Adding upstream version 3.4.23.upstream/3.4.23upstream

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

1 files changed, 683 insertions, 0 deletions

diff --git a/src/global/pipe_command.c b/src/global/pipe_command.c
new file mode 100644
index 0000000..66aec8a
--- /dev/null
+++ b/src/global/pipe_command.c
@@ -0,0 +1,683 @@
+/*++
+/* NAME
+/*	pipe_command 3
+/* SUMMARY
+/*	deliver message to external command
+/* SYNOPSIS
+/*	#include <pipe_command.h>
+/*
+/*	int	pipe_command(src, why, key, value, ...)
+/*	VSTREAM	*src;
+/*	DSN_BUF	*why;
+/*	int	key;
+/* DESCRIPTION
+/*	pipe_command() runs a command with a message as standard
+/*	input.  A limited amount of standard output and standard error
+/*	output is captured for diagnostics purposes.
+/*
+/*	If the command invokes exit() with a non-zero status,
+/*	the delivery status is taken from an RFC 3463-style code
+/*	at the beginning of command output. If that information is
+/*	unavailable, the delivery status is taken from the command
+/*	exit status as per <sysexits.h>.
+/*
+/*	Arguments:
+/* .IP src
+/*	An open message queue file, positioned at the start of the actual
+/*	message content.
+/* .IP why
+/*	Delivery status information. The reason attribute may contain
+/*	a limited portion of command output, among other free text.
+/* .IP key
+/*	Specifies what value will follow. pipe_command() takes a list
+/*	of macros with arguments, terminated by CA_PIPE_CMD_END which
+/*	has no argument. The following is a listing of macros and
+/*	expected argument types.
+/* .RS
+/* .IP "CA_PIPE_CMD_COMMAND(const char *)"
+/*	Specifies the command to execute as a string. The string is
+/*	passed to the shell when it contains shell meta characters
+/*	or when it appears to be a shell built-in command, otherwise
+/*	the command is executed without invoking a shell.
+/*	One of CA_PIPE_CMD_COMMAND or CA_PIPE_CMD_ARGV must be specified.
+/*	See also the CA_PIPE_CMD_SHELL attribute below.
+/* .IP "CA_PIPE_CMD_ARGV(char **)"
+/*	The command is specified as an argument vector. This vector is
+/*	passed without further inspection to the \fIexecvp\fR() routine.
+/*	One of CA_PIPE_CMD_COMMAND or CA_PIPE_CMD_ARGV must be specified.
+/* .IP "CA_PIPE_CMD_CHROOT(const char *)"
+/*	Root and working directory for command execution. This takes
+/*	effect before CA_PIPE_CMD_CWD. A null pointer means don't
+/*	change root and working directory anyway. Failure to change
+/*	directory causes mail delivery to be deferred.
+/* .IP "CA_PIPE_CMD_CWD(const char *)"
+/*	Working directory for command execution, after changing process
+/*	privileges to CA_PIPE_CMD_UID and CA_PIPE_CMD_GID. A null pointer means
+/*	don't change directory anyway. Failure to change directory
+/*	causes mail delivery to be deferred.
+/* .IP "CA_PIPE_CMD_ENV(char **)"
+/*	Additional environment information, in the form of a null-terminated
+/*	list of name, value, name, value, ... elements. By default only the
+/*	command search path is initialized to _PATH_DEFPATH.
+/* .IP "CA_PIPE_CMD_EXPORT(char **)"
+/*	Null-terminated array with names of environment parameters
+/*	that can be exported. By default, everything is exported.
+/* .IP "CA_PIPE_CMD_COPY_FLAGS(int)"
+/*	Flags that are passed on to the \fImail_copy\fR() routine.
+/*	The default flags value is 0 (zero).
+/* .IP "CA_PIPE_CMD_SENDER(const char *)"
+/*	The envelope sender address, which is passed on to the
+/*	\fImail_copy\fR() routine.
