b6bc9d72f6
This is step 4 of https://discourse.llvm.org/t/rfc-customizable-namespace-to-allow-testing-the-libc-when-the-system-libc-is-also-llvms-libc/73079
78 lines
2.6 KiB
C++
78 lines
2.6 KiB
C++
//===--- A platform independent Dir class ---------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIBC_SRC___SUPPORT_FILE_DIR_H
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#define LLVM_LIBC_SRC___SUPPORT_FILE_DIR_H
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#include "src/__support/CPP/span.h"
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#include "src/__support/error_or.h"
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#include "src/__support/threads/mutex.h"
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#include <dirent.h>
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#include <stdlib.h>
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namespace LIBC_NAMESPACE {
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// Platform specific function which will open the directory |name|
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// and return its file descriptor. Upon failure, the error value is returned.
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ErrorOr<int> platform_opendir(const char *name);
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// Platform specific function which will close the directory with
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// file descriptor |fd|. Returns 0 on success, or the error number on failure.
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int platform_closedir(int fd);
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// Platform specific function which will fetch dirents in to buffer.
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// Returns the number of bytes written into buffer or the error number on
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// failure.
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ErrorOr<size_t> platform_fetch_dirents(int fd, cpp::span<uint8_t> buffer);
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// This class is designed to allow implementation of the POSIX dirent.h API.
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// By itself, it is platform independent but calls platform specific
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// functions to perform OS operations.
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class Dir {
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static constexpr size_t BUFSIZE = 1024;
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int fd;
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size_t readptr = 0; // The current read pointer.
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size_t fillsize = 0; // The number of valid bytes availabe in the buffer.
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// This is a buffer of struct dirent values which will be fetched
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// from the OS. Since the d_name of struct dirent can be of a variable
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// size, we store the data in a byte array.
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uint8_t buffer[BUFSIZE];
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Mutex mutex;
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// A directory is to be opened by the static method open and closed
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// by the close method. So, all constructors and destructor are declared
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// as private. Inappropriate constructors are declared as deleted.
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Dir() = delete;
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Dir(const Dir &) = delete;
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explicit Dir(int fdesc)
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: fd(fdesc), readptr(0), fillsize(0), mutex(false, false, false) {}
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~Dir() = default;
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Dir &operator=(const Dir &) = delete;
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public:
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static ErrorOr<Dir *> open(const char *path);
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ErrorOr<struct ::dirent *> read();
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// Returns 0 on success or the error number on failure. If an error number
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// was returned, then the resources associated with the directory are not
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// cleaned up.
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int close();
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int getfd() { return fd; }
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};
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} // namespace LIBC_NAMESPACE
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#endif // LLVM_LIBC_SRC___SUPPORT_FILE_DIR_H
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