Adds support for creating a Context from a non-owned pointer

Cargo.toml

@@ -19,16 +19,17 @@ edition = "2018"
 maintenance = { status = "actively-maintained" }
 
 [features]
-default = ["zmq_has"]
+default = ["zmq_has", "static"]
 # zmq_has was added in zeromq 4.1. As we now require 4.1 or newer,
 # this feature is a no-op and only present for backward-compatibility;
 # it will be removed in the next API-breaking release.
 zmq_has = []
+static = ["zmq-sys/static"]
 
 [dependencies]
 bitflags = "1.0"
 libc = "0.2.15"
-zmq-sys = { version = "0.12.0", path = "zmq-sys" }
+zmq-sys = { version = "0.12.0", path = "zmq-sys", default-features = false }
 
 [dev-dependencies]
 trybuild = { version = "1" }

src/lib.rs

@@ -376,6 +376,7 @@ pub fn version() -> (i32, i32, i32) {
 
 struct RawContext {
     ctx: *mut c_void,
+    owned: bool,
 }
 
 impl RawContext {
@@ -390,9 +391,11 @@ unsafe impl Sync for RawContext {}
 
 impl Drop for RawContext {
     fn drop(&mut self) {
-        let mut e = self.term();
-        while e == Err(Error::EINTR) {
-            e = self.term();
+        if self.owned {
+            let mut e = self.term();
+            while e == Err(Error::EINTR) {
+                e = self.term();
+            }
         }
     }
 }
@@ -428,10 +431,18 @@ impl Context {
         Context {
             raw: Arc::new(RawContext {
                 ctx: unsafe { zmq_sys::zmq_ctx_new() },
+                owned: true,
             }),
         }
     }
 
+    /// Create a Context from a raw context pointer.
+    pub unsafe fn from_raw(ctx: *mut c_void) -> Context {        
+        Context {
+            raw: Arc::new(RawContext { ctx, owned: false }),
+        }
+    }
+
     /// Get the size of the ØMQ thread pool to handle I/O operations.
     pub fn get_io_threads(&self) -> Result<i32> {
         let rc =

zmq-sys/Cargo.toml

@@ -14,13 +14,15 @@ build = "build/main.rs"
 links = "zmq"
 
 [features]
+default = ["static"]
+static = ["dep:zeromq-src"]
 
 [dependencies]
 libc = "0.2.15"
 
 [build-dependencies]
 system-deps = "6"
-zeromq-src = { version = "0.2.1" }
+zeromq-src = { version = "0.2.1", optional = true }
 
 [package.metadata.system-deps]
 libzmq = "4.1"

zmq-sys/build/main.rs

@@ -1,3 +1,4 @@
+#[cfg(feature = "static")]
 pub fn configure() {
     println!("cargo:rerun-if-changed=build/main.rs");
     println!("cargo:rerun-if-env-changed=PROFILE");
@@ -12,5 +13,6 @@ pub fn configure() {
 }
 
 fn main() {
+    #[cfg(feature = "static")]
     configure()
 }