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housesprinkler_config.c
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housesprinkler_config.c
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/* housesprinkler - A simple home web server for sprinkler control
*
* Copyright 2020, Pascal Martin
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*
*
* housesprinkler_config.c - Access the sprinkler config.
*
* SYNOPSYS:
*
* const char *housesprinkler_config_load (int argc, const char **argv);
*
* Load the configuration from the specified config option, or else
* from the default config file.
*
* int housesprinkler_config_file (void);
* int housesprinkler_config_size (void);
*
* Return a file descriptor (and the size) of the configuration file
* being used.
*
* const char *housesprinkler_config_save (const char *text);
*
* Update both the live configuration and the configuration file with
* the provided text.
*
* int housesprinkler_config_exists (int parent, const char *path);
* const char *housesprinkler_config_string (int parent, const char *path);
* int housesprinkler_config_integer (int parent, const char *path);
* int housesprinkler_config_boolean (int parent, const char *path);
*
* Access individual items starting from the specified parent
* (the config root is index 0).
*
* int housesprinkler_config_array (int parent, const char *path);
* int housesprinkler_config_array_length (int array);
*
* Retrieve an array.
*
* int housesprinkler_config_enumerate (int parent, int *index);
*
* Retrieve the elements of an array or object.
*
* int housesprinkler_config_object (int parent, const char *path);
*
* Retrieve an object.
*
* const char *housesprinkler_config_name (void);
*
* Get the name of the current configuration file, for informational
* purpose (e.g. error messages).
*
* void housesprinkler_config_backup_register (BackupWorker *worker);
* long housesprinkler_config_backup_get (const char *path);
* const char *housesprinkler_config_backup_get_string (const char *path);
* void housesprinkler_config_backup_changed (void);
*
* Read from, and write to, the backup file. This backup file contains
* saved live values that can be changed from the user interface and must
* survive a program restart. Supported data types are boolean, integer and
* string (for now). A boolean is reported as an integer (0 or 1).
*
* Modules that need to backup data must register a worker function
* That populates the JSON structure.
*
* Note that saving the backup data is asynchronous: the client indicates
* that the data has changed, but saving the data will be decided later.
* The reason for this is that multiple clients might change their data
* at around the same time, but we do not want to save each time: it is
* better to delay and do the save only once.
*
* void housesprinkler_config_periodic (void);
*
* Background config activity (mostly: save data when changed).
*/
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <echttp_json.h>
#include "houselog.h"
#include "housesprinkler.h"
#include "housesprinkler_config.h"
#define DEBUG if (sprinkler_isdebug()) printf
static ParserToken *ConfigParsed = 0;
static int ConfigTokenAllocated = 0;
static int ConfigTokenCount = 0;
static char *ConfigText = 0;
static int ConfigTextSize = 0;
static int ConfigTextLength = 0;
static const char *ConfigFile = "/etc/house/sprinkler.json";
static const char FactoryDefaultsConfigFile[] =
"/usr/local/share/house/public/sprinkler/defaults.json";
static int UseFactoryDefaults = 0;
static ParserToken *BackupParsed = 0;
static int BackupTokenAllocated = 0;
static int BackupTokenCount = 0;
static char *BackupText = 0;
static const char *BackupFile = "/etc/house/sprinklerbkp.json";
static const char FactoryBackupFile[] =
"/usr/local/share/house/public/sprinkler/backup.json";
static int BackupDataHasChanged = 0;
static const char *housesprinkler_config_parse (char *text) {
int count = echttp_json_estimate(text);
if (count > ConfigTokenAllocated) {
if (ConfigParsed) free (ConfigParsed);
ConfigTokenAllocated = count;
ConfigParsed = calloc (ConfigTokenAllocated, sizeof(ParserToken));
}
ConfigTokenCount = ConfigTokenAllocated;
const char *error = echttp_json_parse (text, ConfigParsed, &ConfigTokenCount);
DEBUG ("Planned config for %d JSON tokens, got %d\n", ConfigTokenAllocated, ConfigTokenCount);
return error;
}
static void housesprinkler_config_loadbackup (void) {
char *newconfig;
if (BackupText) echttp_parser_free (BackupText);
BackupText = 0;
BackupTokenCount = 0;
const char *name = BackupFile;
DEBUG ("Loading backup from %s\n", name);
newconfig = echttp_parser_load (name);
if (!newconfig) {
name = FactoryBackupFile;
DEBUG ("Loading backup from %s\n", name);
newconfig = echttp_parser_load (name);
BackupDataHasChanged = 1; // Force creation of the backup file.
