Adding upstream version 3.4.23.upstream/3.4.23upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 371 insertions, 0 deletions

diff --git a/src/master/master_spawn.c b/src/master/master_spawn.c
new file mode 100644
index 0000000..c3b70f2
--- /dev/null
+++ b/src/master/master_spawn.c
@@ -0,0 +1,371 @@
+/*++
+/* NAME
+/*	master_spawn 3
+/* SUMMARY
+/*	Postfix master - child process birth and death
+/* SYNOPSIS
+/*	#include "master.h"
+/*
+/*	void	master_spawn(serv)
+/*	MASTER_SERV *serv;
+/*
+/*	void	master_reap_child()
+/*
+/*	void	master_delete_children(serv)
+/*	MASTER_SERV *serv;
+/* DESCRIPTION
+/*	This module creates and cleans up child processes, and applies
+/*	a process creation throttle in case of serious trouble.
+/*	This module is the working horse for the master_avail(3) process
+/*	creation policy module.
+/*
+/*	master_spawn() spawns off a child process for the specified service,
+/*	making the child process available for servicing connection requests.
+/*	It is an error to call this function then the specified service is
+/*	throttled.
+/*
+/*	master_reap_child() cleans up all dead child processes.  One typically
+/*	runs this function at a convenient moment after receiving a SIGCHLD
+/*	signal. When a child process terminates abnormally after being used
+/*	for the first time, process creation for that service is throttled
+/*	for a configurable amount of time.
+/*
+/*	master_delete_children() deletes all child processes that provide
+/*	the named service. Upon exit, the process creation throttle for that
+/*	service is released.
+/* DIAGNOSTICS
+/*	Panic: interface violations, internal inconsistencies.
+/*	Fatal errors: out of memory.  Warnings: throttle on/off.
+/* BUGS
+/* SEE ALSO
+/*	master_avail(3), process creation policy.
+/* 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 <sys/wait.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <syslog.h>			/* closelog() */
+#include <signal.h>
+#include <stdarg.h>
+#include <syslog.h>
+
+/* Utility libraries. */
+
+#include <msg.h>
+#include <binhash.h>
+#include <mymalloc.h>
+#include <events.h>
+#include <vstring.h>
+#include <argv.h>
+
+/* Global library. */
+
+#include <mail_conf.h>
+
+/* Application-specific. */
+
+#include "master_proto.h"
+#include "master.h"
+
+BINHASH *master_child_table;
+static void master_unthrottle(MASTER_SERV *serv);
+
+/* master_unthrottle_wrapper - in case (char *) != (struct *) */
+
+static void master_unthrottle_wrapper(int unused_event, void *ptr)
+{
+    MASTER_SERV *serv = (MASTER_SERV *) ptr;
+
+    /*
+     * This routine runs after expiry of the timer set in master_throttle(),
+     * which gets called when it appears that the world is falling apart.
+     */
+    master_unthrottle(serv);
+}
+
+/* master_unthrottle - enable process creation */
+
+static void master_unthrottle(MASTER_SERV *serv)
+{
+
+    /*
+     * Enable process creation within this class. Disable the "unthrottle"
+     * timer just in case we're being called directly from the cleanup
+     * routine, instead of from the event manager.
+     */
+    if ((serv->flags & MASTER_FLAG_THROTTLE) != 0) {
+	serv->flags &= ~MASTER_FLAG_THROTTLE;
+	event_cancel_timer(master_unthrottle_wrapper, (void *) serv);
+	if (msg_verbose)
+	    msg_info("throttle released for command %s", serv->path);
+	master_avail_listen(serv);
+    }
+}
+
+/* master_throttle - suspend process creation */
+
+static void master_throttle(MASTER_SERV *serv)
+{
+
+    /*
+     * Perhaps the command to be run is defective, perhaps some configuration
+     * is wrong, or perhaps the system is out of resources. Disable further
+     * process creation attempts for a while.
+     */
+    if ((serv->flags & MASTER_FLAG_THROTTLE) == 0) {
+	serv->flags |= MASTER_FLAG_THROTTLE;
+	event_request_timer(master_unthrottle_wrapper, (void *) serv,
+			    serv->throttle_delay);
+	if (msg_verbose)
+	    msg_info("throttling command %s", serv->path);
+	master_avail_listen(serv);
+    }
+}
+
+/* master_spawn - spawn off new child process if we can */
+
+void    master_spawn(MASTER_SERV *serv)
+{
+    const char *myname = "master_spawn";
+    MASTER_PROC *proc;
+    MASTER_PID pid;
+    int     n;
+    static unsigned master_generation = 0;
+    static VSTRING *env_gen = 0;
+
+    if (master_child_table == 0)
+	master_child_table = binhash_create(0);
+    if (env_gen == 0)
+	env_gen = vstring_alloc(100);
+
+    /*
+     * Sanity checks. The master_avail module is supposed to know what it is
+     * doing.
