start-stop-daemon: add ability to log stdout or stderr to processes

NEWS.md

@@ -4,6 +4,15 @@ OpenRC NEWS
 This file will contain a list of notable changes for each release. Note
 the information in this file is in reverse order.
 
+## OpenRC 0.37
+
+start-stop-daemon now supports logging stdout and stderr of daemons to
+processes instead of files. These processes are defined by the
+output_logger and error_logger variables in standard service scripts, or
+by the  -3/--output-logger or -4/--error-logger switches if you use
+start-stop-daemon directly. For more information on this, see the
+start-stop-daemon man page.
+
 ## OpenRC 0.36
 
 In this release, the modules-load service has been combined into the

man/openrc-run.8

@@ -173,6 +173,23 @@ variable is set.
 The same thing as
 .Pa output_log
 but for the standard error output.
+.It Ar output_logger
+This is a process which will be used to log the standard output from the
+service.  If you are starting this service with
+.Xr start-stop-daemon 8 ,
+,  you must set
+.Pa command_background
+to true. Keep in mind that this command must be executable as a shell
+command inside the chroot if the
+.Pa chroot
+variable is set. Keep in mind also that this command works by accepting
+the stdout of the service on stdin.
+An example of a command that can be run this way is logger if you want
+your service output to go to syslog.
+.It Ar error_logger
+The same thing as
+.Pa output_logger
+but for the standard error output.
 .It Ar directory
 .Xr start-stop-daemon 8
 and

man/start-stop-daemon.8

@@ -131,9 +131,34 @@ Modifies the scheduling priority of the daemon.
 .It Fl 1 , -stdout Ar logfile
 Redirect the standard output of the process to logfile when started with
 .Fl background .
-Must be an absolute pathname, but relative to the path optionally given with
+The logfile Must be an absolute pathname, but relative to the path
+optionally given with
 .Fl r , -chroot .
 The logfile can also be a named pipe.
+.It Fl 2 , -stderr Ar logfile
+Redirect the standard error of the process to logfile when started with
+.Fl background .
+The logfile must be an absolute pathname, but relative to the path
+optionally given with
+.Fl r , -chroot .
+The logfile can also be a named pipe.
+.It Fl 3 , -stdout-logger Ar cmd
+Run cmd as a child process redirecting the standard output to the
+standard input of cmd when started with
+.Fl background .
+Cmd must be an absolute pathname, but relative to the path optionally given with
+.Fl r , -chroot .
+This process must be prepared to accept input on stdin and be able to
+log it or send it to another location.
+.It Fl 4 , -stderr-logger Ar cmd
+Run cmd as a child process and 
+Redirect the standard error of the process to the standard input of cmd
+when started with
+.Fl background .
+Cmd must be an absolute pathname, but relative to the path optionally given with
+.Fl r , -chroot .
+This process must be prepared to accept input on stdin and be able to
+log it or send it to another location.
 .It Fl w , -wait Ar milliseconds
 Wait
 .Ar milliseconds

sh/start-stop-daemon.sh

@@ -47,6 +47,8 @@ ssd_start()
 		${directory:+--chdir} $directory \
 		${output_log+--stdout} $output_log \
 		${error_log+--stderr} $error_log \
+		${output_logger+--stdout-logger} \"$output_logger\" \
+		${error_logger+--stderr-logger} \"$error_logger\" \
 		${procname:+--name} $procname \
 		${pidfile:+--pidfile} $pidfile \
 		${command_user+--user} $command_user \

src/rc/Makefile

@@ -158,7 +158,7 @@ rc-service: rc-service.o _usage.o rc-misc.o
 rc-update: rc-update.o _usage.o rc-misc.o
 	${CC} ${LOCAL_CFLAGS} ${LOCAL_LDFLAGS} ${CFLAGS} ${LDFLAGS} -o $@ $^ ${LDADD}
 
-start-stop-daemon: start-stop-daemon.o _usage.o rc-misc.o rc-schedules.o
+start-stop-daemon: start-stop-daemon.o _usage.o rc-misc.o rc-pipes.o rc-schedules.o
 	${CC} ${LOCAL_CFLAGS} ${LOCAL_LDFLAGS} ${CFLAGS} ${LDFLAGS} -o $@ $^ ${LDADD}
 
 supervise-daemon: supervise-daemon.o _usage.o rc-misc.o rc-schedules.o

src/rc/start-stop-daemon.c

@@ -59,13 +59,14 @@ static struct pam_conv conv = { NULL, NULL};
 #include "queue.h"
 #include "rc.h"
 #include "rc-misc.h"
+#include "rc-pipes.h"
 #include "rc-schedules.h"
 #include "_usage.h"
 #include "helpers.h"
 
