AT channel: handle command without response prefix

Added at_send_command_with_echo, which can be used for sending AT commands that
have responses without prefixes. There is a race condition in
at_send_command_multiline etc. with such AT commands that can only be avoided
by having echo on while sending the command, which is what
at_send_command_with_echo does.

Signed-off-by: Sverre Vegge <sverre.vegge@stericsson.com>

3 files changed, 75 insertions, 3 deletions

diff --git a/atchannel.c b/atchannel.c
index 5e3d666..7df2117 100644
--- a/atchannel.c
+++ b/atchannel.c
@@ -97,6 +97,9 @@ struct atcontext {
     int readerClosed;
 
     int timeoutMsec;
+
+    bool waitingForEcho;
+    const char* command;
 };
 
 static struct atcontext *s_defaultAtContext = NULL;
@@ -428,6 +431,17 @@ static void processLine(const char *line)
                 handleUnsolicited(line);
 
             break;
+        case ECHOED:
+            if (ac->waitingForEcho) {
+                if (strcmp(line, ac->command) == 0) {
+                    ac->waitingForEcho = false;
+                } else {
+                    handleUnsolicited(line);
+                }
+            } else {
+                addIntermediate(line);
+            }
+            break;
 
         default:               /* This should never be reached */
             LOGE("Unsupported AT command type %d", ac->type);
@@ -1038,6 +1052,8 @@ static int at_send_command_full_nolock(const char *command,
     ac->type = type;
     ac->responsePrefix = responsePrefix;
     ac->smsPDU = smspdu;
+    ac->waitingForEcho = true; /* Only actually used when type is ECHOED */
+    ac->command = command;
 
     ac->response = (ATResponse *) calloc(1, sizeof(ATResponse));
     assert(ac->response != NULL);
@@ -1162,6 +1178,50 @@ int at_send_command(const char *command, ATResponse **pp_outResponse)
     return err;
 }
 
+int at_send_command_with_echo(const char *command, ATResponse **pp_outResponse)
+{
+    int err;
+    int ate0_err;
+
+    struct atcontext *ac = getAtContext();
+
+    if (0 != pthread_equal(ac->tid_reader, pthread_self()))
+        /* Cannot be called from reader thread. */
+        return AT_ERROR_INVALID_THREAD;
+
+    pthread_mutex_lock(&ac->commandmutex);
+
+    err = at_send_command_full_nolock("ATE1", NO_RESULT, NULL, NULL,
+                                      ac->timeoutMsec, pp_outResponse);
+    if (err < 0 || (pp_outResponse != NULL && *pp_outResponse != NULL
+            && (*pp_outResponse)->success == 0))
+        goto exit;
+
+    if (pp_outResponse) {
+        at_response_free(*pp_outResponse);
+        *pp_outResponse = NULL;
+    }
+
+    err = at_send_command_full_nolock(command, ECHOED, NULL, NULL,
+                                      ac->timeoutMsec, pp_outResponse);
+    if (err < 0 || (pp_outResponse != NULL && *pp_outResponse != NULL
+            && (*pp_outResponse)->success == 0))
+        goto exit;
+
+    ate0_err = at_send_command_full_nolock("ATE0", ECHOED, NULL, NULL,
+                                      ac->timeoutMsec, NULL);
+    if (ate0_err == AT_ERROR_TIMEOUT)
+        err = ate0_err;
+
+exit:
+    pthread_mutex_unlock(&ac->commandmutex);
+
+    if (err == AT_ERROR_TIMEOUT && ac->onTimeout != NULL)
+        ac->onTimeout();
+
+    return err;
+}
+
 int at_send_command_with_timeout(const char *command,
                                  ATResponse **pp_outResponse,
                                  long long timeoutMsec)
diff --git a/atchannel.h b/atchannel.h
index 56fffa0..b3511e3 100644
--- a/atchannel.h
+++ b/atchannel.h
@@ -198,8 +198,10 @@ typedef enum {
     NO_RESULT,              /* No intermediate response expected. */
     NUMERIC,                /* A single intermediate response starting with a 0-9. */
     SINGLELINE,             /* A single intermediate response starting with a prefix. */
-    MULTILINE               /* Multiple line intermediate response
+    MULTILINE,              /* Multiple line intermediate response
                                starting with a prefix. */
+    ECHOED,                 /* One or more lines, without prefixes. Requires
+                               echo to be on while sending the command. */
 } ATCommandType;
 
 /** A singly-linked list of intermediate responses. */
@@ -274,6 +276,17 @@ int at_handshake();
 
 int at_send_command(const char *command, ATResponse **pp_outResponse);
 
+/* Send an AT command with echo-aware response handling.
+ *
+ * This function will enable echo before sending the command, and disable it
+ * afterwards. This means that if echo was already enabled, echo may be
+ * disabled on return.
+ *
+ * The default timeout is used for each individual command, so this function
+ * may return successfully after up to three times the default timeout.
+ */
+int at_send_command_with_echo(const char *command, ATResponse **pp_outResponse);
+
 int at_send_command_with_timeout(const char *command,
                                  ATResponse **pp_outResponse,
                                  long long timeoutMsec);
diff --git a/u300-ril-information.c b/u300-ril-information.c
index d32ec2d..82f1fb8 100644
--- a/u300-ril-information.c
+++ b/u300-ril-information.c
@@ -325,8 +325,7 @@ void requestBasebandVersion(void *data, size_t datalen, RIL_Token t)
     ATLine *atline;
     char *line;
 
-    /* TODO: Check if we really should pass an empty string here */
-    err = at_send_command_multiline("AT+CGMR", "", &atresponse);
+    err = at_send_command_with_echo("AT+CGMR", &atresponse);
 
     if (err < 0 ||
             atresponse->success == 0 || atresponse->p_intermediates == NULL)