}
if (newconfig) {
const char *error;
houselog_event ("SYSTEM", "BACKUP", "LOAD", "FILE %s", name);
BackupText = newconfig;
BackupTokenCount = echttp_json_estimate(BackupText);
if (BackupTokenCount > BackupTokenAllocated) {
BackupTokenAllocated = BackupTokenCount+64;
if (BackupParsed) free (BackupParsed);
BackupParsed = calloc (BackupTokenAllocated, sizeof(ParserToken));
}
error = echttp_json_parse (BackupText, BackupParsed, &BackupTokenCount);
if (error) {
DEBUG ("Backup config parsing error: %s\n", error);
echttp_parser_free (BackupText);
BackupText = 0;
BackupTokenCount = 0;
} else {
DEBUG ("Planned %d, read %d items of backup config\n", BackupTokenAllocated, BackupTokenCount);
}
}
}
const char *housesprinkler_config_load (int argc, const char **argv) {
struct stat filestat;
int fd;
char *newconfig;
int i;
for (i = 1; i < argc; ++i) {
if (echttp_option_match ("-config=", argv[i], &ConfigFile)) continue;
if (echttp_option_match ("-backup=", argv[i], &BackupFile)) continue;
}
housesprinkler_config_loadbackup ();
DEBUG ("Loading config from %s\n", ConfigFile);
UseFactoryDefaults = 0;
newconfig = echttp_parser_load (ConfigFile);
if (!newconfig) {
DEBUG ("Loading config from %s\n", FactoryDefaultsConfigFile);
UseFactoryDefaults = 1;
newconfig = echttp_parser_load (FactoryDefaultsConfigFile);
if (!newconfig) return "not accessible";
houselog_event ("SYSTEM", "CONFIG", "LOAD",
"FILE %s", FactoryDefaultsConfigFile);
} else {
houselog_event ("SYSTEM", "CONFIG", "LOAD", "FILE %s", ConfigFile);
}
if (ConfigText) echttp_parser_free (ConfigText);
ConfigText = newconfig;
ConfigTextLength = strlen(ConfigText);
return housesprinkler_config_parse (ConfigText);
}
const char *housesprinkler_config_save (const char *text) {
int fd;
int length = strlen(text);
char *newconfig;
const char *error;
// Protect against bugs leading to the wrong string being used.
//
if (length < 10 || text[0] != '{') {
houselog_trace (HOUSE_FAILURE, "CONFIG",
"Invalid config string: %-0.60s (length %d)",
text, length);
return "invalid string";
}
newconfig = echttp_parser_string(text);
error = housesprinkler_config_parse (newconfig);
if (error) {
houselog_trace (HOUSE_FAILURE, "CONFIG",
"JSON error %s on %-0.60s", error, text);
free (newconfig);
return error;
}
if (ConfigText) echttp_parser_free (ConfigText);
ConfigText = newconfig;
ConfigTextLength = length;
DEBUG("Saving to %s: %s\n", ConfigFile, text);
fd = open (ConfigFile, O_WRONLY|O_TRUNC|O_CREAT, 0777);
if (fd < 0) {
char *desc = strdup(strerror(errno));
houselog_trace (HOUSE_FAILURE, "CONFIG",
"Cannot save to %s: %s", ConfigFile, desc);
free (desc);
return "cannot save to file";
}
write (fd, text, length);
close (fd);
UseFactoryDefaults = 0;
houselog_event ("SYSTEM", "CONFIG", "UPDATED", "FILE %s", ConfigFile);
return 0;
}
int housesprinkler_config_file (void) {
if (UseFactoryDefaults)
return open(FactoryDefaultsConfigFile, O_RDONLY);
return open(ConfigFile, O_RDONLY);
}
int housesprinkler_config_size (void) {
return ConfigTextLength;
}
int housesprinkler_config_find (int parent, const char *path, int type) {
int i;
if (parent < 0 || parent >= ConfigTokenCount) return -1;
i = echttp_json_search(ConfigParsed+parent, path);
if (i >= 0 && ConfigParsed[parent+i].type == type) return parent+i;
return -1;
}
int housesprinkler_config_exists (int parent, const char *path) {
if (parent < 0 || parent >= ConfigTokenCount) return 0;
return (echttp_json_search(ConfigParsed+parent, path) >= 0);
}
const char *housesprinkler_config_string (int parent, const char *path) {
int i = housesprinkler_config_find(parent, path, PARSER_STRING);
return (i >= 0) ? ConfigParsed[i].value.string : 0;
}
int housesprinkler_config_integer (int parent, const char *path) {
int i = housesprinkler_config_find(parent, path, PARSER_INTEGER);
return (i >= 0) ? ConfigParsed[i].value.integer : 0;
}
