tallyman: preserve command's stdout and stderr

* src/tallyman.c: Proxy command's stdout and stderr by default.
Use single -q option to suppress proxying stdout. Use two -q
options to suppress both stdout and stderr (prior behavior).
* src/tallyman.1: Document new behavior

2 files changed, 39 insertions, 7 deletions

diff --git a/src/tallyman.1 b/src/tallyman.1
index 90a1baa..9cdbaaa 100644
--- a/src/tallyman.1
+++ b/src/tallyman.1
@@ -1,11 +1,11 @@
-.TH TALLYMAN 1 "July 18, 2018" "TALLYMAN" "Tallyman User Reference"
+.TH TALLYMAN 1 "August 13, 2019" "TALLYMAN" "Tallyman User Reference"
 .SH NAME
 tallyman \- health state collector for docker containers
 .SH SYNOPSIS
 .na
 .nh
 \fBtallyman\fR\
- [\fB\-d\fR]\
+ [\fB\-dq\fR]\
  [\fB\-h\fR \fINAME\fR]\
  [\fB\-s\fR \fIHOST:PORT\fR]\
  [\fB\-v\fR \fIJSON\fR]\
@@ -13,6 +13,7 @@ tallyman \- health state collector for docker containers
  [\fB\-\-debug\fR]\
  [\fB\-\-execution\-timeout=\fISECONDS\fR]\
  [\fB\-\-hostname=\fINAME\fR]\
+ [\fB\-\-quiet\fR]\
  [\fB\-\-server=\fIHOST:PORT\fR]\
  [\fB\-\-value=\fIJSON\fR]\
  \fISRVID\fR\
@@ -49,6 +50,12 @@ Increase debug verbosity.
 \fB\-h\fR, \fB\-\-hostname=\fINAME\fR
 Set this server hostname. By default it is determined automatically.
 .TP
+\fB\-q\fR, \fB\-\-quiet\fR
+By default, \fBtallyman\fR would transparently pass \fICOMMAND\fR's
+stdout and stderr to the corresponding streams. Single \fB\-q\fR
+option suppresses reproducing the stdout.  Two \fB\-q\fR options
+suppress both stdout and stderr.
+.TP
 \fB\-s\fR, \fB\-\-server=\fIHOST:PORT\fR
 Address and port of the data collector. Default is \fIGW\fR:8990,
 where \fIGW\fR is the default gateway of the container.
@@ -74,7 +81,7 @@ Sergey Poznyakoff
 .SH "BUG REPORTS"
 Report bugs to <gray@gnu.org>.
 .SH COPYRIGHT
-Copyright \(co 2018 Sergey Poznyakoff
+Copyright \(co 2018\-2019 Sergey Poznyakoff
 .br
 .na
 License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
diff --git a/src/tallyman.c b/src/tallyman.c
index f6b095d..fad97b8 100644
--- a/src/tallyman.c
+++ b/src/tallyman.c
@@ -40,7 +40,7 @@ struct option longopts[] = {
         { "version",  no_argument,       0, 'V' },      
         { NULL }
 };
-static char shortopts[] = "+?ds:h:v:V";
+static char shortopts[] = "+?ds:h:qv:V";
                     
 void
 help(void)
@@ -50,6 +50,9 @@ help(void)
         printf("OPTIONS are:\n\n");
         printf("   -d, --debug              increase debug verbosity\n");
         printf("   -h, --hostname=NAME      set this server hostname\n");
+        printf("   -q, --quiet              don't display COMMAND's stderr;\n");
+        printf("                            when used twice, don't display COMMAND's\n");
+        printf("                            stdout either\n");
         printf("   -s, --server=HOST:PORT   remote host server\n");
         printf("   -v, --value=JSON         add JSON object to the report\n");
         printf("       --connection-timeout=SECONDS\n");
@@ -175,6 +178,18 @@ sig_alarm(int sig)
         longjmp(jmpbuf, 1);
 }
 
+static void
+stdout_linemon(const char *bufptr, size_t bufsize, void *closure)
+{
+        fwrite(bufptr, bufsize, 1, stdout);
+}
+
+static void
+stderr_linemon(const char *bufptr, size_t bufsize, void *closure)
+{
+        fwrite(bufptr, bufsize, 1, stderr);
+}
+
 int
 main(int argc, char **argv)
 {
@@ -189,6 +204,7 @@ main(int argc, char **argv)
         struct runcap rc;
         struct shttp_connection *shttp;
         int status;
+        int rcflags = RCF_TIMEOUT|RCF_STDOUT_LINEMON|RCF_STDERR_LINEMON;
         
         setprogname(argv[0]);
         while ((c = getopt_long(argc, argv, shortopts, longopts, NULL))
@@ -212,6 +228,12 @@ main(int argc, char **argv)
                 case 'V':
                         version();
                         exit(0);
+                case 'q':
+                        if (rcflags & RCF_STDOUT_LINEMON)
+                                rcflags &= ~RCF_STDOUT_LINEMON;
+                        else
+                                rcflags &= ~RCF_STDERR_LINEMON;
+                        break;
                 case OPT_CONNECTION_TIMEOUT:
                         exec_timeout = get_timeout(optarg);
                         break;
@@ -266,12 +288,15 @@ main(int argc, char **argv)
         json_array_flatten(ar);
         json_object_set(obj, "command", ar);
 
-
         rc.rc_argv = argv;
         rc.rc_timeout = exec_timeout;
-
+        if (rcflags & RCF_STDOUT_LINEMON)
+                rc.rc_cap[RUNCAP_STDOUT].sc_linemon = stdout_linemon;
+        if (rcflags & RCF_STDERR_LINEMON)
+                rc.rc_cap[RUNCAP_STDERR].sc_linemon = stderr_linemon;
+        
         status = EX_FAILURE;
-        if (runcap(&rc, RCF_TIMEOUT)) {
+        if (runcap(&rc, rcflags)) {
                 json_object_set(obj, "status", json_new_bool(0));
                 json_object_set(obj, "error", json_new_bool(1));
                 json_object_set(obj, "message",