Add NULL checks to memory allocation functions

strdup(), malloc(), realloc(), etc. may return NULL. Hence, the caller
should handle it to prevent NULL pointer exceptions.

This bug was discovered and resolved using Coverity Static Analysis
Security Testing (SAST) by Synopsys, Inc.

Signed-off-by: Metin Kaya <metikaya@amazon.co.uk>

linenoise.c

@@ -879,6 +879,7 @@ linenoiseCompletionCallback * linenoiseSetCompletionCallback(linenoiseCompletion
 
 void linenoiseAddCompletion(linenoiseCompletions *lc, const char *str) {
     lc->cvec = (char **)realloc(lc->cvec,sizeof(char*)*(lc->len+1));
+    assert(lc->cvec);
     lc->cvec[lc->len++] = strdup(str);
 }
 
@@ -1785,8 +1786,10 @@ static int linenoiseEdit(struct current *current) {
             if (history_len > 1) {
                 /* Update the current history entry before to
                  * overwrite it with tne next one. */
-                free(history[history_len - 1 - history_index]);
-                history[history_len - 1 - history_index] = strdup(sb_str(current->buf));
+                int index = history_len - 1 - history_index;
+                free(history[index]);
+                history[index] = strdup(sb_str(current->buf));
+                assert(history[index]);
                 /* Show the new entry */
                 history_index += dir;
                 if (history_index < 0) {
@@ -1951,6 +1954,7 @@ static int linenoiseHistoryAddAllocated(char *line) {
     }
     if (history == NULL) {
         history = (char **)calloc(sizeof(char*), history_max_len);
+        assert(history);
     }
 
     /* do not insert duplicate lines into history */
@@ -1969,7 +1973,9 @@ static int linenoiseHistoryAddAllocated(char *line) {
 }
 
 int linenoiseHistoryAdd(const char *line) {
-    return linenoiseHistoryAddAllocated(strdup(line));
+    char *new_line = strdup(line);
+    assert(new_line);
+    return linenoiseHistoryAddAllocated(new_line);
 }
 
 int linenoiseHistoryGetMaxLen(void) {
@@ -1984,6 +1990,7 @@ int linenoiseHistorySetMaxLen(int len) {
         int tocopy = history_len;
 
         newHistory = (char **)calloc(sizeof(char*), len);
+        assert(newHistory);
 
         /* If we can't copy everything, free the elements we'll not use. */
         if (len < tocopy) {
@@ -2049,6 +2056,7 @@ int linenoiseHistoryLoad(const char *filename) {
     while ((sb = sb_getline(fp)) != NULL) {
         /* Take the stringbuf and decode backslash escaped values */
         char *buf = sb_to_string(sb);
+        assert(buf);
         char *dest = buf;
         const char *src;
 

stringbuf.c

@@ -25,6 +25,7 @@
 stringbuf *sb_alloc(void)
 {
 	stringbuf *sb = (stringbuf *)malloc(sizeof(*sb));
+	assert(sb);
 	sb->remaining = 0;
 	sb->last = 0;
 #ifdef USE_UTF8