path: root/llvm_tools/update_chromeos_llvm_hash.py

#!/usr/bin/env python3
# Copyright 2019 The ChromiumOS Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Updates the LLVM hash and uprevs the build of the specified packages.

For each package, a temporary repo is created and the changes are uploaded
for review.
"""

import argparse
import dataclasses
import enum
import os
from pathlib import Path
import re
import subprocess
import textwrap
from typing import Dict, Iterable, Iterator, List, Optional, Union

import atomic_write_file
import chroot
import failure_modes
import get_llvm_hash
import git
import manifest_utils
import patch_utils
import subprocess_helpers


# Default list of packages to update.
DEFAULT_PACKAGES = patch_utils.CHROMEOS_PATCHES_JSON_PACKAGES

DEFAULT_MANIFEST_PACKAGES = ["sys-devel/llvm"]


# Specify which LLVM hash to update
class LLVMVariant(enum.Enum):
    """Represent the LLVM hash in an ebuild file to update."""

    current = "LLVM_HASH"
    next = "LLVM_NEXT_HASH"


@dataclasses.dataclass(frozen=True, eq=True)
class ChrootOpts:
    """A class that holds chroot options."""

    chromeos_root: Path
    chroot_name: str = "chroot"
    out_name: str = "out"


class PortagePackage:
    """Represents a portage package with location info."""

    def __init__(self, chroot_opts: ChrootOpts, package: str):
        """Create a new PortagePackage.

        Args:
            chroot_opts: options that specify the ChromeOS chroot to use.
            package: "category/package" string.
        """
        self.package = package
        potential_ebuild_path = PortagePackage.find_package_ebuild(
            chroot_opts, package
        )
        if potential_ebuild_path.is_symlink():
            self.uprev_target: Optional[Path] = potential_ebuild_path.absolute()
            self.ebuild_path = potential_ebuild_path.resolve()
        else:
            # Should have a 9999 ebuild, no uprevs needed.
            self.uprev_target = None
            self.ebuild_path = potential_ebuild_path.absolute()

    @staticmethod
    def find_package_ebuild(chroot_opts: ChrootOpts, package: str) -> Path:
        """Look up the package's ebuild location."""
        chromeos_root_str = str(chroot_opts.chromeos_root)
        ebuild_paths = chroot.GetChrootEbuildPaths(
            chromeos_root_str,
            [package],
            chroot_opts.chroot_name,
            chroot_opts.out_name,
        )
        converted = chroot.ConvertChrootPathsToAbsolutePaths(
            chromeos_root_str, ebuild_paths
        )[0]
        return Path(converted)

    def package_dir(self) -> Path:
        """Return the package directory."""
        return self.ebuild_path.parent

    def update(
        self, llvm_variant: LLVMVariant, git_hash: str, svn_version: int
    ):
        """Update the package with the new LLVM git sha and revision.

        Args:
            llvm_variant: Which LLVM hash to update.
                Either LLVM_HASH or LLVM_NEXT_HASH.
            git_hash: Upstream LLVM git hash to update to.
            svn_version: Matching LLVM revision string for the git_hash.
        """
        live_ebuild = self.live_ebuild()
        if live_ebuild:
            # Working with a -9999 ebuild package here, no
            # upreving.
            UpdateEbuildLLVMHash(
                live_ebuild, llvm_variant, git_hash, svn_version
            )
            return
        if not self.uprev_target:
            # We can exit early if we're not working with a live ebuild,
            # and we don't have something to uprev.
            raise RuntimeError(
                "Cannot update: no live ebuild or symlink found"
                f" for {self.package}"
            )

        UpdateEbuildLLVMHash(
            self.ebuild_path, llvm_variant, git_hash, svn_version
        )
        if llvm_variant == LLVMVariant.current:
            UprevEbuildToVersion(str(self.uprev_target), svn_version, git_hash)
        else:
            UprevEbuildSymlink(str(self.uprev_target))

    def live_ebuild(self) -> Optional[Path]:
        """Path to the live ebuild if it exists.

        Returns:
            The patch to the live ebuild if it exists. None otherwise.
        """
        matches = self.package_dir().glob("*-9999.ebuild")
        return next(matches, None)


def defaultCrosRoot() -> Path:
    """Get default location of chromeos_path.

