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wasi-common: change behavior of path_readlink to truncate on too-small buffers (#6225)

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this is the same behavior as exists in posix readlink(2)
This commit is contained in:
Pat Hickey
2023-04-18 11:12:30 -07:00
committed by GitHub
parent 2494867c5f
commit 24b607cf75
2 changed files with 9 additions and 9 deletions
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8
crates/test-programs/wasi-tests/src/bin/readlink.rs
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@@ -22,10 +22,10 @@ unsafe fn test_readlink(dir_fd: wasi::Fd) {
// Read link into smaller buffer than the actual link's length // Read link into smaller buffer than the actual link's length
let buf = &mut [0u8; 4]; let buf = &mut [0u8; 4];
let err = wasi::path_readlink(dir_fd, "symlink", buf.as_mut_ptr(), buf.len()) let bufused = wasi::path_readlink(dir_fd, "symlink", buf.as_mut_ptr(), buf.len())
.err() .expect("readlink with too-small buffer should silently truncate");
.expect("readlink with too-small buffer should fail"); assert_eq!(bufused, 4);
assert_errno!(err, wasi::ERRNO_RANGE); assert_eq!(buf, b"targ");
// Clean up. // Clean up.
wasi::path_unlink_file(dir_fd, "target").expect("removing a file"); wasi::path_unlink_file(dir_fd, "target").expect("removing a file");

10
crates/wasi-common/src/snapshots/preview_1.rs
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@@ -801,11 +801,11 @@ impl wasi_snapshot_preview1::WasiSnapshotPreview1 for WasiCtx {
.into_string() .into_string()
.map_err(|_| Error::illegal_byte_sequence().context("link contents"))?; .map_err(|_| Error::illegal_byte_sequence().context("link contents"))?;
let link_bytes = link.as_bytes(); let link_bytes = link.as_bytes();
let link_len = link_bytes.len(); // Like posix readlink(2), silently truncate links when they are larger than the
if link_len > buf_len as usize { // destination buffer:
return Err(Error::range()); let link_len = std::cmp::min(link_bytes.len(), buf_len as usize);
} buf.as_array(link_len as u32)
buf.as_array(link_len as u32).copy_from_slice(link_bytes)?; .copy_from_slice(&link_bytes[..link_len])?;
Ok(link_len as types::Size) Ok(link_len as types::Size)
} }