consumerd: refactor: split read_subbuf into sub-operations
[lttng-tools.git] / src / common / fs-handle.h
1 /*
2 * Copyright (C) 2020 Jérémie Galarneau <jeremie.galarneau@efficios.com>
3 *
4 * SPDX-License-Identifier: LGPL-2.1-only
5 *
6 */
7
8 #ifndef FS_HANDLE_H
9 #define FS_HANDLE_H
10
11 #include <common/macros.h>
12 #include <stdio.h>
13
14 struct fs_handle;
15
16 /*
17 * Marks the handle as the most recently used and marks the 'fd' as
18 * "in-use". This prevents the tracker from recycling the underlying
19 * file descriptor while it is actively being used by a thread.
20 *
21 * Don't forget that the tracker may be initiating an fd 'suspension'
22 * from another thread as the need to free an fd slot may arise from any
23 * thread within the daemon.
24 *
25 * Note that a restorable fd should never be held for longer than
26 * strictly necessary (e.g. the duration of a syscall()).
27 *
28 * Returns the fd on success, otherwise a negative value may be returned
29 * if the restoration of the fd failed.
30 */
31 LTTNG_HIDDEN
32 int fs_handle_get_fd(struct fs_handle *handle);
33
34 /*
35 * Used by the caller to signal that it is no longer using the underlying fd and
36 * that it may be safely suspended.
37 */
38 LTTNG_HIDDEN
39 void fs_handle_put_fd(struct fs_handle *handle);
40
41 /*
42 * Unlink the file associated to an fs_handle. Note that the unlink
43 * operation will not be performed immediately. It will only be performed
44 * once all references to the underlying file (through other fs_handle objects)
45 * have been released.
46 *
47 * However, note that the file will be renamed so as to provide the observable
48 * effect of an unlink(), that is removing a name from the filesystem.
49 *
50 * Returns 0 on success, otherwise a negative value will be returned
51 * if the operation failed.
52 */
53 LTTNG_HIDDEN
54 int fs_handle_unlink(struct fs_handle *handle);
55
56 /*
57 * Frees the handle and discards the underlying fd.
58 */
59 LTTNG_HIDDEN
60 int fs_handle_close(struct fs_handle *handle);
61
62 LTTNG_HIDDEN
63 ssize_t fs_handle_read(struct fs_handle *handle, void *buf, size_t count);
64
65 LTTNG_HIDDEN
66 ssize_t fs_handle_write(struct fs_handle *handle, const void *buf, size_t count);
67
68 LTTNG_HIDDEN
69 int fs_handle_truncate(struct fs_handle *handle, off_t offset);
70
71 LTTNG_HIDDEN
72 off_t fs_handle_seek(struct fs_handle *handle, off_t offset, int whence);
73
74 #endif /* FS_HANDLE_H */
This page took 0.030261 seconds and 4 git commands to generate.