+/* .IP "CA_PIPE_CMD_ORIG_RCPT(const char *)"
+/*	The original recipient envelope address, which is passed on
+/*	to the \fImail_copy\fR() routine.
+/* .IP "CA_PIPE_CMD_DELIVERED(const char *)"
+/*	The recipient envelope address, which is passed on to the
+/*	\fImail_copy\fR() routine.
+/* .IP "CA_PIPE_CMD_EOL(const char *)"
+/*	End-of-line delimiter. The default is to use the newline character.
+/* .IP "CA_PIPE_CMD_UID(uid_t)"
+/*	The user ID to execute the command as. The default is
+/*	the user ID corresponding to the \fIdefault_privs\fR
+/*	configuration parameter. The user ID must be non-zero.
+/* .IP "CA_PIPE_CMD_GID(gid_t)"
+/*	The group ID to execute the command as. The default is
+/*	the group ID corresponding to the \fIdefault_privs\fR
+/*	configuration parameter. The group ID must be non-zero.
+/* .IP "CA_PIPE_CMD_TIME_LIMIT(int)"
+/*	The amount of time the command is allowed to run before it
+/*	is terminated with SIGKILL. A non-negative CA_PIPE_CMD_TIME_LIMIT
+/*	value must be specified.
+/* .IP "CA_PIPE_CMD_SHELL(const char *)"
+/*	The shell to use when executing the command specified with
+/*	CA_PIPE_CMD_COMMAND. This shell is invoked regardless of the
+/*	command content.
+/* .RE
+/* DIAGNOSTICS
+/*	Panic: interface violations (for example, a zero-valued
+/*	user ID or group ID, or a missing command).
+/*
+/*	pipe_command() returns one of the following status codes:
+/* .IP PIPE_STAT_OK
+/*	The command has taken responsibility for further delivery of
+/*	the message.
+/* .IP PIPE_STAT_DEFER
+/*	The command failed with a "try again" type error.
+/*	The reason is given via the \fIwhy\fR argument.
+/* .IP PIPE_STAT_BOUNCE
+/*	The command indicated that the message was not acceptable,
+/*	or the command did not finish within the time limit.
+/*	The reason is given via the \fIwhy\fR argument.
+/* .IP PIPE_STAT_CORRUPT
+/*	The queue file is corrupted.
+/* SEE ALSO
+/*	mail_copy(3) deliver to any.
+/*	mark_corrupt(3) mark queue file as corrupt.
+/*	sys_exits(3) sendmail-compatible exit status codes.
+/* 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 library. */
+
+#include <sys_defs.h>
+#include <sys/wait.h>
+#include <signal.h>
+#include <unistd.h>
+#include <errno.h>
+#include <stdarg.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#ifdef USE_PATHS_H
+#include <paths.h>
+#endif
+#include <syslog.h>
+
+/* Utility library. */
+
+#include <msg.h>
+#include <vstream.h>
+#include <msg_vstream.h>
+#include <vstring.h>
+#include <stringops.h>
+#include <iostuff.h>
+#include <timed_wait.h>
+#include <set_ugid.h>
+#include <set_eugid.h>
+#include <argv.h>
+#include <chroot_uid.h>
+
+/* Global library. */
+
+#include <mail_params.h>
+#include <mail_copy.h>
+#include <clean_env.h>
+#include <pipe_command.h>
+#include <exec_command.h>
+#include <sys_exits.h>
+#include <dsn_util.h>
+#include <dsn_buf.h>
+
+/* Application-specific. */
+
+struct pipe_args {
+    int     flags;			/* see mail_copy.h */
+    char   *sender;			/* envelope sender */
+    char   *orig_rcpt;			/* original recipient */
+    char   *delivered;			/* envelope recipient */
+    char   *eol;			/* carriagecontrol */
+    char  **argv;			/* either an array */
+    char   *command;			/* or a plain string */
+    uid_t   uid;			/* privileges */
+    gid_t   gid;			/* privileges */
+    char  **env;			/* extra environment */
+    char  **export;			/* exportable environment */
+    char   *shell;			/* command shell */
+    char   *cwd;			/* preferred working directory */
+    char   *chroot;			/* root directory */
+};
+
+static int pipe_command_timeout;	/* command has timed out */
+static int pipe_command_maxtime;	/* available time to complete */
+
+/* get_pipe_args - capture the variadic argument list */
+
+static void get_pipe_args(struct pipe_args * args, va_list ap)
+{
+    const char *myname = "get_pipe_args";
+    int     key;
+
+    /*
+     * First, set the default values.