    The logic assumes that the cros_root is ~/chromiumos, unless llvm_tools is
    inside of a CrOS checkout, in which case that checkout should be used.

    Returns:
        The best guess location for the cros checkout.
    """
    llvm_tools_path = os.path.realpath(os.path.dirname(__file__))
    if llvm_tools_path.endswith("src/third_party/toolchain-utils/llvm_tools"):
        return Path(llvm_tools_path).parent.parent.parent.parent
    return Path.home() / "chromiumos"


def GetCommandLineArgs():
    """Parses the command line for the optional command line arguments.

    Returns:
        The log level to use when retrieving the LLVM hash or google3 LLVM
        version, the chroot path to use for executing chroot commands, a list
        of a package or packages to update their LLVM next hash, and the LLVM
        version to use when retrieving the LLVM hash.
    """

    # Create parser and add optional command-line arguments.
    parser = argparse.ArgumentParser(
        description="Updates the build's hash for llvm-next."
    )

    # Add argument for a specific chroot path.
    parser.add_argument(
        "--chromeos_path",
        type=Path,
        default=defaultCrosRoot(),
        help="the path to the chroot (default: %(default)s)",
    )

    # Add argument for specific builds to uprev and update their llvm-next
    # hash.
    parser.add_argument(
        "--update_packages",
        default=",".join(DEFAULT_PACKAGES),
        help="Comma-separated ebuilds to update llvm-next hash for "
        "(default: %(default)s)",
    )

    parser.add_argument(
        "--manifest_packages",
        default="",
        help="Comma-separated ebuilds to update manifests for "
        "(default: %(default)s)",
    )

    # Add argument for the LLVM hash to update
    parser.add_argument(
        "--is_llvm_next",
        action="store_true",
        help="which llvm hash to update. If specified, update LLVM_NEXT_HASH. "
        "Otherwise, update LLVM_HASH",
    )

    # Add argument for the LLVM version to use.
    parser.add_argument(
        "--llvm_version",
        type=get_llvm_hash.IsSvnOption,
        required=True,
        help="which git hash to use. Either a svn revision, or one "
        f"of {sorted(get_llvm_hash.KNOWN_HASH_SOURCES)}",
    )

    # Add argument for the mode of the patch management when handling patches.
    parser.add_argument(
        "--failure_mode",
        default=failure_modes.FailureModes.FAIL.value,
        choices=[
            failure_modes.FailureModes.FAIL.value,
            failure_modes.FailureModes.CONTINUE.value,
            failure_modes.FailureModes.DISABLE_PATCHES.value,
        ],
        help="the mode of the patch manager when handling failed patches "
        "(default: %(default)s)",
    )

    # Add argument for the patch metadata file.
    parser.add_argument(
        "--patch_metadata_file",
        default="PATCHES.json",
        help="the .json file that has all the patches and their "
        "metadata if applicable (default: PATCHES.json inside $FILESDIR)",
    )
    parser.add_argument(
        "--no_repo_manifest",
        dest="repo_manifest",
        action="store_false",
        help="Skip updating the llvm-project revision attribute"
        " in the internal manifest.",
    )
    parser.add_argument(
        "--no_delete_branch",
        action="store_true",
        help="Do not delete the created overlay branch.",
    )
    parser.add_argument(
        "--no_upload_changes",
        action="store_true",
        help="Do not upload changes to gerrit.",
    )
    parser.add_argument(
        "--no_patching",
        action="store_true",
        help="Do not check or update PATCHES.json.",
    )
    # Parse the command line.
    return parser.parse_args()


def UpdateEbuildLLVMHash(
    ebuild_path: Path,
    llvm_variant: LLVMVariant,
    git_hash: str,
    svn_version: int,
) -> None:
    """Updates the LLVM hash in the ebuild.

    The build changes are staged for commit in the temporary repo.

    Args:
        ebuild_path: The absolute path to the ebuild.
        llvm_variant: Which LLVM hash to update.
        git_hash: The new git hash.
        svn_version: The SVN-style revision number of git_hash.

