mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-09-24 22:02:23 +01:00
Chandler Carruth
2e509e9103
This removes a bunch of manual filesystem helpers and complexity that are directly provided by the new library. It also moves all of the install paths detection to use `std::filesystem::path` instead of the LLVM path library. The goal is to consolidate all our logic onto a single stack, and the standard one seems the best for that purpose. This does give up some of the optimizations of this code to avoid memory allocation, but in practice that likely isn't a critical issue. And with the new filesystem library we can likely do more to avoid that by using directory-object-relative filesystem access. However, that will have to wait for moving more parts of the toolchain over to use this set of filesystem abstractions. There is a related TODO left in the manifest handling code.
101 lines
3.8 KiB
C++
101 lines
3.8 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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#include "toolchain/install/busybox_info.h"
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#include <iterator>
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#include "common/exe_path.h"
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#include "common/filesystem.h"
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#include "llvm/ADT/StringRef.h"
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namespace Carbon {
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// The mode is set to the initial filename used for `argv[0]`.
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static auto GetMode(const std::filesystem::path& argv0)
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-> std::optional<std::string> {
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std::string filename = argv0.filename();
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if (filename != "carbon" && filename != "carbon-busybox") {
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return filename;
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}
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return std::nullopt;
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}
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auto GetBusyboxInfo(const char* argv0) -> ErrorOr<BusyboxInfo> {
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// Need storage due to `unsetenv` affecting `getenv` lifetime; using `path`
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// for `GetMode`.
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std::filesystem::path argv0_path = argv0;
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// Check for an override of `argv[0]` from the environment and apply it.
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if (const char* argv0_override = getenv(Argv0OverrideEnv)) {
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argv0_path = argv0_override;
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unsetenv(Argv0OverrideEnv);
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}
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BusyboxInfo info = {.bin_path = FindExecutablePath(argv0_path.c_str()),
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.mode = GetMode(argv0_path)};
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// Now search through any symlinks to locate the installed busybox binary.
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while (true) {
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if (info.bin_path.filename() == "carbon-busybox") {
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// Check for bazel structure. For example, this makes work:
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// /bin/sh -c "exec -a carbon ./bazel-bin/toolchain/carbon"
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// /bin/sh -c "exec -a llvm-symbolizer ./bazel-bin/toolchain/carbon"
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//
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// This will never occur in a "bin" subdirectory, so doesn't need to be
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// handled in the other return path.
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std::string prefix_root = info.bin_path.parent_path().string() +
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"/prefix_root/lib/carbon/carbon-busybox";
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if (auto access = Filesystem::Cwd().Access(prefix_root);
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access.ok() && *access) {
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info.bin_path = prefix_root;
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}
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return info;
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}
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// If we've not already reached the busybox, look for it relative to the
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// current binary path. This can help more immediately locate an
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// installation tree, and avoids walking through a final layer of symlinks
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// which may point to content-addressed storage or other parts of a build
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// output tree.
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//
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// We break this into two cases we need to handle:
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// - Carbon's CLI will be: `<prefix>/bin/carbon`
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// - Other tools will be: `<prefix>/lib/carbon/<group>/bin/<tool>`
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//
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// We also check that the current path is within a `bin` directory to
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// provide best-effort checking for accidentally walking up from symlinks
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// that aren't within an installation-shaped tree.
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auto parent_path = info.bin_path.parent_path();
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// Strip any `.` path components at the end to simplify processing.
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while (parent_path.filename() == ".") {
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parent_path = parent_path.parent_path();
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}
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if (parent_path.filename() == "bin") {
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auto lib_path = info.bin_path.filename() == "carbon"
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? parent_path / ".." / "lib" / "carbon"
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: parent_path / ".." / "..";
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auto busybox_path = lib_path / "carbon-busybox";
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if (auto access = Filesystem::Cwd().Access(busybox_path);
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access.ok() && *access) {
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info.bin_path = busybox_path;
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return info;
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}
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}
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// Try to walk through another layer of symlinks and see if we can find the
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// installation there or are linked directly to the busybox.
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auto readlink = Filesystem::Cwd().Readlink(info.bin_path);
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if (!readlink.ok()) {
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return ErrorBuilder()
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<< "expected carbon-busybox symlink at `" << info.bin_path << "`";
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}
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// Do a path join, to handle relative symlinks.
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info.bin_path = parent_path / *readlink;
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}
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}
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} // namespace Carbon
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