+     */
+    if (!MASTER_LIMIT_OK(serv->max_proc, serv->total_proc))
+	msg_panic("%s: at process limit %d", myname, serv->total_proc);
+    if (serv->avail_proc > 0)
+	msg_panic("%s: processes available: %d", myname, serv->avail_proc);
+    if (serv->flags & MASTER_FLAG_THROTTLE)
+	msg_panic("%s: throttled service: %s", myname, serv->path);
+
+    /*
+     * Create a child process and connect parent and child via the status
+     * pipe.
+     */
+    master_generation += 1;
+    switch (pid = fork()) {
+
+	/*
+	 * Error. We're out of some essential resource. Best recourse is to
+	 * try again later.
+	 */
+    case -1:
+	msg_warn("%s: fork: %m -- throttling", myname);
+	master_throttle(serv);
+	return;
+
+	/*
+	 * Child process. Redirect child stdin/stdout to the parent-child
+	 * connection and run the requested command. Leave child stderr
+	 * alone. Disable exit handlers: they should be executed by the
+	 * parent only.
+	 * 
+	 * When we reach the process limit on a public internet service, we
+	 * create stress-mode processes until the process count stays below
+	 * the limit for some amount of time. See master_avail_listen().
+	 */
+    case 0:
+	msg_cleanup((void (*) (void)) 0);	/* disable exit handler */
+	closelog();				/* avoid filedes leak */
+
+	if (master_flow_pipe[0] <= MASTER_FLOW_READ)
+	    msg_fatal("%s: flow pipe read descriptor <= %d",
+		      myname, MASTER_FLOW_READ);
+	if (DUP2(master_flow_pipe[0], MASTER_FLOW_READ) < 0)
+	    msg_fatal("%s: dup2: %m", myname);
+	if (close(master_flow_pipe[0]) < 0)
+	    msg_fatal("close %d: %m", master_flow_pipe[0]);
+
+	if (master_flow_pipe[1] <= MASTER_FLOW_WRITE)
+	    msg_fatal("%s: flow pipe read descriptor <= %d",
+		      myname, MASTER_FLOW_WRITE);
+	if (DUP2(master_flow_pipe[1], MASTER_FLOW_WRITE) < 0)
+	    msg_fatal("%s: dup2: %m", myname);
+	if (close(master_flow_pipe[1]) < 0)
+	    msg_fatal("close %d: %m", master_flow_pipe[1]);
+
+	close(serv->status_fd[0]);		/* status channel */
+	if (serv->status_fd[1] <= MASTER_STATUS_FD)
+	    msg_fatal("%s: status file descriptor collision", myname);
+	if (DUP2(serv->status_fd[1], MASTER_STATUS_FD) < 0)
+	    msg_fatal("%s: dup2 status_fd: %m", myname);
+	(void) close(serv->status_fd[1]);
+
+	for (n = 0; n < serv->listen_fd_count; n++) {
+	    if (serv->listen_fd[n] <= MASTER_LISTEN_FD + n)
+		msg_fatal("%s: listen file descriptor collision", myname);
+	    if (DUP2(serv->listen_fd[n], MASTER_LISTEN_FD + n) < 0)
+		msg_fatal("%s: dup2 listen_fd %d: %m",
+			  myname, serv->listen_fd[n]);
+	    (void) close(serv->listen_fd[n]);
+	}
+	vstring_sprintf(env_gen, "%s=%o", MASTER_GEN_NAME, master_generation);
+	if (putenv(vstring_str(env_gen)) < 0)
+	    msg_fatal("%s: putenv: %m", myname);
+	if (serv->stress_param_val && serv->stress_expire_time > event_time())
+	    serv->stress_param_val[0] = CONFIG_BOOL_YES[0];
+
+	execvp(serv->path, serv->args->argv);
+	msg_fatal("%s: exec %s: %m", myname, serv->path);
+	/* NOTREACHED */
+
+	/*
+	 * Parent. Fill in a process member data structure and set up links
+	 * between child and process. Say this process has become available.
+	 * If this service has a wakeup timer that is turned on only when the
+	 * service is actually used, turn on the wakeup timer.
