having trouble compiling on Alpine 3.17

[dmolik]

I'm getting the following with rust 1.66.1, and musl 1.2.3-r4:

error[E0425]: cannot find function `copy_file_range` in crate `libc`
    --> src/devices/src/virtio/fs/linux/passthrough.rs:1721:19
     |
1721 |             libc::copy_file_range(
     |                   ^^^^^^^^^^^^^^^
     |
    ::: /usr/local/cargo/registry/src/github.com-1ecc6299db9ec823/libc-0.2.126/src/unix/linux_like/linux/musl/b64/x86_64/mod.rs:576:1
     |
576  | pub const SYS_copy_file_range: ::c_long = 326;
     | --------------------------------------- similarly named constant `SYS_copy_file_range` defined here
     |
help: a constant with a similar name exists
     |
1721 |             libc::SYS_copy_file_range(
     |                   ~~~~~~~~~~~~~~~~~~~
help: consider importing this function
     |
5    | use nix::fcntl::copy_file_range;
     |
help: if you import `copy_file_range`, refer to it directly
     |
1721 -             libc::copy_file_range(
1721 +             copy_file_range(
     |

[slp]

Seems like either musl is missing support for copy_file_range or libc doesn't yet provide a wrapper for it. After a quick look at both projects, seems to be the latter. Should be a quite straightforward PR for libc, do you have plans to send it yourself?

[dmolik]

I don't have a plan. I did poke around today, and it doesn't seem like a huge lift, but I'm not a rust developer, but from what I could tell it was something like a 12 line patch to libc

[slp]

I've just created a PR adding copy_file_range to musl: rust-lang/libc#3133

Meanwhile, it's possible to build libkrun by patching the dependency:

--- a/Cargo.toml
+++ b/Cargo.toml
@@ -7,3 +7,6 @@ members = ["src/libkrun"]
 [profile.release]
 #panic = "abort"
 lto = true
+
+[patch.crates-io]
+libc = { git = "https://github.com/slp/libc", branch = "musl-copy-file-range" }

[dmolik]

thanks!

[slp]

Closing as copy_file_range is now available in musl.

[dkwo]

At least on Void Linux musl void-linux/void-packages#55983 , it seems one also need this PR rust-lang/libc#4478 to fix

   Compiling zstd v0.13.3
error[E0412]: cannot find type `statx` in crate `libc`
   --> src/devices/src/virtio/fs/linux/passthrough.rs:150:39
    |
150 |       let mut stx = MaybeUninit::<libc::statx>::zeroed();
    |                                         ^^^^^ help: a struct with a similar name exists: `stat`
    |
   ::: /host/cargo/registry/src/index.crates.io-1949cf8c6b5b557f/libc-0.2.172/src/unix/linux_like/linux/musl/b64/x86_64/mod.rs:11:1
    |
11  | / s! {
12  | |     pub struct stat {
13  | |         pub st_dev: crate::dev_t,
14  | |         pub st_ino: crate::ino_t,
...   |
140 | | }
    | |_- similarly named struct `stat` defined here

error[E0425]: cannot find function `statx` in crate `libc`
   --> src/devices/src/virtio/fs/linux/passthrough.rs:158:15
    |
158 |         libc::statx(
    |               ^^^^^ help: a function with a similar name exists: `stat`
    |
   ::: /host/cargo/registry/src/index.crates.io-1949cf8c6b5b557f/libc-0.2.172/src/unix/mod.rs:876:5
    |
876 |     pub fn stat(path: *const c_char, buf: *mut stat) -> c_int;
    |     ---------------------------------------------------------- similarly named function `stat` defined here

error[E0425]: cannot find value `STATX_BASIC_STATS` in crate `libc`
   --> src/devices/src/virtio/fs/linux/passthrough.rs:162:19
    |
162 |             libc::STATX_BASIC_STATS | libc::STATX_MNT_ID,
    |                   ^^^^^^^^^^^^^^^^^ not found in `libc`

error[E0425]: cannot find value `STATX_MNT_ID` in crate `libc`
   --> src/devices/src/virtio/fs/linux/passthrough.rs:162:45
    |
162 |             libc::STATX_BASIC_STATS | libc::STATX_MNT_ID,
    |                                             ^^^^^^^^^^^^ not found in `libc`

and something else to fix

   Compiling nitro-enclaves v0.2.0
error[E0308]: mismatched types
    --> /host/cargo/registry/src/index.crates.io-1949cf8c6b5b557f/nitro-enclaves-0.2.0/src/launch/mod.rs:81:56
     |
81   |             let ret = unsafe { libc::ioctl(self.vm_fd, NE_SET_USER_MEMORY_REGION, r) };
     |                                -----------             ^^^^^^^^^^^^^^^^^^^^^^^^^ expected `i32`, found `u64`
     |                                |
     |                                arguments to this function are incorrect
     |
note: function defined here
    --> /host/cargo/registry/src/index.crates.io-1949cf8c6b5b557f/libc-0.2.172/src/unix/linux_like/linux/mod.rs:7005:12
     |
7005 |     pub fn ioctl(fd: c_int, request: Ioctl, ...) -> c_int;
     |            ^^^^^
help: you can convert a `u64` to an `i32` and panic if the converted value doesn't fit
     |
81   |             let ret = unsafe { libc::ioctl(self.vm_fd, NE_SET_USER_MEMORY_REGION.try_into().unwrap(), r) };
     |                                                                                 ++++++++++++++++++++

For more information about this error, try `rustc --explain E0308`.
error: could not compile `nitro-enclaves` (lib) due to 1 previous error
warning: build failed, waiting for other jobs to finish...
Some errors have detailed explanations: E0412, E0425.
For more information about an error, try `rustc --explain E0412`.
error: could not compile `devices` (lib) due to 4 previous errors
make: *** [Makefile:95: target//release/libkrun.so.1.14.0] Error 101

Any suggestions?

[slp]

@dkwo after PR rust-lang/libc#4478 is merged, you can simply patch Cargo.toml to not include nitro-enclaves since it's not needed for the generic flavor of libkrun.

[dkwo]

@slp Thanks. I assume that the latter can be dropped, if one is only interested to use it with muvm.