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supervise-daemon: implement output_logger and error_logger.
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Allows redirecting process stdin and stdout to another process,
just like is already possible with start-stop-daemon.

Also added --stdout-logger and --stderr-logger to the man page.
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Higgs1 committed Sep 25, 2023
1 parent f1e5510 commit 224294f
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Showing 4 changed files with 49 additions and 1 deletion.
17 changes: 17 additions & 0 deletions man/supervise-daemon.8
Original file line number Diff line number Diff line change
Expand Up @@ -158,6 +158,23 @@ The logfile can also be a named pipe.
The same thing as
.Fl 1 , -stdout
but with the standard error output.
.It Fl -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 -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 -capabilities Ar cap-list
Start the daemon with the listed inheritable, ambient and bounding capabilities.
The format is the same as in cap_iab(3).
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2 changes: 2 additions & 0 deletions sh/supervise-daemon.sh
Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,8 @@ supervise_start()
${chroot:+--chroot} $chroot \
${output_log+--stdout} ${output_log} \
${error_log+--stderr} $error_log \
${output_logger:+--stdout-logger \"$output_logger\"} \
${error_logger:+--stderr-logger \"$error_logger\"} \
${pidfile:+--pidfile} $pidfile \
${respawn_delay:+--respawn-delay} $respawn_delay \
${respawn_max:+--respawn-max} $respawn_max \
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2 changes: 1 addition & 1 deletion src/supervise-daemon/meson.build
Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
executable('supervise-daemon',
['supervise-daemon.c', misc_c, plugin_c, schedules_c, usage_c, version_h],
['supervise-daemon.c', '../start-stop-daemon/pipes.c', misc_c, plugin_c, schedules_c, usage_c, version_h],
c_args : [cc_branding_flags, cc_pam_flags, cc_cap_flags, cc_selinux_flags],
link_with: [libeinfo, librc],
dependencies: [dl_dep, pam_dep, cap_dep, util_dep, selinux_dep],
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29 changes: 29 additions & 0 deletions src/supervise-daemon/supervise-daemon.c
Original file line number Diff line number Diff line change
Expand Up @@ -62,6 +62,7 @@ static struct pam_conv conv = { NULL, NULL};
#include "queue.h"
#include "rc.h"
#include "misc.h"
#include "../start-stop-daemon/pipes.h"
#include "plugin.h"
#include "schedules.h"
#include "_usage.h"
Expand All @@ -79,6 +80,8 @@ enum {
LONGOPT_OOM_SCORE_ADJ,
LONGOPT_NO_NEW_PRIVS,
LONGOPT_SECBITS,
LONGOPT_STDERR_LOGGER,
LONGOPT_STDOUT_LOGGER,
};

const char *applet = NULL;
Expand Down Expand Up @@ -110,6 +113,8 @@ const struct option longopts[] = {
{ "user", 1, NULL, 'u'},
{ "stdout", 1, NULL, '1'},
{ "stderr", 1, NULL, '2'},
{ "stdout-logger",1, NULL, LONGOPT_STDOUT_LOGGER},
{ "stderr-logger",1, NULL, LONGOPT_STDERR_LOGGER},
{ "reexec", 0, NULL, '3'},
longopts_COMMON
};
Expand Down Expand Up @@ -138,6 +143,8 @@ const char * const longopts_help[] = {
"Change the process user",
"Redirect stdout to file",
"Redirect stderr to file",
"Redirect stdout to process",
"Redirect stderr to process",
"reexec (used internally)",
longopts_help_COMMON
};
Expand All @@ -160,6 +167,8 @@ static int stdout_fd;
static int stderr_fd;
static char *redirect_stderr = NULL;
static char *redirect_stdout = NULL;
static char *stderr_process = NULL;
static char *stdout_process = NULL;
#ifdef TIOCNOTTY
static int tty_fd = -1;
#endif
Expand Down Expand Up @@ -549,6 +558,12 @@ RC_NORETURN static void child_process(char *exec, 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,
Expand All @@ -557,6 +572,12 @@ RC_NORETURN static void child_process(char *exec, 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));
}

dup2(stdin_fd, STDIN_FILENO);
Expand Down Expand Up @@ -1039,6 +1060,14 @@ int main(int argc, char **argv)
reexec = true;
break;

case LONGOPT_STDOUT_LOGGER: /* --stdout-logger "command to run for stdout logging" */
stdout_process = optarg;
break;

case LONGOPT_STDERR_LOGGER: /* --stderr-logger "command to run for stderr logging" */
stderr_process = optarg;
break;

case_RC_COMMON_GETOPT
}

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