Merge branch 'wip/smcv/2452-g-string-0-length-replace' into 'main'

g_string_replace: Don't replace empty string more than once per location

Closes #2452

See merge request GNOME/glib!2208

2 files changed, 72 insertions, 24 deletions

diff --git a/glib/gstring.c b/glib/gstring.c
index ad2ec1771..da9c5f7ab 100644
--- a/glib/gstring.c
+++ b/glib/gstring.c
@@ -966,6 +966,11 @@ g_string_erase (GString *string,
  * less than @limit, all instances are replaced. If @limit is `0`,
  * all instances of @find are replaced.
  *
+ * If @find is the empty string, since versions 2.69.1 and 2.68.4 the
+ * replacement will be inserted no more than once per possible position
+ * (beginning of string, end of string and between characters). This did
+ * not work correctly in earlier versions.
+ *
  * Returns: the number of find and replace operations performed.
  *
  * Since: 2.68
@@ -995,6 +1000,15 @@ g_string_replace (GString     *string,
       g_string_insert (string, pos, replace);
       cur = string->str + pos + r_len;
       n++;
+      /* Only match the empty string once at any given position, to
+       * avoid infinite loops */
+      if (f_len == 0)
+        {
+          if (cur[0] == '\0')
+            break;
+          else
+            cur++;
+        }
       if (n == limit)
         break;
     }
diff --git a/glib/tests/string.c b/glib/tests/string.c
index 6e22cd287..24098d1be 100644
--- a/glib/tests/string.c
+++ b/glib/tests/string.c
@@ -498,30 +498,64 @@ test_string_to_bytes (void)
 static void
 test_string_replace (void)
 {
-  GString *s;
-  gint n;
-
-  s = g_string_new ("foo bar foo baz foo bar foobarbaz");
-
-  n = g_string_replace (s, "bar", "baz", 0);
-  g_assert_cmpstr ("foo baz foo baz foo baz foobazbaz", ==, s->str);
-  g_assert_cmpint (n, ==, 3);
-
-  n = g_string_replace (s, "baz", "bar", 3);
-  g_assert_cmpstr ("foo bar foo bar foo bar foobazbaz", ==, s->str);
-  g_assert_cmpint (n, ==, 3);
-
-  n = g_string_replace (s, "foobar", "bar", 1);
-  g_assert_cmpstr ("foo bar foo bar foo bar foobazbaz", ==, s->str);
-  g_assert_cmpint (n, ==, 0);
-
-  s = g_string_assign (s, "aaaaaaaa");
-  n = g_string_replace (s, "a", "abcdefghijkl", 0);
-  g_assert_cmpstr ("abcdefghijklabcdefghijklabcdefghijklabcdefghijklabcdefghijklabcdefghijklabcdefghijklabcdefghijkl",
-                   ==, s->str);
-  g_assert_cmpint (n, ==, 8);
-
-  g_string_free (s, TRUE);
+  static const struct
+  {
+    const char *string;
+    const char *original;
+    const char *replacement;
+    guint limit;
+    const char *expected;
+    guint expected_n;
+  }
+  tests[] =
+  {
+    { "foo bar foo baz foo bar foobarbaz", "bar", "baz", 0,
+      "foo baz foo baz foo baz foobazbaz", 3 },
+    { "foo baz foo baz foo baz foobazbaz", "baz", "bar", 3,
+      "foo bar foo bar foo bar foobazbaz", 3 },
+    { "foo bar foo bar foo bar foobazbaz", "foobar", "bar", 1,
+      "foo bar foo bar foo bar foobazbaz", 0 },
+    { "aaaaaaaa", "a", "abcdefghijkl", 0,
+      "abcdefghijklabcdefghijklabcdefghijklabcdefghijklabcdefghijklabcdefghijklabcdefghijklabcdefghijkl",
+      8 },
+    { "/usr/$LIB/libMangoHud.so", "$LIB", "lib32", 0,
+      "/usr/lib32/libMangoHud.so", 1 },
+    { "food for foals", "o", "", 0,
+      "fd fr fals", 4 },
+    { "aaa", "a", "aaa", 0,
+      "aaaaaaaaa", 3 },
+    { "aaa", "a", "", 0,
+      "", 3 },
+    { "aaa", "aa", "bb", 0,
+      "bba", 1 },
+    { "foo", "", "bar", 0,
+      "barfbarobarobar", 4 },
+    { "", "", "x", 0,
+      "x", 1 },
+    { "", "", "", 0,
+      "", 1 },
+  };
+  gsize i;
+
+  for (i = 0; i < G_N_ELEMENTS (tests); i++)
+    {
+      GString *s;
+      guint n;
+
+      s = g_string_new (tests[i].string);
+      g_test_message ("%" G_GSIZE_FORMAT ": Replacing \"%s\" with \"%s\" (limit %u) in \"%s\"",
+                      i, tests[i].original, tests[i].replacement,
+                      tests[i].limit, tests[i].string);
+      n = g_string_replace (s, tests[i].original, tests[i].replacement,
+                            tests[i].limit);
+      g_test_message ("-> %u replacements, \"%s\"",
+                      n, s->str);
+      g_assert_cmpstr (tests[i].expected, ==, s->str);
+      g_assert_cmpuint (strlen (tests[i].expected), ==, s->len);
+      g_assert_cmpuint (strlen (tests[i].expected) + 1, <=, s->allocated_len);
+      g_assert_cmpuint (tests[i].expected_n, ==, n);
+      g_string_free (s, TRUE);
+    }
 }
 
 int