]> sigrok.org Git - libserialport.git/blobdiff - serialport.c
windows: Use an adaptively sized buffer for nonblocking writes.
[libserialport.git] / serialport.c
index 8c34d2227fb66ec3aea032ce343ff0a7d4b2c1ca..d0618bb91df7f13b225085948122c7efed7a18f0 100644 (file)
@@ -21,6 +21,7 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <config.h>
 #include "libserialport.h"
 #include "libserialport_internal.h"
 
@@ -74,6 +75,20 @@ SP_API enum sp_return sp_get_port_by_name(const char *portname, struct sp_port *
 
        DEBUG_FMT("Building structure for port %s", portname);
 
+#if !defined(_WIN32) && defined(HAVE_REALPATH)
+       /*
+        * get_port_details() below tries to be too smart and figure out
+        * some transport properties from the port name which breaks with
+        * symlinks. Therefore we canonicalize the portname first.
+        */
+       char pathbuf[PATH_MAX + 1];
+       char *res = realpath(portname, pathbuf);
+       if (!res)
+               RETURN_ERROR(SP_ERR_ARG, "Could not retrieve realpath behind port name");
+
+       portname = pathbuf;
+#endif
+
        if (!(port = malloc(sizeof(struct sp_port))))
                RETURN_ERROR(SP_ERR_MEM, "Port structure malloc failed");
 
@@ -89,6 +104,8 @@ SP_API enum sp_return sp_get_port_by_name(const char *portname, struct sp_port *
 #ifdef _WIN32
        port->usb_path = NULL;
        port->hdl = INVALID_HANDLE_VALUE;
+       port->write_buf = NULL;
+       port->write_buf_size = 0;
 #else
        port->fd = -1;
 #endif
@@ -295,6 +312,8 @@ SP_API void sp_free_port(struct sp_port *port)
 #ifdef _WIN32
        if (port->usb_path)
                free(port->usb_path);
+       if (port->write_buf)
+               free(port->write_buf);
 #endif
 
        free(port);
@@ -308,7 +327,8 @@ SP_PRIV struct sp_port **list_append(struct sp_port **list,
        void *tmp;
        unsigned int count;
 
-       for (count = 0; list[count]; count++);
+       for (count = 0; list[count]; count++)
+               ;
        if (!(tmp = realloc(list, sizeof(struct sp_port *) * (count + 2))))
                goto fail;
        list = tmp;
@@ -388,12 +408,12 @@ SP_API void sp_free_port_list(struct sp_port **list)
 #ifdef _WIN32
 #define CHECK_PORT_HANDLE() do { \
        if (port->hdl == INVALID_HANDLE_VALUE) \
-               RETURN_ERROR(SP_ERR_ARG, "Invalid port handle"); \
+               RETURN_ERROR(SP_ERR_ARG, "Port not open"); \
 } while (0)
 #else
 #define CHECK_PORT_HANDLE() do { \
        if (port->fd < 0) \
-               RETURN_ERROR(SP_ERR_ARG, "Invalid port fd"); \
+               RETURN_ERROR(SP_ERR_ARG, "Port not open"); \
 } while (0)
 #endif
 #define CHECK_OPEN_PORT() do { \
@@ -627,6 +647,10 @@ SP_API enum sp_return sp_close(struct sp_port *port)
        CLOSE_OVERLAPPED(write_ovl);
        CLOSE_OVERLAPPED(wait_ovl);
 
+       if (port->write_buf) {
+               free(port->write_buf);
+               port->write_buf = NULL;
+       }
 #else
        /* Returns 0 upon success, -1 upon failure. */
        if (close(port->fd) == -1)
@@ -716,6 +740,27 @@ SP_API enum sp_return sp_drain(struct sp_port *port)
 #endif
 }
 
+#ifdef _WIN32
+static enum sp_return await_write_completion(struct sp_port *port)
+{
+       TRACE("%p", port);
+       DWORD bytes_written;
+       BOOL result;
+
+       /* Wait for previous non-blocking write to complete, if any. */
+       if (port->writing) {
+               DEBUG("Waiting for previous write to complete");
+               result = GetOverlappedResult(port->hdl, &port->write_ovl, &bytes_written, TRUE);
+               port->writing = 0;
+               if (!result)
+                       RETURN_FAIL("Previous write failed to complete");
+               DEBUG("Previous write completed");
+       }
+
+       RETURN_OK();
+}
+#endif
+
 SP_API enum sp_return sp_blocking_write(struct sp_port *port, const void *buf,
                                         size_t count, unsigned int timeout_ms)
 {
@@ -738,17 +783,8 @@ SP_API enum sp_return sp_blocking_write(struct sp_port *port, const void *buf,
 
 #ifdef _WIN32
        DWORD bytes_written = 0;
-       BOOL result;
 
