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Use mem::offset_of! for sockaddr_un.sun_path #130861

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merged 2 commits into from
Sep 27, 2024
Merged

Use mem::offset_of! for sockaddr_un.sun_path #130861

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a51b0a2
Use `mem::offset_of!` for `sockaddr_un.sun_path`
cuviper Sep 25, 2024
9431d1a
Add `sun_path` to the fake doc `sockaddr_un`
cuviper Sep 26, 2024
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21 changes: 9 additions & 12 deletions library/std/src/os/unix/net/addr.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,15 +15,12 @@ mod libc {
pub type socklen_t = u32;
pub struct sockaddr;
#[derive(Clone)]
pub struct sockaddr_un;
pub struct sockaddr_un {
pub sun_path: [u8; 1],
}
}

fn sun_path_offset(addr: &libc::sockaddr_un) -> usize {
// Work with an actual instance of the type since using a null pointer is UB
let base = (addr as *const libc::sockaddr_un).addr();
let path = core::ptr::addr_of!(addr.sun_path).addr();
path - base
}
const SUN_PATH_OFFSET: usize = mem::offset_of!(libc::sockaddr_un, sun_path);

pub(super) fn sockaddr_un(path: &Path) -> io::Result<(libc::sockaddr_un, libc::socklen_t)> {
// SAFETY: All zeros is a valid representation for `sockaddr_un`.
Expand Down Expand Up @@ -53,7 +50,7 @@ pub(super) fn sockaddr_un(path: &Path) -> io::Result<(libc::sockaddr_un, libc::s
ptr::copy_nonoverlapping(bytes.as_ptr(), addr.sun_path.as_mut_ptr().cast(), bytes.len())
};

let mut len = sun_path_offset(&addr) + bytes.len();
let mut len = SUN_PATH_OFFSET + bytes.len();
match bytes.get(0) {
Some(&0) | None => {}
Some(_) => len += 1,
Expand Down Expand Up @@ -114,13 +111,13 @@ impl SocketAddr {
let sun_path: &[u8] =
unsafe { mem::transmute::<&[libc::c_char], &[u8]>(&addr.sun_path) };
len = core::slice::memchr::memchr(0, sun_path)
.map_or(len, |new_len| (new_len + sun_path_offset(&addr)) as libc::socklen_t);
.map_or(len, |new_len| (new_len + SUN_PATH_OFFSET) as libc::socklen_t);
}

if len == 0 {
// When there is a datagram from unnamed unix socket
// linux returns zero bytes of address
len = sun_path_offset(&addr) as libc::socklen_t; // i.e., zero-length address
len = SUN_PATH_OFFSET as libc::socklen_t; // i.e., zero-length address
} else if addr.sun_family != libc::AF_UNIX as libc::sa_family_t {
return Err(io::const_io_error!(
io::ErrorKind::InvalidInput,
Expand Down Expand Up @@ -238,7 +235,7 @@ impl SocketAddr {
}

fn address(&self) -> AddressKind<'_> {
let len = self.len as usize - sun_path_offset(&self.addr);
let len = self.len as usize - SUN_PATH_OFFSET;
let path = unsafe { mem::transmute::<&[libc::c_char], &[u8]>(&self.addr.sun_path) };

// macOS seems to return a len of 16 and a zeroed sun_path for unnamed addresses
Expand Down Expand Up @@ -287,7 +284,7 @@ impl linux_ext::addr::SocketAddrExt for SocketAddr {
addr.sun_path.as_mut_ptr().add(1) as *mut u8,
name.len(),
);
let len = (sun_path_offset(&addr) + 1 + name.len()) as libc::socklen_t;
let len = (SUN_PATH_OFFSET + 1 + name.len()) as libc::socklen_t;
SocketAddr::from_parts(addr, len)
}
}
Expand Down
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