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-rw-r--r--ext/offbase/offbase.hpp393
1 files changed, 393 insertions, 0 deletions
diff --git a/ext/offbase/offbase.hpp b/ext/offbase/offbase.hpp
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+/*
+ * Offbase: a super-minimal in-filesystem JSON object persistence store
+ */
+
+#ifndef OFFBASE_HPP__
+#define OFFBASE_HPP__
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <dirent.h>
+#include <unistd.h>
+#include <sys/stat.h>
+
+#include <vector>
+#include <string>
+#include <map>
+
+#include "json/json.hpp"
+
+#define OFFBASE_PATH_SEP "/"
+
+/**
+ * A super-minimal in-filesystem JSON object persistence store
+ */
+class offbase : public nlohmann::json
+{
+public:
+ offbase(const char *p) :
+ nlohmann::json(nlohmann::json::object()),
+ _path(p),
+ _saved(nlohmann::json::object())
+ {
+ this->load();
+ }
+
+ ~offbase()
+ {
+ this->commit();
+ }
+
+ /**
+ * Load this instance from disk, clearing any existing contents first
+ *
+ * If the 'errors' vector is NULL, false is returned and reading aborts
+ * on any error. If this parameter is non-NULL the paths of errors will
+ * be added to the vector and reading will continue. False will only be
+ * returned on really big errors like no path being defined.
+ *
+ * @param errors If specified, fill this vector with the paths to any objects that fail read
+ * @return True on success, false on fatal error
+ */
+ inline bool load(std::vector<std::string> *errors = (std::vector<std::string> *)0)
+ {
+ if (!_path.length())
+ return false;
+ *this = nlohmann::json::object();
+ if (!_loadObj(_path,*this,errors))
+ return false;
+ _saved = *(reinterpret_cast<nlohmann::json *>(this));
+ return true;
+ }
+
+ /**
+ * Commit any pending changes to this object to disk
+ *
+ * @return True on success or false if an I/O error occurred
+ */
+ inline bool commit(std::vector<std::string> *errors = (std::vector<std::string> *)0)
+ {
+ if (!_path.length())
+ return false;
+ if (!_commitObj(_path,*this,&_saved,errors))
+ return false;
+ _saved = *(reinterpret_cast<nlohmann::json *>(this));
+ return true;
+ }
+
+ static inline std::string escapeKey(const std::string &k)
+ {
+ std::string e;
+ const char *ptr = k.data();
+ const char *eof = ptr + k.length();
+ char tmp[8];
+ while (ptr != eof) {
+ if ( ((*ptr >= 'a')&&(*ptr <= 'z')) || ((*ptr >= 'A')&&(*ptr <= 'Z')) || ((*ptr >= '0')&&(*ptr <= '9')) || (*ptr == '.') || (*ptr == '_') || (*ptr == '-') || (*ptr == ',') )
+ e.push_back(*ptr);
+ else {
+ snprintf(tmp,sizeof(tmp),"~%.2x",(unsigned int)*ptr);
+ e.append(tmp);
+ }
+ ++ptr;
+ }
+ return e;
+ }
+
+ static inline std::string unescapeKey(const std::string &k)
+ {
+ std::string u;
+ const char *ptr = k.data();
+ const char *eof = ptr + k.length();
+ char tmp[8];
+ while (ptr != eof) {
+ if (*ptr == '~') {
+ if (++ptr == eof) break;
+ tmp[0] = *ptr;
+ if (++ptr == eof) break;
+ tmp[1] = *(ptr++);
+ tmp[2] = (char)0;
+ u.push_back((char)strtol(tmp,(char **)0,16));
+ } else {
+ u.push_back(*(ptr++));
+ }
+ }
+ return u;
+ }
+
+private:
+ static inline bool _readFile(const char *path,std::string &buf)
+ {
+ char tmp[4096];
+ FILE *f = fopen(path,"rb");
+ if (f) {
+ for(;;) {
+ long n = (long)fread(tmp,1,sizeof(tmp),f);
+ if (n > 0)
+ buf.append(tmp,n);
+ else break;
+ }
+ fclose(f);
+ return true;
+ }
+ return false;
+ }
+
+ static inline bool _loadArr(const std::string &path,nlohmann::json &arr,std::vector<std::string> *errors)
+ {
+ std::map<unsigned long,nlohmann::json> atmp; // place into an ordered container first because filesystem does not guarantee this
+
+ struct dirent dbuf;
+ struct dirent *de;