-       /* Wait for previous non-blocking write to complete, if any. */
-       if (port->writing) {
-               DEBUG("Waiting for previous write to complete");
-               result = GetOverlappedResult(port->hdl, &port->write_ovl, &bytes_written, TRUE);
-               port->writing = 0;
-               if (!result)
-                       RETURN_FAIL("Previous write failed to complete");
-               DEBUG("Previous write completed");
-       }
+       TRY(await_write_completion(port));
 
        /* Set timeout. */
        if (port->timeouts.WriteTotalTimeoutConstant != timeout_ms) {
@@ -763,8 +799,14 @@ SP_API enum sp_return sp_blocking_write(struct sp_port *port, const void *buf,
                RETURN_INT(count);
        } else if (GetLastError() == ERROR_IO_PENDING) {
                DEBUG("Waiting for write to complete");
-               if (GetOverlappedResult(port->hdl, &port->write_ovl, &bytes_written, TRUE) == 0)
-                       RETURN_FAIL("GetOverlappedResult() failed");
+               if (GetOverlappedResult(port->hdl, &port->write_ovl, &bytes_written, TRUE) == 0) {
+                       if (GetLastError() == ERROR_SEM_TIMEOUT) {
+                               DEBUG("Write timed out");
+                               RETURN_INT(0);
+                       } else {
+                               RETURN_FAIL("GetOverlappedResult() failed");
+                       }
+               }
                DEBUG_FMT("Write completed, %d/%d bytes written", bytes_written, count);
                RETURN_INT(bytes_written);
        } else {
@@ -858,8 +900,7 @@ SP_API enum sp_return sp_nonblocking_write(struct sp_port *port,
                RETURN_INT(0);
 
 #ifdef _WIN32
-       DWORD written = 0;
-       BYTE *ptr = (BYTE *) buf;
+       DWORD buf_bytes;
 
        /* Check whether previous write is complete. */
        if (port->writing) {
@@ -880,48 +921,39 @@ SP_API enum sp_return sp_nonblocking_write(struct sp_port *port,
                        RETURN_FAIL("SetCommTimeouts() failed");
        }
 
-       /*
-        * Keep writing data until the OS has to actually start an async IO
-        * for it. At that point we know the buffer is full.
-        */
-       while (written < count) {
-               /* Copy first byte of user buffer. */
-               port->pending_byte = *ptr++;
-
-               /* Start asynchronous write. */
-               if (WriteFile(port->hdl, &port->pending_byte, 1, NULL, &port->write_ovl) == 0) {
-                       if (GetLastError() == ERROR_IO_PENDING) {
-                               if (HasOverlappedIoCompleted(&port->write_ovl)) {
-                                       DEBUG("Asynchronous write completed immediately");
-                                       port->writing = 0;
-                                       written++;
-                                       continue;
-                               } else {
-                                       DEBUG("Asynchronous write running");
-                                       port->writing = 1;
-                                       RETURN_INT(++written);
-                               }
-                       } else {
-                               /* Actual failure of some kind. */
-                               RETURN_FAIL("WriteFile() failed");
-                       }
+       /* Copy data to our write buffer. */
+       buf_bytes = min(port->write_buf_size, count);
+       memcpy(port->write_buf, buf, buf_bytes);
+
+       /* Start asynchronous write. */
+       if (WriteFile(port->hdl, port->write_buf, buf_bytes, NULL, &port->write_ovl) == 0) {
+               if (GetLastError() == ERROR_IO_PENDING) {
+                       if ((port->writing = !HasOverlappedIoCompleted(&port->write_ovl)))
+                               DEBUG("Asynchronous write completed immediately");
+                       else
+                               DEBUG("Asynchronous write running");
                } else {
-                       DEBUG("Single byte written immediately");
-                       written++;
+                       /* Actual failure of some kind. */
+                       RETURN_FAIL("WriteFile() failed");
                }
        }
 
        DEBUG("All bytes written immediately");
 
-       RETURN_INT(written);
+       RETURN_INT(buf_bytes);
 #else
        /* Returns the number of bytes written, or -1 upon failure. */
        ssize_t written = write(port->fd, buf, count);
 
-       if (written < 0)
-               RETURN_FAIL("write() failed");
-       else
+       if (written < 0) {
+               if (errno == EAGAIN)
+                       // Buffer is full, no bytes written.
+                       RETURN_INT(0);
+               else
+                       RETURN_FAIL("write() failed");
+       } else {
                RETURN_INT(written);
+       }
 #endif
 }
 
@@ -998,7 +1030,7 @@ SP_API enum sp_return sp_blocking_read(struct sp_port *port, void *buf,
 