+     */
+    args->flags = 0;
+    args->sender = 0;
+    args->orig_rcpt = 0;
+    args->delivered = 0;
+    args->eol = "\n";
+    args->argv = 0;
+    args->command = 0;
+    args->uid = var_default_uid;
+    args->gid = var_default_gid;
+    args->env = 0;
+    args->export = 0;
+    args->shell = 0;
+    args->cwd = 0;
+    args->chroot = 0;
+
+    pipe_command_maxtime = -1;
+
+    /*
+     * Then, override the defaults with user-supplied inputs.
+     */
+    while ((key = va_arg(ap, int)) != PIPE_CMD_END) {
+	switch (key) {
+	case PIPE_CMD_COPY_FLAGS:
+	    args->flags |= va_arg(ap, int);
+	    break;
+	case PIPE_CMD_SENDER:
+	    args->sender = va_arg(ap, char *);
+	    break;
+	case PIPE_CMD_ORIG_RCPT:
+	    args->orig_rcpt = va_arg(ap, char *);
+	    break;
+	case PIPE_CMD_DELIVERED:
+	    args->delivered = va_arg(ap, char *);
+	    break;
+	case PIPE_CMD_EOL:
+	    args->eol = va_arg(ap, char *);
+	    break;
+	case PIPE_CMD_ARGV:
+	    if (args->command)
+		msg_panic("%s: got PIPE_CMD_ARGV and PIPE_CMD_COMMAND", myname);
+	    args->argv = va_arg(ap, char **);
+	    break;
+	case PIPE_CMD_COMMAND:
+	    if (args->argv)
+		msg_panic("%s: got PIPE_CMD_ARGV and PIPE_CMD_COMMAND", myname);
+	    args->command = va_arg(ap, char *);
+	    break;
+	case PIPE_CMD_UID:
+	    args->uid = va_arg(ap, uid_t);	/* in case uid_t is short */
+	    break;
+	case PIPE_CMD_GID:
+	    args->gid = va_arg(ap, gid_t);	/* in case gid_t is short */
+	    break;
+	case PIPE_CMD_TIME_LIMIT:
+	    pipe_command_maxtime = va_arg(ap, int);
+	    break;
+	case PIPE_CMD_ENV:
+	    args->env = va_arg(ap, char **);
+	    break;
+	case PIPE_CMD_EXPORT:
+	    args->export = va_arg(ap, char **);
+	    break;
+	case PIPE_CMD_SHELL:
+	    args->shell = va_arg(ap, char *);
+	    break;
+	case PIPE_CMD_CWD:
+	    args->cwd = va_arg(ap, char *);
+	    break;
+	case PIPE_CMD_CHROOT:
+	    args->chroot = va_arg(ap, char *);
+	    break;
+	default:
+	    msg_panic("%s: unknown key: %d", myname, key);
+	}
+    }
+    if (args->command == 0 && args->argv == 0)
+	msg_panic("%s: missing PIPE_CMD_ARGV or PIPE_CMD_COMMAND", myname);
+    if (args->uid == 0)
+	msg_panic("%s: privileged uid", myname);
+    if (args->gid == 0)
+	msg_panic("%s: privileged gid", myname);
+    if (pipe_command_maxtime < 0)
+	msg_panic("%s: missing or invalid PIPE_CMD_TIME_LIMIT", myname);
+}
+
+/* pipe_command_write - write to command with time limit */
+
+static ssize_t pipe_command_write(int fd, void *buf, size_t len,
+				          int unused_timeout,
+				          void *unused_context)
+{
+    int     maxtime = (pipe_command_timeout == 0) ? pipe_command_maxtime : 0;
+    const char *myname = "pipe_command_write";
+
+    /*
+     * Don't wait when all available time was already used up.