    Raises:
        ValueError: Invalid ebuild path provided or failed to stage the commit
        of the changes or failed to update the LLVM hash.
    """

    # For each ebuild, read the file in
    # advance and then create a temporary file
    # that gets updated with the new LLVM hash
    # and revision number and then the ebuild file
    # gets updated to the temporary file.
    if not os.path.isfile(ebuild_path):
        raise ValueError(f"Invalid ebuild path provided: {ebuild_path}")

    with open(ebuild_path, encoding="utf-8") as ebuild_file:
        new_lines = list(
            ReplaceLLVMHash(ebuild_file, llvm_variant, git_hash, svn_version)
        )
    with atomic_write_file.atomic_write(
        ebuild_path, "w", encoding="utf-8"
    ) as ebuild_file:
        ebuild_file.writelines(new_lines)
    # Stage the changes.
    subprocess.check_output(
        ["git", "-C", ebuild_path.parent, "add", ebuild_path]
    )


def ReplaceLLVMHash(
    ebuild_lines: Iterable[str],
    llvm_variant: LLVMVariant,
    git_hash: str,
    svn_version: int,
) -> Iterator[str]:
    """Updates the LLVM git hash.

    Args:
        ebuild_lines: The contents of the ebuild file.
        llvm_variant: The LLVM hash to update.
        git_hash: The new git hash.
        svn_version: The SVN-style revision number of git_hash.

    Yields:
        lines of the modified ebuild file
    """
    is_updated = False
    llvm_regex = re.compile(
        "^" + re.escape(llvm_variant.value) + '="[a-z0-9]+"'
    )
    for cur_line in ebuild_lines:
        if not is_updated and llvm_regex.search(cur_line):
            # Update the git hash and revision number.
            cur_line = f'{llvm_variant.value}="{git_hash}" # r{svn_version}\n'

            is_updated = True

        yield cur_line

    if not is_updated:
        raise ValueError(f"Failed to update {llvm_variant.value}")


def UprevEbuildSymlink(symlink: str) -> None:
    """Uprevs the symlink's revision number.

    Increases the revision number by 1 and stages the change in
    the temporary repo.

    Args:
        symlink: The absolute path of an ebuild symlink.

    Raises:
        ValueError: Failed to uprev the symlink or failed to stage the changes.
    """

    if not os.path.islink(symlink):
        raise ValueError(f"Invalid symlink provided: {symlink}")

    new_symlink, is_changed = re.subn(
        r"r([0-9]+).ebuild",
        lambda match: "r%s.ebuild" % str(int(match.group(1)) + 1),
        symlink,
        count=1,
    )

    if not is_changed:
        raise ValueError("Failed to uprev the symlink.")

    # rename the symlink
    subprocess.check_output(
        ["git", "-C", os.path.dirname(symlink), "mv", symlink, new_symlink]
    )


def UprevEbuildToVersion(symlink: str, svn_version: int, git_hash: str) -> None:
    """Uprevs the ebuild's revision number.

    Increases the revision number by 1 and stages the change in
    the temporary repo.

    Args:
        symlink: The absolute path of an ebuild symlink.
        svn_version: The SVN-style revision number of git_hash.
        git_hash: The new git hash.

    Raises:
        ValueError: Failed to uprev the ebuild or failed to stage the changes.
        AssertionError: No llvm version provided for an LLVM uprev
    """

    if not os.path.islink(symlink):
        raise ValueError(f"Invalid symlink provided: {symlink}")

    ebuild = os.path.realpath(symlink)
    llvm_major_version = get_llvm_hash.GetLLVMMajorVersion(git_hash)
    # llvm
    package = os.path.basename(os.path.dirname(symlink))
    if not package:
        raise ValueError("Tried to uprev an unknown package")
    if package == "llvm":
        new_ebuild, is_changed = re.subn(
            r"(\d+)\.(\d+)_pre([0-9]+)(_p[0-9]+)?",
            "%s.\\2_pre%s"
            % (
                llvm_major_version,
                str(svn_version),
            ),
            ebuild,
            count=1,
        )
    # any other package
    else:
        new_ebuild, is_changed = re.subn(
            r"(\d+)\.(\d+)_pre([0-9]+)",
            "%s.\\2_pre%s" % (llvm_major_version, str(svn_version)),
            ebuild,
            count=1,
        )

    if not is_changed:  # failed to increment the revision number
        raise ValueError("Failed to uprev the ebuild.")

    symlink_dir = os.path.dirname(symlink)

    # Rename the ebuild
    subprocess.check_output(
        ["git", "-C", symlink_dir, "mv", ebuild, new_ebuild]
    )

    # Create a symlink of the renamed ebuild
    new_symlink = new_ebuild[: -len(".ebuild")] + "-r1.ebuild"
    subprocess.check_output(["ln", "-s", "-r", new_ebuild, new_symlink])
    subprocess.check_output(["git", "-C", symlink_dir, "add", new_symlink])
    # Remove the old symlink
    subprocess.check_output(["git", "-C", symlink_dir, "rm", symlink])


def RemovePatchesFromFilesDir(patches: Iterable[str]) -> None:
    """Removes the patches from $FILESDIR of a package.

