Improve Display and Debug impls of Error (#58)

* expose public functions for the name (e.g. "INVAL") and docs corresponding to errno

* regenerate lib_generated, use funcs in Error's display and debug impls

* bump version to 0.10.2

* add documentation to generate lib_generated.rs

Author: Pat Hickey

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "wasi"
-version = "0.10.1+wasi-snapshot-preview1"
+version = "0.10.2+wasi-snapshot-preview1"
 authors = ["The Cranelift Project Developers"]
 license = "Apache-2.0 WITH LLVM-exception OR Apache-2.0 OR MIT"
 description = "Experimental WASI API bindings for Rust"

README.md

@@ -64,6 +64,24 @@ $ cargo wasi run
 Hello, World!
 ```
 
+# Development
+
+The bulk of the `wasi` crate is generated by the `witx-bindgen` tool, which lives at
+`crates/witx-bindgen` and is part of the cargo workspace.
+
+The `src/lib_generated.rs` file can be re-generated with the following
+command:
+
+```
+cargo run -p witx-bindgen -- crates/witx-bindgen/WASI/phases/snapshot/witx/wasi_snapshot_preview1.witx > src/lib_generated.rs
+```
+
+Note that this uses the WASI standard repository as a submodule. If you do not
+have this submodule present in your source tree, run:
+```
+git submodule update --init
+```
+
 # License
 
 This project is licensed under the Apache 2.0 license with the LLVM exception.

crates/witx-bindgen/src/lib.rs

@@ -172,7 +172,21 @@ fn render_enum(src: &mut String, name: &str, e: &EnumDatatype) {
     }
 
     if name == "errno" {
-        src.push_str("pub(crate) fn strerror(code: u16) -> &'static str {");
+        src.push_str("pub fn errno_name(code: u16) -> &'static str {");
+        src.push_str("match code {");
+        for variant in e.variants.iter() {
+            src.push_str(&name.to_shouty_snake_case());
+            src.push_str("_");
+            src.push_str(&variant.name.as_str().to_shouty_snake_case());
+            src.push_str(" => \"");
+            src.push_str(&variant.name.as_str().to_shouty_snake_case());
+            src.push_str("\",");
+        }
+        src.push_str("_ => \"Unknown error.\",");
+        src.push_str("}");
+        src.push_str("}");
+
+        src.push_str("pub fn errno_docs(code: u16) -> &'static str {");
         src.push_str("match code {");
         for variant in e.variants.iter() {
             src.push_str(&name.to_shouty_snake_case());

src/error.rs

@@ -29,7 +29,7 @@ impl fmt::Display for Error {
         write!(
             f,
             "{} (error {})",
-            super::strerror(self.code.get()),
+            super::errno_name(self.code.get()),
             self.code
         )?;
         Ok(())
@@ -40,7 +40,8 @@ impl fmt::Debug for Error {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_struct("Error")
             .field("code", &self.code)
-            .field("message", &super::strerror(self.code.get()))
+            .field("name", &super::errno_name(self.code.get()))
+            .field("message", &super::errno_docs(self.code.get()))
             .finish()
     }
 }

src/lib_generated.rs

@@ -177,7 +177,89 @@ pub const ERRNO_TXTBSY: Errno = 74;
 pub const ERRNO_XDEV: Errno = 75;
 /// Extension: Capabilities insufficient.