+     */
+    if (write_wait(fd, maxtime) < 0) {
+	if (pipe_command_timeout == 0) {
+	    msg_warn("%s: write time limit exceeded", myname);
+	    pipe_command_timeout = 1;
+	}
+	return (0);
+    } else {
+	return (write(fd, buf, len));
+    }
+}
+
+/* pipe_command_read - read from command with time limit */
+
+static ssize_t pipe_command_read(int fd, void *buf, size_t len,
+				         int unused_timeout,
+				         void *unused_context)
+{
+    int     maxtime = (pipe_command_timeout == 0) ? pipe_command_maxtime : 0;
+    const char *myname = "pipe_command_read";
+
+    /*
+     * Don't wait when all available time was already used up.
+     */
+    if (read_wait(fd, maxtime) < 0) {
+	if (pipe_command_timeout == 0) {
+	    msg_warn("%s: read time limit exceeded", myname);
+	    pipe_command_timeout = 1;
+	}
+	return (0);
+    } else {
+	return (read(fd, buf, len));
+    }
+}
+
+/* kill_command - terminate command forcibly */
+
+static void kill_command(pid_t pid, int sig, uid_t kill_uid, gid_t kill_gid)
+{
+    uid_t   saved_euid = geteuid();
+    gid_t   saved_egid = getegid();
+
+    /*
+     * Switch privileges to that of the child process. Terminate the child
+     * and its offspring.
+     */
+    set_eugid(kill_uid, kill_gid);
+    if (kill(-pid, sig) < 0 && kill(pid, sig) < 0)
+	msg_warn("cannot kill process (group) %lu: %m",
+		 (unsigned long) pid);
+    set_eugid(saved_euid, saved_egid);
+}
+
+/* pipe_command_wait_or_kill - wait for command with time limit, or kill it */
+
+static int pipe_command_wait_or_kill(pid_t pid, WAIT_STATUS_T *statusp, int sig,
+				             uid_t kill_uid, gid_t kill_gid)
+{
+    int     maxtime = (pipe_command_timeout == 0) ? pipe_command_maxtime : 1;
+    const char *myname = "pipe_command_wait_or_kill";
+    int     n;
+
+    /*
+     * Don't wait when all available time was already used up.
+     */
+    if ((n = timed_waitpid(pid, statusp, 0, maxtime)) < 0 && errno == ETIMEDOUT) {
+	if (pipe_command_timeout == 0) {
+	    msg_warn("%s: child wait time limit exceeded", myname);
+	    pipe_command_timeout = 1;
+	}
+	kill_command(pid, sig, kill_uid, kill_gid);
+	n = waitpid(pid, statusp, 0);
+    }
+    return (n);
+}
+
+/* pipe_child_cleanup - child fatal error handler */
+
+static void pipe_child_cleanup(void)
+{
+
+    /*
+     * WARNING: don't place code here. This code may run as mail_owner, as
+     * root, or as the user/group specified with the "user" attribute. The
+     * only safe action is to terminate.
+     * 
+     * Future proofing. If you need exit() here then you broke Postfix.
+     */
+    _exit(EX_TEMPFAIL);
+}
+
+/* pipe_command - execute command with extreme prejudice */
+
+int     pipe_command(VSTREAM *src, DSN_BUF *why,...)
+{
+    const char *myname = "pipe_command";
+    va_list ap;
+    VSTREAM *cmd_in_stream;
+    VSTREAM *cmd_out_stream;
+    char    log_buf[VSTREAM_BUFSIZE + 1];
+    ssize_t log_len;
+    pid_t   pid;
+    int     write_status;
+    int     write_errno;
+    WAIT_STATUS_T wait_status;
+    int     cmd_in_pipe[2];
+    int     cmd_out_pipe[2];
+    struct pipe_args args;
+    char  **cpp;
+    ARGV   *argv;
+    DSN_SPLIT dp;
+    const SYS_EXITS_DETAIL *sp;
+
+    /*
+     * Process the variadic argument list. This also does sanity checks on
+     * what data the caller is passing to us.
