Add diff_string_lists utility function

Includes a unit test

2 files changed, 209 insertions, 0 deletions

diff --git a/src/util/util.c b/src/util/util.c
index 9a9731222..206984c7a 100644
--- a/src/util/util.c
+++ b/src/util/util.c
@@ -22,6 +22,7 @@
 
 #include "talloc.h"
 #include "util/util.h"
+#include "dhash.h"
 
 /* split a string into an allocated array of strings.
  * the separator is a string, and is case-sensitive.
@@ -235,3 +236,198 @@ fail:
     free_args(ret);
     return NULL;
 }
+
+
+
+/* Take two string lists (terminated on a NULL char*)
+ * and return up to three arrays of strings based on
+ * shared ownership.
+ *
+ * Pass NULL to any return type you don't care about
+ */
+errno_t diff_string_lists(TALLOC_CTX *memctx,
+                          char **_list1,
+                          char **_list2,
+                          char ***_list1_only,
+                          char ***_list2_only,
+                          char ***_both_lists)
+{
+    int error;
+    errno_t ret;
+    int i;
+    int i2 = 0;
+    int i12 = 0;
+    hash_table_t *table;
+    hash_key_t key;
+    hash_value_t value;
+    char **list1 = NULL;
+    char **list2 = NULL;
+    char **list1_only = NULL;
+    char **list2_only = NULL;
+    char **both_lists = NULL;
+    unsigned long count;
+    hash_key_t *keys;
+
+    TALLOC_CTX *tmp_ctx = talloc_new(memctx);
+    if (!tmp_ctx) {
+        return ENOMEM;
+    }
+
+    if (!_list1) {
+        list1 = talloc_array(tmp_ctx, char *, 1);
+        if (!list1) {
+            talloc_free(tmp_ctx);
+            return ENOMEM;
+        }
+        list1[0] = NULL;
+    }
+    else {
+        list1 = _list1;
+    }
+
+    if (!_list2) {
+        list2 = talloc_array(tmp_ctx, char *, 1);
+        if (!list2) {
+            talloc_free(tmp_ctx);
+            return ENOMEM;
+        }
+        list2[0] = NULL;
+    }
+    else {
+        list2 = _list2;
+    }
+
+    error = hash_create(10, &table, NULL, NULL);
+    if (error != HASH_SUCCESS) {
+        talloc_free(tmp_ctx);
+        return EIO;
+    }
+
+    key.type = HASH_KEY_STRING;
+    value.type = HASH_VALUE_UNDEF;
+
+    /* Add all entries from list 1 into a hash table */
+    i = 0;
+    while (list1[i]) {
+        key.str = talloc_strdup(tmp_ctx, list1[i]);
+        error = hash_enter(table, &key, &value);
+        if (error != HASH_SUCCESS) {
+            ret = EIO;
+            goto done;
+        }
+        i++;
+    }
+
+    /* Iterate through list 2 and remove matching items */
+    i = 0;
+    while (list2[i]) {
+        key.str = talloc_strdup(tmp_ctx, list2[i]);
+        error = hash_delete(table, &key);
+        if (error == HASH_SUCCESS) {
+            if (_both_lists) {
+                /* String was present in both lists */
+                i12++;
+                both_lists = talloc_realloc(tmp_ctx, both_lists, char *, i12+1);
+                if (!both_lists) {
+                    ret = ENOMEM;
+                    goto done;
+                }
+                both_lists[i12-1] = talloc_strdup(both_lists, list2[i]);
+                if (!both_lists[i12-1]) {
+                    ret = ENOMEM;
+                    goto done;
+                }
+
+                both_lists[i12] = NULL;
+            }
+        }
+        else if (error == HASH_ERROR_KEY_NOT_FOUND) {
+            if (_list2_only) {
+                /* String was present only in list2 */
+                i2++;
+                list2_only = talloc_realloc(tmp_ctx, list2_only,
+                                            char *, i2+1);
+                if (!list2_only) {
+                    ret = ENOMEM;
+                    goto done;
+                }
+                list2_only[i2-1] = talloc_strdup(list2_only, list2[i]);
+                if (!list2_only[i2-1]) {
+                    ret = ENOMEM;
+                    goto done;
+                }
+
+                list2_only[i2] = NULL;
+            }
+        }
+        else {
+            /* An error occurred */
+            ret = EIO;
+            goto done;
+        }
+        i++;
+    }
+
+    /* Get the leftover entries in the hash table */
+    if (_list1_only) {
+        error = hash_keys(table, &count, &keys);
+        if (error != HASH_SUCCESS) {
+            ret = EIO;
+            goto done;
+        }
+
+        list1_only = talloc_array(tmp_ctx, char *, count+1);
+        if (!list1_only) {
+            ret = ENOMEM;
+            goto done;
+        }
+
+        for (i = 0; i < count; i++) {
+            list1_only[i] = talloc_strdup(list1_only, keys[i].str);
+            if (!list1_only[i]) {
+                ret = ENOMEM;
+                goto done;
+            }
+        }
+        list1_only[count] = NULL;
+
+        free(keys);
+
+        *_list1_only = talloc_steal(memctx, list1_only);
+    }
+
+    if (_list2_only) {
+        if (list2_only) {
+            *_list2_only = talloc_steal(memctx, list2_only);
+        }
+        else {
+            *_list2_only = talloc_array(memctx, char *, 1);
+            if (!(*_list2_only)) {
+                ret = ENOMEM;
+                goto done;
+            }
+            *_list2_only[0] = NULL;
+        }
+    }
+
+    if (_both_lists) {
+        if (both_lists) {
+            *_both_lists = talloc_steal(memctx, both_lists);
+        }
+        else {
+            *_both_lists = talloc_array(memctx, char *, 1);
+            if (!(*_both_lists)) {
+                ret = ENOMEM;
+                goto done;
+            }
+            *_both_lists[0] = NULL;
+        }
+    }
+
+    ret = EOK;
+
+done:
+    hash_destroy(table);
+    talloc_free(tmp_ctx);
+    return ret;
+}
diff --git a/src/util/util.h b/src/util/util.h
index 3c95f7a20..da92ae68c 100644
--- a/src/util/util.h
+++ b/src/util/util.h
@@ -331,4 +331,17 @@ int split_on_separator(TALLOC_CTX *mem_ctx, const char *str,
                        const char sep, bool trim, char ***_list, int *size);
 
 char **parse_args(const char *str);
+
+/* Take two string lists (terminated on a NULL char*)
+ * and return up to three arrays of strings based on
+ * shared ownership.
+ *
+ * Pass NULL to any return type you don't care about
+ */
+errno_t diff_string_lists(TALLOC_CTX *memctx,
+                          char **string1,
+                          char **string2,
+                          char ***string1_only,
+                          char ***string2_only,
+                          char ***both_strings);
 #endif /* __SSSD_UTIL_H__ */