    Args:
        patches: A list of absolute paths of patches to remove

    Raises:
        ValueError: Failed to remove a patch in $FILESDIR.
    """

    for patch in patches:
        subprocess.check_output(
            ["git", "-C", os.path.dirname(patch), "rm", "-f", patch]
        )


def StagePatchMetadataFileForCommit(patch_metadata_file_path: str) -> None:
    """Stages the updated patch metadata file for commit.

    Args:
        patch_metadata_file_path: The absolute path to the patch metadata file.

    Raises:
        ValueError: Failed to stage the patch metadata file for commit or
        invalid patch metadata file.
    """

    if not os.path.isfile(patch_metadata_file_path):
        raise ValueError(
            f"Invalid patch metadata file provided: {patch_metadata_file_path}"
        )

    # Cmd to stage the patch metadata file for commit.
    subprocess.check_output(
        [
            "git",
            "-C",
            os.path.dirname(patch_metadata_file_path),
            "add",
            patch_metadata_file_path,
        ]
    )


def StagePackagesPatchResultsForCommit(
    package_info_dict: Dict[str, patch_utils.PatchInfo],
    commit_messages: List[str],
) -> List[str]:
    """Stages the patch results of the packages to the commit message.

    Args:
        package_info_dict: A dictionary where the key is the package name and
        the value is a dictionary that contains information about the patches
        of the package (key).
        commit_messages: The commit message that has the updated ebuilds and
        upreving information.

    Returns:
        commit_messages with new additions
    """

    # For each package, check if any patches for that package have
    # changed, if so, add which patches have changed to the commit
    # message.
    for package_name, patch_info in package_info_dict.items():
        if (
            patch_info.disabled_patches
            or patch_info.removed_patches
            or patch_info.modified_metadata
        ):
            cur_package_header = f"\nFor the package {package_name}:"
            commit_messages.append(cur_package_header)

        # Add to the commit message that the patch metadata file was modified.
        if patch_info.modified_metadata:
            patch_metadata_path = patch_info.modified_metadata
            metadata_file_name = os.path.basename(patch_metadata_path)
            commit_messages.append(
                f"The patch metadata file {metadata_file_name} was modified"
            )

            StagePatchMetadataFileForCommit(patch_metadata_path)

        # Add each disabled patch to the commit message.
        if patch_info.disabled_patches:
            commit_messages.append("The following patches were disabled:")

            for patch_path in patch_info.disabled_patches:
                commit_messages.append(os.path.basename(patch_path))

        # Add each removed patch to the commit message.
        if patch_info.removed_patches:
            commit_messages.append("The following patches were removed:")

            for patch_path in patch_info.removed_patches:
                commit_messages.append(os.path.basename(patch_path))

            RemovePatchesFromFilesDir(patch_info.removed_patches)

    return commit_messages


def UpdatePortageManifests(
    packages: Iterable[str], chromeos_path: Path
) -> None:
    """Updates portage manifest files for packages.

    Args:
        packages: A list of packages to update manifests for.
        chromeos_path: The absolute path to the chromeos checkout.

    Raises:
        CalledProcessError: ebuild failed to update manifest.
    """
    manifest_ebuilds = chroot.GetChrootEbuildPaths(chromeos_path, packages)
    for ebuild_path in manifest_ebuilds:
        ebuild_dir = os.path.dirname(ebuild_path)
        subprocess_helpers.ChrootRunCommand(
            chromeos_path, ["ebuild", ebuild_path, "manifest"]
        )
        subprocess_helpers.ChrootRunCommand(
            chromeos_path, ["git", "-C", ebuild_dir, "add", "Manifest"]
        )


def UpdatePackages(
    packages: Iterable[str],
    manifest_packages: Iterable[str],
    llvm_variant: LLVMVariant,
    git_hash: str,
    svn_version: int,
    chroot_opts: ChrootOpts,
    mode: Optional[failure_modes.FailureModes],
    git_hash_source: Union[int, str],
    extra_commit_msg_lines: Optional[Iterable[str]],
    delete_branch: bool = True,
    upload_changes: bool = True,
    wip: bool = False,
) -> Optional[git.CommitContents]:
    """Updates an LLVM hash and uprevs the ebuild of the packages.

