lower limit for minimum msg size, update docs

Signed-off-by: Michał Łyszczek <michal.lyszczek@bofc.pl>

5 files changed, 37 insertions, 51 deletions

diff --git a/configure.ac b/configure.ac
index d458250..8c377b0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -126,9 +126,10 @@ AC_ARG_VAR([PSMQ_MSG_MAX], [Maximum length of message (topic + payload)])
 AS_IF([test "x$PSMQ_MSG_MAX" = x], [PSMQ_MSG_MAX="255"])
 #AC_DEFINE_UNQUOTED([PSMQ_MSG_MAX], [$PSMQ_MSG_MAX], [Maximum length of message (topic + payload])
 
-AS_IF([test $PSMQ_MSG_MAX -lt 9],
+# reason for this limit is documented in inc/psmq.h.in
+AS_IF([test $PSMQ_MSG_MAX -lt 6],
 [
-    AC_MSG_ERROR(PSMQ_MSG_MAX must be at least 9)
+    AC_MSG_ERROR(PSMQ_MSG_MAX must be at least 6)
 ])
 
 AC_OUTPUT
diff --git a/inc/psmq.h.in b/inc/psmq.h.in
index d5577bd..fbcf504 100644
--- a/inc/psmq.h.in
+++ b/inc/psmq.h.in
@@ -50,7 +50,7 @@ struct psmq
 };
 
 /* broker and clients both use this structure to communicate with
- * each other. psmq will create single mqueue with size of this
+ * each other. psmqd will create single mqueue with size of this
  * structure and one for each connected client, so it's worth keeping
  * it as small as possible. */
 struct psmq_msg
@@ -65,7 +65,7 @@ struct psmq_msg
 		 * descriptor of a client, an id to identify which client
 		 * is performing request
 		 *
-		 * during reply from the broker it hold request result
+		 * during reply from the broker it holds request result
 		 * (0 for success or errno when error occured) */
 		unsigned char  data;
 	} ctrl;
@@ -78,7 +78,19 @@ struct psmq_msg
 	 * null-terminated after which payload follows. This allows
 	 * for some flexibility, ie if PSMQ_MSG_MAX was be 10, then
 	 * topic could be 3 bytes long and payload 7, but also
-	 * topic could take 9 bytes and payload only 1. */
+	 * topic could take 9 bytes and payload only 1.
+	 *
+	 * Minium value of PSMQ_MSG_MAX that makes sense is 4,
+	 * 2 characters for topic (which always starts with '/'),
+	 * null terminator for topic, and one byte of data. You
+	 * could live with 3 bytes, but that would make psmq to
+	 * be able to only send topics without any payload.
+	 *
+	 * timeout ioctl needs 3 bytes of data, thus increasing
+	 * minimum value of PSMQ_MSG_MAX to 6. You still manually
+	 * se this to lower value like 3, but you would get
+	 * errors and hangs when calling timeout ioctl, so it's
+	 * not recommended nor supported. */
 	char  data[PSMQ_MSG_MAX];
 };
 
diff --git a/psmq-common.h b/psmq-common.h
index 28d320a..63e70f3 100644
--- a/psmq-common.h
+++ b/psmq-common.h
@@ -18,19 +18,6 @@
  * psmq cannot properly work with different values that these or
  * internal types forbids some values to be bigger */
 
-/* psmq reserves 5 bytes in psmq_msg buffer for control
- * messages. Request control messages can take up to 7 bytes.
- * Format of request control message is "xNNN\0", where "x" is a
- * command, and "NNN" is a file descriptor of a client.  "N"
- * would be enough when there is less than 10 clients, but we
- * support up to 256 clients so to prevent any bugs, we force max
- * value here. Control topic must always end with null character.
- *
- * When broker sends back reply, topic is in format "x\0", so we
- * are well within 5 bytes reserved for request.
- */
-#define PSMQ_CTRL_LEN 7
-
 #if PSMQ_MAX_CLIENTS > (UCHAR_MAX - 1)
 	/* psmq uses unsigned char to hold, and transmit client's file
 	 * descriptors, so you cannot set max clients to be bigger than
@@ -39,14 +26,6 @@
 #   error PSMQ_MAX_CLIENTS must not be bigger than (UCHAR_MAX - 1)
 #endif
 
-#define PSMQ_MAX_CLIENTS_HARD_MAX 999
-#if PSMQ_MAX_CLIENTS > PSMQ_MAX_CLIENTS_HARD_MAX
-	/* some systems might have char size 10bits or bigger, but even
-	 * then, we cannot go beyond 999 clients, which is 9bytes long
-	 * in string representation. */
-#   error PSMQ_MAX_CLIENTS must not be bigger than 999
-#endif
-
 #define PSMQ_MAX_CLIENTS_HARD_MIN 2
 #if PSMQ_MAX_CLIENTS < PSMQ_MAX_CLIENTS_HARD_MIN
 	/* psmq is a publish subscriber program, so at least one client
diff --git a/tst/psmq-progs.sh b/tst/psmq-progs.sh
index a406119..87765db 100755
--- a/tst/psmq-progs.sh
+++ b/tst/psmq-progs.sh
@@ -390,8 +390,8 @@ psmq_pub_missing_t_argument()
 psmq_pub_from_stdin()
 {
     start_psmqs
-    echo "test" | ${psmqp_bin} -n${psmqp_name} -b${broker_name} -t/1
-    mt_fail "psmq_grep "test.." \"${psmqs_stdout}\""
+    echo "t" | ${psmqp_bin} -n${psmqp_name} -b${broker_name} -t/1
+    mt_fail "psmq_grep "t.." \"${psmqs_stdout}\""
     stop_psmqs
 }
 psmq_pub_from_stdin_max_line()
@@ -439,9 +439,9 @@ psmq_pub_from_stdin_multi_line()
     # -3 since topic is 3 bytes long "/1\0";
     msg1="$(randstr $((psmq_msg_max - 3 - 2)) )"
     msg2="$(randstr $((psmq_msg_max - 3 - 2)) )"
-    msg3="$(randstr 2)"
+    msg3="$(randstr 1)"
     msg4="$(randstr $((psmq_msg_max - 3 - 2)) )"
-    msg5="$(randstr 2)"
+    msg5="$(randstr 1)"
 
