util/scfg: Simple config lib on top of sys/config

util/scfg/include/scfg/scfg.h

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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#ifndef H_SCFG_
+#define H_SCFG_
+
+#include "config/config.h"
+
+struct scfg_setting {
+    /** The name of the setting. */
+    const char *name;
+
+    /** Points to the RAM replica of the setting value. */
+    void *val;
+
+    /**
+     * Only needed for string settings.  Indicates the maximum length this
+     * setting's value can by.
+     */
+    int max_len;
+
+    /** This setting's data data.  One of the CONF_[...] constants. */
+    uint8_t type;
+
+    /**
+     * Whether this setting contains private data.  If 1, the value is hidden
+     * in config dump output.
+     */
+    uint8_t f_private : 1;
+};
+
+struct scfg_group {
+    /*** Public */
+    /** This array must be terminated with an `{ 0 }` entry. */
+    const struct scfg_setting *settings;
+
+    /*** Private */
+    struct conf_handler handler;
+};
+
+/**
+ * Persists a single setting.
+ *
+ * @param group                 The group that the setting belongs to.
+ * @param setting               The setting to save.
+ *
+ * @return                      0 on success; SYS_E[...] code on failure.
+ */
+int scfg_save_setting(const struct scfg_group *group,
+                      const struct scfg_setting *setting);
+
+/**
+ * Persists the setting with the specified name.
+ *
+ * @param group                 The group that the setting belongs to.
+ * @param setting_name          The name of the setting to save.
+ *
+ * @return                      0 on success; SYS_E[...] code on failure.
+ */
+int scfg_save_name(const struct scfg_group *group, const char *setting_name);
+
+/**
+ * Persists the setting whose value is stored in the specified variable.  The
+ * specified value address should be the same one that was specified in the
+ * `scfg_setting` definition.
+ *
+ * @param group                 The group that the setting belongs to.
+ * @param val                   The address of the setting's value variable.
+ *
+ * @return                      0 on success; SYS_E[...] code on failure.
+ */
+int scfg_save_val(const struct scfg_group *group, const void *val);
+
+/**
+ * Registers a group of configuration settings.  The group's public members
+ * must be populated before this function is called.
+ *
+ * @param group                 The group to register
+ * @param name                  The name of the settings group.
+ *
+ * @return                      0 on success; SYS_E[...] code on failure.
+ */
+int scfg_register(struct scfg_group *group, char *name);
+
+#endif

util/scfg/pkg.yml

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+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+# 
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+#
+
+pkg.name: util/scfg
+pkg.description: XXX
+pkg.deps:
+    - "@apache-mynewt-core/sys/config"

