diff --git a/ev3dev.cpp b/ev3dev.cpp
index 6237e48..8f97efe 100644
--- a/ev3dev.cpp
+++ b/ev3dev.cpp
@@ -27,7 +27,6 @@
#include <iostream>
#include <sstream>
-#include <fstream>
#include <list>
#include <map>
#include <array>
@@ -38,7 +37,8 @@
#include <thread>
#include <stdexcept>
#include <string.h>
-#include <math.h>
+#include <cmath>
+#include <cstdio>
#include <dirent.h>
#include <sys/mman.h>
@@ -66,6 +66,160 @@ static const int bits_per_long = sizeof(long) * 8;
namespace ev3dev {
namespace {
+//-----------------------------------------------------------------------------
+class file_reader {
+ public:
+ file_reader() : f(0) {}
+
+ file_reader(file_reader &&other)
+ : fname(std::move(other.fname)), f(other.f)
+ {
+ other.f = 0;
+ }
+
+ ~file_reader() {
+ if (f) fclose(f);
+ }
+
+ bool is_open() const {
+ return f != 0;
+ }
+
+ void open(const std::string &_fname) {
+ fname = _fname;
+ f = fopen(fname.c_str(), "r");
+ setbuf(f, NULL);
+
+ if (!f) {
+ throw std::system_error(std::make_error_code(static_cast<std::errc>(errno)),
+ std::string("Failed to open \"") + fname + "\"");
+ }
+ }
+
+ std::string get_string() {
+ char buf[256];
+ try_read([this, &buf](){ return 1 == fscanf(f, "%255s", buf); });
+ return buf;
+ }
+
+ std::string get_line() {
+ char buf[256];
+ try_read([this, &buf](){
+ if (!fgets(buf, 255, f)) return false;
+ char *pos;
+ if ((pos=strchr(buf, '\n')) != NULL) *pos = '\0';
+ return true;
+ });
+ return buf;
+ }
+
+ int get_int() {
+ int v;
+ try_read([this, &v](){return 1 == fscanf(f, "%d", &v); });
+ return v;
+ }
+
+ void get_data(char *data, size_t count) {
+ try_read([this, &data, count](){ return count == fread(data, count, count, f); });
+ }
+ private:
+ std::string fname;
+ FILE *f;
+
+ void reopen() {
+ if (f) fclose(f);
+ f = fopen(fname.c_str(), "r");
+ setbuf(f, NULL);
+ }
+
+ template <class Callable>
+ void try_read(Callable w) {
+ for(int attempt = 0; attempt < 2; ++attempt) {
+ fseek(f, 0, SEEK_SET);
+
+ if (w()) return;
+
+ // Failed to read the value.
+ // This could mean the sysfs attribute was recreated and the
+ // corresponding file handle got stale. Lets close the file and try
+ // again (once):
+ if (attempt != 0) {
+ throw std::system_error(std::make_error_code(static_cast<std::errc>(errno)), fname);
+ }
+
+ reopen();
+ }
+ }
+};
+
+//-----------------------------------------------------------------------------
+class file_writer {
+ public:
+ file_writer() : f(0) {}
+
+ file_writer(file_writer &&other)
+ : fname(std::move(other.fname)), f(other.f)
+ {
+ other.f = 0;
+ }
+
+ ~file_writer() {
+ if (f) fclose(f);
+ }
+
+ bool is_open() const {
+ return f != 0;
+ }
+
+ void open(const std::string &_fname) {
+ fname = _fname;
+ f = fopen(fname.c_str(), "w");
+ setbuf(f, NULL);
+
+ if (!f) {
+ throw std::system_error(std::make_error_code(static_cast<std::errc>(errno)),
+ std::string("Failed to open \"") + fname + "\"");
+ }
+ }
+
+ void put_string(const std::string &v) {
+ try_write([this, &v](){ return EOF != fputs(v.c_str(), f); });
+ }
+
+ void put_int(int v) {
+ try_write([this, v](){ return fprintf(f, "%d", v) >= 0; });
+ }
+
+ private:
+ std::string fname;
+ FILE *f;
+
+ void reopen() {
+ if (f) fclose(f);
+ f = fopen(fname.c_str(), "w");
+ setbuf(f, NULL);
+ }
+
+ template <class Callable>
+ void try_write(Callable w) {
+ for(int attempt = 0; attempt < 2; ++attempt) {
+ fseek(f, 0, SEEK_SET);
+
+ if (w()) return;
+
+ // Failed to write the value.
+ // This could mean the sysfs attribute was recreated and the
+ // corresponding file handle got stale. Lets close the file and try
+ // again (once):
+ if (attempt != 0) {
+ throw std::system_error(std::make_error_code(static_cast<std::errc>(errno)), fname);
+ }
+
+ reopen();
+ }
+ }
+};
+
// This class implements a small LRU cache. It assumes the number of elements
// is small, and so uses a simple linear search.
template <typename K, typename V>
@@ -118,46 +272,24 @@ class lru_cache {
};
// A global cache of files.
