Data commit

Task/Use-another-language-to-call-a-function/Rust/use-another-language-to-call-a-function.rust

@@ -0,0 +1,44 @@
+//! In order to run this task, you will need to compile the C program locating in the task linked
+//! above. The C program will need to be linked with the library produced by this file.
+//!
+//! 1. Compile this library:
+//!
+//!     ```bash
+//!     $ cargo build --release
+//!     ```
+//!
+//! 2. Copy the C program into query.c.
+//! 3. Compile and link the C program with the produced library:
+//!
+//!     ```bash
+//!     $ LD_LIBRARY_PATH=/path/to/library gcc query.c -o query -Wall -Werror libquery
+//!     ```
+//! 4. Run the resulting binary.
+//!
+//!     ```bash
+//!     $ LD_LIBRARY_PATH=/path/to/library ./query
+//!     Here am I
+//!     ```
+
+#![crate_type = "cdylib"]
+
+extern crate libc;
+
+use std::ffi::CString;
+
+use libc::{c_char, c_int, size_t};
+
+#[no_mangle]
+#[allow(non_snake_case)]
+#[allow(clippy::missing_safety_doc)]
+pub unsafe extern "C" fn Query(data: *mut c_char, length: *mut size_t) -> c_int {
+    let string = "Here am I";
+    if *length + 1 < string.len() {
+        0
+    } else {
+        let c_string = CString::new(string).unwrap();
+        libc::strcpy(data, c_string.as_ptr());
+        *length = string.len();
+        1
+    }
+}