lib: follow symlinks in maildirs

Until now, mu would _not_ follow symlinks; with these changes, we do.

There were some complications with that ~10 years ago, but I forgot the
details. So let's re-enable. At least one thing is in place now: moving
between file systems.

Fixes #1489
Fixes #1628 (technically, this came with slightly earlier commit)

lib/utils/mu-util.c

@@ -340,14 +340,21 @@ mu_util_play (const char *path, gboolean allow_local, gboolean allow_remote,
 
 
 unsigned char
-mu_util_get_dtype_with_lstat (const char *path)
+mu_util_get_dtype (const char *path, gboolean use_lstat)
 {
+	int res;
 	struct stat statbuf;
 
 	g_return_val_if_fail (path, DT_UNKNOWN);
 
-	if (lstat (path, &statbuf) != 0) {
-		g_warning ("stat failed on %s: %s", path, strerror(errno));
+	if (use_lstat)
+		res = lstat (path, &statbuf);
+	else
+		res = stat (path, &statbuf);
+
+	if (res != 0) {
+		g_warning ("%sstat failed on %s: %s",
+			   use_lstat ? "l" : "", path, strerror(errno));
 		return DT_UNKNOWN;
 	}
 
@@ -363,6 +370,7 @@ mu_util_get_dtype_with_lstat (const char *path)
 }
 
 
+
 gboolean
 mu_util_locale_is_utf8 (void)
 {

lib/utils/mu-util.h

@@ -257,15 +257,16 @@ enum {
 
 
 /**
- * get the d_type (as in direntry->d_type) for the file at path, using
-* lstat(3)
+ * get the d_type (as in direntry->d_type) for the file at path, using either
+ * stat(3) or lstat(3)
  *
  * @param path full path
+ * @param use_lstat whether to use lstat (otherwise use stat)
  *
- * @return DT_REG, DT_DIR, DT_LNK, or DT_UNKNOWN (other values are not
- * supported currently )
+ * @return DT_REG, DT_DIR, DT_LNK, or DT_UNKNOWN (other values are not supported
+ * currently )
  */
-unsigned char mu_util_get_dtype_with_lstat (const char *path);
+unsigned char mu_util_get_dtype (const char *path, gboolean use_lstat);
 
 
 /**

lib/utils/test-mu-util.c

@@ -165,11 +165,11 @@ static void
 test_mu_util_get_dtype_with_lstat (void)
 {
 	g_assert_cmpuint (
-		mu_util_get_dtype_with_lstat (MU_TESTMAILDIR), ==, DT_DIR);
+		mu_util_get_dtype (MU_TESTMAILDIR, TRUE), ==, DT_DIR);
 	g_assert_cmpuint (
-		mu_util_get_dtype_with_lstat (MU_TESTMAILDIR2), ==, DT_DIR);
+		mu_util_get_dtype (MU_TESTMAILDIR2, TRUE), ==, DT_DIR);
 	g_assert_cmpuint (
-		mu_util_get_dtype_with_lstat (MU_TESTMAILDIR2 "/Foo/cur/mail5"),
+		mu_util_get_dtype (MU_TESTMAILDIR2 "/Foo/cur/mail5", TRUE),
 		==, DT_REG);
 }