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957: Add support for new WASI snapshot, backwards compat too r=MarkMcCaskey a=MarkMcCaskey # Review - [x] Add a short description of the the change to the CHANGELOG.md file Co-authored-by: Mark McCaskey <mark@wasmer.io> Co-authored-by: Mark McCaskey <5770194+markmccaskey@users.noreply.github.com>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,6 @@ | ||
| //! These modules provide wrappers and implementations for older version of WASI. | ||
| //! | ||
| //! If you are relying on legacy WASI, please upgrade for the best experience. | ||
| #[cfg(feature = "snapshot0")] | ||
| pub mod snapshot0; |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,178 @@ | ||
| use crate::ptr::{Array, WasmPtr}; | ||
| use crate::syscalls; | ||
| use crate::syscalls::types::{self, snapshot0}; | ||
| use wasmer_runtime_core::vm::Ctx; | ||
|
|
||
| /// Wrapper around `syscalls::fd_filestat_get` with extra logic to handle the size | ||
| /// difference of `wasi_filestat_t` | ||
| /// | ||
| /// WARNING: this function involves saving, clobbering, and restoring unrelated | ||
| /// Wasm memory. If the memory clobbered by the current syscall is also used by | ||
| /// that syscall, then it may break. | ||
| pub fn fd_filestat_get( | ||
| ctx: &mut Ctx, | ||
| fd: types::__wasi_fd_t, | ||
| buf: WasmPtr<snapshot0::__wasi_filestat_t>, | ||
| ) -> types::__wasi_errno_t { | ||
| let memory = ctx.memory(0); | ||
|
|
||
| // transmute the WasmPtr<T1> into a WasmPtr<T2> where T2 > T1, this will read extra memory. | ||
| // The edge case of this causing an OOB is not handled, if the new field is OOB, then the entire | ||
| // memory access will fail. | ||
| let new_buf: WasmPtr<types::__wasi_filestat_t> = unsafe { std::mem::transmute(buf) }; | ||
|
|
||
| // Copy the data including the extra data | ||
| let new_filestat_setup: types::__wasi_filestat_t = | ||
| wasi_try!(new_buf.deref(memory)).get().clone(); | ||
|
|
||
| // Set up complete, make the call with the pointer that will write to the | ||
| // struct and some unrelated memory after the struct. | ||
| let result = syscalls::fd_filestat_get(ctx, fd, new_buf); | ||
|
|
||
| // reborrow memory | ||
| let memory = ctx.memory(0); | ||
|
|
||
| // get the values written to memory | ||
| let new_filestat = wasi_try!(new_buf.deref(memory)).get(); | ||
| // translate the new struct into the old struct in host memory | ||
| let old_stat = snapshot0::__wasi_filestat_t { | ||
| st_dev: new_filestat.st_dev, | ||
| st_ino: new_filestat.st_ino, | ||
| st_filetype: new_filestat.st_filetype, | ||
| st_nlink: new_filestat.st_nlink as u32, | ||
| st_size: new_filestat.st_size, | ||
| st_atim: new_filestat.st_atim, | ||
| st_mtim: new_filestat.st_mtim, | ||
| st_ctim: new_filestat.st_ctim, | ||
| }; | ||
|
|
||
| // write back the original values at the pointer's memory locations | ||
| // (including the memory unrelated to the pointer) | ||
| wasi_try!(new_buf.deref(memory)).set(new_filestat_setup); | ||
|
|
||
| // Now that this memory is back as it was, write the translated filestat | ||
| // into memory leaving it as it should be | ||
| wasi_try!(buf.deref(memory)).set(old_stat); | ||
|
|
||
| result | ||
| } | ||
|
|
||
| /// Wrapper around `syscalls::path_filestat_get` with extra logic to handle the size | ||
| /// difference of `wasi_filestat_t` | ||
| pub fn path_filestat_get( | ||
| ctx: &mut Ctx, | ||
| fd: types::__wasi_fd_t, | ||
| flags: types::__wasi_lookupflags_t, | ||
| path: WasmPtr<u8, Array>, | ||
| path_len: u32, | ||
| buf: WasmPtr<snapshot0::__wasi_filestat_t>, | ||
| ) -> types::__wasi_errno_t { | ||
| // see `fd_filestat_get` in this file for an explanation of this strange behavior | ||
| let memory = ctx.memory(0); | ||
|
|
||
| let new_buf: WasmPtr<types::__wasi_filestat_t> = unsafe { std::mem::transmute(buf) }; | ||
