tmp

RAII-wrappers for unique temporary files and directories that are deleted automatically for C++17 and later.

This library provides functionality for efficient management of temporary files and directories in long-running applications, automatically deleting them as soon as your app is done with them to optimize resource management.

Overview

When developing applications with long uptimes, such as server software, the management of temporary files and directories can become crucial. While the system may eventually clean up temporary files, this process may not occur frequently enough to meet the needs of applications with extended operational periods. Relying solely on the system for this task may lead to an accumulation of unnecessary temporary data on the device.

To address this challenge, this library provides functionality for creating temporary files and directories that are automatically deleted as soon as the application finishes using them. This ensures efficient resource management and prevents unnecessary clutter. Even in the event of a crash, the system will eventually clean up any temporary files created by this library, ensuring a seamless user experience and optimal performance.

The location of temporary files generated by this library is determined by the std::filesystem::temp_directory_path function.

This library has been tested on:

• macOS
• Linux systems (e.g. Ubuntu Linux, Arch Linux, etc.)
• FreeBSD (and should work on other BSD systems too)
• Windows

Features

Temporary directories

tmp::directory is a smart handle that manages a temporary directory, ensuring its recursive deletion when the handle goes out of scope. When a tmp::directory object is created, it generates a unique temporary directory in the current user's temporary directory.

The temporary directory is deleted when either of the following happens:

• the tmp::directory object is destroyed
• the tmp::directory object is assigned another directory using operator=

The example below demonstrates a usage of a tmp::directory object to run a subprocess within it and archive its logs; when the function returns, the temporary directory is recursively deleted:

#include <tmp/directory>

auto func() {
  auto tmpdir = tmp::directory("org.example.product");
  process::exec(executable, args, tmpdir);

  return archive::glob(tmpdir, "*.log");

  // The temporary directory is deleted recursively when the
  // tmp::directory object goes out of scope
}

Temporary files

tmp::file is a smart handle that manages a temporary file, ensuring its deletion when the handle goes out of scope. Upon creation, a tmp::file object generates a unique temporary file in the current user's temporary directory, opening it for both reading and writing.

The temporary file is deleted of when either of the following happens:

• the tmp::file object is destroyed
• the tmp::file object is assigned another file using operator=

tmp::file inherits from the std::iostream class, allowing it to be used seamlessly with standard input/output operations and simplifying file handling while maintaining the flexibility of stream operations.

The example below demonstrates a usage of a tmp::file object to validate a request content and then move it to persistent storage; note that after the move() call, the temporary file will not be deleted, as its ownership is transferred to the specified location:

#include <tmp/file>

auto func(std::string_view content) {
  auto tmpfile = tmp::file(std::ios::binary);
  tmpfile << contents << std::flush;
  if (validate(tmpfile)) {
    // Save the file to the persistent storage
    tmpfile.move(storage / "new_file");
  } else {
    // The file is deleted automatically
    throw InvalidRequestError();
  }
}

Building

To build the project without tests, use the -DBUILD_TESTING=OFF flag:

cmake -B build -DBUILD_TESTING=OFF && cmake --build build

To build the project with tests, run:

cmake -B build && cmake --build build --target tmp.test

To run tests:

ctest --output-on-failure --test-dir build

Installing

To install the project, configure it in the Release configuration:

cmake -B build -DCMAKE_BUILD_TYPE=Release -DBUILD_TESTING=OFF -DBUILD_SHARED_LIBS=ON

build it:

cmake --build build

and then install:

sudo cmake --install build

OR use dpkg package manager (requires dpkg-shlibdeps):

cd build && cpack -G DEB && sudo dpkg -i *.deb

OR use rpm package manager (requires rpmbuild):

cd build && cpack -G RPM && sudo rpm -i *.rpm

Package managers

If you are using homebrew, use the following command:

brew install bugdea1er/tap/tmp

Integration

CMake integration

You can also use the CMake interface target tmp::tmp and described below:

External

To use this library from a CMake project, locate it using find_package:

find_package(tmp REQUIRED)
# ...
add_library(foo ...)
target_link_libraries(foo PUBLIC tmp::tmp)

Embedded

To embed the library into your existing CMake project, place the entire source tree in a subdirectory (for example, using git submodule commands) and call add_subdirectory() in your CMakeLists.txt file:

add_subdirectory(tmp)
# ...
add_library(foo ...)
target_link_libraries(foo PUBLIC tmp::tmp)

FetchContent

You can also use the FetchContent functions to automatically download a dependency. Put this in your CMakeLists.txt file:

include(FetchContent)

FetchContent_Declare(tmp URL https://github.com/bugdea1er/tmp/releases/download/<version>/tmp.tar.xz)
FetchContent_MakeAvailable(tmp)

target_link_libraries(foo PUBLIC tmp::tmp)

Contributing

Contributions are always welcome!