make workspace and upload c-bindings

.gitignore

@@ -0,0 +1 @@
+/target

Cargo.lock

@@ -0,0 +1,36 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "c-bindings"
+version = "0.1.0"
+dependencies = [
+ "cc",
+ "cty",
+]
+
+[[package]]
+name = "cc"
+version = "1.0.83"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f1174fb0b6ec23863f8b971027804a42614e347eafb0a95bf0b12cdae21fc4d0"
+dependencies = [
+ "libc",
+]
+
+[[package]]
+name = "cty"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b365fabc795046672053e29c954733ec3b05e4be654ab130fe8f1f94d7051f35"
+
+[[package]]
+name = "libc"
+version = "0.2.148"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9cdc71e17332e86d2e1d38c1f99edcb6288ee11b815fb1a4b049eaa2114d369b"
+
+[[package]]
+name = "rs-unsafe"
+version = "0.1.0"

Cargo.toml

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+[workspace]
+members = [
+	".",
+	"members/c-bindings"
+]
+default-members = [
+	".",
+	"members/c-bindings"
+]
+
+[package]
+name = "rs-unsafe"
+version = "0.1.0"
+edition = "2021"
+authors = ["Christoph J. Scherr <softwar@cscherr.de>"]
+publish = false
+autobins = true
+default-run = "rs-unsafe"

members/c-bindings/Cargo.toml

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+[package]
+name = "c-bindings"
+version = "0.1.0"
+edition = "2021"
+links = "test" 		# this is the important part! cargo will search for some library called `test` (i.e. libtest.a)
+build = "src/build.rs"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+cty = "0.2.2"
+
+[build-dependencies]
+cc = "1.0.83"

members/c-bindings/lib/CMakeLists.txt

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+cmake_minimum_required(VERSION 3.9)
+project(test VERSION 1.0.1 DESCRIPTION "test lib")
+include(GNUInstallDirs)
+add_library(test STATIC test.c)
+set_target_properties(test PROPERTIES
+    VERSION ${PROJECT_VERSION}
+    SOVERSION 1
+    PUBLIC_HEADER test.h)
+# configure_file(test.pc.in test.pc @ONLY)
+target_include_directories(test PRIVATE .)
+install(TARGETS test
+    LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
+    PUBLIC_HEADER DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
+install(FILES ${CMAKE_BINARY_DIR}/test.pc
+    DESTINATION ${CMAKE_INSTALL_DATAROOTDIR}/pkgconfig)

members/c-bindings/lib/test.c

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+#include "test.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+int ret19() {
+	return 19;
+}
+
+char* structInfo(MyStruct *st) {
+		char* buf = malloc(1024*sizeof(char));
+		sprintf(buf,
+				"Infos about the struct:\n"
+				"\tfoo:\t%d\n"
+				"\tbar:\t%c\n"
+				"\n"
+				"greetings from C"
+				,
+				st->foo,
+				st->bar
+		);
+
+		return buf;
+}

members/c-bindings/lib/test.h

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+int ret19();
+typedef struct MyStruct {
+	int foo;
+	char bar;
+} MyStruct;
+char* stuctInfo(MyStruct st);

members/c-bindings/src/build.rs

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+/// we could simply do this to compile the test lib to a static lib,
+/// but that solution might not scale as good as calling a professional
+/// build system
+#[allow(unused)]
+fn main() {
+    // Tell Cargo that if the given file changes, to rerun this build script.
+    println!("cargo:rerun-if-changed=src/hello.c");
+    cc::Build::new()
+        .file("lib/test.c")
+        .compile("test");
+}

members/c-bindings/src/main.rs

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+use cty;
+
+// we first need to declare bindings for our C code.
+// This can be automated too, but I did it myself here.
+#[derive(Debug)]
+#[repr(C)]
+pub struct MyStruct {
+    pub foo: cty::c_int,
+    pub bar: cty::c_char,
+}
+
+// The functions too of course
+extern "C" {
+    pub fn ret19() -> isize;
+    pub fn structInfo(st: &MyStruct) -> *const cty::c_char;
+}
+
+///////////////////////////////////////////////////////////////////////
+
+fn main() {
+    // calling random C functions is generally treated as unsafe.
+    // Best practice is programming wrapper functions that give it
+    // confirmed safe inputs
+    let qux = unsafe { ret19() };
+    println!("`ret19()` returned {qux}");
+    let st = MyStruct {
+        foo: 17, bar: 0x41
+    };
+    // converting a c "string" to a real rust String is
+    // a bit complicated
+    let info: &str = unsafe {
+        // convert the returned value to a rust internal CStr.
+        std::ffi::CStr::from_ptr(
+            // the function returns a pointer to a array of chars on the heap
+            structInfo(&st)
+        )
+            // now to a string slice (result)
+            .to_str()
+            .unwrap()
+    };
+    println!("{info}");
+}

src/main.rs

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+fn main() {
+    println!(
+"The dark power of unsafe rust awakens!
+
+This is the default executable! It does not do much, use another executable.
+
+Select your target like this:
+`cargo run --bin $TARGET`
+
+To see a list of all runnable binaries, you can use the following command.
+`cargo run --bin`
+");
+}