    A temporary repo is created for the changes. The changes are
    then uploaded for review.

    Args:
        packages: A list of all the packages that are going to be updated.
        manifest_packages: A list of packages to update manifests for.
        llvm_variant: The LLVM hash to update.
        git_hash: The new git hash.
        svn_version: The SVN-style revision number of git_hash.
        chroot_opts: options that specify the ChromeOS chroot to use.
        mode: The mode of the patch manager when handling an applicable patch.
          If None is passed, the patch manager won't be invoked.
        that failed to apply.
            Ex. 'FailureModes.FAIL'
        git_hash_source: The source of which git hash to use based off of.
            Ex. 'google3', 'tot', or <version> such as 365123
        extra_commit_msg_lines: extra lines to append to the commit message.
            Newlines are added automatically.
        delete_branch: Delete the git branch as a final step.
        upload_changes: Upload the commit to gerrit as a CL.
        wip: if True, any changes uploaded will be uploaded as
            work-in-progress.

    Returns:
        If upload_changes is set, a git.CommitContents object. Otherwise None.
    """
    portage_packages = (PortagePackage(chroot_opts, pkg) for pkg in packages)
    chromiumos_overlay_path = (
        chroot_opts.chromeos_root / "src" / "third_party" / "chromiumos-overlay"
    )
    branch_name = "update-" + llvm_variant.value + "-" + git_hash

    commit_message_header = "llvm"
    if llvm_variant == LLVMVariant.next:
        commit_message_header = "llvm-next"
    if git_hash_source in get_llvm_hash.KNOWN_HASH_SOURCES:
        commit_message_header += (
            f"/{git_hash_source}: upgrade to {git_hash} (r{svn_version})"
        )
    else:
        commit_message_header += f": upgrade to {git_hash} (r{svn_version})"

    commit_lines = [
        commit_message_header + "\n",
        "The following packages have been updated:",
    ]

    # Holds the list of packages that are updating.
    updated_packages: List[str] = []
    change_list = None
    git.CreateBranch(chromiumos_overlay_path, branch_name)
    try:
        for pkg in portage_packages:
            pkg.update(llvm_variant, git_hash, svn_version)
            updated_packages.append(pkg.package)
            commit_lines.append(pkg.package)
        if manifest_packages:
            UpdatePortageManifests(manifest_packages, chroot_opts.chromeos_root)
            commit_lines.append("Updated manifest for:")
            commit_lines.extend(manifest_packages)
        EnsurePackageMaskContains(chroot_opts.chromeos_root, git_hash)
        # Handle the patches for each package.
        if mode is not None:
            package_info_dict = UpdatePackagesPatchMetadataFile(
                chroot_opts, svn_version, updated_packages, mode
            )
            # Update the commit message if changes were made to a package's
            # patches.
            commit_lines = StagePackagesPatchResultsForCommit(
                package_info_dict, commit_lines
            )
        if extra_commit_msg_lines:
            commit_lines.extend(extra_commit_msg_lines)
        git.CommitChanges(chromiumos_overlay_path, commit_lines)
        if upload_changes:
            change_list = git.UploadChanges(
                chromiumos_overlay_path,
                branch_name,
                wip=wip,
            )
    finally:
        if delete_branch:
            git.DeleteBranch(chromiumos_overlay_path, branch_name)
        else:
            print(f"Not deleting branch {branch_name}")
    return change_list


def EnsurePackageMaskContains(
    chromeos_path: Union[Path, str], git_hash: str
) -> None:
    """Adds the major version of llvm to package.mask if not already present.

    Args:
        chromeos_path: The absolute path to the chromeos checkout.
        git_hash: The new git hash.

