Use select() for arbitrary read timeouts

examples/read.c

@@ -27,7 +27,7 @@ int main(int argc, char **argv) {
         goto error_link_open;
     }
 
-    while (skipstone_link_recv(link, buf, &len, &endpoint) >= 0) {
+    while (skipstone_link_recv(link, buf, &len, &endpoint, NULL) >= 0) {
         printf("Received message %hu bytes for endpoint %hu\n",
             len, endpoint);
     }

examples/read.c-e

@@ -27,7 +27,7 @@ int main(int argc, char **argv) {
         goto error_link_open;
     }
 
-    while (skipstone_link_recv(link, buf, &len, &endpoint) >= 0) {
+    while (skipstone_link_recv(link, buf, &len, &endpoint, NULL) >= 0) {
         printf("Received message %hu bytes for endpoint %hu\n",
             len, endpoint);
     }

examples/test.c

@@ -78,14 +78,24 @@ int main(int argc, char **argv) {
     skipstone_message_service_register(service, 17, answer_phone_version_message, NULL);
     skipstone_message_service_register(service, 32, answer_music_message,         NULL);
 
-    skipstone_message_service_run(service, link);
+    while (1) {
+        struct timeval timeout = {
+            .tv_sec  = 0,
+            .tv_usec = 50000
+        };
 
-    perror("skipstone_message_service_run()");
+        if (skipstone_message_service_next_event(service, link, &timeout) < 0) {
+            perror("skipstone_message_service_next_event()");
+
+            goto error_io;
+        }
+    }
 
     skipstone_link_close(link);
 
     return 0;
 
+error_io:
 error_message_service_new:
     skipstone_link_close(link);
 

examples/test.c-e

@@ -78,14 +78,24 @@ int main(int argc, char **argv) {
     skipstone_message_service_register(service, 17, answer_phone_version_message, NULL);
     skipstone_message_service_register(service, 32, answer_music_message,         NULL);
 
-    skipstone_message_service_run(service, link);
+    while (1) {
+        struct timeval timeout = {
+            .tv_sec  = 0,
+            .tv_usec = 50000
+        };
 
-    perror("skipstone_message_service_run()");
+        if (skipstone_message_service_next_event(service, link, &timeout) < 0) {
+            perror("skipstone_message_service_next_event()");
+
+            goto error_io;
+        }
+    }
 
     skipstone_link_close(link);
 
     return 0;
 
+error_io:
 error_message_service_new:
     skipstone_link_close(link);
 

include/skipstone/link.h

@@ -2,6 +2,7 @@
 #define _SKIPSTONE_LINK_H
 
 #include <stdint.h>
+#include <sys/time.h>
 
 typedef struct _skipstone_link skipstone_link;
 
@@ -10,9 +11,9 @@ skipstone_link *skipstone_link_open_serial(const char *device);
 int skipstone_link_close(skipstone_link *link);
 
 int skipstone_link_send(skipstone_link *link,
-    void *buf, uint16_t size, uint16_t id);
+        void *buf, uint16_t size, uint16_t id);
 
 int skipstone_link_recv(skipstone_link *link,
-    void *buf, uint16_t *size, uint16_t *id);
+        void *buf, uint16_t *size, uint16_t *id, struct timeval *timeout);
 
 #endif /* _SKIPSTONE_LINK_H */

include/skipstone/message.h

@@ -73,9 +73,6 @@ int skipstone_message_service_queue(skipstone_message_service *service,
         skipstone_message *message, uint16_t id);
 
 int skipstone_message_service_next_event(skipstone_message_service *service,
-        skipstone_link *link);
+        skipstone_link *link, struct timeval *timeout);
-
-int skipstone_message_service_run(skipstone_message_service *service,
-        skipstone_link *link);
 
 #endif /* _SKIPSTONE_MESSAGE_H */

src/link.c

@@ -6,6 +6,7 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <sys/ioctl.h>
+#include <sys/select.h>
 #include "util.h"
 
 #include <skipstone/link.h>
@@ -134,12 +135,27 @@ error_toobig:
     return -1;
 }
 
-int skipstone_link_recv(skipstone_link *link, void *buf, uint16_t *size, uint16_t *id) {
+int skipstone_link_recv(skipstone_link *link,
+        void *buf, uint16_t *size, uint16_t *id, struct timeval *timeout) {
     skipstone_message_header header;
 
     ssize_t len_read;
      size_t len_wanted, offset = 0;
 