     printf "%s\n%s\n%s\n%s\n%s\n" ${msg1} ${msg2} ${msg3} ${msg4} ${msg5} | \
         ${psmqp_bin} -n${psmqp_name} -b${broker_name} -t/1 2> ${psmqp_stderr}
@@ -465,7 +465,7 @@ psmq_pub_with_prio()
 psmq_pub_with_invalid_prio()
 {
     start_psmqs
-    ${psmqp_bin} -n${psmqp_name} -b${broker_name} -t/1 -mtest -p7812364 \
+    ${psmqp_bin} -n${psmqp_name} -b${broker_name} -t/1 -mt -p7812364 \
         2> ${psmqp_stderr}
     mt_fail "psmq_grep \"f/failed to publish, invalid prio 7812364\" \
         \"${psmqp_stderr}\""
@@ -474,10 +474,10 @@ psmq_pub_with_invalid_prio()
 psmq_pub_from_stdin_with_prio()
 {
     start_psmqs
-    echo test | ${psmqp_bin} -n${psmqp_name} -b${broker_name} -t/1 -p2
-    mt_fail "psmq_grep \"topic: /1, priority: 2, paylen: 6, payload\" \
+    echo t | ${psmqp_bin} -n${psmqp_name} -b${broker_name} -t/1 -p2
+    mt_fail "psmq_grep \"topic: /1, priority: 2, paylen: 3, payload\" \
         \"${psmqs_stdout}\""
-    mt_fail "psmq_grep \"test.\" \"${psmqs_stdout}\""
+    mt_fail "psmq_grep \"t..\" \"${psmqs_stdout}\""
     stop_psmqs
 }
 psmq_pub_empty_message()
@@ -551,7 +551,7 @@ psmq_pub_binary_many_split()
 psmq_pub_from_stdin_with_invalid_prio()
 {
     start_psmqs
-    echo test | ${psmqp_bin} -n${psmqp_name} -b${broker_name} -t/1 -p7812364 \
+    echo t | ${psmqp_bin} -n${psmqp_name} -b${broker_name} -t/1 -p7812364 \
         2> ${psmqp_stderr}
     mt_fail "psmq_grep \"f/failed to publish, invalid prio 7812364\" \
         \"${psmqp_stderr}\""
diff --git a/tst/psmqd.c b/tst/psmqd.c
index b1163b1..01d3a03 100644
--- a/tst/psmqd.c
+++ b/tst/psmqd.c
@@ -667,7 +667,7 @@ static void psmqd_detect_dead_client(void)
 	struct psmq      sub_psmq;
 	struct psmq_msg  msg;
 	struct timespec  tp;
-	int              i;
+	char             i;
 	/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
 
 
@@ -712,6 +712,7 @@ static void psmqd_detect_dead_client(void)
 /* ==========================================================================
    ========================================================================== */
 
+#if PSMQ_MSG_MAX > 5
 
 static void psmqd_multi_pub_sub(void *arg)
 {
@@ -920,6 +921,7 @@ static void psmqd_multi_pub_sub(void *arg)
 	free(psmq_pub);
 }
 
+#endif
 
 /* ==========================================================================
    ========================================================================== */
@@ -1328,35 +1330,27 @@ void psmqd_test_group(void)
 	char             mps_name[64];
 	struct multi_ps  mps;
 
-#if PSMQ_MSG_MAX < 6
-	/* these tests may spawn a lot of mqueues, so to prevent
-	 * name clashes (and thus weird test failures), payload
-	 * must be big enough to create that much queues */
+#if PSMQ_MAX_CLIENTS < 5
 	num_pub_max = 0;
 	num_sub_max = 0;
-#else
-#   if PSMQ_MAX_CLIENTS < 5
-	num_pub_max = 0;
-	num_sub_max = 0;
-#   elif PSMQ_MAX_CLIENTS < 10
+#elif PSMQ_MAX_CLIENTS < 10
 	num_pub_max = 2;
 	num_sub_max = 3;
-#   elif PSMQ_MAX_CLIENTS < 19
+#elif PSMQ_MAX_CLIENTS < 19
 	num_pub_max = 3;
 	num_sub_max = 7;
-#   elif PSMQ_MAX_CLIENTS < 36
+#elif PSMQ_MAX_CLIENTS < 36
 	num_pub_max = 4;
 	num_sub_max = 15;
-#   elif PSMQ_MAX_CLIENTS < 69
+#elif PSMQ_MAX_CLIENTS < 69
 	num_pub_max = 5;
 	num_sub_max = 31;
-#   elif PSMQ_MAX_CLIENTS < 134
+#elif PSMQ_MAX_CLIENTS < 134
 	num_pub_max = 6;
 	num_sub_max = 63;
-#   else
+#else
 	num_pub_max = 7;
 	num_sub_max = 127;
-#   endif
 #endif
 	/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/