 const char *applet = NULL;
 const char *extraopts = NULL;
-const char *getoptstring = "I:KN:PR:Sa:bc:d:e:g:ik:mn:op:s:tu:r:w:x:1:2:" \
+const char *getoptstring = "I:KN:PR:Sa:bc:d:e:g:ik:mn:op:s:tu:r:w:x:1:2:3:4:" \
 	getoptstring_COMMON;
 const struct option longopts[] = {
 	{ "ionice",       1, NULL, 'I'},
@@ -93,6 +94,8 @@ const struct option longopts[] = {
 	{ "exec",         1, NULL, 'x'},
 	{ "stdout",       1, NULL, '1'},
 	{ "stderr",       1, NULL, '2'},
+	{ "stdout-logger",1, NULL, '3'},
+	{ "stderr-logger",1, NULL, '4'},
 	{ "progress",     0, NULL, 'P'},
 	longopts_COMMON
 };
@@ -122,6 +125,8 @@ const char * const longopts_help[] = {
 	"Binary to start/stop",
 	"Redirect stdout to file",
 	"Redirect stderr to file",
+	"Redirect stdout to process",
+	"Redirect stderr to process",
 	"Print dots each second while waiting",
 	longopts_help_COMMON
 };
@@ -276,6 +281,8 @@ int main(int argc, char **argv)
 	int tid = 0;
 	char *redirect_stderr = NULL;
 	char *redirect_stdout = NULL;
+	char *stderr_process = NULL;
+	char *stdout_process = NULL;
 	int stdin_fd;
 	int stdout_fd;
 	int stderr_fd;
@@ -500,6 +507,14 @@ int main(int argc, char **argv)
 			redirect_stderr = optarg;
 			break;
 
+		case '3':   /* --stdout-logger "command to run for stdout logging" */
+			stdout_process = optarg;
+			break;
+
+		case '4':  /* --stderr-logger "command to run for stderr logging" */
+			stderr_process = optarg;
+			break;
+
 		case_RC_COMMON_GETOPT
 		}
 
@@ -551,6 +566,9 @@ int main(int argc, char **argv)
 		if (redirect_stdout || redirect_stderr)
 			eerrorx("%s: --stdout and --stderr are only relevant"
 			    " with --start", applet);
+		if (stdout_process || stderr_process)
+			eerrorx("%s: --stdout-logger and --stderr-logger are only relevant"
+			    " with --start", applet);
 		if (start_wait)
 			ewarn("using --wait with --stop has no effect,"
 			    " use --retry instead");
@@ -563,6 +581,15 @@ int main(int argc, char **argv)
 		if ((redirect_stdout || redirect_stderr) && !background)
 			eerrorx("%s: --stdout and --stderr are only relevant"
 			    " with --background", applet);
+		if ((stdout_process || stderr_process) && !background)
+			eerrorx("%s: --stdout-logger and --stderr-logger are only relevant"
+			    " with --background", applet);
+		if (redirect_stdout && stdout_process)
+			eerrorx("%s: do not use --stdout and --stdout-logger together",
+					applet);
+		if (redirect_stderr && stderr_process)
+			eerrorx("%s: do not use --stderr and --stderr-logger together",
+					applet);
 	}
 
 	/* Expand ~ */
@@ -603,7 +630,6 @@ int main(int argc, char **argv)
 		    *exec_file ? exec_file : exec);
 		free(exec_file);
 		exit(EXIT_FAILURE);
-
 	}
 	if (start && retry)
 		ewarn("using --retry with --start has no effect,"
@@ -886,6 +912,12 @@ int main(int argc, char **argv)
 				eerrorx("%s: unable to open the logfile"
 				    " for stdout `%s': %s",
 				    applet, redirect_stdout, strerror(errno));
+		}else if (stdout_process) {
+			stdout_fd = rc_pipe_command(stdout_process);
+			if (stdout_fd == -1)
+				eerrorx("%s: unable to open the logging process"
+				    " for stdout `%s': %s",
+				    applet, stdout_process, strerror(errno));
 		}
 		if (redirect_stderr) {
 			if ((stderr_fd = open(redirect_stderr,
@@ -894,13 +926,21 @@ int main(int argc, char **argv)
 				eerrorx("%s: unable to open the logfile"
 				    " for stderr `%s': %s",
 				    applet, redirect_stderr, strerror(errno));
+		}else if (stderr_process) {
+			stderr_fd = rc_pipe_command(stderr_process);
+			if (stderr_fd == -1)
+				eerrorx("%s: unable to open the logging process"
+				    " for stderr `%s': %s",
+				    applet, stderr_process, strerror(errno));
 		}
 
 		if (background)
 			dup2(stdin_fd, STDIN_FILENO);
-		if (background || redirect_stdout || rc_yesno(getenv("EINFO_QUIET")))
+		if (background || redirect_stdout || stdout_process
+				|| rc_yesno(getenv("EINFO_QUIET")))
 			dup2(stdout_fd, STDOUT_FILENO);
-		if (background || redirect_stderr || rc_yesno(getenv("EINFO_QUIET")))
+		if (background || redirect_stderr || stderr_process
+				|| rc_yesno(getenv("EINFO_QUIET")))
 			dup2(stderr_fd, STDERR_FILENO);
 
 		for (i = getdtablesize() - 1; i >= 3; --i)