status_fd[0]) != 0)
+ msg_warn("%s: close status descriptor (read side): %m", myname);
+ if (close(serv->status_fd[1]) != 0)
+ msg_warn("%s: close status descriptor (write side): %m", myname);
+ serv->status_fd[0] = serv->status_fd[1] = -1;
+}