    Raises:
        FileExistsError: package.mask not found in ../../chromiumos-overlay
    """

    llvm_major_version = get_llvm_hash.GetLLVMMajorVersion(git_hash)

    overlay_dir = os.path.join(
        chromeos_path, "src/third_party/chromiumos-overlay"
    )
    mask_path = os.path.join(
        overlay_dir, "profiles/targets/chromeos/package.mask"
    )
    with open(mask_path, "r+", encoding="utf-8") as mask_file:
        mask_contents = mask_file.read()
        expected_line = f"=sys-devel/llvm-{llvm_major_version}.0_pre*\n"
        if expected_line not in mask_contents:
            mask_file.write(expected_line)

    subprocess.check_output(["git", "-C", overlay_dir, "add", mask_path])


def UpdatePackagesPatchMetadataFile(
    chroot_opts: ChrootOpts,
    svn_version: int,
    packages: Iterable[str],
    mode: failure_modes.FailureModes,
) -> Dict[str, patch_utils.PatchInfo]:
    """Updates the packages metadata file.

    Args:
        chroot_opts: options that specify the ChromeOS chroot to use.
        svn_version: The version to use for patch management.
        packages: All the packages to update their patch metadata file.
        mode: The mode for the patch manager to use when an applicable patch
        fails to apply.
            Ex: 'FailureModes.FAIL'

    Returns:
        A dictionary where the key is the package name and the value is a
        dictionary that has information on the patches.
    """

    # A dictionary where the key is the package name and the value is a
    # dictionary that has information on the patches.
    package_info: Dict[str, patch_utils.PatchInfo] = {}

    llvm_hash = get_llvm_hash.LLVMHash()

    with llvm_hash.CreateTempDirectory() as temp_dir:
        with get_llvm_hash.CreateTempLLVMRepo(temp_dir) as dirname:
            # Ensure that 'svn_version' exists in the chromiumum mirror of
            # LLVM by finding its corresponding git hash.
            git_hash = get_llvm_hash.GetGitHashFrom(dirname, svn_version)
            move_head_cmd = ["git", "-C", dirname, "checkout", git_hash, "-q"]
            subprocess.run(move_head_cmd, stdout=subprocess.DEVNULL, check=True)

            for cur_package in packages:
                # Get the absolute path to $FILESDIR of the package.
                chroot_ebuild_str = subprocess_helpers.ChrootRunCommand(
                    chroot_opts.chromeos_root,
                    ["equery", "w", cur_package],
                    chroot_name=chroot_opts.chroot_name,
                    out_name=chroot_opts.out_name,
                ).strip()
                if not chroot_ebuild_str:
                    raise RuntimeError(
                        f"could not find ebuild for {cur_package}"
                    )
                chroot_ebuild_path = Path(
                    chroot.ConvertChrootPathsToAbsolutePaths(
                        str(chroot_opts.chromeos_root), [chroot_ebuild_str]
                    )[0]
                )
                patches_json_fp = (
                    chroot_ebuild_path.parent / "files" / "PATCHES.json"
                )
                if not patches_json_fp.is_file():
                    raise RuntimeError(
                        f"patches file {patches_json_fp} is not a file"
                    )

                src_path = Path(dirname)
                with patch_utils.git_clean_context(src_path):
                    if mode in (
                        failure_modes.FailureModes.FAIL,
                        failure_modes.FailureModes.CONTINUE,
                    ):
                        patches_info = patch_utils.apply_all_from_json(
                            svn_version=svn_version,
                            llvm_src_dir=src_path,
                            patches_json_fp=patches_json_fp,
                            continue_on_failure=mode
                            == failure_modes.FailureModes.CONTINUE,
                        )
                    elif mode == failure_modes.FailureModes.DISABLE_PATCHES:
                        patches_info = patch_utils.update_version_ranges(
                            svn_version, src_path, patches_json_fp
                        )
                    else:
                        raise RuntimeError(f"unsupported failure mode: {mode}")

                package_info[cur_package] = patches_info

    return package_info


def ChangeRepoManifest(
    git_hash: str,
    src_tree: Path,
    extra_commit_msg_lines: Optional[Iterable[str]] = None,
    delete_branch=True,
    upload_changes=True,
):
    """Change the repo internal manifest for llvm-project.

    Args:
        git_hash: The LLVM git hash to change to.
        src_tree: ChromiumOS source tree checkout.
        extra_commit_msg_lines: Lines to append to the commit message.
        delete_branch: Delete the branch as a final step.
        upload_changes: Upload the changes to gerrit.

