feat: succinct-zkvm std-lib support

compiler/rustc_target/src/spec/targets/riscv32im_succinct_zkvm_elf.rs

@@ -10,7 +10,7 @@ pub(crate) fn target() -> Target {
             description: Some("Succinct's zero-knowledge Virtual Machine (RV32IM ISA)".into()),
             tier: Some(3),
             host_tools: Some(false),
-            std: None,
+            std: Some(true),
         },
         pointer_width: 32,
         arch: "riscv32".into(),

library/panic_abort/Cargo.toml

@@ -19,3 +19,10 @@ compiler_builtins = "0.1.0"
 
 [target.'cfg(not(all(windows, target_env = "msvc")))'.dependencies]
 libc = { version = "0.2", default-features = false }
+
+[lints.rust.unexpected_cfgs]
+level = "warn"
+check-cfg = [
+    'cfg(bootstrap)',
+    'cfg(target_os, values("succinct-zkvm"))'
+]

library/panic_abort/src/lib.rs

@@ -20,7 +20,7 @@
 #[cfg(target_os = "android")]
 mod android;
 
-#[cfg(target_os = "zkvm")]
+#[cfg(any(target_os = "zkvm", target_os = "succinct-zkvm"))]
 mod zkvm;
 
 use core::any::Any;
@@ -40,7 +40,7 @@ pub unsafe fn __rust_start_panic(_payload: &mut dyn PanicPayload) -> u32 {
     unsafe {
         android::android_set_abort_message(_payload);
     }
-    #[cfg(target_os = "zkvm")]
+    #[cfg(any(target_os = "zkvm", target_os = "succinct-zkvm"))]
     unsafe {
         zkvm::zkvm_set_abort_message(_payload);
     }

library/panic_abort/src/zkvm.rs

@@ -1,8 +1,7 @@
 use alloc::string::String;
 use core::panic::PanicPayload;
 
-// Forward the abort message to zkVM's sys_panic. This is implemented by RISC Zero's
-// platform crate which exposes system calls specifically for the zkVM.
+/// Note this function works with both `zkvm` and `succinct-zkvm`.
 pub(crate) unsafe fn zkvm_set_abort_message(payload: &mut dyn PanicPayload) {
     let payload = payload.get();
     let msg = match payload.downcast_ref::<&'static str>() {

library/std/Cargo.toml

@@ -163,4 +163,6 @@ check-cfg = [
     # and to the `backtrace` crate which messes-up with Cargo list
     # of declared features, we therefor expect any feature cfg
     'cfg(feature, values(any()))',
+    'cfg(target_os, values("succinct-zkvm"))'
 ]
+

library/std/build.rs

@@ -60,9 +60,9 @@ fn main() {
         || target_os == "uefi"
         || target_os == "teeos"
         || target_os == "zkvm"
+        || target_os == "succinct-zkvm"
         || target_os == "rtems"
         || target_os == "nuttx"
-
         // See src/bootstrap/src/core/build_steps/synthetic_targets.rs
         || env::var("RUSTC_BOOTSTRAP_SYNTHETIC_TARGET").is_ok()
     {

library/std/src/random.rs

@@ -48,6 +48,7 @@ use crate::sys::random as sys;
 /// VxWorks                | `randABytes` after waiting for `randSecure` to become ready
 /// WASI                   | [`random_get`](https://github.com/WebAssembly/WASI/blob/main/legacy/preview1/docs.md#-random_getbuf-pointeru8-buf_len-size---result-errno)
 /// ZKVM                   | `sys_rand`
+/// SUCCINCT-ZKVM          | `sys_rand` 
 ///
 /// Note that the sources used might change over time.
 ///

library/std/src/sys/alloc/mod.rs

@@ -7,7 +7,7 @@ use crate::ptr;
 // add fast paths for low alignment values.
 #[allow(dead_code)]
 const MIN_ALIGN: usize = if cfg!(any(
-    all(target_arch = "riscv32", any(target_os = "espidf", target_os = "zkvm")),
+    all(target_arch = "riscv32", any(target_os = "espidf", target_os = "zkvm", target_os = "succinct-zkvm")),
     all(target_arch = "xtensa", target_os = "espidf"),
 )) {
     // The allocator on the esp-idf and zkvm platforms guarantees 4 byte alignment.
@@ -89,7 +89,7 @@ cfg_if::cfg_if! {
         mod wasm;
     } else if #[cfg(target_os = "xous")] {
         mod xous;
-    } else if #[cfg(target_os = "zkvm")] {
+    } else if #[cfg(any(target_os = "zkvm", target_os = "succinct-zkvm"))] {
         mod zkvm;
     }
 }

library/std/src/sys/alloc/zkvm.rs

@@ -1,6 +1,7 @@
 use crate::alloc::{GlobalAlloc, Layout, System};
 use crate::sys::pal::abi;
 