+    fd_set fds;
+    int ready;
+
+    FD_ZERO(&fds);
+    FD_SET(link->serial.fd, &fds);
+
+    if ((ready = select(1 + link->serial.fd, &fds, NULL, NULL, timeout)) < 0) {
+        goto error_io;
+    }
+
+    if (ready == 0) {
+        return 0;
+    }
+
     if (read(link->serial.fd, &header, sizeof(header)) < 0) {
         goto error_io;
     }
@@ -162,7 +178,7 @@ int skipstone_link_recv(skipstone_link *link, void *buf, uint16_t *size, uint16_
     *size = be16toh(header.size);
     *id   = be16toh(header.id);
 
-    return 0;
+    return 1;
 
 error_io:
     return -1;

src/link.c-e

@@ -6,6 +6,7 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <sys/ioctl.h>
+#include <sys/select.h>
 #include "util.h"
 
 #include <skipstone/link.h>
@@ -134,12 +135,27 @@ error_toobig:
     return -1;
 }
 
-int skipstone_link_recv(skipstone_link *link, void *buf, uint16_t *size, uint16_t *id) {
+int skipstone_link_recv(skipstone_link *link,
+        void *buf, uint16_t *size, uint16_t *id, struct timeval *timeout) {
     skipstone_message_header header;
 
     ssize_t len_read;
      size_t len_wanted, offset = 0;
 
+    fd_set fds;
+    int ready;
+
+    FD_ZERO(&fds);
+    FD_SET(link->serial.fd, &fds);
+
+    if ((ready = select(1 + link->serial.fd, &fds, NULL, NULL, timeout)) < 0) {
+        goto error_io;
+    }
+
+    if (ready == 0) {
+        return 0;
+    }
+
     if (read(link->serial.fd, &header, sizeof(header)) < 0) {
         goto error_io;
     }
@@ -162,7 +178,7 @@ int skipstone_link_recv(skipstone_link *link, void *buf, uint16_t *size, uint16_
     *size = be16toh(header.size);
     *id   = be16toh(header.id);
 
-    return 0;
+    return 1;
 
 error_io:
     return -1;

src/message.c

@@ -298,16 +298,17 @@ error_malloc_packed:
 }
 
 int skipstone_message_service_next_event(skipstone_message_service *service,
-        skipstone_link *link) {
+        skipstone_link *link, struct timeval *timeout) {
     skipstone_message_header *message;
     struct endpoint *endpoint;
     uint16_t size, id;
+    int ready;
 
-    if (skipstone_link_recv(link, service->buf, &size, &id) < 0) {
+    if ((ready = skipstone_link_recv(link, service->buf, &size, &id, timeout)) < 0) {
         goto error_io;
     }
 
-    if ((endpoint = skipstone_map_get(service->endpoints, id)) != NULL) {
+    if (ready && (endpoint = skipstone_map_get(service->endpoints, id)) != NULL) {
         if (endpoint->handler(service, service->buf, size, id, endpoint->context) < 0) {
             goto error_io;
         }
@@ -324,17 +325,3 @@ int skipstone_message_service_next_event(skipstone_message_service *service,
 error_io:
     return -1;
 }
-
-int skipstone_message_service_run(skipstone_message_service *service,
-        skipstone_link *link) {
-    while (1) {
-        if (skipstone_message_service_next_event(service, link) < 0) {
-            goto error_service_next_event;
-        }
-    }
-
-    return 0;
-
-error_service_next_event:
-    return -1;
-}

src/message.c-e

@@ -298,16 +298,17 @@ error_malloc_packed:
 }
 
 int skipstone_message_service_next_event(skipstone_message_service *service,
-        skipstone_link *link) {
+        skipstone_link *link, struct timeval *timeout) {
     skipstone_message_header *message;
     struct endpoint *endpoint;
     uint16_t size, id;
+    int ready;
 
-    if (skipstone_link_recv(link, service->buf, &size, &id) < 0) {
+    if ((ready = skipstone_link_recv(link, service->buf, &size, &id, timeout)) < 0) {
         goto error_io;
     }
 
-    if ((endpoint = skipstone_map_get(service->endpoints, id)) != NULL) {
+    if (ready && (endpoint = skipstone_map_get(service->endpoints, id)) != NULL) {
         if (endpoint->handler(service, service->buf, size, id, endpoint->context) < 0) {
             goto error_io;
         }
@@ -324,17 +325,3 @@ int skipstone_message_service_next_event(skipstone_message_service *service,
 error_io:
     return -1;
 }
-
-int skipstone_message_service_run(skipstone_message_service *service,
-        skipstone_link *link) {
-    while (1) {
-        if (skipstone_message_service_next_event(service, link) < 0) {
-            goto error_service_next_event;
-        }
-    }
-
-    return 0;
-
-error_service_next_event:
-    return -1;
-}