+     */
+    va_start(ap, why);
+    get_pipe_args(&args, ap);
+    va_end(ap);
+
+    /*
+     * For convenience...
+     */
+    if (args.command == 0)
+	args.command = args.argv[0];
+
+    /*
+     * Set up pipes that connect us to the command input and output streams.
+     * We're using a rather disgusting hack to capture command output: set
+     * the output to non-blocking mode, and don't attempt to read the output
+     * until AFTER the process has terminated. The rationale for this is: 1)
+     * the command output will be used only when delivery fails; 2) the
+     * amount of output is expected to be small; 3) the output can be
+     * truncated without too much loss. I could even argue that truncating
+     * the amount of diagnostic output is a good thing to do, but I won't go
+     * that far.
+     * 
+     * Turn on non-blocking writes to the child process so that we can enforce
+     * timeouts after partial writes.
+     * 
+     * XXX Too much trouble with different systems returning weird write()
+     * results when a pipe is writable.
+     */
+    if (pipe(cmd_in_pipe) < 0 || pipe(cmd_out_pipe) < 0)
+	msg_fatal("%s: pipe: %m", myname);
+    non_blocking(cmd_out_pipe[1], NON_BLOCKING);
+#if 0
+    non_blocking(cmd_in_pipe[1], NON_BLOCKING);
+#endif
+
+    /*
+     * Spawn off a child process and irrevocably change privilege to the
+     * user. This includes revoking all rights on open files (via the close
+     * on exec flag). If we cannot run the command now, try again some time
+     * later.
+     */
+    switch (pid = fork()) {
+
+	/*
+	 * Error. Instead of trying again right now, back off, give the
+	 * system a chance to recover, and try again later.
+	 */
+    case -1:
+	msg_warn("fork: %m");
+	dsb_unix(why, "4.3.0", sys_exits_detail(EX_OSERR)->text,
+		 "Delivery failed: %m");
+	return (PIPE_STAT_DEFER);
+
+	/*
+	 * Child. Run the child in a separate process group so that the
+	 * parent can kill not just the child but also its offspring.
+	 * 
+	 * Redirect fatal exits to our own fatal exit handler (never leave the
+	 * parent's handler enabled :-) so we can replace random exit status
+	 * codes by EX_TEMPFAIL.
+	 */
+    case 0:
+	(void) msg_cleanup(pipe_child_cleanup);
+
+	/*
+	 * In order to chroot it is necessary to switch euid back to root.
+	 * Right after chroot we call set_ugid() so all privileges will be
+	 * dropped again.
+	 * 
+	 * XXX For consistency we use chroot_uid() to change root+current
+	 * directory. However, we must not use chroot_uid() to change process
+	 * privileges (assuming a version that accepts numeric privileges).
+	 * That would create a maintenance problem, because we would have two
+	 * different code paths to set the external command's privileges.
+	 */
+	if (args.chroot) {
+	    seteuid(0);
+	    chroot_uid(args.chroot, (char *) 0);
+	}
+
+	/*
+	 * XXX If we put code before the set_ugid() call, then the code that
+	 * changes root directory must switch back to the mail_owner UID,
+	 * otherwise we'd be running with root privileges.
+	 */
+	set_ugid(args.uid, args.gid);
+	if (setsid() < 0)
+	    msg_warn("setsid failed: %m");
+
+	/*
+	 * Pipe plumbing.
