[thin_check] Spot XML and be helpful.

functional-tests/functional-tests.scm

@@ -19,7 +19,8 @@
 
     assert-equal
     assert-eof
-    assert-starts-with)
+    assert-starts-with
+    assert-matches)
 
   (import
     (chezscheme)
@@ -27,6 +28,7 @@
     (list-utils)
     (logging)
     (process)
+    (regex)
     (temp-file)
     (utils)
     (srfi s8 receive))
@@ -215,6 +217,9 @@
                  (dsp ", ")
                  (wrt str)))))
 
+  (define (assert-matches pattern str)
+          (unless ((regex pattern) str)
+                  (fail (fmt #f "string should match: " pattern ", " str))))
 
   )
 

functional-tests/thin-functional-tests.scm

@@ -111,6 +111,19 @@
     (with-valid-metadata (md)
       (thin-check "--clear-needs-check-flag" md)))
 
+  (define-scenario (thin-check tiny-metadata)
+    "Prints helpful message in case XML metadata given"
+    (with-thin-xml (xml)
+      (receive (_ stderr) (run-fail "thin_check" xml)
+        (assert-starts-with "Metadata device/file too small.  Is this binary metadata?" stderr))))
+
+  (define-scenario (thin-check spot-accidental-xml-data)
+    "Prints helpful message if XML metadata given"
+    (with-thin-xml (xml)
+      (system (fmt #f "man bash >> " xml))
+      (receive (_ stderr) (run-fail "thin_check" xml)
+        (assert-matches ".*This looks like XML.  thin_check only checks the binary metadata format." stderr))))
+
   ;;;-----------------------------------------------------------
   ;;; thin_restore scenarios
   ;;;-----------------------------------------------------------

thin-provisioning/thin_check.cc

@@ -24,6 +24,7 @@
 
 #include "base/application.h"
 #include "base/error_state.h"
+#include "base/file_utils.h"
 #include "base/nested_output.h"
 #include "persistent-data/data-structures/btree_counter.h"
 #include "persistent-data/space-maps/core.h"
@@ -201,13 +202,25 @@ namespace {
 		return err;
 	}
 
-	error_state metadata_check(string const &path, flags fs) {
+	void check_for_xml(block_manager<>::ptr bm, nested_output &out) {
-		block_manager<>::ptr bm = open_bm(path);
+		block_manager<>::read_ref b = bm->read_lock(superblock_detail::SUPERBLOCK_LOCATION);
+		if (!strncmp(reinterpret_cast<const char *>(b.data()), "<superblock", 10))
+			out << "This looks like XML.  thin_check only checks the binary metadata format." << end_message();
+	}
 
+	error_state metadata_check(string const &path, flags fs) {
 		nested_output out(cerr, 2);
 		if (fs.quiet)
 			out.disable();
 
+		if (file_utils::get_file_length(path) < persistent_data::MD_BLOCK_SIZE) {
+			out << "Metadata device/file too small.  Is this binary metadata?"
+			    << end_message();
+			return FATAL;
+		}
+
+		block_manager<>::ptr bm = open_bm(path);
+
 		superblock_reporter sb_rep(out);
 		devices_reporter dev_rep(out);
 		mapping_reporter mapping_rep(out);
@@ -218,8 +231,10 @@ namespace {
 			check_superblock(bm, sb_rep);
 		}
 
-		if (sb_rep.get_error() == FATAL)
+		if (sb_rep.get_error() == FATAL) {
+			check_for_xml(bm, out);
 			return FATAL;
+		}
 
 		superblock_detail::superblock sb = read_superblock(bm);
 		transaction_manager::ptr tm = open_tm(bm);