lokinet/llarp/util/file.hpp
Jason Rhinelander d335527a70
Add binary file slurp/dump utility functions
We have basically this same bit of code in tons of places; consolidate
it into llarp::util::slurp_file/llarp::util::dump_file.

Also renames all the extra junk that crept into llarp/util/fs.hpp out of
there into llarp/util/file.hpp instead.
2022-10-05 16:34:32 -03:00

104 lines
2.7 KiB
C++

#pragma once
#include "fs.hpp"
#include <optional>
#include <set>
#include <string>
#include <string_view>
#ifndef _MSC_VER
#include <dirent.h>
#endif
namespace llarp::util
{
/// Reads a binary file from disk into a string. Throws on error.
std::string
slurp_file(const fs::path& filename);
/// Reads a binary file from disk directly into a buffer. Throws a std::length_error if the
/// file is bigger than the buffer. Returns the bytes copied on success.
size_t
slurp_file(const fs::path& filename, char* buffer, size_t buffer_size);
/// Same, but for some non-char but single-byte char type (e.g. byte_t, std::byte, unsigned char).
template <
typename Char,
std::enable_if_t<sizeof(Char) == 1 and not std::is_same_v<Char, char>, int> = 1>
inline size_t
slurp_file(const fs::path& filename, Char* buffer, size_t buffer_size)
{
return slurp_file(filename, reinterpret_cast<char*>(buffer), buffer_size);
}
/// Dumps binary string contents to disk. The file is overwritten if it already exists. Throws
/// on error.
void
dump_file(const fs::path& filename, std::string_view contents);
/// Same as above, but works via char-like buffer
template <typename Char, std::enable_if_t<sizeof(Char) == 1, int> = 0>
inline void
dump_file(const fs::path& filename, const Char* buffer, size_t buffer_size)
{
return dump_file(
filename, std::string_view{reinterpret_cast<const char*>(buffer), buffer_size});
}
struct FileHash
{
size_t
operator()(const fs::path& f) const
{
std::hash<std::string> h;
return h(f.string());
}
};
using error_code_t = std::error_code;
/// Ensure that a file exists and has correct permissions
/// return any error code or success
error_code_t
EnsurePrivateFile(fs::path pathname);
/// open a stream to a file and ensure it exists before open
/// sets any permissions on creation
template <typename T>
std::optional<T>
OpenFileStream(fs::path pathname, std::ios::openmode mode)
{
if (EnsurePrivateFile(pathname))
return {};
return std::make_optional<T>(pathname, mode);
}
template <typename PathVisitor>
static void
IterDir(const fs::path& path, PathVisitor visit)
{
DIR* d = opendir(path.string().c_str());
if (d == nullptr)
return;
struct dirent* ent = nullptr;
std::set<fs::path> entries;
do
{
ent = readdir(d);
if (not ent)
break;
if (ent->d_name[0] == '.')
continue;
entries.emplace(path / fs::path{ent->d_name});
} while (ent);
closedir(d);
for (const auto& p : entries)
{
if (not visit(p))
return;
}
}
} // namespace llarp::util