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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 19:33:14 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 19:33:14 +0000 |
commit | 36d22d82aa202bb199967e9512281e9a53db42c9 (patch) | |
tree | 105e8c98ddea1c1e4784a60a5a6410fa416be2de /third_party/rust/nix/src/sys/memfd.rs | |
parent | Initial commit. (diff) | |
download | firefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.tar.xz firefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.zip |
Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'third_party/rust/nix/src/sys/memfd.rs')
-rw-r--r-- | third_party/rust/nix/src/sys/memfd.rs | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/third_party/rust/nix/src/sys/memfd.rs b/third_party/rust/nix/src/sys/memfd.rs new file mode 100644 index 0000000000..ad9345e89d --- /dev/null +++ b/third_party/rust/nix/src/sys/memfd.rs @@ -0,0 +1,64 @@ +//! Interfaces for managing memory-backed files. + +use cfg_if::cfg_if; +use std::os::unix::io::RawFd; + +use crate::errno::Errno; +use crate::Result; +use std::ffi::CStr; + +libc_bitflags!( + /// Options that change the behavior of [`memfd_create`]. + pub struct MemFdCreateFlag: libc::c_uint { + /// Set the close-on-exec ([`FD_CLOEXEC`]) flag on the new file descriptor. + /// + /// By default, the new file descriptor is set to remain open across an [`execve`] + /// (the `FD_CLOEXEC` flag is initially disabled). This flag can be used to change + /// this default. The file offset is set to the beginning of the file (see [`lseek`]). + /// + /// See also the description of the `O_CLOEXEC` flag in [`open(2)`]. + /// + /// [`execve`]: crate::unistd::execve + /// [`lseek`]: crate::unistd::lseek + /// [`FD_CLOEXEC`]: crate::fcntl::FdFlag::FD_CLOEXEC + /// [`open(2)`]: https://man7.org/linux/man-pages/man2/open.2.html + MFD_CLOEXEC; + /// Allow sealing operations on this file. + /// + /// See also the file sealing notes given in [`memfd_create(2)`]. + /// + /// [`memfd_create(2)`]: https://man7.org/linux/man-pages/man2/memfd_create.2.html + MFD_ALLOW_SEALING; + } +); + +/// Creates an anonymous file that lives in memory, and return a file-descriptor to it. +/// +/// The file behaves like a regular file, and so can be modified, truncated, memory-mapped, and so on. +/// However, unlike a regular file, it lives in RAM and has a volatile backing storage. +/// +/// For more information, see [`memfd_create(2)`]. +/// +/// [`memfd_create(2)`]: https://man7.org/linux/man-pages/man2/memfd_create.2.html +pub fn memfd_create(name: &CStr, flags: MemFdCreateFlag) -> Result<RawFd> { + let res = unsafe { + cfg_if! { + if #[cfg(all( + // Android does not have a memfd_create symbol + not(target_os = "android"), + any( + target_os = "freebsd", + // If the OS is Linux, gnu and musl expose a memfd_create symbol but not uclibc + target_env = "gnu", + target_env = "musl", + )))] + { + libc::memfd_create(name.as_ptr(), flags.bits()) + } else { + libc::syscall(libc::SYS_memfd_create, name.as_ptr(), flags.bits()) + } + } + }; + + Errno::result(res).map(|r| r as RawFd) +} |