storage: Add initial set of utilities

Makefile.am

@@ -56,6 +56,7 @@ src_iwd_SOURCES = src/main.c linux/nl80211.h linux/kdbus.h \
 					src/scan.h src/scan.c \
 					src/util.h src/util.c \
 					src/agent.h src/agent.c \
+					src/storage.h src/storage.c \
 					iwd.h
 src_iwd_LDADD = ell/libell-internal.la
 

configure.ac

@@ -51,6 +51,23 @@ AC_ARG_ENABLE(pie, AC_HELP_STRING([--enable-pie],
 	fi
 ])
 
+if (test "${prefix}" = "NONE"); then
+	dnl no prefix and no localstatedir, so default to /var
+	if (test "$localstatedir" = '${prefix}/var'); then
+		AC_SUBST([localstatedir], ['/var'])
+	fi
+
+	prefix="${ac_default_prefix}"
+fi
+
+if (test "$localstatedir" = '${prefix}/var'); then
+	storagedir="${prefix}/var/lib/iwd"
+else
+	storagedir="${localstatedir}/lib/iwd"
+fi
+
+AC_DEFINE_UNQUOTED(STORAGEDIR, "${storagedir}",
+			[Directory for the storage files])
 AC_CHECK_HEADERS(linux/types.h linux/if_alg.h)
 
 AC_PATH_PROG(A2X, [a2x], [], $PATH:/sbin:/usr/sbin)

src/storage.c

@@ -0,0 +1,198 @@
+/*
+ *
+ *  Wireless daemon for Linux
+ *
+ *  Copyright (C) 2013-2015  Intel Corporation. All rights reserved.
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Lesser General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2.1 of the License, or (at your option) any later version.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#define _GNU_SOURCE
+#include <string.h>
+#include <stdarg.h>
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include <ell/ell.h>
+
+#include "storage.h"
+
+#ifdef TEMP_FAILURE_RETRY
+#define TFR TEMP_FAILURE_RETRY
+#else
+#define TFR
+#endif
+
+#define STORAGE_DIR_MODE (S_IRUSR | S_IWUSR | S_IXUSR)
+#define STORAGE_FILE_MODE (S_IRUSR | S_IWUSR)
+
+int create_dirs(const char *filename)
+{
+	struct stat st;
+	char *dir;
+	const char *prev, *next;
+	int err;
+
+	if (filename[0] != '/')
+		return -1;
+
+	err = stat(filename, &st);
+	if (!err && S_ISREG(st.st_mode))
+		return 0;
+
+	dir = l_malloc(strlen(filename) + 1);
+	strcpy(dir, "/");
+
+	for (prev = filename; (next = strchr(prev + 1, '/')); prev = next) {
+		/* Skip consecutive '/' characters */
+		if (next - prev == 1)
+			continue;
+
+		strncat(dir, prev + 1, next - prev);
+
+		if (mkdir(dir, STORAGE_DIR_MODE) == -1 && errno != EEXIST) {
+			l_free(dir);
+			return -1;
+		}
+	}
+
+	l_free(dir);
+	return 0;
+}
+
+ssize_t read_file(void *buffer, size_t len, const char *path_fmt, ...)
+{
+	va_list ap;
+	char *path;
+	ssize_t r;
+	int fd;
+
+	va_start(ap, path_fmt);
+	path = l_strdup_vprintf(path_fmt, ap);
+	va_end(ap);
+
+	fd = TFR(open(path, O_RDONLY));
+
+	l_free(path);
+
+	if (fd == -1)
+		return -1;
+
+	r = TFR(read(fd, buffer, len));
+
+	TFR(close(fd));
+
+	return r;
+}
+
+/*
+ * Write a buffer to a file in a transactionally safe form
+ *
+ * Given a buffer, write it to a file named after
+ * @path_fmt+args. However, to make sure the file contents are
+ * consistent (ie: a crash right after opening or during write()
+ * doesn't leave a file half baked), the contents are written to a
+ * file with a temporary name and when closed, it is renamed to the
+ * specified name (@path_fmt+args).
+ */
+ssize_t write_file(const void *buffer, size_t len,
+			const char *path_fmt, ...)
+{
+	va_list ap;
+	char *tmp_path, *path;
+	ssize_t r;
+	int fd;
+
+	va_start(ap, path_fmt);
+	path = l_strdup_vprintf(path_fmt, ap);
+	va_end(ap);
+
+	tmp_path = l_strdup_printf("%s.XXXXXX.tmp", path);
+
+	r = -1;
+	if (create_dirs(path) != 0)
+		goto error_create_dirs;
+
+	fd = TFR(mkostemps(tmp_path, 4, O_CLOEXEC));
+	if (fd == -1)
+		goto error_mkostemps;
+
+	r = TFR(write(fd, buffer, len));
+
+	TFR(close(fd));
+
+	if (r != (ssize_t) len) {
+		r = -1;
+		goto error_write;
+	}
+
+	/*
+	 * Now that the file contents are written, rename to the real
+	 * file name; this way we are uniquely sure that the whole
+	 * thing is there.
+	 */
+	unlink(path);
+
+	/* conserve @r's value from 'write' */
+	if (link(tmp_path, path) == -1)
+		r = -1;
+
+error_write:
+	unlink(tmp_path);
+error_mkostemps:
+error_create_dirs:
+	l_free(tmp_path);
+	l_free(path);
+	return r;
+}
+
+struct l_settings *storage_network_open(const char *type, const char *ssid)
+{
+	struct l_settings *settings;
+	char *path;
+
+	if (ssid == NULL || type == NULL)
+		return NULL;
+
+	/* TODO: Handle SSID's with filesystem-reserved characters */
+	path = l_strdup_printf(STORAGEDIR "/%s.%s", ssid, type);
+	settings = l_settings_new();
+
+	l_settings_load_from_file(settings, path);
+	l_free(path);
+
+	return settings;
+}
+
+void storage_network_sync(const char *type, const char *ssid,
+				struct l_settings *settings)
+{
+	char *data;
+	size_t length = 0;
+
+	/* TODO: Handle SSID's with filesystem-reserved characters */
+	data = l_settings_to_data(settings, &length);
+	write_file(data, length, STORAGEDIR "/%s.%s", ssid, type);
+	l_free(data);
+}

src/storage.h

@@ -0,0 +1,35 @@
+/*
+ *
+ *  Wireless daemon for Linux
+ *
+ *  Copyright (C) 2013-2015  Intel Corporation. All rights reserved.
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Lesser General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2.1 of the License, or (at your option) any later version.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+struct l_settings;
+
+int create_dirs(const char *filename);
+
+ssize_t read_file(void *buffer, size_t len, const char *path_fmt, ...)
+	__attribute__((format(printf, 3, 4)));
+
+ssize_t write_file(const void *buffer, size_t len, const char *path_fmt, ...)
+	__attribute__((format(printf, 3, 4)));
+
+struct l_settings *storage_network_open(const char *type, const char *ssid);
+void storage_network_sync(const char *type, const char *ssid,
+				struct l_settings *settings);