 pub const ERRNO_NOTCAPABLE: Errno = 76;
-pub(crate) fn strerror(code: u16) -> &'static str {
+pub fn errno_name(code: u16) -> &'static str {
+    match code {
+        ERRNO_SUCCESS => "SUCCESS",
+        ERRNO_2BIG => "2BIG",
+        ERRNO_ACCES => "ACCES",
+        ERRNO_ADDRINUSE => "ADDRINUSE",
+        ERRNO_ADDRNOTAVAIL => "ADDRNOTAVAIL",
+        ERRNO_AFNOSUPPORT => "AFNOSUPPORT",
+        ERRNO_AGAIN => "AGAIN",
+        ERRNO_ALREADY => "ALREADY",
+        ERRNO_BADF => "BADF",
+        ERRNO_BADMSG => "BADMSG",
+        ERRNO_BUSY => "BUSY",
+        ERRNO_CANCELED => "CANCELED",
+        ERRNO_CHILD => "CHILD",
+        ERRNO_CONNABORTED => "CONNABORTED",
+        ERRNO_CONNREFUSED => "CONNREFUSED",
+        ERRNO_CONNRESET => "CONNRESET",
+        ERRNO_DEADLK => "DEADLK",
+        ERRNO_DESTADDRREQ => "DESTADDRREQ",
+        ERRNO_DOM => "DOM",
+        ERRNO_DQUOT => "DQUOT",
+        ERRNO_EXIST => "EXIST",
+        ERRNO_FAULT => "FAULT",
+        ERRNO_FBIG => "FBIG",
+        ERRNO_HOSTUNREACH => "HOSTUNREACH",
+        ERRNO_IDRM => "IDRM",
+        ERRNO_ILSEQ => "ILSEQ",
+        ERRNO_INPROGRESS => "INPROGRESS",
+        ERRNO_INTR => "INTR",
+        ERRNO_INVAL => "INVAL",
+        ERRNO_IO => "IO",
+        ERRNO_ISCONN => "ISCONN",
+        ERRNO_ISDIR => "ISDIR",
+        ERRNO_LOOP => "LOOP",
+        ERRNO_MFILE => "MFILE",
+        ERRNO_MLINK => "MLINK",
+        ERRNO_MSGSIZE => "MSGSIZE",
+        ERRNO_MULTIHOP => "MULTIHOP",
+        ERRNO_NAMETOOLONG => "NAMETOOLONG",
+        ERRNO_NETDOWN => "NETDOWN",
+        ERRNO_NETRESET => "NETRESET",
+        ERRNO_NETUNREACH => "NETUNREACH",
+        ERRNO_NFILE => "NFILE",
+        ERRNO_NOBUFS => "NOBUFS",
+        ERRNO_NODEV => "NODEV",
+        ERRNO_NOENT => "NOENT",
+        ERRNO_NOEXEC => "NOEXEC",
+        ERRNO_NOLCK => "NOLCK",
+        ERRNO_NOLINK => "NOLINK",
+        ERRNO_NOMEM => "NOMEM",
+        ERRNO_NOMSG => "NOMSG",
+        ERRNO_NOPROTOOPT => "NOPROTOOPT",
+        ERRNO_NOSPC => "NOSPC",
+        ERRNO_NOSYS => "NOSYS",
+        ERRNO_NOTCONN => "NOTCONN",
+        ERRNO_NOTDIR => "NOTDIR",
+        ERRNO_NOTEMPTY => "NOTEMPTY",
+        ERRNO_NOTRECOVERABLE => "NOTRECOVERABLE",
+        ERRNO_NOTSOCK => "NOTSOCK",
+        ERRNO_NOTSUP => "NOTSUP",
+        ERRNO_NOTTY => "NOTTY",
+        ERRNO_NXIO => "NXIO",
+        ERRNO_OVERFLOW => "OVERFLOW",
+        ERRNO_OWNERDEAD => "OWNERDEAD",
+        ERRNO_PERM => "PERM",
+        ERRNO_PIPE => "PIPE",
+        ERRNO_PROTO => "PROTO",
+        ERRNO_PROTONOSUPPORT => "PROTONOSUPPORT",
+        ERRNO_PROTOTYPE => "PROTOTYPE",
+        ERRNO_RANGE => "RANGE",
+        ERRNO_ROFS => "ROFS",
+        ERRNO_SPIPE => "SPIPE",
+        ERRNO_SRCH => "SRCH",
+        ERRNO_STALE => "STALE",
+        ERRNO_TIMEDOUT => "TIMEDOUT",
+        ERRNO_TXTBSY => "TXTBSY",
+        ERRNO_XDEV => "XDEV",
+        ERRNO_NOTCAPABLE => "NOTCAPABLE",
+        _ => "Unknown error.",
+    }
+}
+pub fn errno_docs(code: u16) -> &'static str {
     match code {
         ERRNO_SUCCESS => "No error occurred. System call completed successfully.",
         ERRNO_2BIG => "Argument list too long.",