Merge pull request #2639 from mpranj/mmapstorage-export

mmapstorage: add import/export compatibility
ElektraInitiative · Apr 22, 2019 · 096900b · 096900b
2 parents 90d0808 + 9b3c6f4
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diff --git a/doc/news/_preparation_next_release.md b/doc/news/_preparation_next_release.md
@@ -271,6 +271,11 @@ The following section lists news about the [modules](https://www.libelektra.org/
 - [cache](https://www.libelektra.org/plugins/cache) is a new global caching plugin. It uses [mmapstorage](https://www.libelektra.org/plugins/mmapstorage) as its storage backend and lazily stores keysets from previous ´kdbGet()´ calls. We added initial support for the default resolver and multifile resolver. _(Mihael Pranjić)_
 - Add check of resolved filenames, fixes false cache hits. _(Mihael Pranjić)_
 
+### mmapstorage
+
+- [mmapstorage](https://www.libelektra.org/plugins/mmapstorage) is now able to persist the Global KeySet, which is used by the `cache` plugin. _(Mihael Pranjić)_
+- Fixed support for `kdb import` and `kdb export`. _(Mihael Pranjić)_
+
 ## Libraries
 
 The text below summarizes updates to the [C (and C++)-based libraries](https://www.libelektra.org/libraries/readme) of Elektra.

diff --git a/src/plugins/mmapstorage/README.md b/src/plugins/mmapstorage/README.md
@@ -88,3 +88,8 @@ sudo kdb umount user/tests/mmapstorage
 ## Limitations
 
 Mapped files shall not be altered, otherwise the behavior is undefined.
+
+The `mmap()` system call only supports regular files and so does the mmapstorage
+plugin with one notable exception: The plugin detects when it is called with the
+files `/dev/stdin` and `/dev/stdout` and makes an internal copy. This makes the
+plugin compatible with `kdb import` and `kdb export`.
diff --git a/src/plugins/mmapstorage/internal.h b/src/plugins/mmapstorage/internal.h
@@ -37,9 +37,18 @@
 /** Mmap format version */
 #define ELEKTRA_MMAP_FORMAT_VERSION (1)
 
+/** Mmap temp file template */
+#define ELEKTRA_MMAP_TMP_NAME "/tmp/elektraMmapTmpXXXXXX"
+
+/** Buffer size for file I/O */
+#define ELEKTRA_MMAP_BUFSIZE (4096)
+
+#define STDOUT_FILENAME ("/dev/stdout")
+#define STDIN_FILENAME ("/dev/stdin")
+
 /** Suppress warnings in cache mode to debug level */
 #define ELEKTRA_MMAP_LOG_WARNING(...)                                                                                                      \
-	if (mode == MODE_GLOBALCACHE)                                                                                                      \
+	if (test_bit (mode, MODE_GLOBALCACHE))                                                                                             \
 	{                                                                                                                                  \
 		ELEKTRA_LOG_DEBUG (__VA_ARGS__);                                                                                           \
 	}                                                                                                                                  \