dlt_common: correct read/write position

In dlt_buffer_read_block() and dlt_buffer_write_block(), read/write position
should be updated in case these positions are equal to the size of ringbuffer.

Adding boundary check in gtest_dlt_common.cpp

Signed-off-by: Dinh Cong Toan <toan.dinhcong@vn.bosch.com>

2 files changed, 40 insertions, 7 deletions

diff --git a/src/shared/dlt_common.c b/src/shared/dlt_common.c
index 8757296..c597468 100644
--- a/src/shared/dlt_common.c
+++ b/src/shared/dlt_common.c
@@ -2431,7 +2431,10 @@ void dlt_buffer_write_block(DltBuffer *buf, int *write, const unsigned char *dat
                 *write += (int) size;
             }
             else {
-                if(buf->size > (unsigned int) (*write)) {
+                /* when (*write) = buf->size, write only the second block
+                * and update write position correspondingly.
+                */
+                if((unsigned int) (*write) <= buf->size) {
                     /* write two blocks */
                     memcpy(buf->mem + *write, data, buf->size - (unsigned int) (*write));
                     memcpy(buf->mem, data + buf->size - *write, size - buf->size + (unsigned int) (*write));
@@ -2458,11 +2461,14 @@ void dlt_buffer_read_block(DltBuffer *buf, int *read, unsigned char *data, unsig
             *read += (int)size;
         }
         else {
-            if (buf->size > (unsigned int)(*read)) {
+            /* when (*read) = buf->size, read only the second block
+            * and update read position correspondingly.
+            */
+            if ((unsigned int)(*read) <= buf->size) {
                 /* read two blocks */
                 memcpy(data, buf->mem + *read, buf->size - (unsigned int)(*read));
                 memcpy(data + buf->size - *read, buf->mem, size - buf->size + (unsigned int)(*read));
-                *read += (int)(size - buf->size);
+                *read += (int) (size - buf->size);
             }
         }
     }
diff --git a/tests/gtest_dlt_common.cpp b/tests/gtest_dlt_common.cpp
index 9afb830..4e08d9a 100644
--- a/tests/gtest_dlt_common.cpp
+++ b/tests/gtest_dlt_common.cpp
@@ -1277,8 +1277,20 @@ TEST(t_dlt_buffer_write_block, normal)
 }
 TEST(t_dlt_buffer_write_block, abnormal)
 {
-    /* actual no abnormal test cases */
-    /* because of void funktion and missing gtest tools for that */
+    /* Boundary check of write position */
+    DltBuffer buf;
+    const char *data = "data";
+    int write = DLT_USER_RINGBUFFER_MIN_SIZE;
+    write -= sizeof(DltBufferHead);
+    int size = sizeof(data);
+    // when write = buf->size, it should not throw any warning
+    // and write should equal to size.
+    EXPECT_LE(DLT_RETURN_OK,
+              dlt_buffer_init_dynamic(&buf,DLT_USER_RINGBUFFER_MIN_SIZE, DLT_USER_RINGBUFFER_MAX_SIZE,
+                                      DLT_USER_RINGBUFFER_STEP_SIZE));
+    EXPECT_NO_THROW(dlt_buffer_write_block(&buf, &write, (unsigned char *)&data, size));
+    EXPECT_EQ(size , write);
+    EXPECT_LE(DLT_RETURN_OK, dlt_buffer_free_dynamic(&buf));
 }
 TEST(t_dlt_buffer_write_block, nullpointer)
 {
@@ -1358,8 +1370,23 @@ TEST(t_dlt_buffer_read_block, normal)
 }
 TEST(t_dlt_buffer_read_block, abnormal)
 {
-    /* actual no abnormal test cases */
-    /* because of void funktion and missing gtest tools for that */
+    /* Boundary check of read position */
+    DltBuffer buf;
+    /* Buffer to read data from DltBuffer */
+    unsigned char *data_read;
+    data_read = (unsigned char *) calloc(1000, sizeof(char));
+    int read = DLT_USER_RINGBUFFER_MIN_SIZE;
+    read -= sizeof(DltBufferHead);
+    int size = 1000;
+    // when read = buf->size, it should not throw any warning
+    // and read position should equal to size.
+    EXPECT_LE(DLT_RETURN_OK,
+              dlt_buffer_init_dynamic(&buf, DLT_USER_RINGBUFFER_MIN_SIZE, DLT_USER_RINGBUFFER_MAX_SIZE,
+                                      DLT_USER_RINGBUFFER_STEP_SIZE));
+    EXPECT_NO_THROW(dlt_buffer_read_block(&buf, &read, data_read, size));
+    EXPECT_EQ(size,read);
+    EXPECT_LE(DLT_RETURN_OK, dlt_buffer_free_dynamic(&buf));
+    free(data_read);
 }
 TEST(t_dlt_buffer_read_block, nullpointer)
 {