+/// Note this allocator works with both `zkvm` and `succinct-zkvm`.
 #[stable(feature = "alloc_system_type", since = "1.28.0")]
 unsafe impl GlobalAlloc for System {
     #[inline]

library/std/src/sys/pal/mod.rs

@@ -64,6 +64,9 @@ cfg_if::cfg_if! {
     } else if #[cfg(target_os = "zkvm")] {
         mod zkvm;
         pub use self::zkvm::*;
+    } else if #[cfg(target_os = "succinct-zkvm")] {
+        mod succinct_zkvm;
+        pub use self::succinct_zkvm::*;
     } else {
         mod unsupported;
         pub use self::unsupported::*;

library/std/src/sys/pal/succint-zkvm/abi.rs

@@ -0,0 +1,35 @@
+//! ABI definitions for symbols exported by <_>-zkvm targets.
+//! 
+//! Ideally, these should be the minimum viable symbols to support the std-lib.
+
+#![allow(dead_code)]
+pub const DIGEST_WORDS: usize = 8;
+
+/// Standard IO file descriptors for use with sys_read and sys_write.
+pub mod fileno {
+    pub const STDIN: u32 = 0;
+    pub const STDOUT: u32 = 1;
+    pub const STDERR: u32 = 2;
+}
+
+unsafe extern "C" {
+    pub fn sys_halt();
+    pub fn sys_rand(recv_buf: *mut u8, words: usize);
+    pub fn sys_panic(msg_ptr: *const u8, len: usize) -> !;
+    pub fn sys_write(fd: u32, write_buf: *const u8, nbytes: usize);
+    pub fn sys_getenv(
+        recv_buf: *mut u32,
+        words: usize,
+        varname: *const u8,
+        varname_len: usize,
+    ) -> usize;
+    pub fn sys_argv(out_words: *mut u32, out_nwords: usize, arg_index: usize) -> usize;
+    pub fn sys_alloc_aligned(nwords: usize, align: usize) -> *mut u8;
+}
+
+// Note: sys_read is not implemented for succinct-zkvm.
+// However, it is a function used in the standard library, so we need to
+// implement it.
+pub unsafe extern "C" fn sys_read(_: u32, _: *mut u8, _: usize) -> usize {
+    panic!("sys_read not implemented for succinct");
+}

library/std/src/sys/pal/succint-zkvm/args.rs

@@ -0,0 +1,61 @@
+use crate::ffi::OsString;
+use crate::fmt;
+
+pub struct Args {
+    i_forward: usize,
+    i_back: usize,
+    count: usize,
+}
+
+pub fn args() -> Args {
+    panic!("args not implemented for succinct");
+}
+
+impl Args {
+    #[cfg(target_os = "succinct-zkvm")]
+    fn argv(_: usize) -> OsString {
+        panic!("argv not implemented for succinct");
+    }
+}
+
+impl fmt::Debug for Args {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_list().finish()
+    }
+}
+
+impl Iterator for Args {
+    type Item = OsString;
+
+    fn next(&mut self) -> Option<OsString> {
+        if self.i_forward >= self.count - self.i_back {
+            None
+        } else {
+            let arg = Self::argv(self.i_forward);
+            self.i_forward += 1;
+            Some(arg)
+        }
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        (self.count, Some(self.count))
+    }
+}
+
+impl ExactSizeIterator for Args {
+    fn len(&self) -> usize {
+        self.count
+    }
+}
+
+impl DoubleEndedIterator for Args {
+    fn next_back(&mut self) -> Option<OsString> {
+        if self.i_back >= self.count - self.i_forward {
+            None
+        } else {
+            let arg = Self::argv(self.count - 1 - self.i_back);
+            self.i_back += 1;
+            Some(arg)
+        }
+    }
+}

library/std/src/sys/pal/succint-zkvm/env.rs

@@ -0,0 +1,9 @@
+pub mod os {
+    pub const FAMILY: &str = "";
+    pub const OS: &str = "";
+    pub const DLL_PREFIX: &str = "";
+    pub const DLL_SUFFIX: &str = ".elf";
+    pub const DLL_EXTENSION: &str = "elf";
+    pub const EXE_SUFFIX: &str = ".elf";
+    pub const EXE_EXTENSION: &str = "elf";
+}