+	 */
+	close(cmd_in_pipe[1]);
+	close(cmd_out_pipe[0]);
+	if (DUP2(cmd_in_pipe[0], STDIN_FILENO) < 0
+	    || DUP2(cmd_out_pipe[1], STDOUT_FILENO) < 0
+	    || DUP2(cmd_out_pipe[1], STDERR_FILENO) < 0)
+	    msg_fatal("%s: dup2: %m", myname);
+	close(cmd_in_pipe[0]);
+	close(cmd_out_pipe[1]);
+
+	/*
+	 * Working directory plumbing.
+	 */
+	if (args.cwd && chdir(args.cwd) < 0)
+	    msg_fatal("cannot change directory to \"%s\" for uid=%lu gid=%lu: %m",
+		      args.cwd, (unsigned long) args.uid,
+		      (unsigned long) args.gid);
+
+	/*
+	 * Environment plumbing. Always reset the command search path. XXX
+	 * That should probably be done by clean_env().
+	 */
+	if (args.export)
+	    clean_env(args.export);
+	if (setenv("PATH", _PATH_DEFPATH, 1))
+	    msg_fatal("%s: setenv: %m", myname);
+	if (args.env)
+	    for (cpp = args.env; *cpp; cpp += 2)
+		if (setenv(cpp[0], cpp[1], 1))
+		    msg_fatal("setenv: %m");
+
+	/*
+	 * Process plumbing. If possible, avoid running a shell.
+	 * 
+	 * As a safety for buggy libraries, we close the syslog socket.
+	 * Otherwise we could leak a file descriptor that was created by a
+	 * privileged process.
+	 * 
+	 * XXX To avoid losing fatal error messages we open a VSTREAM and
+	 * capture the output in the parent process.
+	 */
+	closelog();
+	msg_vstream_init(var_procname, VSTREAM_ERR);
+	if (args.argv) {
+	    execvp(args.argv[0], args.argv);
+	    msg_fatal("%s: execvp %s: %m", myname, args.argv[0]);
+	} else if (args.shell && *args.shell) {
+	    argv = argv_split(args.shell, CHARS_SPACE);
+	    argv_add(argv, args.command, (char *) 0);
+	    argv_terminate(argv);
+	    execvp(argv->argv[0], argv->argv);
+	    msg_fatal("%s: execvp %s: %m", myname, argv->argv[0]);
+	} else {
+	    exec_command(args.command);
+	}
+	/* NOTREACHED */
+
+	/*
+	 * Parent.
+	 */
+    default:
+	close(cmd_in_pipe[0]);
+	close(cmd_out_pipe[1]);
+
+	cmd_in_stream = vstream_fdopen(cmd_in_pipe[1], O_WRONLY);
+	cmd_out_stream = vstream_fdopen(cmd_out_pipe[0], O_RDONLY);
+
+	/*
+	 * Give the command a limited amount of time to run, by enforcing
+	 * timeouts on all I/O from and to it.
+	 */
+	vstream_control(cmd_in_stream,
+			CA_VSTREAM_CTL_WRITE_FN(pipe_command_write),
+			CA_VSTREAM_CTL_END);
+	vstream_control(cmd_out_stream,
+			CA_VSTREAM_CTL_READ_FN(pipe_command_read),
+			CA_VSTREAM_CTL_END);
+	pipe_command_timeout = 0;
+
+	/*
+	 * Pipe the message into the command. Examine the error report only
+	 * if we can't recognize a more specific error from the command exit
+	 * status or from the command output.
+	 */
+	write_status = mail_copy(args.sender, args.orig_rcpt,
+				 args.delivered, src,
+				 cmd_in_stream, args.flags,
+				 args.eol, why);
+	write_errno = errno;
+
+	/*
+	 * Capture a limited amount of command output, for inclusion in a
+	 * bounce message. Turn tabs and newlines into whitespace, and
+	 * replace other non-printable characters by underscore.
