file cache: import the bare minimum implementation

This will act as the fallback implementation if no modern event monitoring
system API is available.

Signed-off-by: Josef 'Jeff' Sipek <[email protected]>

Author: jeffpc

CMakeLists.txt

@@ -92,6 +92,7 @@ add_library(jeffpc SHARED
 	buffer_stdio.c
 	cstr.c
 	error.c
+	file_cache.c
 	fmt_cbor.c
 	hexdump.c
 	init.c
@@ -156,6 +157,7 @@ install(FILES	include/jeffpc/atomic.h
 		include/jeffpc/buffer.h
 		include/jeffpc/cstr.h
 		include/jeffpc/error.h
+		include/jeffpc/file-cache.h
 		include/jeffpc/hexdump.h
 		include/jeffpc/int.h
 		include/jeffpc/io.h

file_cache.c

@@ -0,0 +1,65 @@
+/*
+ * Copyright (c) 2019 Josef 'Jeff' Sipek <[email protected]>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <jeffpc/file-cache.h>
+#include <jeffpc/io.h>
+
+/*
+ * This is the fallback implementation.  It doesn't actually do any caching,
+ * it simply reads the file contents every time.
+ */
+
+#pragma weak file_cache_init
+int file_cache_init(void)
+{
+	/* nothing to do */
+	return 0;
+}
+
+#pragma weak file_cache_get
+struct str *file_cache_get(const char *name, uint64_t *rev)
+{
+	struct stat statbuf;
+	char *tmp;
+
+	if (rev)
+		*rev = 0;
+
+	tmp = read_file_common(AT_FDCWD, name, &statbuf);
+	if (IS_ERR(tmp))
+		return ERR_CAST(tmp);
+
+	return str_alloc(tmp);
+}
+
+#pragma weak file_cache_has_newer
+bool file_cache_has_newer(const char *name, uint64_t rev)
+{
+	/* pretend that the file has changed to make the caller read it again */
+	return true;
+}
+
+#pragma weak file_cache_uncache_all
+void file_cache_uncache_all(void)
+{
+	/* nothing to do */
+}

include/jeffpc/file-cache.h

@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) 2019 Josef 'Jeff' Sipek <[email protected]>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef __JEFFPC_FILE_CACHE_H
+#define __JEFFPC_FILE_CACHE_H
+
+#include <jeffpc/int.h>
+#include <jeffpc/str.h>
+
+extern int file_cache_init(void);
+extern void file_cache_uncache_all(void);
+extern struct str *file_cache_get(const char *name, uint64_t *rev);
+extern bool file_cache_has_newer(const char *name, uint64_t rev);
+
+#endif

mapfile-vers

@@ -94,6 +94,12 @@ JEFFPC_0.10 {
 		save_stacktrace;
 		xstrerror;
 
+		# file cache
+		file_cache_get;
+		file_cache_has_newer;
+		file_cache_init;
+		file_cache_uncache_all;
+
 		# hexdump
 		hexdump;
 		hexdumpz;