data_dir.cpp

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// SPDX-License-Identifier: Apache-2.0
#include <entropic/config/loader.h>
#include <entropic/entropic_config.h>
#include <entropic/types/logging.h>
 
#include <cstdlib>
#include <vector>
 
#include <dlfcn.h>
 
static auto s_log = entropic::log::get("config");
 
namespace entropic::config {
 
static std::filesystem::path share_dir_from_library()
{
    // Take the address of resolve_data_dir itself — guaranteed to be
    // inside librentropic.so (we're in it). dladdr resolves this
    // pointer back to the .so's filesystem path.
    Dl_info info = {};
    if (dladdr(reinterpret_cast<void*>(&share_dir_from_library), &info) == 0
        || info.dli_fname == nullptr) {
        return {};
    }
    auto lib_path = std::filesystem::path(info.dli_fname);
    // dli_fname may be a relative path (e.g. just "librentropic.so")
    // when the loader resolved via LD_LIBRARY_PATH. Make it absolute
    // so ".." traversal is meaningful.
    std::error_code ec;
    auto abs_lib = std::filesystem::absolute(lib_path, ec);
    if (ec) {
        return {};
    }
    // <prefix>/lib/librentropic.so.2.0.5 → <prefix>/share/entropic
    return abs_lib.parent_path().parent_path() / "share" / "entropic";
}
 
std::filesystem::path resolve_data_dir(const ParsedConfig& config)
{
    struct Candidate {
        std::filesystem::path path;
        const char* label;
    };
 
    std::vector<Candidate> candidates;
 
    // Priority 1: ENTROPIC_DATA_DIR env var (explicit operator override)
    if (const char* env = std::getenv("ENTROPIC_DATA_DIR"); env && *env) {
        candidates.push_back({env, "ENTROPIC_DATA_DIR env"});
    }
 
    // Priority 2: config.config_dir / "data"
    if (!config.config_dir.empty()) {
        candidates.push_back({config.config_dir / "data", "config.config_dir"});
    }
 
    // Priority 3: binary-relative discovery (portable across prefixes)
    if (auto from_lib = share_dir_from_library(); !from_lib.empty()) {
        candidates.push_back({from_lib, "binary-relative (dladdr)"});
    }
 
    // Priority 4-5: compile-time install path, then source-tree / CWD fallbacks
    candidates.push_back({CONFIG_ENTROPIC_DATA_DIR,        "compile-time install path"});
    candidates.push_back({CONFIG_ENTROPIC_SOURCE_DATA_DIR, "source tree (dev fallback)"});
    candidates.push_back({"data",                          "CWD-relative (dev fallback)"});
 
    std::filesystem::path result;
    for (const auto& [path, label] : candidates) {
        if (std::filesystem::is_directory(path)) {
            s_log->info("Data dir from {}: {}", label, path.string());
            result = path;
            break;
        }
    }
 
    if (result.empty()) {
        s_log->warn("No data directory found — bundled files unavailable");
    }
    return result;
}
 
} // namespace entropic::config