Refactor subblock iterators.

Always initialize iterators.

Try to avoid pointer arithmetics on NULL; in other words, move all pointer
arithmetics inside g_isi_sb_iter_init().

There are 4 different ways for representing sub blocks in ISI message:
- 8-bit sub_blocks count, 8-bit sub_block_id/sub_block_len
- 16-bit sub_blocks count, 8-bit sub_block_id/sub_block_len
- 8-bit sub_blocks count, 16-bit sub_block_id/sub_block_len
- 16-bit sub_blocks count, 16-bit sub_block_id/sub_block_len

The compact form g_isi_sb_iter_init() supports 8-bit sub_block count before
start of the sub blocks themselves and 8-bit sub_block_id and sub_block_len.
The full form g_isi_sb_iter_init_full() with explicit longhdr and sub_block
count supports all other cases.

3 files changed, 12 insertions, 23 deletions

diff --git a/drivers/isimodem/devinfo.c b/drivers/isimodem/devinfo.c
index 60d82102..5f8d85ef 100644
--- a/drivers/isimodem/devinfo.c
+++ b/drivers/isimodem/devinfo.c
@@ -118,11 +118,9 @@ static bool info_resp_cb(GIsiClient *client, const void *restrict data,
 		goto error;
 	}
 
-	if (!g_isi_sb_iter_init(msg+3, len-3, &iter, false))
-		goto error;
-
-	while (g_isi_sb_iter_is_valid(&iter)) {
-
+	for (g_isi_sb_iter_init(&iter, msg, len, 3);
+	     g_isi_sb_iter_is_valid(&iter);
+	     g_isi_sb_iter_next(&iter)) {
 		switch (g_isi_sb_iter_get_id(&iter)) {
 
 		case INFO_SB_PRODUCT_INFO_MANUFACTURER:
@@ -151,7 +149,6 @@ static bool info_resp_cb(GIsiClient *client, const void *restrict data,
 				g_isi_sb_iter_get_len(&iter));
 			break;
 		}
-		g_isi_sb_iter_next(&iter);
 	}
 
 error:
diff --git a/drivers/isimodem/network-registration.c b/drivers/isimodem/network-registration.c
index 83075a94..9394921d 100644
--- a/drivers/isimodem/network-registration.c
+++ b/drivers/isimodem/network-registration.c
@@ -197,8 +197,7 @@ static gboolean decode_reg_status(struct netreg_data *nd, const guint8 *msg,
 {
 	GIsiSubBlockIter iter;
 
-	if (!g_isi_sb_iter_init(msg, len, &iter, false))
-		return FALSE;
+	g_isi_sb_iter_init(&iter, msg, len, 0);
 
 	while (g_isi_sb_iter_is_valid(&iter)) {
 
@@ -396,8 +395,7 @@ static bool name_get_resp_cb(GIsiClient *client, const void *restrict data,
 		goto error;
 	}
 
-	if (!g_isi_sb_iter_init(msg+7, len-7, &iter, false))
-		goto error;
+	g_isi_sb_iter_init(&iter, msg, len, 7);
 
 	while (g_isi_sb_iter_is_valid(&iter)) {
 
@@ -510,8 +508,7 @@ static bool available_resp_cb(GIsiClient *client, const void *restrict data,
 	total = msg[2] / 2;
 	list = alloca(total * sizeof(struct ofono_network_operator));
 
-	if (!g_isi_sb_iter_init(msg + 3, len - 3, &iter, false))
-		goto error;
+	g_isi_sb_iter_init(&iter, msg, len, 3);
 
 	while (g_isi_sb_iter_is_valid(&iter)) {
 
@@ -767,8 +764,7 @@ static void rat_ind_cb(GIsiClient *client, const void *restrict data,
 	if (!msg || len < 3 || msg[0] != NET_RAT_IND)
 		return;
 
-	if (!g_isi_sb_iter_init(msg + 3, len - 3, &iter, false))
-		return;
+	g_isi_sb_iter_init(&iter, msg, len, 3);
 
 	while (g_isi_sb_iter_is_valid(&iter)) {
 
@@ -822,8 +818,7 @@ static bool rat_resp_cb(GIsiClient *client, const void *restrict data,
 		return true;
 	}
 
-	if (!g_isi_sb_iter_init(msg + 3, len - 3, &iter, false))
-		return true;
+	g_isi_sb_iter_init(&iter, msg, len, 3);
 
 	while (g_isi_sb_iter_is_valid(&iter)) {
 
@@ -891,8 +886,7 @@ static bool rssi_resp_cb(GIsiClient *client, const void *restrict data,
 		goto error;
 	}
 
-	if (!g_isi_sb_iter_init(msg + 3, len - 3, &iter, false))
-		goto error;
+	g_isi_sb_iter_init(&iter, msg, len, 3);
 
 	while (g_isi_sb_iter_is_valid(&iter)) {
 
diff --git a/drivers/isimodem/phonebook.c b/drivers/isimodem/phonebook.c
index ac98bbe9..c24320a6 100644
--- a/drivers/isimodem/phonebook.c
+++ b/drivers/isimodem/phonebook.c
@@ -99,10 +99,9 @@ static int decode_read_response(const unsigned char *msg, size_t len,
 	if (msg[1] != SIM_PB_READ)
 		goto error;
 
-	if (!g_isi_sb_iter_init(msg+3, len-3, &iter, true))
-		goto error;
-
-	while (g_isi_sb_iter_is_valid(&iter)) {
+	for (g_isi_sb_iter_init_full(&iter, msg, len, 3, true, msg[2]);
+	     g_isi_sb_iter_is_valid(&iter);
+	     g_isi_sb_iter_next(&iter)) {
 
 		switch (g_isi_sb_iter_get_id(&iter)) {
 
@@ -177,7 +176,6 @@ static int decode_read_response(const unsigned char *msg, size_t len,
 				g_isi_sb_iter_get_len(&iter));
 			break;
 		}
-		g_isi_sb_iter_next(&iter);
 	}
 
 	if (status != SIM_SERV_OK) {