Merge #2042 #2044

2042: feat(cli) Improve environment variables parsing r=Hywan a=Hywan

# Description

This PR fixes #2028. In #1762 we have already improved environment variables syntax, but the same work must be done in the CLI crate.

The following environment variables are considered incorrect:

* `A`, no equal sign,
* `A=`, value is missing,
* `=A`, key is missing.

The following environment variables are considered correct:

* `A=B` with `A` for the name and `B` for the value,
* `A=B=C` with `A` for the name and `B=C` for the value.

The environment variable is trimmed before being parsed with [`str::trim`](https://doc.rust-lang.org/std/primitive.str.html#method.trim).

This PR also adds tests for the `parse_envvar` function, which was missing.

# Review

- [x] Add a short description of the the change to the CHANGELOG.md file


2044: feat(c-api) Do not build C headers if the env var `DOCS_RS` exists r=Hywan a=Hywan

# Description

Fix #1954.

According to https://docs.rs/about/builds, the `DOCS_RS` environment variable is set when the documentation is built from docs.rs. In this case, we must not build the C headers because it generates such error (see #1954 to learn more):

> Unable to copy the generated C bindings: `Os { code: 30, kind: Other, message: "Read-only file system" }`

# Review

- [x] Add a short description of the the change to the CHANGELOG.md file


Co-authored-by: Ivan Enderlin <[email protected]>

CHANGELOG.md

@@ -11,9 +11,11 @@
 - [#2026](https://github.com/wasmerio/wasmer/pull/2010) Expose trap code of a `RuntimeError`, if it's a `Trap`.
 
 ### Changed
+- [#2042](https://github.com/wasmerio/wasmer/pull/2042) Parse more exotic environment variables in `wasmer run`.
 - [#2041](https://github.com/wasmerio/wasmer/pull/2041) Documentation diagrams now have a solid white background rather than a transparent background.
 
 ### Fixed
+- [#2044](https://github.com/wasmerio/wasmer/pull/2044) Do not build C headers on docs.rs.
 
 ## 1.0.1 - 2021-01-12
 

lib/c-api/build.rs

@@ -1,3 +1,8 @@
+//! This build script aims at:
+//!
+//! * generating the C header files for the C API,
+//! * setting `inline-c` up.
+
 use cbindgen::{Builder, Language};
 use std::{env, fs, path::PathBuf};
 
@@ -59,11 +64,22 @@ fn main() {
     let crate_dir = env::var("CARGO_MANIFEST_DIR").unwrap();
     let out_dir = env::var("OUT_DIR").unwrap();
 
-    build_wasm_c_api_headers(&crate_dir, &out_dir);
-    build_wasmer_headers(&crate_dir, &out_dir);
+    if building_c_api_headers() {
+        build_wasm_c_api_headers(&crate_dir, &out_dir);
+        build_wasmer_c_api_headers(&crate_dir, &out_dir);
+    }
+
     build_inline_c_env_vars();
 }
 
+/// Check whether we should build the C API headers.
+///
+/// For the moment, it's always enabled, unless if the `DOCS_RS`
+/// environment variable is present.
+fn building_c_api_headers() -> bool {
+    env::var("DOCS_RS").is_err()
+}
+
 /// Build the header files for the `wasm_c_api` API.
 fn build_wasm_c_api_headers(crate_dir: &str, out_dir: &str) {
     let mut crate_header_file = PathBuf::from(crate_dir);
@@ -126,7 +142,7 @@ fn build_wasm_c_api_headers(crate_dir: &str, out_dir: &str) {
 }
 
 /// Build the header files for the `deprecated` API.
-fn build_wasmer_headers(crate_dir: &str, out_dir: &str) {
+fn build_wasmer_c_api_headers(crate_dir: &str, out_dir: &str) {
     let mut crate_header_file = PathBuf::from(crate_dir);
     crate_header_file.push("wasmer");
 

lib/cli/src/utils.rs

@@ -40,14 +40,53 @@ pub fn parse_mapdir(entry: &str) -> Result<(String, PathBuf)> {
     }
 }
 
-/// Parses a mapdir from an env var
+/// Parses an environment variable.
 pub fn parse_envvar(entry: &str) -> Result<(String, String)> {
-    if let [env_var, value] = entry.split('=').collect::<Vec<&str>>()[..] {
-        Ok((env_var.to_string(), value.to_string()))
-    } else {
-        bail!(
-            "Env vars must be of the form <var_name>=<value>. Found {}",
+    let entry = entry.trim();
+
+    match entry.find('=') {
+        None => bail!(
+            "Environment variable must be of the form `<name>=<value>`; found `{}`",
+            &entry
+        ),
+
+        Some(0) => bail!(
+            "Environment variable is not well formed, the `name` is missing in `<name>=<value>`; got `{}`",
+            &entry
+        ),
+
+        Some(position) if position == entry.len() - 1 => bail!(
+            "Environment variable is not well formed, the `value` is missing in `<name>=<value>`; got `{}`",
             &entry
+        ),
+
+        Some(position) => Ok((entry[..position].into(), entry[position + 1..].into())),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::parse_envvar;
+
+    #[test]
+    fn test_parse_envvar() {
+        assert_eq!(
+            parse_envvar("A").unwrap_err().to_string(),
+            "Environment variable must be of the form `<name>=<value>`; found `A`"
+        );
+        assert_eq!(
+            parse_envvar("=A").unwrap_err().to_string(),
+            "Environment variable is not well formed, the `name` is missing in `<name>=<value>`; got `=A`"
+        );
+        assert_eq!(
+            parse_envvar("A=").unwrap_err().to_string(),
+            "Environment variable is not well formed, the `value` is missing in `<name>=<value>`; got `A=`"
+        );
+        assert_eq!(parse_envvar("A=B").unwrap(), ("A".into(), "B".into()));
+        assert_eq!(parse_envvar("   A=B\t").unwrap(), ("A".into(), "B".into()));
+        assert_eq!(
+            parse_envvar("A=B=C=D").unwrap(),
+            ("A".into(), "B=C=D".into())
         );
     }
 }