-std::ifstream& ifstream_cache(const std::string &path) {
- static lru_cache<std::string, std::ifstream> cache(FSTREAM_CACHE_SIZE);
+file_reader& reader_cache(const std::string &path) {
+ static lru_cache<std::string, file_reader> cache(FSTREAM_CACHE_SIZE);
static std::mutex mx;
std::lock_guard<std::mutex> lock(mx);
- return cache[path];
+ file_reader &f = cache[path];
+ if (!f.is_open()) f.open(path);
+ return f;
}
-std::ofstream& ofstream_cache(const std::string &path) {
- static lru_cache<std::string, std::ofstream> cache(FSTREAM_CACHE_SIZE);
+file_writer& writer_cache(const std::string &path) {
+ static lru_cache<std::string, file_writer> cache(FSTREAM_CACHE_SIZE);
static std::mutex mx;
std::lock_guard<std::mutex> lock(mx);
- return cache[path];
-}
-
-//-----------------------------------------------------------------------------
-std::ofstream &ofstream_open(const std::string &path) {
- std::ofstream &file = ofstream_cache(path);
- if (!file.is_open()) {
- // Don't buffer writes to avoid latency. Also saves a bit of memory.
- file.rdbuf()->pubsetbuf(NULL, 0);
- file.open(path);
- } else {
- // Clear the error bits in case something happened.
- file.clear();
- }
- return file;
-}
-
-std::ifstream &ifstream_open(const std::string &path) {
- std::ifstream &file = ifstream_cache(path);
- if (!file.is_open()) {
- file.open(path);
- } else {
- // Clear the flags bits in case something happened (like reaching EOF).
- file.clear();
- file.seekg(0, std::ios::beg);
- }
- return file;
+ file_writer &f = cache[path];
+ if (!f.is_open()) f.open(path);
+ return f;
}
} // namespace
@@ -243,25 +375,7 @@ int device::get_attr_int(const std::string &name) const {
if (_path.empty())
throw system_error(make_error_code(errc::function_not_supported), "no device connected");
- for(int attempt = 0; attempt < 2; ++attempt) {
- ifstream &is = ifstream_open(_path + name);
- if (is.is_open()) {
- int result = 0;
- try {
- is >> result;
- return result;
- } catch(...) {
- // This could mean the sysfs attribute was recreated and the
- // corresponding file handle got stale. Lets close the file and try
- // again (once):
- if (attempt != 0) throw;
-
- is.close();
- is.clear();
- }
- } else break;
- }
- throw system_error(make_error_code(errc::no_such_device), _path+name);
+ return reader_cache(_path + name).get_int();
}
//-----------------------------------------------------------------------------
@@ -271,23 +385,7 @@ void device::set_attr_int(const std::string &name, int value) {
if (_path.empty())
throw system_error(make_error_code(errc::function_not_supported), "no device connected");
- for(int attempt = 0; attempt < 2; ++attempt) {
- ofstream &os = ofstream_open(_path + name);
- if (os.is_open()) {
- if (os << value) return;
-
- // An error could mean that sysfs attribute was recreated and the cached
- // file handle is stale. Lets close the file and try again (once):
- if (attempt == 0 && errno == ENODEV) {
- os.close();
- os.clear();
- } else {
- throw system_error(std::error_code(errno, std::system_category()));
- }
- } else {
- throw system_error(make_error_code(errc::no_such_device), _path + name);
- }
- }
+ writer_cache(_path + name).put_int(value);
}
//-----------------------------------------------------------------------------
@@ -297,14 +395,7 @@ std::string device::get_attr_string(const std::string &name) const {
if (_path.empty())
throw system_error(make_error_code(errc::function_not_supported), "no device connected");
- ifstream &is = ifstream_open(_path + name);
- if (is.is_open()) {
- string result;
- is >> result;
- return result;
- }
-
- throw system_error(make_error_code(errc::no_such_device), _path+name);
+ return reader_cache(_path + name).get_string();
}
//-----------------------------------------------------------------------------
@@ -314,13 +405,7 @@ void device::set_attr_string(const std::string &name, const std::string &value)
if (_path.empty())
throw system_error(make_error_code(errc::function_not_supported), "no device connected");
- ofstream &os = ofstream_open(_path + name);
- if (os.is_open()) {
- if (!(os << value)) throw system_error(std::error_code(errno, std::system_category()));
- return;
- }
-
- throw system_error(make_error_code(errc::no_such_device), _path+name);
+ writer_cache(_path + name).put_string(value);
}
//-----------------------------------------------------------------------------
@@ -330,14 +415,7 @@ std::string device::get_attr_line(const std::string &name) const {
if (_path.empty())
throw system_error(make_error_code(errc::function_not_supported), "no device connected");
- ifstream &is = ifstream_open(_path + name);
- if (is.is_open()) {
- string result;
- getline(is, result);
- return result;
- }
-
- throw system_error(make_error_code(errc::no_such_device), _path+name);
+ return reader_cache(_path + name).get_line();
}
//-----------------------------------------------------------------------------
@@ -513,14 +591,8 @@ const std::vector<char>& sensor::bin_data() const {
_bin_data.resize(num_values() * value_size);
}
- const string fname = _path + "bin_data";
- ifstream &is = ifstream_open(fname);
- if (is.is_open()) {
- is.read(_bin_data.data(), _bin_data.size());
- return _bin_data;
- }
-
- throw system_error(make_error_code(errc::no_such_device), fname);
+ reader_cache(_path + "bin_data").get_data(_bin_data.data(), _bin_data.size());
+ return _bin_data;
}
//-----------------------------------------------------------------------------