+ DIR *d = opendir(path.c_str());
+ if (d) {
+ while (!readdir_d(d,&dbuf,&de)) {
+ if (!de) break;
+ const std::string name(de->d_name);
+ if (name.length() != 12) continue; // array entries are XXXXXXXXXX.T
+ if (name[name.length()-2] == '.') {
+ if (name[name.length()-1] == 'V') {
+ std::string buf;
+ if (_readFile((path + OFFBASE_PATH_SEP + name).c_str(),buf)) {
+ try {
+ atmp[strtoul(name.substr(0,10).c_str(),(char **)0,16)] = nlohmann::json::parse(buf);
+ } catch ( ... ) {
+ if (errors) {
+ errors->push_back(path + OFFBASE_PATH_SEP + name);
+ } else {
+ return false;
+ }
+ }
+ } else if (errors) {
+ errors->push_back(path + OFFBASE_PATH_SEP + name);
+ } else return false;
+ } else if (name[name.length()-1] == 'O') {
+ if (!_loadObj(path + OFFBASE_PATH_SEP + name,atmp[strtoul(name.substr(0,10).c_str(),(char **)0,16)] = nlohmann::json::object(),errors))
+ return false;
+ } else if (name[name.length()-1] == 'A') {
+ if (!_loadArr(path + OFFBASE_PATH_SEP + name,atmp[strtoul(name.substr(0,10).c_str(),(char **)0,16)] = nlohmann::json::array(),errors))
+ return false;
+ }
+ }
+ }
+ closedir(d);
+ } else if (errors) {
+ errors->push_back(path);
+ } else return false;
+
+ if (atmp.size() > 0) {
+ unsigned long lasti = 0;
+ for(std::map<unsigned long,nlohmann::json>::iterator i(atmp.begin());i!=atmp.end();++i) {
+ for(unsigned long k=lasti;k<i->first;++k) // fill any gaps with nulls
+ arr.push_back(nlohmann::json(std::nullptr_t));
+ lasti = i->first;
+ arr.push_back(i->second);
+ }
+ }
+
+ return true;
+ }
+
+ static inline bool _loadObj(const std::string &path,nlohmann::json &obj,std::vector<std::string> *errors)
+ {
+ struct dirent dbuf;
+ struct dirent *de;
+ DIR *d = opendir(path.c_str());
+ if (d) {
+ while (!readdir_d(d,&dbuf,&de)) {
+ if (!de) break;
+ if ((strcmp(de->d_name,".") == 0)||(strcmp(de->d_name,"..") == 0)) continue; // sanity check
+ const std::string name(de->d_name);
+ if (name.length() <= 2) continue;
+ if (name[name.length()-2] == '.') {
+ if (name[name.length()-1] == 'V') {
+ std::string buf;
+ if (_readFile((path + OFFBASE_PATH_SEP + name).c_str(),buf)) {
+ try {
+ obj[unescapeKey(name)] = nlohmann::json::parse(buf);
+ } catch ( ... ) {
+ if (errors) {
+ errors->push_back(path + OFFBASE_PATH_SEP + name);
+ } else {
+ return false;
+ }
+ }
+ } else if (errors) {
+ errors->push_back(path + OFFBASE_PATH_SEP + name);
+ } else return false;
+ } else if (name[name.length()-1] == 'O') {
+ if (!_loadObj(path + OFFBASE_PATH_SEP + name,obj[unescapeKey(name)] = nlohmann::json::object(),errors))
+ return false;
+ } else if (name[name.length()-1] == 'A') {
+ if (!_loadArr(path + OFFBASE_PATH_SEP + name,obj[unescapeKey(name)] = nlohmann::json::array(),errors))
+ return false;
+ }
+ }
+ }
+ closedir(d);
+ } else if (errors) {
+ errors->push_back(path);
+ } else return false;
+ return true;
+ }
+
+ static inline void _rmDashRf(const std::string &path)
+ {
+ struct dirent dbuf;
+ struct dirent *de;
+ DIR *d = opendir(path.c_str());
+ if (d) {
+ while (!readdir_r(d,&dbuf,&de)) {
+ if (!de) break;
+ if ((strcmp(de->d_name,".") == 0)||(strcmp(de->d_name,"..") == 0)) continue; // sanity check
+ const std::string full(path + OFFBASE_PATH_SEP + de->d_name);
+ if (unlink(full.c_str())) {
+ _rmDashRf(full);
+ rmdir(full.c_str());
+ }
+ }
+ closedir(d);
+ }
+ rmdir(path.c_str());
+ }
+
+ static inline bool _commitArr(const std::string &path,const nlohmann::json &arr,const nlohmann::json *previous,std::vector<std::string> *errors)
+ {
+ char tmp[32];
+
+ if (!arr.is_array())
+ return false;
+
+ mkdir(path.c_str(),0755);
+
+ for(unsigned long i=0;i<(unsigned long)arr.size();++i) {