    Returns:
        The uploaded changelist CommitContents.
    """
    manifest_dir = manifest_utils.get_chromeos_manifest_path(src_tree).parent
    branch_name = "update-llvm-project-" + git_hash
    commit_lines = (
        textwrap.dedent(
            f"""
            manifest: Update llvm-project to {git_hash}

            Upgrade the local LLVM revision to match the new llvm ebuild
            hash. This must be merged along with any chromiumos-overlay
            changes to LLVM. Automatic uprevs rely on the manifest hash
            to match what is specified by LLVM_HASH.

            This CL is generated by the update_chromeos_llvm_hash.py script.

            BUG=None
            TEST=CQ
            """
        )
        .lstrip()
        .splitlines()
    )

    change_list = None
    git.CreateBranch(manifest_dir, branch_name)
    try:
        manifest_path = manifest_utils.update_chromeos_manifest(
            git_hash,
            src_tree,
        )
        subprocess.run(
            ["git", "-C", manifest_dir, "add", manifest_path.name], check=True
        )
        if extra_commit_msg_lines:
            commit_lines.extend(extra_commit_msg_lines)
        git.CommitChanges(manifest_dir, commit_lines)
        if upload_changes:
            change_list = git.UploadChanges(manifest_dir, branch_name)
    finally:
        if delete_branch:
            git.DeleteBranch(manifest_dir, branch_name)
        else:
            print(f"Not deleting branch {branch_name}")
    return change_list


def main():
    """Updates the LLVM next hash for each package.

    Raises:
        AssertionError: The script was run inside the chroot.
    """

    chroot.VerifyOutsideChroot()

    args_output = GetCommandLineArgs()

    chroot.VerifyChromeOSRoot(args_output.chromeos_path)

    llvm_variant = LLVMVariant.current
    if args_output.is_llvm_next:
        llvm_variant = LLVMVariant.next

    git_hash_source = args_output.llvm_version

    git_hash, svn_version = get_llvm_hash.GetLLVMHashAndVersionFromSVNOption(
        git_hash_source
    )
    # Filter out empty strings. For example "".split{",") returns [""].
    packages = set(p for p in args_output.update_packages.split(",") if p)
    manifest_packages = set(
        p for p in args_output.manifest_packages.split(",") if p
    )
    if not manifest_packages and not args_output.is_llvm_next:
        # Set default manifest packages only for the current llvm.
        manifest_packages = set(DEFAULT_MANIFEST_PACKAGES)

    if args_output.no_patching:
        patch_update_mode = None
    else:
        patch_update_mode = failure_modes.FailureModes(args_output.failure_mode)

    change_list = UpdatePackages(
        packages=packages,
        manifest_packages=manifest_packages,
        llvm_variant=llvm_variant,
        git_hash=git_hash,
        svn_version=svn_version,
        chroot_opts=ChrootOpts(args_output.chromeos_path),
        mode=patch_update_mode,
        git_hash_source=git_hash_source,
        extra_commit_msg_lines=None,
        delete_branch=not args_output.no_delete_branch,
        upload_changes=not args_output.no_upload_changes,
    )
    if change_list:
        print(f"Successfully updated packages to {git_hash} ({svn_version})")
        print(f"Gerrit URL: {change_list.url}")
        print(f"Change list number: {change_list.cl_number}")
    else:
        print("--no-upload passed, did not create a change list")

    if args_output.repo_manifest and not args_output.is_llvm_next:
        print(
            f"Updating internal manifest to {git_hash} ({svn_version})...",
            end="",
        )
        cq_depend_line = (
            [f"Cq-Depend: chromium:{change_list.cl_number}"]
            if change_list
            else None
        )
        change_list = ChangeRepoManifest(
            git_hash,
            args_output.chromeos_path,
            extra_commit_msg_lines=cq_depend_line,
            delete_branch=not args_output.no_delete_branch,
            upload_changes=not args_output.no_upload_changes,
        )
        print(" Done!")
        if change_list:
            print("New repo manifest CL:")
            print(f"  URL: {change_list.url}")
            print(f"  CL Number: {change_list.cl_number}")
        else:
            print("--no-upload passed, did not create a change list")


if __name__ == "__main__":
    main()