Add UT for CellularUtil::hex_to_char and ::hex_str_to_char_str

Also added checks for pointer validity.

UNITTESTS/features/cellular/framework/common/util/utiltest.cpp

@@ -53,6 +53,47 @@ TEST_F(Testutil, test_util_binary_str_to_uint)
     EXPECT_TRUE(0 == binary_str_to_uint(binary_str, 0));
 }
 
+TEST_F(Testutil, hex_to_char)
+{
+    char output;
+
+    // 0
+    hex_to_char("00", output);
+    EXPECT_EQ((char)0x00, output);
+
+    // <128
+    hex_to_char("10", output);
+    EXPECT_EQ((char)0x10, output);
+
+    // =128
+    hex_to_char("80", output);
+    EXPECT_EQ((char)0x80, output);
+
+    // >128
+    hex_to_char("FF", output);
+    EXPECT_EQ((char)0xFF, output);
+
+    // Null -> output is not modified
+    hex_to_char(NULL, output);
+    EXPECT_EQ((char)0xFF, output);
+}
+
+TEST_F(Testutil, hex_str_to_char_str)
+{
+    char input[] = "0165AABBCC";
+    char output[32];
+    EXPECT_EQ(5, hex_str_to_char_str(input, strlen(input), output));
+    EXPECT_EQ((char)0x01, output[0]);
+    EXPECT_EQ((char)0x65, output[1]);
+    EXPECT_EQ((char)0xAA, output[2]);
+    EXPECT_EQ((char)0xBB, output[3]);
+    EXPECT_EQ((char)0xCC, output[4]);
+
+    // NULL params
+    EXPECT_EQ(0, hex_str_to_char_str(NULL, 2, output));
+    EXPECT_EQ(0, hex_str_to_char_str(input, strlen(input), NULL));
+}
+
 TEST_F(Testutil, test_util_uint_to_binary_string)
 {
     char str[33];

features/cellular/framework/common/CellularUtil.cpp

@@ -278,11 +278,13 @@ int hex_str_to_int(const char *hex_string, int hex_string_length)
 int hex_str_to_char_str(const char *str, uint16_t len, char *buf)
 {
     int strcount = 0;
-    for (int i = 0; i + 1 < len; i += 2) {
+    if (str && buf) {
-        char tmp;
+        for (int i = 0; i + 1 < len; i += 2) {
-        hex_to_char(str + i, tmp);
+            char tmp;
-        buf[strcount] = tmp;
+            hex_to_char(str + i, tmp);
-        strcount++;
+            buf[strcount] = tmp;
+            strcount++;
+        }
     }
 
     return strcount;
@@ -290,9 +292,11 @@ int hex_str_to_char_str(const char *str, uint16_t len, char *buf)
 
 void hex_to_char(const char *hex, char &buf)
 {
-    int upper = hex_str_to_int(hex, 1);
+    if (hex) {
-    int lower = hex_str_to_int(hex + 1, 1);
+        int upper = hex_str_to_int(hex, 1);
-    buf = ((upper << 4) & 0xF0) | (lower & 0x0F);
+        int lower = hex_str_to_int(hex + 1, 1);
+        buf = ((upper << 4) & 0xF0) | (lower & 0x0F);
+    }
 }
 
 void uint_to_binary_str(uint32_t num, char *str, int str_size, int bit_cnt)