# Building libdpm-core.so and the dpm binary

## Prerequisites

- GCC/G++ supporting C++20
- CMake 3.22 or later
- Make
- Doxygen (optional, for the code reference)
- `pdflatex` and `makeindex` (optional, for the PDF code reference)

The library itself depends only on libc and libstdc++, so it builds and runs on a minimal system.

## Development Builds

Configure a build tree and compile it:

```
cmake -B <build-dir> -DCMAKE_BUILD_TYPE=Debug
cmake --build <build-dir>
```

Artifacts land in:

```
<build-dir>/bin/dpm             the dpm binary
<build-dir>/lib/libdpm-core.so  the library
<build-dir>/modules/info.so     the bundled info module
```

The `dpm` binary built here finds the locally built `libdpm-core.so` on its own — an embedded library search path points it at the `lib/` directory next to it in the build tree, so running it directly uses the library you just built with nothing to set up first. This is only the default: `LD_LIBRARY_PATH` takes precedence over the embedded path, so the binary can be pointed at any other libdpm-core, including the system-installed one.

### Automated Testing

```
ctest --test-dir <build-dir> --output-on-failure
```

This runs the API test binary (which exercises the full load-time validation matrix against the fixture modules in `tests/fixtures/`) and the CLI end-to-end tests.

### Manual Execution

The build tree plus the test fixtures form a complete self-contained environment; no installation is required. Point the `dpm` binary at local paths with its override flags:

```
<build-dir>/bin/dpm --config-dir ./tests/fixtures/conf --module-path <build-dir>/modules info version
```

The flags `--config-dir`, `--module-path`, `--root`, and `--log-level` each redirect the corresponding system default; `--root` sets the target root that package-operation modules act on.

## Release Builds

One build tree carries the whole sequence, so the artifacts that get tested are the artifacts that get installed:

```
cmake -B <build-dir> -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/usr
cmake --build <build-dir>
ctest --test-dir <build-dir> --output-on-failure
cmake --install <build-dir>
```

This is the packaging flow: configure once, build once, test what was built, install what was tested.

### Automated Testing

The test suite builds and runs in any configuration, so a release tree is tested by the same command a development tree is:

```
ctest --test-dir <build-dir> --output-on-failure
```

Running it between the build and the install step is what makes the sequence above a packaging flow rather than four unrelated commands.

### Installation

```
cmake --install <build-dir>
```

Omit `-DCMAKE_INSTALL_PREFIX=/usr` at configure time for a `/usr/local` install. Under the install prefix this installs:

```
bin/dpm                   the dpm binary
lib/libdpm-core.so        the library
lib/dpm/modules/info.so   the bundled info module
include/dpm/              the public header
```

The library's own configuration installs to `/etc/dpm/conf.d/core.conf` regardless of prefix.