+++ /dev/null
-/*
- * Copyright (C) 2018 Jérémie Galarneau <jeremie.galarneau@efficios.com>
- *
- * SPDX-License-Identifier: GPL-2.0-only
- *
- */
-
-#ifndef FD_TRACKER_H
-#define FD_TRACKER_H
-
-#include <common/compat/directory-handle.h>
-#include <common/macros.h>
-#include <stdint.h>
-#include <sys/types.h>
-
-struct fs_handle;
-struct fd_tracker;
-
-/*
- * Callback which returns a file descriptor to track through the fd
- * tracker. This callback must not make use of the fd_tracker as a deadlock
- * may occur.
- *
- * The int pointer argument is an output parameter that should be used to return
- * the advertised number of file descriptors.
- *
- * Must return zero on success. Negative values should map to a UNIX error code.
- */
-typedef int (*fd_open_cb)(void *, int *out_fds);
-
-/*
- * Callback to allow the user to close a now-untracked file descriptor. This
- * callback must not make use of the fd_tracker as a deadlock may occur.
- *
- * The callback can freely modify the in_fds argument as it is copied by the
- * fd_tracker before being used. The fd tracker assumes in_fds to be closed by
- * the time the callback returns.
- *
- * Must return zero on success. Negative values should map to a UNIX error code.
- */
-typedef int (*fd_close_cb)(void *, int *in_fds);
-
-/*
- * Set the maximal number of fds that the process should be allowed to open at
- * any given time. This function must be called before any other of this
- * interface.
- *
- * The unlinked_file_path is an absolute path (which does not need to exist)
- * under which unlinked files will be stored for as long as a reference to them
- * is held.
- */
-struct fd_tracker *fd_tracker_create(const char *unlinked_file_path,
- unsigned int capacity);
-
-/* Returns an error if file descriptors are leaked. */
-int fd_tracker_destroy(struct fd_tracker *tracker);
-
-/*
- * Open a handle to a suspendable filesystem file descriptor.
- *
- * See OPEN(3) for an explanation of flags and mode. NULL is returned in case of
- * error and errno is left untouched. Note that passing NULL as mode will result
- * in open()'s default behaviour being used (using the process' umask).
- *
- * A fs_handle wraps a file descriptor created by OPEN(3). It is suspendable
- * meaning that the underlying file may be closed at any time unless the
- * handle is marked as being in-use (see fs_handle_get_fd() and
- * fs_handle_put_fd()).
- *
- * If the tracker opted to close the underlying file descriptor, it will
- * be restored to its last known state when it is obtained through
- * the fs_handle's fs_handle_get_fd() method.
- *
- * Note that a suspendable file descriptor can be closed by the fd tracker at
- * anytime when it is not in use. This means that the user should not rely on it
- * being safe to unlink the file. Moreover, concurent modifications to the file
- * (e.g. truncation) may react differently than if the file descriptor was kept
- * open.
- */
-struct fs_handle *fd_tracker_open_fs_handle(struct fd_tracker *tracker,
- struct lttng_directory_handle *directory,
- const char *path,
- int flags,
- mode_t *mode);
-
-/*
- * Open a tracked unsuspendable file descriptor.
- *
- * This function allows the fd tracker to keep track of unsuspendable
- * file descriptors. A callback, open, is passed to allow the tracker
- * to atomically reserve an entry for a given count of new file descriptors,
- * suspending file descriptors as needed, and invoke the provided callback
- * without ever exceeding the tracker's capacity.
- *
- * fd_count indicates the count of file descriptors that will be opened and
- * returned by the open callback. The storage location at out_fds is assumed
- * to be large enough to hold 'fd_count * sizeof(int)'.
- *
- * Names may be provided to allow easier debugging of file descriptor
- * exhaustions.
- *
- * The callback's return value is returned to the user. Additionally, two
- * negative tracker-specific codes may be returned:
- * - ENOMEM: allocation of a new entry failed,
- * - EMFILE: too many unsuspendable fds are opened and the tracker can't
- * accommodates the request for a new unsuspendable entry.
- */
-int fd_tracker_open_unsuspendable_fd(struct fd_tracker *tracker,
- int *out_fds,
- const char **names,
- unsigned int fd_count,
- fd_open_cb open,
- void *data);
-
-/*
- * Close a tracked unsuspendable file descriptor.
- *
- * This function allows the fd tracker to keep track of unsuspendable
- * file descriptors. A callback, close, is passed to allow the tracker
- * to atomically release a file descriptor entry.
- *
- * Returns 0 if the close callback returned success. Returns the value returned
- * by the close callback if it is negative. Additionally, a tracker-specific
- * code may be returned:
- * - EINVAL: a file descriptor was unknown to the tracker
- *
- * Closed fds are set to -1 in the fds array which, in the event of an error,
- * allows the user to know which file descriptors are no longer being tracked.
- */
-int fd_tracker_close_unsuspendable_fd(struct fd_tracker *tracker,
- int *fds,
- unsigned int fd_count,
- fd_close_cb close,
- void *data);
-
-/*
- * Log the contents of the fd_tracker.
- */
-void fd_tracker_log(struct fd_tracker *tracker);
-
-#endif /* FD_TRACKER_H */
projects / lttng-tools.git / blobdiff