Clean up main a bit

Author: brson

src/rustup-cli/main.rs

@@ -1,3 +1,17 @@
+//! The main rustup commandline application
+//!
+//! The rustup binary is a chimera, changing its behavior based on the
+//! name of the binary. This is used most prominently to enable
+//! rustup's tool 'proxies' - that is, rustup itself and the rustup
+//! proxies are the same binary; when the binary is called 'rustup' or
+//! 'rustup.exe' rustup behaves like the rustup commandline
+//! application; when it is called 'rustc' it behaves as a proxy to
+//! 'rustc'.
+//!
+//! This scheme is further used to distingush the rustup installer,
+//! called 'rustup-init' which is again just the rustup binary under a
+//! different name.
+
 #![recursion_limit = "1024"]
 
 extern crate rustup_dist;
@@ -51,29 +65,26 @@ use rustup_dist::dist::TargetTriple;
 use rustup::env_var::RUST_RECURSION_COUNT_MAX;
 
 fn main() {
-    if let Err(ref e) = run_multirust() {
+    if let Err(ref e) = run_rustup() {
         common::report_error(e);
         std::process::exit(1);
     }
 }
 
-fn run_multirust() -> Result<()> {
-    // Guard against infinite recursion
-    let recursion_count = env::var("RUST_RECURSION_COUNT").ok()
-        .and_then(|s| s.parse().ok()).unwrap_or(0);
-    if recursion_count > RUST_RECURSION_COUNT_MAX {
-        return Err(ErrorKind::InfiniteRecursion.into());
-    }
+fn run_rustup() -> Result<()> {
+    // Guard against infinite proxy recursion. This mostly happens due to
+    // bugs in rustup.
+    do_recursion_guard()?;
 
-    // Do various things to clean up past messes
-    // FIXME: Remove this soon to get it out of the proxy path
+    // Do various hacks to clean up past messes
     do_compatibility_hacks();
 
     // The name of arg0 determines how the program is going to behave
     let arg0 = env::args().next().map(PathBuf::from);
     let name = arg0.as_ref()
         .and_then(|a| a.file_stem())
         .and_then(|a| a.to_str());
+
     match name {
         Some("rustup") => {
             rustup_mode::main()
@@ -120,6 +131,16 @@ fn run_multirust() -> Result<()> {
     }
 }
 
+fn do_recursion_guard() -> Result<()> {
+    let recursion_count = env::var("RUST_RECURSION_COUNT").ok()
+        .and_then(|s| s.parse().ok()).unwrap_or(0);
+    if recursion_count > RUST_RECURSION_COUNT_MAX {
+        return Err(ErrorKind::InfiniteRecursion.into());
+    }
+
+    Ok(())
+}
+
 fn do_compatibility_hacks() {
     make_environment_compatible();
     fix_windows_reg_key();