| let new_filestat_setup: types::__wasi_filestat_t = | ||
| wasi_try!(new_buf.deref(memory)).get().clone(); | ||
|
|
||
| let result = syscalls::path_filestat_get(ctx, fd, flags, path, path_len, new_buf); | ||
|
|
||
| let memory = ctx.memory(0); | ||
| let new_filestat = wasi_try!(new_buf.deref(memory)).get(); | ||
| let old_stat = snapshot0::__wasi_filestat_t { | ||
| st_dev: new_filestat.st_dev, | ||
| st_ino: new_filestat.st_ino, | ||
| st_filetype: new_filestat.st_filetype, | ||
| st_nlink: new_filestat.st_nlink as u32, | ||
| st_size: new_filestat.st_size, | ||
| st_atim: new_filestat.st_atim, | ||
| st_mtim: new_filestat.st_mtim, | ||
| st_ctim: new_filestat.st_ctim, | ||
| }; | ||
|
|
||
| wasi_try!(new_buf.deref(memory)).set(new_filestat_setup); | ||
| wasi_try!(buf.deref(memory)).set(old_stat); | ||
|
|
||
| result | ||
| } | ||
|
|
||
| /// Wrapper around `syscalls::fd_seek` with extra logic to remap the values | ||
| /// of `__wasi_whence_t` | ||
| pub fn fd_seek( | ||
| ctx: &mut Ctx, | ||
| fd: types::__wasi_fd_t, | ||
| offset: types::__wasi_filedelta_t, | ||
| whence: snapshot0::__wasi_whence_t, | ||
| newoffset: WasmPtr<types::__wasi_filesize_t>, | ||
| ) -> types::__wasi_errno_t { | ||
| let new_whence = match whence { | ||
| snapshot0::__WASI_WHENCE_CUR => types::__WASI_WHENCE_CUR, | ||
| snapshot0::__WASI_WHENCE_END => types::__WASI_WHENCE_END, | ||
| snapshot0::__WASI_WHENCE_SET => types::__WASI_WHENCE_SET, | ||
| // if it's invalid, let the new fd_seek handle it | ||
| _ => whence, | ||
| }; | ||
| syscalls::fd_seek(ctx, fd, offset, new_whence, newoffset) | ||
| } | ||
|
|
||
| /// Wrapper around `syscalls::poll_oneoff` with extra logic to add the removed | ||
| /// userdata field back | ||
| pub fn poll_oneoff( | ||
| ctx: &mut Ctx, | ||
| in_: WasmPtr<snapshot0::__wasi_subscription_t, Array>, | ||
| out_: WasmPtr<types::__wasi_event_t, Array>, | ||
| nsubscriptions: u32, | ||
| nevents: WasmPtr<u32>, | ||
| ) -> types::__wasi_errno_t { | ||
| // in this case the new type is smaller than the old type, so it all fits into memory, | ||
| // we just need to readjust and copy it | ||
|
|
||
| // we start by adjusting `in_` into a format that the new code can understand | ||
| let memory = ctx.memory(0); | ||
| let mut in_origs: Vec<snapshot0::__wasi_subscription_t> = vec![]; | ||
| for in_sub in wasi_try!(in_.deref(memory, 0, nsubscriptions)) { | ||
| in_origs.push(in_sub.get().clone()); | ||
| } | ||
|
|
||
| // get a pointer to the smaller new type | ||
| let in_new_type_ptr: WasmPtr<types::__wasi_subscription_t, Array> = | ||
| unsafe { std::mem::transmute(in_) }; | ||
|
|
||
| for (in_sub_new, orig) in wasi_try!(in_new_type_ptr.deref(memory, 0, nsubscriptions)) | ||
| .iter() | ||
| .zip(in_origs.iter()) | ||
| { | ||
| in_sub_new.set(types::__wasi_subscription_t { | ||
| userdata: orig.userdata, | ||
| type_: orig.type_, | ||
| u: if orig.type_ == types::__WASI_EVENTTYPE_CLOCK { | ||
| types::__wasi_subscription_u { | ||
| clock: types::__wasi_subscription_clock_t { | ||
| clock_id: unsafe { orig.u.clock.clock_id }, | ||
| timeout: unsafe { orig.u.clock.timeout }, | ||
| precision: unsafe { orig.u.clock.precision }, | ||
| flags: unsafe { orig.u.clock.flags }, | ||
| }, | ||
| } | ||
| } else { | ||
| types::__wasi_subscription_u { | ||
| fd_readwrite: unsafe { orig.u.fd_readwrite }, | ||
| } | ||
| }, | ||
| }); | ||
| } | ||
|
|
||
| // make the call | ||
| let result = syscalls::poll_oneoff(ctx, in_new_type_ptr, out_, nsubscriptions, nevents); | ||
|
|
||
| // replace the old values of in, in case the calling code reuses the memory | ||
| let memory = ctx.memory(0); | ||
|
|
||
| for (in_sub, orig) in wasi_try!(in_.deref(memory, 0, nsubscriptions)) | ||
| .iter() | ||
| .zip(in_origs.into_iter()) | ||
| { | ||
| in_sub.set(orig); | ||
| } | ||
|
|
||
| result | ||
| } |
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