 #else
        size_t bytes_read = 0;
-       unsigned char *ptr = (unsigned char *) buf;
+       unsigned char *ptr = (unsigned char *)buf;
        struct timeval start, delta, now, end = {0, 0};
        int started = 0;
        fd_set fds;
@@ -1111,9 +1143,8 @@ SP_API enum sp_return sp_blocking_read_next(struct sp_port *port, void *buf,
        /* Loop until we have at least one byte, or timeout is reached. */
        while (bytes_read == 0) {
                /* Start read. */
-               if (ReadFile(port->hdl, buf, count, NULL, &port->read_ovl)) {
+               if (ReadFile(port->hdl, buf, count, &bytes_read, &port->read_ovl)) {
                        DEBUG("Read completed immediately");
-                       bytes_read = count;
                } else if (GetLastError() == ERROR_IO_PENDING) {
                        DEBUG("Waiting for read to complete");
                        if (GetOverlappedResult(port->hdl, &port->read_ovl, &bytes_read, TRUE) == 0)
@@ -1233,10 +1264,11 @@ SP_API enum sp_return sp_nonblocking_read(struct sp_port *port, void *buf,
 
        /* Do read. */
        if (ReadFile(port->hdl, buf, count, NULL, &port->read_ovl) == 0)
-               RETURN_FAIL("ReadFile() failed");
+               if (GetLastError() != ERROR_IO_PENDING)
+                       RETURN_FAIL("ReadFile() failed");
 
        /* Get number of bytes read. */
-       if (GetOverlappedResult(port->hdl, &port->read_ovl, &bytes_read, TRUE) == 0)
+       if (GetOverlappedResult(port->hdl, &port->read_ovl, &bytes_read, FALSE) == 0)
                RETURN_FAIL("GetOverlappedResult() failed");
 
        TRY(restart_wait_if_needed(port, bytes_read));
@@ -1420,7 +1452,10 @@ SP_API enum sp_return sp_wait(struct sp_event_set *event_set,
        RETURN_OK();
 #else
        struct timeval start, delta, now, end = {0, 0};
-       int started = 0;
+       const struct timeval max_delta = {
+               (INT_MAX / 1000), (INT_MAX % 1000) * 1000
+       };
+       int started = 0, timeout_overflow = 0;
        int result, timeout_remaining_ms;
        struct pollfd *pollfds;
        unsigned int i;
@@ -1429,7 +1464,7 @@ SP_API enum sp_return sp_wait(struct sp_event_set *event_set,
                RETURN_ERROR(SP_ERR_MEM, "pollfds malloc() failed");
 
        for (i = 0; i < event_set->count; i++) {
-               pollfds[i].fd = ((int *) event_set->handles)[i];
+               pollfds[i].fd = ((int *)event_set->handles)[i];
                pollfds[i].events = 0;
                pollfds[i].revents = 0;
                if (event_set->masks[i] & SP_EVENT_RX_READY)
@@ -1460,7 +1495,8 @@ SP_API enum sp_return sp_wait(struct sp_event_set *event_set,
                if (!timeout_ms) {
                        timeout_remaining_ms = -1;
                } else if (!started) {
-                       timeout_remaining_ms = timeout_ms;
+                       timeout_overflow = (timeout_ms > INT_MAX);
+                       timeout_remaining_ms = timeout_overflow ? INT_MAX : timeout_ms;
                } else {
                        gettimeofday(&now, NULL);
                        if (timercmp(&now, &end, >)) {
@@ -1468,6 +1504,8 @@ SP_API enum sp_return sp_wait(struct sp_event_set *event_set,
                                break;
                        }
                        timersub(&end, &now, &delta);
+                       if ((timeout_overflow = timercmp(&delta, &max_delta, >)))
+                               delta = max_delta;
                        timeout_remaining_ms = delta.tv_sec * 1000 + delta.tv_usec / 1000;
                }
 
@@ -1484,7 +1522,8 @@ SP_API enum sp_return sp_wait(struct sp_event_set *event_set,
                        }
                } else if (result == 0) {
                        DEBUG("poll() timed out");
-                       break;
+                       if (!timeout_overflow)
+                               break;
                } else {
                        DEBUG("poll() completed");
                        break;
@@ -1835,6 +1874,9 @@ static enum sp_return set_config(struct sp_port *port, struct port_data *data,
        DEBUG_FMT("Setting configuration for port %s", port->name);
 
 #ifdef _WIN32
+
+       TRY(await_write_completion(port));
+
        if (config->baudrate >= 0) {
                for (i = 0; i < NUM_STD_BAUDRATES; i++) {
                        if (config->baudrate == std_baudrates[i].value) {
@@ -1845,6 +1887,14 @@ static enum sp_return set_config(struct sp_port *port, struct port_data *data,
 
                if (i == NUM_STD_BAUDRATES)
                        data->dcb.BaudRate = config->baudrate;
+
+               /* Allocate write buffer for 50ms of data at baud rate. */
+               port->write_buf_size = max(config->baudrate / (8 * 20), 1);
+               port->write_buf = realloc(port->write_buf,
+                                         port->write_buf_size);
+
+               if (!port->write_buf)
+                       RETURN_ERROR(SP_ERR_MEM, "Allocating write buffer failed");
        }
 
        if (config->bits >= 0)