int housesprinkler_config_boolean (int parent, const char *path) {
int i = housesprinkler_config_find(parent, path, PARSER_BOOL);
return (i >= 0) ? ConfigParsed[i].value.bool : 0;
}
int housesprinkler_config_array (int parent, const char *path) {
return housesprinkler_config_find(parent, path, PARSER_ARRAY);
}
int housesprinkler_config_array_length (int array) {
if (array < 0
|| array >= ConfigTokenCount
|| ConfigParsed[array].type != PARSER_ARRAY) return 0;
return ConfigParsed[array].length;
}
int housesprinkler_config_enumerate (int parent, int *index) {
int i, length;
if (parent < 0 || parent >= ConfigTokenCount) return 0;
const char *error = echttp_json_enumerate (ConfigParsed+parent, index);
if (error) {
fprintf (stderr, "Cannot enumerate %s: %s\n",
ConfigParsed[parent].key, error);
return -1;
}
length = ConfigParsed[parent].length;
for (i = 0; i < length; ++i) index[i] += parent;
return length;
}
int housesprinkler_config_object (int parent, const char *path) {
return housesprinkler_config_find(parent, path, PARSER_OBJECT);
}
const char *housesprinkler_config_name (void) {
return ConfigFile;
}
const char *housesprinkler_config_backup_get_string (const char *path) {
int i = echttp_json_search(BackupParsed, path);
if (i < 0) return 0;
switch (BackupParsed[i].type) {
case PARSER_STRING: return BackupParsed[i].value.string;
}
return 0;
}
long housesprinkler_config_backup_get (const char *path) {
// Support boolean and integer, all converted to integer.
// Anything else: return 0
//
long value = 0;
int i = echttp_json_search(BackupParsed, path);
if (i < 0) return 0;
switch (BackupParsed[i].type) {
case PARSER_BOOL: value = BackupParsed[i].value.bool; break;
case PARSER_INTEGER: value = BackupParsed[i].value.integer; break;
}
return value;
}
// The backup mechanism relies on collaboration from the modules that
// need to backup data: only these modules know what data is to be saved.
// For the time being, assume that there is no more than 16 of these modules..
//
static BackupWorker *BackupRegistered[16];
static int BackupRegisteredCount = 0;
void housesprinkler_config_backup_register (BackupWorker *worker) {
int i;
if (! worker) return; // Just a check against gross error.
for (i = 0; i < BackupRegisteredCount; ++i) {
if (BackupRegistered[i] == worker) return; // Already registered.
}
if (BackupRegisteredCount < 16) {
BackupRegistered[BackupRegisteredCount++] = worker;
}
}
void housesprinkler_config_backup_changed (void) {
if (!BackupDataHasChanged)
DEBUG("Backup data has changed.\n");
BackupDataHasChanged = 1;
}
static int housesprinkler_config_backup_save (void) {
static char *buffer = 0;
static int size = 0;
int status = 1;
int cursor = 0;
int i;
if (!buffer) {
size = 1024;
buffer = malloc(size);
}
DEBUG("Saving backup data to %s\n", BackupFile);
const char *sep = "{";
for (i = 0; i < BackupRegisteredCount; ++i) {
cursor += snprintf (buffer+cursor, size-cursor, sep);
if (cursor >= size) goto abort;
cursor += BackupRegistered[i] (buffer+cursor, size-cursor);
if (cursor >= size) goto abort;
sep = ",";
}
cursor += snprintf (buffer+cursor, size-cursor, "}");
if (cursor >= size) goto abort;
int fd = open (BackupFile, O_WRONLY|O_TRUNC|O_CREAT, 0777);
if (fd < 0) {
DEBUG ("Cannot open %s\n", BackupFile);
return 0; // Failure.
}
int written = write (fd, buffer, cursor);
if (written < 0) {
DEBUG ("Cannot write to %s\n", BackupFile);
status = 0; // failure.
} else {
DEBUG ("Wrote %d characters to %s\n", written, BackupFile);
}
close(fd);
return status;
abort:
DEBUG ("Backup failed: buffer too small\n");
houselog_trace (HOUSE_FAILURE, "BACKUP",
"BUFFER TOO SMALL (NEED %d bytes)", cursor);
size += 1024;
free (buffer);
buffer = malloc(size);
return housesprinkler_config_backup_save (); // Retry.
}
void housesprinkler_config_periodic (void) {
if (BackupDataHasChanged) {
if (housesprinkler_config_backup_save()) BackupDataHasChanged = 0;
}
}