minor compiler warning gcc 7.x (#30)

* Fix -Wpointer-compare of compare with null char

Signed-off-by: Phong Tran <tranmanphong@gmail.com>

* dlt_common: fix -Wformat-truncation of snprintf

Avoid snprintf output truncation by handling return value

Signed-off-by: Phong Tran <tranmanphong@gmail.com>

* dlt_offline_trace: Fix Wformat-truncation of snprintf

Compile with Gcc 7.x has the warning of snprintf buffer length size.
Check return value of snprintf() for avoiding the warning.

Signed-off-by: Phong Tran <tranmanphong@gmail.com>

* dlt_common_test: Fix memleak t_dlt_message_read

some resources were not free after using.
Detected by running

valgrind --leak-check=full ./gtest_dlt_common

Signed-off-by: Phong Tran <tranmanphong@gmail.com>

2 files changed, 24 insertions, 4 deletions

diff --git a/src/shared/dlt_common.c b/src/shared/dlt_common.c
index b98c7fa..818f3ef 100644
--- a/src/shared/dlt_common.c
+++ b/src/shared/dlt_common.c
@@ -186,8 +186,11 @@ DltReturnValue dlt_print_mixed_string(char *text, int textlength ,uint8_t *ptr,
     /* print full lines */
     for (lines=0; lines< (size / DLT_COMMON_HEX_CHARS); lines++)
     {
+        int ret = 0;
         /* Line number */
-        snprintf(text,DLT_COMMON_HEX_LINELEN+1,"%.6x: ",lines * DLT_COMMON_HEX_CHARS);
+        ret = snprintf(text,DLT_COMMON_HEX_LINELEN+1,"%.6x: ",lines * DLT_COMMON_HEX_CHARS);
+        if ((ret < 0 ) || (ret >= (DLT_COMMON_HEX_LINELEN + 1)))
+            dlt_log(LOG_WARNING, "line was truncated\n");
         text+=DLT_COMMON_HEX_LINELEN; /* 'XXXXXX: ' */
 
         /* Hex-Output */
@@ -222,7 +225,12 @@ DltReturnValue dlt_print_mixed_string(char *text, int textlength ,uint8_t *ptr,
     if (rest>0)
     {
         /* Line number */
-        snprintf(text,9,"%.6x: ", (size / DLT_COMMON_HEX_CHARS) * DLT_COMMON_HEX_CHARS);
+        int ret = 0;
+        ret = snprintf(text,9,"%.6x: ", (size / DLT_COMMON_HEX_CHARS) * DLT_COMMON_HEX_CHARS);
+        if ((ret < 0) || (ret >= 9))
+        {
+            dlt_log(LOG_WARNING, "line number was truncated");
+        }
         text+=DLT_COMMON_HEX_LINELEN; /* 'XXXXXX: ' */
 
         /* Hex-Output */
diff --git a/src/shared/dlt_offline_trace.c b/src/shared/dlt_offline_trace.c
index 32b5253..6b7a10a 100644
--- a/src/shared/dlt_offline_trace.c
+++ b/src/shared/dlt_offline_trace.c
@@ -216,6 +216,7 @@ DltReturnValue dlt_offline_trace_create_new_file(DltOfflineTrace *trace) {
     /* set filename */
     if(trace->filenameTimestampBased)
     {
+        int ret = 0;
         t = time(NULL);
         tmp = localtime(&t);
         if (NULL == tmp) {
@@ -224,16 +225,27 @@ DltReturnValue dlt_offline_trace_create_new_file(DltOfflineTrace *trace) {
         }
         if (strftime(outstr, sizeof(outstr),"%Y%m%d_%H%M%S", tmp) == 0) {
         }
-        snprintf(trace->filename, NAME_MAX + 1, "%s/dlt_offlinetrace_%s.dlt", trace->directory, outstr);
+        ret = snprintf(trace->filename, NAME_MAX , "%s/dlt_offlinetrace_%s.dlt", trace->directory, outstr);
+        if ((ret < 0) || (ret >= NAME_MAX))
+        {
+            printf("dlt_offlinetrace filename cannot be concatenated\n");
+            return DLT_RETURN_ERROR;
+        }
     }
     else
     {
+        int ret = 0;
         /* targeting newest file, ignoring number of files in dir returned */
         dlt_offline_trace_storage_dir_info(trace->directory, DLT_OFFLINETRACE_FILENAME_BASE, newest, oldest);
         idx = dlt_offline_trace_get_idx_of_log_file(newest) + 1;
 
         dlt_offline_trace_file_name(outstr, DLT_OFFLINETRACE_FILENAME_BASE, idx);
-        snprintf(trace->filename, NAME_MAX + 1, "%s/%s", trace->directory, outstr);
+        ret = snprintf(trace->filename, NAME_MAX, "%s/%s", trace->directory, outstr);
+        if ((ret < 0) || (ret >= NAME_MAX))
+        {
+            printf("filename cannot be concatenated\n");
+            return DLT_RETURN_ERROR;
+        }
     }