[PATCH] core: process SMS +CGMR response with regex

[Stevens, Nick]

Variability in the response style from certain modems would cause the parsing
of the +CGMR response to fail. For example, the Telit HE910 inserts an empty
string ("") in the second field of the response, which caused the previous
sscanf implementation to fail.

This patch converts the parsing of the CGMR response to a regex that allows
for more flexibility and robustness.

Signed-off-by: Nick Stevens <Nick.Stevens at digi.com>
---
 src/mm-broadband-modem.c | 63 +++++++++++++++++++++++++++++++++++++++++-------
 src/mm-sms-part-3gpp.h   |  2 --
 2 files changed, 54 insertions(+), 11 deletions(-)

diff --git a/src/mm-broadband-modem.c b/src/mm-broadband-modem.c
index 085d4d7..a6346f1 100644
--- a/src/mm-broadband-modem.c
+++ b/src/mm-broadband-modem.c
@@ -5614,10 +5614,12 @@ sms_part_ready (MMBroadbandModem *self,
                 SmsPartContext *ctx)
 {
     MMSmsPart *part;
-    gint rv, status, tpdu_len;
-    gchar pdu[MM_SMS_PART_3GPP_MAX_PDU_LEN + 1];
+    gint matches, status, tpdu_len;
+    gchar *pdu;
     const gchar *response;
     GError *error = NULL;
+    GRegex *r = NULL;
+    GMatchInfo *match_info = NULL;
 
     /* Always always always unlock mem1 storage. Warned you've been. */
     mm_broadband_modem_unlock_sms_storages (self, TRUE, FALSE);
@@ -5633,16 +5635,51 @@ sms_part_ready (MMBroadbandModem *self,
         return;
     }
 
-    rv = sscanf (response, "+CMGR: %d,,%d %" G_STRINGIFY (MM_SMS_PART_3GPP_MAX_PDU_LEN) "s",
-                 &status, &tpdu_len, pdu);
-    if (rv != 3) {
+    /* +CMGR: <status>,(ignored),<tpdu_len>(whitespace)<data> */
+    r = g_regex_new ("\\+CMGR:\\s*(\\d+)\\s*,[^,]*,\\s*(\\d+)\\s*([^\\r\\n]*)",
+                     0, 0, NULL);
+    g_assert (r);
+
+    if (!g_regex_match_full (r, response, strlen (response), 0, 0, &match_info, NULL)) {
         error = g_error_new (MM_CORE_ERROR,
                              MM_CORE_ERROR_FAILED,
-                             "Failed to parse CMGR response (parsed %d items)", rv);
+                             "Failed to parse CMGR response");
         mm_warn ("Couldn't retrieve SMS part: '%s'", error->message);
-        g_simple_async_result_take_error (ctx->result, error);
-        sms_part_context_complete_and_free (ctx);
-        return;
+        goto error;
+    }
+
+    matches = g_match_info_get_match_count (match_info);
+    if (matches != 4) {
+        error = g_error_new (MM_CORE_ERROR,
+                             MM_CORE_ERROR_FAILED,
+                             "Failed to match entire CMGR response (count %d)", matches);
+        mm_warn ("Couldn't retrieve SMS part: '%s'", error->message);
+        goto error;
+    }
+
+    if (!mm_get_int_from_match_info (match_info, 1, &status)) {
+        error = g_error_new (MM_CORE_ERROR,
+                             MM_CORE_ERROR_FAILED,
+                             "Failed to convert status");
+        mm_warn ("Couldn't retrieve SMS part: '%s'", error->message);
+        goto error;
+    }
+
+    if (!mm_get_int_from_match_info (match_info, 2, &tpdu_len)) {
+        error = g_error_new (MM_CORE_ERROR,
+                             MM_CORE_ERROR_FAILED,
+                             "Failed to convert tpdu_len");
+        mm_warn ("Couldn't retrieve SMS part: '%s'", error->message);
+        goto error;
+    }
+
+    pdu = mm_get_string_unquoted_from_match_info (match_info, 3);
+    if (!pdu) {
+        error = g_error_new (MM_CORE_ERROR,
+                             MM_CORE_ERROR_FAILED,
+                             "Failed to get PDU");
+        mm_warn ("Couldn't retrieve SMS part: '%s'", error->message);
+        goto error;
     }
 
     part = mm_sms_part_3gpp_new_from_pdu (ctx->idx, pdu, &error);
@@ -5659,8 +5696,16 @@ sms_part_ready (MMBroadbandModem *self,
     }
 
     /* All done */
+    g_regex_unref(r);
     g_simple_async_result_set_op_res_gboolean (ctx->result, TRUE);
     sms_part_context_complete_and_free (ctx);
+
+    return;
+
+error:
+    g_regex_unref(r);
+    g_simple_async_result_take_error (ctx->result, error);
+    sms_part_context_complete_and_free (ctx);
 }
 
 static void
diff --git a/src/mm-sms-part-3gpp.h b/src/mm-sms-part-3gpp.h
index 82709a2..a21d734 100644
--- a/src/mm-sms-part-3gpp.h
+++ b/src/mm-sms-part-3gpp.h
@@ -22,8 +22,6 @@
 
 #include "mm-sms-part.h"
 
-#define MM_SMS_PART_3GPP_MAX_PDU_LEN 344
-
 MMSmsPart *mm_sms_part_3gpp_new_from_pdu  (guint index,
                                            const gchar *hexpdu,
                                            GError **error);
-- 
2.5.0