From d30bdcb096774c1f56d9823fb2fbb78bf5cd3584 Mon Sep 17 00:00:00 2001
From: Jorge Aparicio <jorge@japaric.io>
Date: Sat, 9 Dec 2017 17:14:51 +0100
Subject: [PATCH] safe `&'static mut` references via init.resources

---
 examples/safe-static-mut-ref.rs         | 32 ++++++++++++++++++++++
 macros/Cargo.toml                       |  3 ++-
 macros/src/check.rs                     | 31 +++++++++++++++++++++
 macros/src/trans.rs                     | 30 ++++++++++++++-------
 tests/cfail/init-resource-share-idle.rs | 31 +++++++++++++++++++++
 tests/cfail/init-resource-share-task.rs | 36 +++++++++++++++++++++++++
 6 files changed, 153 insertions(+), 10 deletions(-)
 create mode 100644 examples/safe-static-mut-ref.rs
 create mode 100644 tests/cfail/init-resource-share-idle.rs
 create mode 100644 tests/cfail/init-resource-share-task.rs

diff --git a/examples/safe-static-mut-ref.rs b/examples/safe-static-mut-ref.rs
new file mode 100644
index 0000000000..bb87212281
--- /dev/null
+++ b/examples/safe-static-mut-ref.rs
@@ -0,0 +1,32 @@
+//! Safe creation of `&'static mut` references
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![feature(proc_macro)]
+#![no_std]
+
+extern crate cortex_m_rtfm as rtfm;
+extern crate stm32f103xx;
+
+use rtfm::app;
+
+app! {
+    device: stm32f103xx,
+
+    resources: {
+        static BUFFER: [u8; 16] = [0; 16];
+    },
+
+    init: {
+        resources: [BUFFER],
+    },
+}
+
+fn init(_p: init::Peripherals, r: init::Resources) {
+    let _buf: &'static mut [u8] = r.BUFFER;
+}
+
+fn idle() -> ! {
+    loop {
+        rtfm::wfi();
+    }
+}
diff --git a/macros/Cargo.toml b/macros/Cargo.toml
index d51cbc2629..d2e4da5b6b 100644
--- a/macros/Cargo.toml
+++ b/macros/Cargo.toml
@@ -12,7 +12,8 @@ version = "0.2.1"
 [dependencies]
 error-chain = "0.10.0"
 quote = "0.3.15"
-rtfm-syntax = "0.2.0"
+# rtfm-syntax = "0.2.0"
+rtfm-syntax = { git = "https://github.com/japaric/rtfm-syntax", branch = "init-resources" }
 syn = "0.11.11"
 
 [lib]
diff --git a/macros/src/check.rs b/macros/src/check.rs
index 63cac1fa5e..f6fd9cc609 100644
--- a/macros/src/check.rs
+++ b/macros/src/check.rs
@@ -77,7 +77,38 @@ pub fn app(app: check::App) -> Result<App> {
 }
 
 fn resources(app: &App) -> Result<()> {
+    for name in &app.init.resources {
+        if let Some(resource) = app.resources.get(name) {
+            ensure!(
+                resource.expr.is_some(),
+                "resource `{}`, allocated to `init`, must have an initial value",
+                name
+            );
+        } else {
+            bail!(
+                "resource `{}`, allocated to `init`, must be a data resource",
+                name
+            );
+        }
+
+        ensure!(
+            !app.idle.resources.contains(name),
+            "resources assigned to `init` can't be shared with `idle`"
+        );
+
+        ensure!(
+            app.tasks
+                .iter()
+                .all(|(_, task)| !task.resources.contains(name)),
+            "resources assigned to `init` can't be shared with tasks"
+        )
+    }
+
     for resource in app.resources.keys() {
+        if app.init.resources.contains(resource) {
+            continue;
+        }
+
         if app.idle.resources.contains(resource) {
             continue;
         }
diff --git a/macros/src/trans.rs b/macros/src/trans.rs
index 1008dfedab..b540fd1d63 100644
--- a/macros/src/trans.rs
+++ b/macros/src/trans.rs
@@ -249,18 +249,30 @@ fn init(app: &App, main: &mut Vec<Tokens>, root: &mut Vec<Tokens>) {
         let mut rexprs = vec![];
 
         for (name, resource) in init_resources {
-            let _name = Ident::new(format!("_{}", name.as_ref()));
-            lifetime = Some(quote!('a));
-
             let ty = &resource.ty;
 
-            fields.push(quote! {
-                pub #name: &'a mut #ty,
-            });
+            if app.init.resources.contains(name) {
+                fields.push(quote! {
+                    pub #name: &'static mut #ty,
+                });
 
-            rexprs.push(quote! {
-                #name: &mut ::#_name,
-            });
+                let expr = &resource.expr;
+                rexprs.push(quote!(#name: {
+                    static mut #name: #ty = #expr;
+                    &mut #name
+                }));
+            } else {
+                let _name = Ident::new(format!("_{}", name.as_ref()));
+                lifetime = Some(quote!('a));
+
+                fields.push(quote! {
+                    pub #name: &'a mut #ty,
+                });
+
+                rexprs.push(quote! {
+                    #name: &mut ::#_name,
+                });
+            }
         }
 
         root.push(quote! {
diff --git a/tests/cfail/init-resource-share-idle.rs b/tests/cfail/init-resource-share-idle.rs
new file mode 100644
index 0000000000..d8332469d8
--- /dev/null
+++ b/tests/cfail/init-resource-share-idle.rs
@@ -0,0 +1,31 @@
+#![deny(warnings)]
+#![feature(proc_macro)]
+#![no_std]
+
+extern crate cortex_m_rtfm as rtfm;
+extern crate stm32f103xx;
+
+use rtfm::app;
+
+app! { //~ proc macro panicked
+    device: stm32f103xx,
+
+    resources: {
+        static BUFFER: [u8; 16] = [0; 16];
+    },
+
+    init: {
+        resources: [BUFFER],
+    },
+
+    idle: {
+        // ERROR resources assigned to `init` can't be shared with `idle`
+        resources: [BUFFER],
+    },
+}
+
+fn init(_p: init::Peripherals, _r: init::Resources) {}
+
+fn idle(_r: init::Resources) -> ! {
+    loop {}
+}
diff --git a/tests/cfail/init-resource-share-task.rs b/tests/cfail/init-resource-share-task.rs
new file mode 100644
index 0000000000..8fe688993e
--- /dev/null
+++ b/tests/cfail/init-resource-share-task.rs
@@ -0,0 +1,36 @@
+#![deny(warnings)]
+#![feature(proc_macro)]
+#![no_std]
+
+extern crate cortex_m_rtfm as rtfm;
+extern crate stm32f103xx;
+
+use rtfm::app;
+
+app! { //~ proc macro panicked
+    device: stm32f103xx,
+
+    resources: {
+        static BUFFER: [u8; 16] = [0; 16];
+    },
+
+    init: {
+        resources: [BUFFER],
+    },
+
+    tasks: {
+        SYS_TICK: {
+            path: sys_tick,
+            // ERROR resources assigned to `init` can't be shared with tasks
+            resources: [BUFFER],
+        },
+    },
+}
+
+fn init(_p: init::Peripherals) {}
+
+fn idle() -> ! {
+    loop {}
+}
+
+fn sys_tick() {}