Make error codes returned by librabbitmq functions opaque

Windows doesn't generally use POSIX error codes, which poses a problem
for librabbitmq's approach of using those error codes in its API.  So
make the librabbitmq error codes opaque: They are still be integers,
but client code is not supposed to assume anything about them, except
that they can be passed to a new amqp_error_string() function which
returns the corresponding error message

Internally, the error codes are either taken from a set of
librabbitmq-specific values, or correspond to an OS-specific (POSIX or
win32) error code, with a simple encoding to indicate which is which.

4 files changed, 15 insertions, 12 deletions

diff --git a/examples/amqp_consumer.c b/examples/amqp_consumer.c
index 45db990..5dfbb33 100644
--- a/examples/amqp_consumer.c
+++ b/examples/amqp_consumer.c
@@ -94,7 +94,8 @@ static void run(amqp_connection_state_t conn)
 
     amqp_maybe_release_buffers(conn);
     result = amqp_simple_wait_frame(conn, &frame);
-    if (result <= 0) return;
+    if (result < 0)
+      return;
 
     if (frame.frame_type != AMQP_FRAME_METHOD)
       continue;
@@ -103,7 +104,9 @@ static void run(amqp_connection_state_t conn)
       continue;
 
     result = amqp_simple_wait_frame(conn, &frame);
-    if (result <= 0) return;
+    if (result < 0)
+      return;
+    
     if (frame.frame_type != AMQP_FRAME_HEADER) {
       fprintf(stderr, "Expected header!");
       abort();
@@ -114,7 +117,8 @@ static void run(amqp_connection_state_t conn)
 
     while (body_received < body_target) {
       result = amqp_simple_wait_frame(conn, &frame);
-      if (result <= 0) return;
+      if (result < 0)
+	return;
 
       if (frame.frame_type != AMQP_FRAME_BODY) {
 	fprintf(stderr, "Expected body!");
diff --git a/examples/amqp_listen.c b/examples/amqp_listen.c
index c1401ee..412dcd5 100644
--- a/examples/amqp_listen.c
+++ b/examples/amqp_listen.c
@@ -125,7 +125,7 @@ int main(int argc, char const * const *argv) {
       amqp_maybe_release_buffers(conn);
       result = amqp_simple_wait_frame(conn, &frame);
       printf("Result %d\n", result);
-      if (result <= 0)
+      if (result < 0)
 	break;
 
       printf("Frame type %d, channel %d\n", frame.frame_type, frame.channel);
@@ -143,7 +143,7 @@ int main(int argc, char const * const *argv) {
 	     (int) d->routing_key.len, (char *) d->routing_key.bytes);
 
       result = amqp_simple_wait_frame(conn, &frame);
-      if (result <= 0)
+      if (result < 0)
 	break;
 
       if (frame.frame_type != AMQP_FRAME_HEADER) {
@@ -162,7 +162,7 @@ int main(int argc, char const * const *argv) {
 
       while (body_received < body_target) {
 	result = amqp_simple_wait_frame(conn, &frame);
-	if (result <= 0)
+	if (result < 0)
 	  break;
 
 	if (frame.frame_type != AMQP_FRAME_BODY) {
diff --git a/examples/amqp_listenq.c b/examples/amqp_listenq.c
index 00dd2d7..1fc7db0 100644
--- a/examples/amqp_listenq.c
+++ b/examples/amqp_listenq.c
@@ -107,7 +107,7 @@ int main(int argc, char const * const *argv) {
       amqp_maybe_release_buffers(conn);
       result = amqp_simple_wait_frame(conn, &frame);
       printf("Result %d\n", result);
-      if (result <= 0)
+      if (result < 0)
 	break;
 
       printf("Frame type %d, channel %d\n", frame.frame_type, frame.channel);
@@ -125,7 +125,7 @@ int main(int argc, char const * const *argv) {
 	     (int) d->routing_key.len, (char *) d->routing_key.bytes);
 
       result = amqp_simple_wait_frame(conn, &frame);
-      if (result <= 0)
+      if (result < 0)
 	break;
 
       if (frame.frame_type != AMQP_FRAME_HEADER) {
@@ -144,7 +144,7 @@ int main(int argc, char const * const *argv) {
 
       while (body_received < body_target) {
 	result = amqp_simple_wait_frame(conn, &frame);
-	if (result <= 0)
+	if (result < 0)
 	  break;
 
 	if (frame.frame_type != AMQP_FRAME_BODY) {
diff --git a/examples/example_utils.c b/examples/example_utils.c
index 628572c..ae8f093 100644
--- a/examples/example_utils.c
+++ b/examples/example_utils.c
@@ -61,7 +61,7 @@
 
 void die_on_error(int x, char const *context) {
   if (x < 0) {
-    fprintf(stderr, "%s: %s\n", context, strerror(-x));
+    fprintf(stderr, "%s: %s\n", context, amqp_error_string(-x));
     exit(1);
   }
 }
@@ -76,8 +76,7 @@ void die_on_amqp_error(amqp_rpc_reply_t x, char const *context) {
       break;
 
     case AMQP_RESPONSE_LIBRARY_EXCEPTION:
-      fprintf(stderr, "%s: %s\n", context,
-	      x.library_errno ? strerror(x.library_errno) : "(end-of-stream)");
+      fprintf(stderr, "%s: %s\n", context, amqp_error_string(x.library_error));
       break;
 
     case AMQP_RESPONSE_SERVER_EXCEPTION: