Resize array in remove_from_array() and fix a crash

When an item is added to an array, then the array is realloc()ed (to size+1), and the item is copied (strdup()) to the array. Thus, when an item is removed from an array, allocated memory pointed by the item (not the item itself) should be freed, successive items should be left-shifted and the array realloc()ed again (size-1). Additional changes: - Initialize an array in list_all_containers(). Signed-off-by: Tomasz Blaszczak <tomasz.blaszczak@consult.red>

Resize array in remove_from_array() and fix a crash
5364ae41 · Tomasz Blaszczak · fe444ea6 · 5364ae41
Commit 5364ae41 authored Jun 25, 2021 by Tomasz Blaszczak
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Showing with 10 additions and 8 deletions

lxccontainer.c src/lxc/lxccontainer.c +10 -8

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--- a/src/lxc/lxccontainer.c
+++ b/src/lxc/lxccontainer.c
@@ -2262,7 +2262,7 @@ static inline int container_cmp(struct lxc_container **first,
 static bool add_to_array(char ***names, char *cname, int pos)
 {
-	char **newnames = realloc(*names, (pos+1) * sizeof(char *));
+	char **newnames = (char**)realloc(*names, (pos+1) * sizeof(char *));
 	if (!newnames) {
 		ERROR("Out of memory");
 		return false;
@@ -2270,10 +2270,8 @@ static bool add_to_array(char ***names, char *cname, int pos)
 	*names = newnames;
 	newnames[pos] = strdup(cname);
-	if (!newnames[pos]) {
+	if (!newnames[pos])
-		*names = (char**)realloc(*names, (pos) * sizeof(char *));
 		return false;
-	}
 	/* Sort the array as we will use binary search on it. */
 	qsort(newnames, pos + 1, sizeof(char *),
@@ -2322,12 +2320,16 @@ static bool remove_from_array(char ***names, char *cname, int size)
 {
 	char **result = get_from_array(names, cname, size);
 	if (result != NULL) {
-		int i;
+		size_t i = result - *names;
-		for (i = 0; (*names)[i] != *result && i < size; i++) {
-		}
 		free(*result);
 		memmove(*names+i, *names+i+1, (size-i-1) * sizeof(char*));
-		*names = (char**)realloc(*names, (size-1) * sizeof(char *));
+		char **newnames = (char**)realloc(*names, (size-1) * sizeof(char *));
+		if (!newnames) {
+			ERROR("Out of memory");
+			return false;
+		}
+		*names = newnames;
 		return true;
 	}