tests: Respect compression formats rpmio supports in module_index test

If rpm does not support all compression formats and libmodulemd is
configured with rpmio support, module_index_release test failed:

    $ MESON_SOURCE_ROOT=/tmp/libmodulemd-2.15.0 TEST_DATA_PATH=/tmp/libmodulemd-2.15.0/modulemd/tests/test_data /tmp/b/modulemd/module_index
    TAP version 14
    # random seed: R02Sf9e05b79de9e908ae8cb3de188499581
    1..18
    # Start of modulemd tests
    # Start of v2 tests
    # Start of module tests
    # Start of index tests
    ok 1 /modulemd/v2/module/index/dump
    ok 2 /modulemd/v2/module/index/read
    ok 3 /modulemd/v2/module/index/remove_module
    ok 4 /modulemd/v2/module/index/custom_read
    ok 5 /modulemd/v2/module/index/custom_write
    ok 6 /modulemd/v2/module/index/get_default_streams
    ok 7 /modulemd/v2/module/index/empty
    **
    libmodulemd:ERROR:../libmodulemd-2.15.0/modulemd/tests/test-modulemd-moduleindex.c:1493:test_module_index_read_compressed: assertion failed (error == NULL): Parser error (modulemd-yaml-error-quark, 2)
    not ok /modulemd/v2/module/index/compressed - libmodulemd:ERROR:../libmodulemd-2.15.0/modulemd/tests/test-modulemd-moduleindex.c:1493:test_module_index_read_compressed: assertion failed (error == NULL): Parser
    +error (modulemd-yaml-error-quark, 2)
    Bail out!

The test assumed that rpmio library supports all compression formats.
That's not guaranteed, the support is optional for each format.

This patch fixes it by probing rpmio library for each compression
format and if that does not work (rpmio returns compressed data), the
test will assume that that format is not supported.

Implementation details: The probing happens at run-time and thus links
the rpmio library to the the tests. Probing at configure time would
not work when crosscompiling.

Resolve: #630

Author: ppisar

modulemd/meson.build

@@ -377,6 +377,7 @@ foreach name, sources : c_tests
         sources,
         dependencies : [
             modulemd_dep,
+            rpm,
         ],
         link_with : [
             test_utils_lib,

modulemd/tests/test-modulemd-moduleindex.c

@@ -11,13 +11,18 @@
  * For more information on free software, see <https://www.gnu.org/philosophy/free-sw.en.html>.
  */
 
+#include "config.h"
+
 #include <glib.h>
 #include <glib/gstdio.h>
 #include <locale.h>
 #include <signal.h>
 #include <yaml.h>
 
-#include "config.h"
+#ifdef HAVE_RPMIO
+#include <rpm/rpmio.h>
+#endif
+
 #include "modulemd.h"
 #include "modulemd-defaults.h"
 #include "modulemd-obsoletes.h"
@@ -1377,6 +1382,10 @@ module_index_test_dump_empty_index (void)
 struct expected_compressed_read_t
 {
   const gchar *filename;
+#ifdef HAVE_RPMIO
+  /* Determines a compression type */
+  const gchar *rpmio_mode;
+#endif
 
   /* Whether this should succeed at reading */
   gboolean succeeds;
@@ -1386,6 +1395,33 @@ struct expected_compressed_read_t
   int error_code;
 };
 
+#ifdef HAVE_RPMIO
+/* Probe whether rpmio library supports that type of compression.
+ * @file_path is a file name to open
+ * @compression_type is rpmio mode string specifying the desired compression
+ * format.
+ * It assumes that an uncompressed content of the file starts with "---\n"
+ * string and checks the first chararter is '-'. That's because rpmio library
+ * silenty returns original, undecompressed, content if it does not support
+ * the compression format. */
+static gboolean
+rpmio_can_read_compressed_file (const gchar *file_path,
+                                const gchar *compression_type)
+{
+  FD_t rpmfd;
+  ssize_t read;
+  unsigned char buffer;
+
+  rpmfd = Fopen ((const char *)file_path, (const char *)compression_type);
+  g_assert_nonnull (rpmfd);
+  read = Fread (&buffer, sizeof (buffer), 1, rpmfd);
+  Fclose (rpmfd);
+  g_assert_cmpint (read, ==, 1);
+
+  return (buffer == (unsigned char)'-');
+}
+#endif
+
 static void
 test_module_index_read_compressed (void)
 {
@@ -1402,16 +1438,22 @@ test_module_index_read_compressed (void)
   struct expected_compressed_read_t expected[] = {
     {
       .filename = "bzipped",
+      .rpmio_mode = "r.bzdio",
       .succeeds = TRUE,
     },
     {
       .filename = "bzipped.yaml.bz2",
+      .rpmio_mode = "r.bzdio",
       .succeeds = TRUE,
     },
-    { .filename = "gzipped", .succeeds = TRUE },
-    { .filename = "gzipped.yaml.gz", .succeeds = TRUE },
-    { .filename = "xzipped", .succeeds = TRUE },
-    { .filename = "xzipped.yaml.xz", .succeeds = TRUE },
+    { .filename = "gzipped", .rpmio_mode = "r.gzdio", .succeeds = TRUE },
+    { .filename = "gzipped.yaml.gz",
+      .rpmio_mode = "r.gzdio",
+      .succeeds = TRUE },
+    { .filename = "xzipped", .rpmio_mode = "r.xzdio", .succeeds = TRUE },
+    { .filename = "xzipped.yaml.xz",
+      .rpmio_mode = "r.xzdio",
+      .succeeds = TRUE },
     { .filename = NULL }
   };
 
@@ -1475,6 +1517,19 @@ test_module_index_read_compressed (void)
                                    expected[i].filename);
       g_assert_nonnull (file_path);
 
+#ifdef HAVE_RPMIO
+      /* Support for various compression formats in RPMIO is optional. Probe
+       * the support first and set expected success/error accordingly. */
+      if (!rpmio_can_read_compressed_file (file_path, expected[i].rpmio_mode))
+        {
+          g_debug ("rpmio library does not support %s compression mode",
+                   expected[i].rpmio_mode);
+          expected[i].succeeds = FALSE;
+          expected[i].error_domain = MODULEMD_YAML_ERROR;
+          expected[i].error_code = MMD_YAML_ERROR_UNPARSEABLE;
+        }
+#endif
+
       g_debug ("Processing %s, expecting %s",
                file_path,
                expected[i].succeeds ? "success" : "failure");