Module procfs

Available on crate feature dep_rustix only.

Utilities for working with /proc, where Linux’s procfs is typically mounted.

/proc serves as an adjunct to Linux’s main syscall surface area, providing additional features with an awkward interface.

This module does a considerable amount of work to determine whether /proc is mounted, with actual procfs, and without any additional mount points on top of the paths we open.

Why all the effort to detect bind mount points? People are doing all kinds of things with Linux containers these days, with many different privilege schemes, and we want to avoid making any unnecessary assumptions. Rustix and its users will sometimes use procfs implicitly (when Linux gives them no better options), in ways that aren’t obvious from their public APIs. These filesystem accesses might not be visible to someone auditing the main code of an application for places which may be influenced by the filesystem namespace. So with the checking here, they may fail, but they won’t be able to succeed with bogus results.

Functions

proc_self_fd

Returns a handle to Linux’s /proc/self/fd directory.

proc_self_fdinfo_fd

Returns a handle to a Linux /proc/self/fdinfo/<fd> file.

proc_self_maps

Returns a handle to a Linux /proc/self/maps file.

proc_self_pagemap

Returns a handle to a Linux /proc/self/pagemap file.

proc_self_status

Returns a handle to a Linux /proc/self/status file.