Retrieves the current Git hash for a given .git path.

currentGitHash.php

<?php

/**
* Retrieves the current Git hash for a given .git path.
*
* @param string $dotGitPath The path to the .git directory or file.
* @return string The current Git hash.
* @throws \ErrorException If there is an error reading the .git path or its contents.
*/
function currentGitHash(string $path): string {
	if ($dotGitPath = realpath($path)) {
		if ($headPath = realpath("{$dotGitPath}/HEAD")) {
			if ($headContents = file_get_contents($headPath)) {
				if (false === strstr($headContents, 'ref:')) {
					return $headContents;
				} else {
					$branchPath = explode('ref:', $headContents);
					$branchPath = trim(array_pop($branchPath));
					$branchPath = "{$dotGitPath}/{$branchPath}";

					if ($branchContents = file_get_contents($branchPath)) {
						return trim($branchContents);
					} else {
						$error = error_get_last();
						throw new \ErrorException('Cannot read branch contents. '.($error['message'] ?? 'Unknown error occurred'), 0, $error['type'] ?? E_ERROR);
					}
				}
			} else {
				$error = error_get_last();
				throw new \ErrorException('Cannot read HEAD contents. '.($error['message'] ?? 'Unknown error occurred'), 0, $error['type'] ?? E_ERROR);
			}
		} else {
			$error = error_get_last();
			throw new \ErrorException('Invalid HEAD path. '.($error['message'] ?? 'Unknown error occurred'), 0, $error['type'] ?? E_ERROR);
		}
	} elseif (is_file($path)) {
		if ($submoduleContents = file_get_contents($path)) {
			$submoduleContents = explode('gitdir:', $submoduleContents);
			$submoduleContents = trim(array_pop($submoduleContents));
			$submoduleContents = dirname($dotGitPath)."/$submoduleContents";
			
      return currentGitHash($submoduleContents);
		} else {
			$error = error_get_last();
			throw new \ErrorException('Cannot read submodule contents. '.($error['message'] ?? 'Unknown error occurred'), 0, $error['type'] ?? E_ERROR);
		}
	} else {
		throw new \ErrorException('Invalid path to Git directory specified: '.json_encode($path), 0, E_ERROR);
	}
}