+	 */
+    default:
+	if (msg_verbose)
+	    msg_info("spawn command %s; pid %d", serv->path, pid);
+	proc = (MASTER_PROC *) mymalloc(sizeof(MASTER_PROC));
+	proc->serv = serv;
+	proc->pid = pid;
+	proc->gen = master_generation;
+	proc->use_count = 0;
+	proc->avail = 0;
+	binhash_enter(master_child_table, (void *) &pid,
+		      sizeof(pid), (void *) proc);
+	serv->total_proc++;
+	master_avail_more(serv, proc);
+	if (serv->flags & MASTER_FLAG_CONDWAKE) {
+	    serv->flags &= ~MASTER_FLAG_CONDWAKE;
+	    master_wakeup_init(serv);
+	    if (msg_verbose)
+		msg_info("start conditional timer for %s", serv->name);
+	}
+	return;
+    }
+}
+
+/* master_delete_child - destroy child process info */
+
+static void master_delete_child(MASTER_PROC *proc)
+{
+    MASTER_SERV *serv;
+
+    /*
+     * Undo the things that master_spawn did. Stop the process if it still
+     * exists, and remove it from the lookup tables. Update the number of
+     * available processes.
+     */
+    serv = proc->serv;
+    serv->total_proc--;
+    if (proc->avail == MASTER_STAT_AVAIL)
+	master_avail_less(serv, proc);
+    else
+	master_avail_listen(serv);
+    binhash_delete(master_child_table, (void *) &proc->pid,
+		   sizeof(proc->pid), (void (*) (void *)) 0);
+    myfree((void *) proc);
+}
+
+/* master_reap_child - reap dead children */
+
+void    master_reap_child(void)
+{
+    MASTER_SERV *serv;
+    MASTER_PROC *proc;
+    MASTER_PID pid;
+    WAIT_STATUS_T status;
+
+    /*
+     * Pick up termination status of all dead children. When a process failed
+     * on its first job, assume we see the symptom of a structural problem
+     * (configuration problem, system running out of resources) and back off.
+     */
+    while ((pid = waitpid((pid_t) - 1, &status, WNOHANG)) > 0) {
+	if (msg_verbose)
+	    msg_info("master_reap_child: pid %d", pid);
+	if ((proc = (MASTER_PROC *) binhash_find(master_child_table,
+					(void *) &pid, sizeof(pid))) == 0) {
+	    if (init_mode)
+		continue;			/* non-Postfix process */
+	    msg_panic("master_reap: unknown pid: %d", pid);
+	}
+	serv = proc->serv;
+
+#define MASTER_KILL_SIGNAL	SIGTERM
+#define MASTER_SENT_SIGNAL(serv, status) \
+	(MASTER_MARKED_FOR_DELETION(serv) \
+	    && WTERMSIG(status) == MASTER_KILL_SIGNAL)
+
+	/*
+	 * XXX The code for WIFSTOPPED() is here in case some buggy kernel
+	 * reports WIFSTOPPED() events to a Postfix daemon's parent process
+	 * (the master(8) daemon) instead of the tracing process (e.g., gdb).
+	 * 
+	 * The WIFSTOPPED() test prevents master(8) from deleting its record of
+	 * a child process that is stopped. That would cause a master(8)
+	 * panic (unknown child) when the child terminates.
+	 */
+	if (!NORMAL_EXIT_STATUS(status)) {
+	    if (WIFSTOPPED(status)) {
+		msg_warn("process %s pid %d stopped by signal %d",
+			 serv->path, pid, WSTOPSIG(status));
+		continue;
+	    }
+	    if (WIFEXITED(status))
+		msg_warn("process %s pid %d exit status %d",
+			 serv->path, pid, WEXITSTATUS(status));
+	    if (WIFSIGNALED(status) && !MASTER_SENT_SIGNAL(serv, status))
+		msg_warn("process %s pid %d killed by signal %d",
+			 serv->path, pid, WTERMSIG(status));
+	    /* master_delete_children() throttles first, then kills. */
+	    if (proc->use_count == 0
+		&& (serv->flags & MASTER_FLAG_THROTTLE) == 0) {
+		msg_warn("%s: bad command startup -- throttling", serv->path);
+		master_throttle(serv);
+	    }
+	}
+	master_delete_child(proc);
+    }
+}
+
+/* master_delete_children - delete all child processes of service */
+
+void    master_delete_children(MASTER_SERV *serv)
+{
+    BINHASH_INFO **list;
+    BINHASH_INFO **info;
+    MASTER_PROC *proc;
+
+    /*
+     * XXX turn on the throttle so that master_reap_child() doesn't. Someone
+     * has to turn off the throttle in order to stop the associated timer
+     * request, so we might just as well do it at the end.
+     */
+    master_throttle(serv);
+    for (info = list = binhash_list(master_child_table); *info; info++) {
+	proc = (MASTER_PROC *) info[0]->value;
+	if (proc->serv == serv)
+	    (void) kill(proc->pid, MASTER_KILL_SIGNAL);
+    }
+    while (serv->total_proc > 0)
+	master_reap_child();
+    myfree((void *) list);
+    master_unthrottle(serv);
+}