util/scfg/src/scfg.c

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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#include "os/mynewt.h"
+#include "scfg/scfg.h"
+
+#define SCFG_MAX_SETTING_ID_LEN    64
+#define SCFG_MAX_NUM_STR_LEN       (sizeof "18446744073709551615")
+
+#define SCFG_FOREACH_SETTING(group, s) \
+    for (s = (group)->settings; s->name != NULL; s++)
+
+static void
+scfg_setting_id(const char *group_name, const char *setting_name, char *buf)
+{
+    int setting_len;
+    int group_len;
+    int off;
+
+    group_len = strlen(group_name);
+    setting_len = strlen(setting_name);
+
+    /* <group>/<setting> */
+    assert(group_len + 1 + setting_len <= SCFG_MAX_SETTING_ID_LEN);
+
+    off = 0;
+
+    memcpy(&buf[off], group_name, group_len);
+    off += group_len;
+
+    buf[off] = '/';
+    off++;
+
+    memcpy(&buf[off], setting_name, setting_len);
+    off += setting_len;
+
+    buf[off] = '\0';
+    off++;
+}
+
+static struct scfg_setting *
+scfg_find_setting_by_name(const struct scfg_group *group,
+                          const char *setting_name)
+{
+    const struct scfg_setting *setting;
+
+    SCFG_FOREACH_SETTING(group, setting) {
+        if (strcmp(setting->name, setting_name) == 0) {
+            return (struct scfg_setting *)setting;
+        }
+    }
+
+    return NULL;
+}
+
+static struct scfg_setting *
+scfg_find_setting_by_val(const struct scfg_group *group, const void *val)
+{
+    const struct scfg_setting *setting;
+
+    SCFG_FOREACH_SETTING(group, setting) {
+        if (setting->val == val) {
+            return (struct scfg_setting *)setting;
+        }
+    }
+
+    return NULL;
+}
+
+/**
+ * Conf get handler.  Converts a setting's underlying variable to a string.
+ */
+static char *
+scfg_handler_get(int argc, char **argv, char *buf, int max_len, void *arg)
+{
+    const struct scfg_setting *setting;
+    struct scfg_group *group;
+
+    group = arg;
+
+    if (argc < 1) {
+        return NULL;
+    }
+
+    setting = scfg_find_setting_by_name(group, argv[0]);
+    if (setting == NULL) {
+        return NULL;
+    }
+
+    return conf_str_from_value(setting->type, setting->val, buf, max_len);
+}
+
+/**
+ * Conf set handler.  Converts from a string-representation and writes the
+ * result to the setting's underlying variable.
+ */
+static int
+scfg_handler_set(int argc, char **argv, char *val, void *arg)
+{
+    const struct scfg_setting *setting;
+    struct scfg_group *group;
+    int rc;
+
+    group = arg;
+
+    if (argc < 1) {
+        return SYS_EINVAL;
+    }
+
+    setting = scfg_find_setting_by_name(group, argv[0]);
+    if (setting == NULL) {
+        return SYS_ENOENT;
+    }
+
+    rc = conf_value_from_str(val, setting->type, setting->val,
+                             setting->max_len);
+    if (rc != 0) {
+        return os_error_to_sys(rc);
+    }
+
+    return 0;
+}
+
+static int
+scfg_handler_export(void (*func)(char *name, char *val),
+                    enum conf_export_tgt tgt, void *arg)
+{
+    const struct scfg_setting *setting;
+    struct scfg_group *group;
+    char val_buf[SCFG_MAX_NUM_STR_LEN];
+    char id_buf[SCFG_MAX_SETTING_ID_LEN];
+    char *val;
+
+    group = arg;
+
+    SCFG_FOREACH_SETTING(group, setting) {
+        scfg_setting_id(group->handler.ch_name, setting->name, id_buf);
+        if (setting->f_private) {
+            val = "<set>";
+        } else {
+            val = conf_str_from_value(setting->type, setting->val,
+                                      val_buf, sizeof val_buf);
+        }
+        func(id_buf, val);
+    }
+
+    return 0;
+}
+
+int
+scfg_save_setting(const struct scfg_group *group,
+                  const struct scfg_setting *setting)
+{
+    char id_buf[SCFG_MAX_SETTING_ID_LEN];
+    char val_buf[SCFG_MAX_NUM_STR_LEN];
+    char *val;
+    int rc;
+
+    val = conf_str_from_value(setting->type, setting->val,
+                              val_buf, sizeof val_buf);
+    if (val == NULL) {
+        return SYS_EUNKNOWN;
+    }
+
+    scfg_setting_id(group->handler.ch_name, setting->name, id_buf);
+
+    rc = conf_save_one(id_buf, val);
+    if (rc != 0) {
+        return os_error_to_sys(rc);
+    }
+
+    return 0;
+}
+
+int
+scfg_save_name(const struct scfg_group *group, const char *setting_name)
+{
+    const struct scfg_setting *setting;
+
+    setting = scfg_find_setting_by_name(group, setting_name);
+    if (setting == NULL) {
+        return SYS_ENOENT;
+    }
+
+    return scfg_save_setting(group, setting);
+}
+
+int
+scfg_save_val(const struct scfg_group *group, const void *val)
+{
+    const struct scfg_setting *setting;
+
+    setting = scfg_find_setting_by_val(group, val);
+    if (setting == NULL) {
+        return SYS_ENOENT;
+    }
+
+    return scfg_save_setting(group, setting);
+}
+
+int
+scfg_register(struct scfg_group *group, char *name)
+{
+    const struct scfg_setting *setting;
+    int rc;
+
+    SCFG_FOREACH_SETTING(group, setting) {
+        switch (setting->type) {
+        case CONF_INT8:
+        case CONF_INT16:
+        case CONF_INT32:
+        case CONF_INT64:
+        case CONF_STRING:
+        case CONF_BOOL:
+            break;
+
+        default:
+            /* We don't know how to (de)serialize the other data types. */
+            return SYS_EINVAL;
+        }
+    }
+
+    group->handler = (struct conf_handler) {
+        .ch_name = name,
+        .ch_get_ext = scfg_handler_get,
+        .ch_set_ext = scfg_handler_set,
+        .ch_export_ext = scfg_handler_export,
+        .ch_arg = group,
+        .ch_ext = true,
+    };
+
+    rc = conf_register(&group->handler);
+    if (rc != 0) {
+        return os_error_to_sys(rc);
+    }
+
+    return 0;
+}