Struct close_fds::CloseFdsBuilder [−][src]
pub struct CloseFdsBuilder<'a> { /* fields omitted */ }
Expand description
A “builder” for either closing all open file descriptors or setting them as close-on-exec.
Implementations
Leave the file descriptors listed in keep_fds
alone; i.e. do not close them or set the
close-on-exec flag on them.
Calling this method multiple times will replace the list of file descriptors to be left alone, not extend it. Additionally, it’s not recommended to call this method multiple times, since it pre-scans the list to collect information for later use.
Efficiency
It is highly recommended to sort the keep_fds
slice first (see also
Self::keep_fds_sorted()
. This will give you significant performance improvements
(especially on Linux 5.9+ and FreeBSD 12.2+).
close_fds
can’t just copy the slice and sort it for you because allocating memory is not
async-signal-safe (see “Async-signal-safety”).
Identical to Self::keep_fds()
, but assumes that the given list of file descriptors is
sorted.
Safety
keep_fds
must be sorted in ascending order.
Set whether Self::cloexecfrom()
needs to behave reliably in multithreaded programs
(default is false
).
See FdIterBuilder::threadsafe()
for more
information.
Note that this only applies when using Self::cloexecfrom()
. Self::closefrom()
is unsafe in the presence of threads anyway, so it is not required to honor this.
Set whether this crate is allowed to look at special files for speedups when closing the
specified file descriptors (default is true
).
See
FdIterBuilder::allow_filesystem()
for more information.
Identical to Self::closefrom()
, but sets the FD_CLOEXEC
flag on the file descriptors
instead of closing them.
On some platforms (most notably, some of the BSDs), this is significantly less efficient than
Self::closefrom()
, and use of that function should be preferred when possible.
Close all of the file descriptors starting at minfd
and not excluded by
Self::keep_fds()
.
Safety
This function is NOT safe to use if other threads are interacting with files, networking,
or anything else that could possibly involve file descriptors in any way, shape, or form.
(Note: On some systems, file descriptor use may be more common than you think! For example,
on Linux with some versions of musl libc, std::fs::canonicalize()
will open a file
descriptor to the given path.)
In addition, some objects, such as std::fs::File
, may open file descriptors and then
assume that they will remain open. This function, by closing those file descriptors,
violates those assumptions.
This function is safe to use if it can be verified that these are not concerns. For
example, it should be safe at startup or just before an exec()
. At all other times,
exercise extreme caution when using this function, as it may lead to race conditions and/or
security issues.
(Note: The above warnings, by definition, make it unsafe to call this function concurrently from multiple threads. As a result, this function may perform other non-thread-safe operations.)
Trait Implementations
Auto Trait Implementations
impl<'a> Send for CloseFdsBuilder<'a>
impl<'a> Sync for CloseFdsBuilder<'a>
impl<'a> Unpin for CloseFdsBuilder<'a>