# Building DPM Core

## 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, libstdc++, and libdl, so it builds and runs on a minimal system.

## Building for development

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

Artifacts land in:

```
<build-dir>/bin/dpm             the CLI
<build-dir>/lib/libdpm-core.so  the core 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 core 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 core, including the system-installed one.

### Running the tests

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

This runs the core 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.

### Running the CLI from the build tree

The build tree plus the test fixtures form a complete self-contained environment; no installation is required. Point the CLI 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.

## Generating the code reference

When Doxygen is present, the build offers a docs target that generates the API and source reference from the documentation comments carried in the headers and sources. Two output formats are available as configure-time options:

- **-DDPM_DOCS_PDF** (default ON) — PDF reference, via Doxygen's native LaTeX output; requires pdflatex and makeindex
- **-DDPM_DOCS_HTML** (default OFF) — HTML reference

Generate and compile the PDF reference:

```
cmake --build <build-dir> --target docs-pdf
```

The PDF lands at <build-dir>/docs/latex/refman.pdf.

With DPM_DOCS_HTML enabled at configure time, the docs target additionally produces the HTML reference in <build-dir>/docs/html:

```
cmake -B <build-dir> -DDPM_DOCS_HTML=ON
cmake --build <build-dir> --target docs
```

## Building, testing, and installing a release

One build tree carries the whole sequence — the test suite builds and runs in any configuration, 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. Omit -DCMAKE_INSTALL_PREFIX=/usr for a /usr/local install. Under the install prefix this installs:

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

Core configuration installs to /etc/dpm/conf.d/core.conf regardless of prefix.