diff options
| -rw-r--r-- | CHANGELOG.md | 1 | ||||
| -rw-r--r-- | src/sys/mman.rs | 35 | ||||
| -rw-r--r-- | test/sys/test_mman.rs | 80 |
3 files changed, 116 insertions, 0 deletions
diff --git a/CHANGELOG.md b/CHANGELOG.md index e018ab20..ff4c9beb 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -5,6 +5,7 @@ This project adheres to [Semantic Versioning](http://semver.org/). ## [Unreleased] - ReleaseDate ### Added +- Added `mremap` (#[1306](https://github.com/nix-rust/nix/pull/1306)) ### Changed ### Fixed ### Removed diff --git a/src/sys/mman.rs b/src/sys/mman.rs index b2bed6e4..63a0779c 100644 --- a/src/sys/mman.rs +++ b/src/sys/mman.rs @@ -139,6 +139,17 @@ libc_bitflags!{ } } +#[cfg(target_os = "linux")] +libc_bitflags!{ + /// Options for `mremap()`. + pub struct MRemapFlags: c_int { + /// Permit the kernel to relocate the mapping to a new virtual address, if necessary. + MREMAP_MAYMOVE; + /// Place the mapping at exactly the address specified in `new_address`. + MREMAP_FIXED; + } +} + libc_enum!{ /// Usage information for a range of memory to allow for performance optimizations by the kernel. /// @@ -315,6 +326,30 @@ pub unsafe fn mmap(addr: *mut c_void, length: size_t, prot: ProtFlags, flags: Ma } } +/// Expands (or shrinks) an existing memory mapping, potentially moving it at +/// the same time. +/// +/// # Safety +/// +/// See the `mremap(2)` [man page](https://man7.org/linux/man-pages/man2/mremap.2.html) for +/// detailed requirements. +#[cfg(target_os = "linux")] +pub unsafe fn mremap( + addr: *mut c_void, + old_size: size_t, + new_size: size_t, + flags: MRemapFlags, + new_address: Option<* mut c_void>, +) -> Result<*mut c_void> { + let ret = libc::mremap(addr, old_size, new_size, flags.bits(), new_address.unwrap_or(std::ptr::null_mut())); + + if ret == libc::MAP_FAILED { + Err(Error::Sys(Errno::last())) + } else { + Ok(ret) + } +} + /// remove a mapping /// /// # Safety diff --git a/test/sys/test_mman.rs b/test/sys/test_mman.rs new file mode 100644 index 00000000..152fff69 --- /dev/null +++ b/test/sys/test_mman.rs @@ -0,0 +1,80 @@ +use nix::Error; +use nix::libc::{c_void, size_t}; +use nix::sys::mman::{mmap, MapFlags, ProtFlags}; + +#[cfg(target_os = "linux")] +use nix::sys::mman::{mremap, MRemapFlags}; + +#[test] +fn test_mmap_anonymous() { + let ref mut byte = unsafe { + let ptr = mmap(std::ptr::null_mut(), 1, + ProtFlags::PROT_READ | ProtFlags::PROT_WRITE, + MapFlags::MAP_PRIVATE | MapFlags::MAP_ANONYMOUS, -1, 0) + .unwrap(); + *(ptr as * mut u8) + }; + assert_eq !(*byte, 0x00u8); + *byte = 0xffu8; + assert_eq !(*byte, 0xffu8); +} + +#[test] +#[cfg(target_os = "linux")] +fn test_mremap_grow() { + const ONE_K : size_t = 1024; + let slice : &mut[u8] = unsafe { + let mem = mmap(std::ptr::null_mut(), ONE_K, + ProtFlags::PROT_READ | ProtFlags::PROT_WRITE, + MapFlags::MAP_ANONYMOUS | MapFlags::MAP_PRIVATE, -1, 0) + .unwrap(); + std::slice::from_raw_parts_mut(mem as * mut u8, ONE_K) + }; + assert_eq !(slice[ONE_K - 1], 0x00); + slice[ONE_K - 1] = 0xFF; + assert_eq !(slice[ONE_K - 1], 0xFF); + + let slice : &mut[u8] = unsafe { + let mem = mremap(slice.as_mut_ptr() as * mut c_void, ONE_K, 10 * ONE_K, + MRemapFlags::MREMAP_MAYMOVE, None) + .unwrap(); + std::slice::from_raw_parts_mut(mem as * mut u8, 10 * ONE_K) + }; + + // The first KB should still have the old data in it. + assert_eq !(slice[ONE_K - 1], 0xFF); + + // The additional range should be zero-init'd and accessible. + assert_eq !(slice[10 * ONE_K - 1], 0x00); + slice[10 * ONE_K - 1] = 0xFF; + assert_eq !(slice[10 * ONE_K - 1], 0xFF); +} + +#[test] +#[cfg(target_os = "linux")] +fn test_mremap_shrink() { + const ONE_K : size_t = 1024; + let slice : &mut[u8] = unsafe { + let mem = mmap(std::ptr::null_mut(), 10 * ONE_K, + ProtFlags::PROT_READ | ProtFlags::PROT_WRITE, + MapFlags::MAP_ANONYMOUS | MapFlags::MAP_PRIVATE, -1, 0) + .unwrap(); + std::slice::from_raw_parts_mut(mem as * mut u8, ONE_K) + }; + assert_eq !(slice[ONE_K - 1], 0x00); + slice[ONE_K - 1] = 0xFF; + assert_eq !(slice[ONE_K - 1], 0xFF); + + let slice : &mut[u8] = unsafe { + let mem = mremap(slice.as_mut_ptr() as * mut c_void, 10 * ONE_K, ONE_K, + MRemapFlags::empty(), None) + .unwrap(); + // Since we didn't supply MREMAP_MAYMOVE, the address should be the + // same. + assert_eq !(mem, slice.as_mut_ptr() as * mut c_void); + std::slice::from_raw_parts_mut(mem as * mut u8, ONE_K) + }; + + // The first KB should still be accessible and have the old data in it. + assert_eq !(slice[ONE_K - 1], 0xFF); +} |