1//===--- A platform independent Dir class ---------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef LLVM_LIBC_SRC___SUPPORT_FILE_DIR_H
10#define LLVM_LIBC_SRC___SUPPORT_FILE_DIR_H
11
12#include "src/__support/CPP/span.h"
13#include "src/__support/error_or.h"
14#include "src/__support/macros/config.h"
15#include "src/__support/threads/mutex.h"
16
17#include <dirent.h>
18
19namespace LIBC_NAMESPACE_DECL {
20
21// Platform specific function which will open the directory |name|
22// and return its file descriptor. Upon failure, the error value is returned.
23ErrorOr<int> platform_opendir(const char *name);
24
25// Platform specific function which will close the directory with
26// file descriptor |fd|. Returns 0 on success, or the error number on failure.
27int platform_closedir(int fd);
28
29// Platform specific function which will fetch dirents in to buffer.
30// Returns the number of bytes written into buffer or the error number on
31// failure.
32ErrorOr<size_t> platform_fetch_dirents(int fd, cpp::span<uint8_t> buffer);
33
34// This class is designed to allow implementation of the POSIX dirent.h API.
35// By itself, it is platform independent but calls platform specific
36// functions to perform OS operations.
37class Dir {
38 static constexpr size_t BUFSIZE = 1024;
39 int fd;
40 size_t readptr = 0; // The current read pointer.
41 size_t fillsize = 0; // The number of valid bytes availabe in the buffer.
42
43 // This is a buffer of struct dirent values which will be fetched
44 // from the OS. Since the d_name of struct dirent can be of a variable
45 // size, we store the data in a byte array.
46 uint8_t buffer[BUFSIZE];
47
48 Mutex mutex;
49
50 // A directory is to be opened by the static method open and closed
51 // by the close method. So, all constructors and destructor are declared
52 // as private. Inappropriate constructors are declared as deleted.
53 LIBC_INLINE Dir() = delete;
54 LIBC_INLINE Dir(const Dir &) = delete;
55
56 LIBC_INLINE explicit Dir(int fdesc)
57 : fd(fdesc), readptr(0), fillsize(0),
58 mutex(/*timed=*/false, /*recursive=*/false, /*robust=*/false,
59 /*pshared=*/false) {}
60 LIBC_INLINE ~Dir() = default;
61
62 LIBC_INLINE Dir &operator=(const Dir &) = delete;
63
64public:
65 static ErrorOr<Dir *> open(const char *path);
66
67 ErrorOr<struct ::dirent *> read();
68
69 // Returns 0 on success or the error number on failure. If an error number
70 // was returned, then the resources associated with the directory are not
71 // cleaned up.
72 int close();
73
74 LIBC_INLINE int getfd() { return fd; }
75};
76
77} // namespace LIBC_NAMESPACE_DECL
78
79#endif // LLVM_LIBC_SRC___SUPPORT_FILE_DIR_H
80

source code of libc/src/__support/File/dir.h