library/std/src/sys/pal/succint-zkvm/mod.rs

@@ -0,0 +1,53 @@
+//! System bindings for the succinct-zkvm platform
+//!
+//! This module contains the facade (aka platform-specific) implementations of
+//! OS level functionality for succinct-zkvm.
+//!
+//! This is all super highly experimental and not actually intended for
+//! wide/production use yet, it's still all in the experimental category. This
+//! will likely change over time.
+#![forbid(unsafe_op_in_unsafe_fn)]
+
+pub mod abi;
+#[path = "../succinct-zkvm/args.rs"]
+pub mod args;
+pub mod env;
+pub mod os;
+#[path = "../unsupported/pipe.rs"]
+pub mod pipe;
+#[path = "../unsupported/process.rs"]
+pub mod process;
+#[path = "../unsupported/thread.rs"]
+pub mod thread;
+#[path = "../unsupported/time.rs"]
+pub mod time;
+
+use crate::io as std_io;
+
+// SAFETY: must be called only once during runtime initialization.
+// NOTE: this is not guaranteed to run, for example when Rust code is called externally.
+pub unsafe fn init(_argc: isize, _argv: *const *const u8, _sigpipe: u8) {}
+
+// SAFETY: must be called only once during runtime cleanup.
+// NOTE: this is not guaranteed to run, for example when the program aborts.
+pub unsafe fn cleanup() {}
+
+pub fn unsupported<T>() -> std_io::Result<T> {
+    Err(unsupported_err())
+}
+
+pub fn unsupported_err() -> std_io::Error {
+    std_io::Error::UNSUPPORTED_PLATFORM
+}
+
+pub fn is_interrupted(_code: i32) -> bool {
+    false
+}
+
+pub fn decode_error_kind(_code: i32) -> crate::io::ErrorKind {
+    crate::io::ErrorKind::Uncategorized
+}
+
+pub fn abort_internal() -> ! {
+    core::intrinsics::abort();
+}

library/std/src/sys/pal/succint-zkvm/os.rs

@@ -0,0 +1,118 @@
+use super::unsupported;
+use crate::error::Error as StdError;
+use crate::ffi::{OsStr, OsString};
+use crate::marker::PhantomData;
+use crate::path::{self, PathBuf};
+use crate::{fmt, io};
+
+pub fn errno() -> i32 {
+    0
+}
+
+pub fn error_string(_errno: i32) -> String {
+    "operation successful".to_string()
+}
+
+pub fn getcwd() -> io::Result<PathBuf> {
+    unsupported()
+}
+
+pub fn chdir(_: &path::Path) -> io::Result<()> {
+    unsupported()
+}
+
+pub struct SplitPaths<'a>(!, PhantomData<&'a ()>);
+
+pub fn split_paths(_unparsed: &OsStr) -> SplitPaths<'_> {
+    panic!("unsupported")
+}
+
+impl<'a> Iterator for SplitPaths<'a> {
+    type Item = PathBuf;
+    fn next(&mut self) -> Option<PathBuf> {
+        self.0
+    }
+}
+
+#[derive(Debug)]
+pub struct JoinPathsError;
+
+pub fn join_paths<I, T>(_paths: I) -> Result<OsString, JoinPathsError>
+where
+    I: Iterator<Item = T>,
+    T: AsRef<OsStr>,
+{
+    Err(JoinPathsError)
+}
+
+impl fmt::Display for JoinPathsError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        "not supported on this platform yet".fmt(f)
+    }
+}
+
+impl StdError for JoinPathsError {
+    #[allow(deprecated)]
+    fn description(&self) -> &str {
+        "not supported on this platform yet"
+    }
+}
+
+pub fn current_exe() -> io::Result<PathBuf> {
+    unsupported()
+}
+
+pub struct Env(!);
+
+impl Iterator for Env {
+    type Item = (OsString, OsString);
+    fn next(&mut self) -> Option<(OsString, OsString)> {
+        self.0
+    }
+}
+
+pub fn env() -> Env {
+    panic!("not supported on this platform")
+}
+
+impl Env {
+    pub fn str_debug(&self) -> impl fmt::Debug + '_ {
+        let Self(inner) = self;
+        match *inner {}
+    }
+}
+
+impl fmt::Debug for Env {
+    fn fmt(&self, _: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let Self(inner) = self;
+        match *inner {}
+    }
+}
+
+pub fn getenv(_: &OsStr) -> Option<OsString> {
+    panic!("getenv not implemented for succinct");
+}
+
+pub unsafe fn setenv(_: &OsStr, _: &OsStr) -> io::Result<()> {
+    Err(io::const_error!(io::ErrorKind::Unsupported, "cannot set env vars on this platform"))
+}
+
+pub unsafe fn unsetenv(_: &OsStr) -> io::Result<()> {
+    Err(io::const_error!(io::ErrorKind::Unsupported, "cannot unset env vars on this platform"))
+}
+
+pub fn temp_dir() -> PathBuf {
+    panic!("no filesystem on this platform")
+}
+
+pub fn home_dir() -> Option<PathBuf> {
+    None
+}
+
+pub fn exit(_code: i32) -> ! {
+    crate::intrinsics::abort()
+}
+
+pub fn getpid() -> u32 {
+    panic!("no pids on this platform")
+}