pce-322a: unbreak send_command() return code

Data was sent to the serial port, and the non-zero positive write length
was mistaken as an error, since it did not match the SR_OK code's value.
This snuck in with commit 379e95c587e1d in 2017-08.

Rephrase the check for successful serial writes in the pce-322a driver.
Pass on error codes from the serial layer in verbatim form. Check for
the exact expected write length and derive SR_ERR_IO upon mismatch. Do
return SR_OK upon success.

Reported-By: Michael Ströder <redacted>
Tested-By: Michael Ströder <redacted>

diff --git a/src/hardware/pce-322a/protocol.c b/src/hardware/pce-322a/protocol.c
index ee637e802dcb82b390276ab8a8169520f4643b15..ee98c7c61128cd82cb0a1bdbb2d0a7ab724524d8 100644 (file)
--- a/src/hardware/pce-322a/protocol.c
+++ b/src/hardware/pce-322a/protocol.c
@@ -26,6 +26,7 @@ static int send_command(const struct sr_dev_inst *sdi, uint16_t command)
 {
        struct sr_serial_dev_inst *serial;
        uint8_t buffer[2];
+       int ret;
 
        buffer[0] = command >> 8;
        buffer[1] = command;
@@ -33,13 +34,20 @@ static int send_command(const struct sr_dev_inst *sdi, uint16_t command)
        if (!(serial = sdi->conn))
                return SR_ERR;
 
-       return serial_write_blocking(serial, (const void *)buffer, 2, 0);
+       ret = serial_write_blocking(serial, buffer, sizeof(buffer), 0);
+       if (ret < 0)
+               return ret;
+       if ((size_t)ret != sizeof(buffer))
+               return SR_ERR_IO;
+
+       return SR_OK;
 }
 
 static int send_long_command(const struct sr_dev_inst *sdi, uint32_t command)
 {
        struct sr_serial_dev_inst *serial;
        uint8_t buffer[4];
+       int ret;
 
        buffer[0] = command >> 24;
        buffer[1] = command >> 16;
@@ -49,7 +57,13 @@ static int send_long_command(const struct sr_dev_inst *sdi, uint32_t command)
        if (!(serial = sdi->conn))
                return SR_ERR;
 
-       return serial_write_blocking(serial, (const void *)buffer, 4, 0);
+       ret = serial_write_blocking(serial, buffer, sizeof(buffer), 0);
+       if (ret < 0)
+               return ret;
+       if ((size_t)ret != sizeof(buffer))
+               return SR_ERR_IO;
+
+       return SR_OK;
 }
 
 static void send_data(const struct sr_dev_inst *sdi, float sample)