+	 */
+	log_len = vstream_fread(cmd_out_stream, log_buf, sizeof(log_buf) - 1);
+	(void) vstream_fclose(cmd_out_stream);
+	log_buf[log_len] = 0;
+	translit(log_buf, "\t\n", "  ");
+	printable(log_buf, '_');
+
+	/*
+	 * Just because the child closes its output streams, don't assume
+	 * that it will terminate. Instead, be prepared for the situation
+	 * that the child does not terminate, even when the parent
+	 * experiences no read/write timeout. Make sure that the child
+	 * terminates before the parent attempts to retrieve its exit status,
+	 * otherwise the parent could become stuck, and the mail system would
+	 * eventually run out of delivery agents. Do a thorough job, and kill
+	 * not just the child process but also its offspring.
+	 */
+	if (pipe_command_timeout)
+	    kill_command(pid, SIGKILL, args.uid, args.gid);
+	if (pipe_command_wait_or_kill(pid, &wait_status, SIGKILL,
+				      args.uid, args.gid) < 0)
+	    msg_fatal("wait: %m");
+	if (pipe_command_timeout) {
+	    dsb_unix(why, "5.3.0", log_len ?
+		     log_buf : sys_exits_detail(EX_SOFTWARE)->text,
+		     "Command time limit exceeded: \"%s\"%s%s",
+		     args.command,
+		     log_len ? ". Command output: " : "", log_buf);
+	    return (PIPE_STAT_BOUNCE);
+	}
+
+	/*
+	 * Command exits. Give special treatment to sendmail style exit
+	 * status codes.
+	 */
+	if (!NORMAL_EXIT_STATUS(wait_status)) {
+	    if (WIFSIGNALED(wait_status)) {
+		dsb_unix(why, "4.3.0", log_len ?
+			 log_buf : sys_exits_detail(EX_SOFTWARE)->text,
+			 "Command died with signal %d: \"%s\"%s%s",
+			 WTERMSIG(wait_status), args.command,
+			 log_len ? ". Command output: " : "", log_buf);
+		return (PIPE_STAT_DEFER);
+	    }
+	    /* Use "D.S.N text" command output. XXX What diagnostic code? */
+	    else if (dsn_valid(log_buf) > 0) {
+		dsn_split(&dp, "5.3.0", log_buf);
+		dsb_unix(why, DSN_STATUS(dp.dsn), dp.text, "%s", dp.text);
+		return (DSN_CLASS(dp.dsn) == '4' ?
+			PIPE_STAT_DEFER : PIPE_STAT_BOUNCE);
+	    }
+	    /* Use <sysexits.h> compatible exit status. */
+	    else if (SYS_EXITS_CODE(WEXITSTATUS(wait_status))) {
+		sp = sys_exits_detail(WEXITSTATUS(wait_status));
+		dsb_unix(why, sp->dsn,
+			 log_len ? log_buf : sp->text, "%s%s%s", sp->text,
+			 log_len ? ". Command output: " : "", log_buf);
+		return (sp->dsn[0] == '4' ?
+			PIPE_STAT_DEFER : PIPE_STAT_BOUNCE);
+	    }
+
+	    /*
+	     * No "D.S.N text" or <sysexits.h> compatible status. Fake it.
+	     */
+	    else {
+		sp = sys_exits_detail(WEXITSTATUS(wait_status));
+		dsb_unix(why, sp->dsn,
+			 log_len ? log_buf : sp->text,
+			 "Command died with status %d: \"%s\"%s%s",
+			 WEXITSTATUS(wait_status), args.command,
+			 log_len ? ". Command output: " : "", log_buf);
+		return (PIPE_STAT_BOUNCE);
+	    }
+	} else if (write_status &
+		   MAIL_COPY_STAT_CORRUPT) {
+	    return (PIPE_STAT_CORRUPT);
+	} else if (write_status && write_errno != EPIPE) {
+	    vstring_prepend(why->reason, "Command failed: ",
+			    sizeof("Command failed: ") - 1);
+	    vstring_sprintf_append(why->reason, ": \"%s\"", args.command);
+	    return (PIPE_STAT_BOUNCE);
+	} else {
+	    vstring_strcpy(why->reason, log_buf);
+	    return (PIPE_STAT_OK);
+	}
+    }
+}