+ const nlohmann::json &value = arr[i];
+
+ const nlohmann::json *next = (const nlohmann::json *)0;
+ if ((previous)&&(previous->is_array())&&(i < previous->size())) {
+ next = &((*previous)[i]);
+ if (*next == value)
+ continue;
+ }
+
+ if (value.is_object()) {
+ snprintf(tmp,sizeof(tmp),"%s%.10lx.O",OFFBASE_PATH_SEP,i);
+ if (!_commitObj(path + tmp,value,next,errors))
+ return false;
+ snprintf(tmp,sizeof(tmp),"%s%.10lx.V",OFFBASE_PATH_SEP,i);
+ unlink((path + tmp).c_str());
+ snprintf(tmp,sizeof(tmp),"%s%.10lx.A",OFFBASE_PATH_SEP,i);
+ _rmDashRf(path + tmp);
+ } else if (value.is_array()) {
+ snprintf(tmp,sizeof(tmp),"%s%.10lx.A",OFFBASE_PATH_SEP,i);
+ if (!_commitArr(path + tmp,value,next,errors))
+ return false;
+ snprintf(tmp,sizeof(tmp),"%s%.10lx.O",OFFBASE_PATH_SEP,i);
+ _rmDashRf(path + tmp);
+ snprintf(tmp,sizeof(tmp),"%s%.10lx.V",OFFBASE_PATH_SEP,i);
+ unlink((path + tmp).c_str());
+ } else {
+ snprintf(tmp,sizeof(tmp),"%s%.10lx.V",OFFBASE_PATH_SEP,i);
+ FILE *f = fopen((path + tmp).c_str(),"w");
+ if (f) {
+ const std::string v(value.dump());
+ if (fwrite(v.c_str(),v.length(),1,f) != 1) {
+ fclose(f);
+ return false;
+ } else {
+ fclose(f);
+ }
+ } else {
+ return false;
+ }
+ snprintf(tmp,sizeof(tmp),"%s%.10lx.A",OFFBASE_PATH_SEP,i);
+ _rmDashRf(path + tmp);
+ snprintf(tmp,sizeof(tmp),"%s%.10lx.O",OFFBASE_PATH_SEP,i);
+ _rmDashRf(path + tmp);
+ }
+ }
+
+ if ((previous)&&(previous->is_array())) {
+ for(unsigned long i=(unsigned long)arr.size();i<(unsigned long)previous->size();++i) {
+ snprintf(tmp,sizeof(tmp),"%s%.10lx.V",OFFBASE_PATH_SEP,i);
+ unlink((path + tmp).c_str());
+ snprintf(tmp,sizeof(tmp),"%s%.10lx.A",OFFBASE_PATH_SEP,i);
+ _rmDashRf(path + tmp);
+ snprintf(tmp,sizeof(tmp),"%s%.10lx.O",OFFBASE_PATH_SEP,i);
+ _rmDashRf(path + tmp);
+ }
+ }
+
+ return true;
+ }
+
+ static inline bool _commitObj(const std::string &path,const nlohmann::json &obj,const nlohmann::json *previous,std::vector<std::string> *errors)
+ {
+ if (!obj.is_object())
+ return false;
+
+ mkdir(path.c_str(),0755);
+
+ for(nlohmann::json::const_iterator i(obj.begin());i!=obj.end();++i) {
+ if (i.key().length() == 0)
+ continue;
+
+ const nlohmann::json *next = (const nlohmann::json *)0;
+ if ((previous)&&(previous->is_object())) {
+ nlohmann::json::const_iterator saved(previous->find(i.key()));
+ if (saved != previous->end()) {
+ next = &(saved.value());
+ if (i.value() == *next)
+ continue;
+ }
+ }
+
+ const std::string keyp(path + OFFBASE_PATH_SEP + escapeKey(i.key()));
+ if (i.value().is_object()) {
+ if (!_commitObj(keyp + ".O",i.value(),next,errors))
+ return false;
+ unlink((keyp + ".V").c_str());
+ _rmDashRf(keyp + ".A");
+ } else if (i.value().is_array()) {
+ if (!_commitArr(keyp + ".A",i.value(),next,errors))
+ return false;
+ unlink((keyp + ".V").c_str());
+ _rmDashRf(keyp + ".O");
+ } else {
+ FILE *f = fopen((keyp + ".V").c_str(),"w");
+ if (f) {
+ const std::string v(i.value().dump());
+ if (fwrite(v.c_str(),v.length(),1,f) != 1) {
+ fclose(f);
+ return false;
+ } else {
+ fclose(f);
+ }
+ } else {
+ return false;
+ }
+ _rmDashRf(keyp + ".A");
+ _rmDashRf(keyp + ".O");
+ }
+ }
+
+ if ((previous)&&(previous->is_object())) {
+ for(nlohmann::json::const_iterator i(previous->begin());i!=previous->end();++i) {
+ if ((i.key().length() > 0)&&(obj.find(i.key()) == obj.end())) {
+ const std::string keyp(path + OFFBASE_PATH_SEP + escapeKey(i.key()));
+ unlink((keyp + ".V").c_str());
+ _rmDashRf(keyp + ".A");
+ _rmDashRf(keyp + ".O");
+ }
+ }
+ }
+
+ return true;
+ }
+
+ std::string _path;
+ nlohmann::json _saved;
+};
+
+#endif
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