fix: block terminal prompts in find source (#918)

Signed-off-by: Ben Selwyn-Smith <[email protected]>

src/macaron/repo_finder/repo_finder.py

@@ -36,7 +36,6 @@
 import os
 from urllib.parse import ParseResult, urlunparse
 
-import git
 from packageurl import PackageURL
 
 from macaron.config.defaults import defaults
@@ -47,7 +46,7 @@
 from macaron.repo_finder.repo_finder_deps_dev import DepsDevRepoFinder
 from macaron.repo_finder.repo_finder_java import JavaRepoFinder
 from macaron.repo_finder.repo_utils import generate_report, prepare_repo
-from macaron.slsa_analyzer.git_url import GIT_REPOS_DIR
+from macaron.slsa_analyzer.git_url import GIT_REPOS_DIR, list_remote_references
 
 logger: logging.Logger = logging.getLogger(__name__)
 
@@ -170,11 +169,11 @@ def find_source(purl_string: str, input_repo: str | None) -> bool:
 
     # Disable other loggers for cleaner output.
     logging.getLogger("macaron.slsa_analyzer.analyzer").disabled = True
-    logging.getLogger("macaron.slsa_analyzer.git_url").disabled = True
 
     if defaults.getboolean("repofinder", "find_source_should_clone"):
         logger.debug("Preparing repo: %s", found_repo)
         repo_dir = os.path.join(global_config.output_path, GIT_REPOS_DIR)
+        logging.getLogger("macaron.slsa_analyzer.git_url").disabled = True
         git_obj = prepare_repo(
             repo_dir,
             found_repo,
@@ -233,12 +232,10 @@ def get_tags_via_git_remote(repo: str) -> dict[str, str] | None:
     dict[str]
         A dictionary of tags mapped to their commits, or None if the operation failed..
     """
-    tags = {}
-    try:
-        tag_data = git.cmd.Git().ls_remote("--tags", repo)
-    except git.exc.GitCommandError as error:
-        logger.debug("Failed to retrieve tags: %s", error)
+    tag_data = list_remote_references(["--tags"], repo)
+    if not tag_data:
         return None
+    tags = {}
 
     for tag_line in tag_data.splitlines():
         tag_line = tag_line.strip()

src/macaron/slsa_analyzer/git_url.py

@@ -19,6 +19,7 @@
 from pydriller.git import Git
 
 from macaron.config.defaults import defaults
+from macaron.config.global_config import global_config
 from macaron.environment_variables import get_patched_env
 from macaron.errors import CloneError
 
@@ -376,6 +377,47 @@ def clone_remote_repo(clone_dir: str, url: str) -> Repo | None:
     return Repo(path=clone_dir)
 
 
+def list_remote_references(arguments: list[str], repo: str) -> str | None:
+    """Retrieve references from a remote repository using Git's ``ls-remote``.
+
+    Parameters
+    ----------
+    arguments: list[str]
+        The arguments to pass into the command.
+    repo: str
+        The repository to run the command on.
+
+    Returns
+    -------
+    str
+        The result of the command.
+    """
+    try:
+        result = subprocess.run(  # nosec B603
+            args=["git", "ls-remote"] + arguments + [repo],
+            capture_output=True,
+            # By setting stdin to /dev/null and using a new session, we prevent all possible user input prompts.
+            stdin=subprocess.DEVNULL,
+            start_new_session=True,
+            cwd=global_config.output_path,
+            check=False,
+        )
+    except (subprocess.CalledProcessError, OSError):
+        return None
+
+    if result.returncode != 0:
+        error_string = result.stderr.decode("utf-8").strip()
+        if error_string.startswith("fatal: could not read Username"):
+            # Occurs when a repository cannot be accessed either because it does not exist, or it requires a login
+            # that is blocked.
+            logger.error("Could not access repository: %s", repo)
+        else:
+            logger.error("Failed to retrieve remote references from repo: %s", repo)
+        return None
+
+    return result.stdout.decode("utf-8")
+
+
 def resolve_local_path(start_dir: str, local_path: str) -> str:
     """Resolve the local path and check if it's within a directory.
 

tests/integration/cases/find_source_fail/test.yaml

@@ -0,0 +1,20 @@
+# Copyright (c) 2024 - 2024, Oracle and/or its affiliates. All rights reserved.
+# Licensed under the Universal Permissive License v 1.0 as shown at https://oss.oracle.com/licenses/upl/.
+
+description: |
+  Analyzing the find source command on a non-existent repository.
+
+tags:
+- macaron-python-package
+- macaron-docker-image
+
+steps:
+- name: Run macaron find source on private repository
+  kind: find-source
+  options:
+    command_args:
+    - -purl
+    - pkg:maven/com.example/[email protected]
+    - -rp
+    - https://github.com/oracle/hopefully-this-repository-will-never-exist-0
+    expect_fail: true