Add icon to Windows executable (helix-editor#9104)

* injecting the icon through a resource file, no extra deps

* formatted

* scripted rc compilation

* formatted and restructured

* simplified conditional func call

helix-term/build.rs

@@ -6,4 +6,150 @@ fn main() {
         build_grammars(Some(std::env::var("TARGET").unwrap()))
             .expect("Failed to compile tree-sitter grammars");
     }
+
+    #[cfg(windows)]
+    windows_rc::link_icon_in_windows_exe("../contrib/helix-256p.ico");
+}
+
+#[cfg(windows)]
+mod windows_rc {
+    use std::io::prelude::Write;
+    use std::{env, io, path::Path, path::PathBuf, process};
+
+    pub(crate) fn link_icon_in_windows_exe(icon_path: &str) {
+        let rc_exe = find_rc_exe().expect("Windows SDK is to be installed along with MSVC");
+
+        let output = env::var("OUT_DIR").expect("Env var OUT_DIR should have been set by compiler");
+        let output_dir = PathBuf::from(output);
+
+        let rc_path = output_dir.join("resource.rc");
+        write_resource_file(&rc_path, icon_path).unwrap();
+
+        let resource_file = PathBuf::from(&output_dir).join("resource.lib");
+        compile_with_toolkit_msvc(rc_exe, resource_file, rc_path);
+
+        println!("cargo:rustc-link-search=native={}", output_dir.display());
+        println!("cargo:rustc-link-lib=dylib=resource");
+    }
+
+    fn compile_with_toolkit_msvc(rc_exe: PathBuf, output: PathBuf, input: PathBuf) {
+        let mut command = process::Command::new(rc_exe);
+        let command = command.arg(format!(
+            "/I{}",
+            env::var("CARGO_MANIFEST_DIR")
+                .expect("CARGO_MANIFEST_DIR should have been set by Cargo")
+        ));
+
+        let status = command
+            .arg(format!("/fo{}", output.display()))
+            .arg(format!("{}", input.display()))
+            .output()
+            .unwrap();
+
+        println!(
+            "RC Output:\n{}\n------",
+            String::from_utf8_lossy(&status.stdout)
+        );
+        println!(
+            "RC Error:\n{}\n------",
+            String::from_utf8_lossy(&status.stderr)
+        );
+    }
+
+    fn find_rc_exe() -> io::Result<PathBuf> {
+        let find_reg_key = process::Command::new("reg")
+            .arg("query")
+            .arg(r"HKLM\SOFTWARE\Microsoft\Windows Kits\Installed Roots")
+            .arg("/reg:32")
+            .arg("/v")
+            .arg("KitsRoot10")
+            .output();
+
+        match find_reg_key {
+            Err(find_reg_key) => {
+                return Err(io::Error::new(
+                    io::ErrorKind::Other,
+                    format!("Failed to run registry query: {}", find_reg_key),
+                ))
+            }
+            Ok(find_reg_key) => {
+                if find_reg_key.status.code().unwrap() != 0 {
+                    return Err(io::Error::new(
+                        io::ErrorKind::Other,
+                        "Can not find Windows SDK",
+                    ));
+                } else {
+                    let lines = String::from_utf8(find_reg_key.stdout)
+                        .expect("Should be able to parse the output");
+                    let mut lines: Vec<&str> = lines.lines().collect();
+                    let mut rc_exe_paths: Vec<PathBuf> = Vec::new();
+                    lines.reverse();
+                    for line in lines {
+                        if line.trim().starts_with("KitsRoot") {
+                            let kit: String = line
+                                .chars()
+                                .skip(line.find("REG_SZ").unwrap() + 6)
+                                .skip_while(|c| c.is_whitespace())
+                                .collect();
+
+                            let p = PathBuf::from(&kit);
+                            let rc = if cfg!(target_arch = "x86_64") {
+                                p.join(r"bin\x64\rc.exe")
+                            } else {
+                                p.join(r"bin\x86\rc.exe")
+                            };
+
+                            if rc.exists() {
+                                println!("{:?}", rc);
+                                rc_exe_paths.push(rc.to_owned());
+                            }
+
+                            if let Ok(bin) = p.join("bin").read_dir() {
+                                for e in bin.filter_map(|e| e.ok()) {
+                                    let p = if cfg!(target_arch = "x86_64") {
+                                        e.path().join(r"x64\rc.exe")
+                                    } else {
+                                        e.path().join(r"x86\rc.exe")
+                                    };
+                                    if p.exists() {
+                                        println!("{:?}", p);
+                                        rc_exe_paths.push(p.to_owned());
+                                    }
+                                }
+                            }
+                        }
+                    }
+                    if rc_exe_paths.is_empty() {
+                        return Err(io::Error::new(
+                            io::ErrorKind::Other,
+                            "Can not find Windows SDK",
+                        ));
+                    }
+
+                    println!("{:?}", rc_exe_paths);
+                    let rc_path = rc_exe_paths.pop().unwrap();
+
+                    let rc_exe = if !rc_path.exists() {
+                        if cfg!(target_arch = "x86_64") {
+                            PathBuf::from(rc_path.parent().unwrap()).join(r"bin\x64\rc.exe")
+                        } else {
+                            PathBuf::from(rc_path.parent().unwrap()).join(r"bin\x86\rc.exe")
+                        }
+                    } else {
+                        rc_path
+                    };
+
+                    println!("Selected RC path: '{}'", rc_exe.display());
+                    Ok(rc_exe)
+                }
+            }
+        }
+    }
+
+    fn write_resource_file(rc_path: &Path, icon_path: &str) -> io::Result<()> {
+        let mut f = std::fs::File::create(rc_path)?;
+        writeln!(f, "{} ICON \"{}\"", 1, icon_path)?;
+
+        Ok(())
+    }
 }