Add windows askpass named pipe support for fetch/pull fork/exec implementation

gitbutler-git/Cargo.toml

@@ -8,11 +8,11 @@ path = "src/lib.rs"
 
 [[bin]]
 name = "gitbutler-git-askpass"
-path = "src/cli/bin/askpass.rs"
+path = "src/bin/askpass.rs"
 
 [[bin]]
 name = "gitbutler-git-setsid"
-path = "src/cli/bin/setsid.rs"
+path = "src/bin/setsid.rs"
 
 [features]
 default = ["serde", "tokio"]
@@ -29,3 +29,8 @@ sysinfo = "0.30.5"
 
 [target."cfg(unix)".dependencies]
 nix = { version = "0.27.1", features = ["process", "socket", "user"] }
+
+[target."cfg(windows)".dependencies]
+winapi = { version = "0.3.9", features = ["winbase", "namedpipeapi"] }
+# synchronous named pipes for the askpass utility
+windows-named-pipe = "0.1.0"

gitbutler-git/src/bin/askpass.rs

@@ -0,0 +1,49 @@
+#[cfg(unix)]
+#[path = "askpass/unix.rs"]
+mod unix;
+#[cfg(windows)]
+#[path = "askpass/windows.rs"]
+mod windows;
+
+#[cfg(windows)]
+use self::windows::UnixCompatibility;
+
+use std::io::{BufRead, BufReader, BufWriter, Write};
+
+pub fn main() {
+    let pipe_name = std::env::var("GITBUTLER_ASKPASS_PIPE").expect("do not run this binary yourself; it's only meant to be run by GitButler (missing GITBUTLER_ASKPASS_PIPE env var)");
+    let pipe_secret = std::env::var("GITBUTLER_ASKPASS_SECRET").expect("do not run this binary yourself; it's only meant to be run by GitButler (missing GITBUTLER_ASKPASS_SECRET env var)");
+    let prompt = std::env::args().nth(1).expect("do not run this binary yourself; it's only meant to be run by GitButler (missing prompt arg)");
+
+    #[cfg(unix)]
+    let raw_stream = self::unix::establish(&pipe_name);
+    #[cfg(windows)]
+    let raw_stream = self::windows::establish(&pipe_name);
+
+    let mut reader = BufReader::new(raw_stream.try_clone().unwrap());
+    let mut writer = BufWriter::new(raw_stream.try_clone().unwrap());
+
+    // Write the secret.
+    writeln!(writer, "{pipe_secret}").expect("write(secret):");
+
+    // Write the prompt that Git gave us.
+    writeln!(writer, "{prompt}").expect("write(prompt):");
+
+    writer.flush().expect("flush():");
+
+    // Clear the timeout (it's now time for the user to provide a response)
+    raw_stream
+        .set_read_timeout(None)
+        .expect("set_read_timeout(None):");
+
+    // Wait for the response.
+    let mut password = String::new();
+    let nread = reader.read_line(&mut password).expect("read_line():");
+    if nread == 0 {
+        panic!("read_line() returned 0");
+    }
+
+    // Write the response back to Git.
+    // `password` already has a newline at the end.
+    write!(std::io::stdout(), "{password}").expect("write(password):");
+}

gitbutler-git/src/bin/askpass/unix.rs

@@ -0,0 +1,5 @@
+use std::os::unix::net::UnixStream;
+
+pub fn establish(sock_path: &str) -> UnixStream {
+    UnixStream::connect(sock_path).expect("connect():")
+}

gitbutler-git/src/bin/askpass/windows.rs

@@ -0,0 +1,59 @@
+use std::{
+    io,
+    os::windows::io::{AsRawHandle, FromRawHandle},
+    time::Duration,
+};
+use windows_named_pipe::PipeStream;
+
+pub fn establish(sock_path: &str) -> PipeStream {
+    PipeStream::connect(sock_path).unwrap()
+}
+
+/// There are some methods we need in order to run askpass correctly,
+/// and those methods are not available out of the box on windows.
+/// We stub them using this trait so we don't have to newtype
+/// the pipestream itself (which would be extensive and un-DRY).
+pub trait UnixCompatibility: Sized {
+    fn try_clone(&self) -> Option<Self>;
+    fn set_read_timeout(&self, timeout: Option<Duration>) -> io::Result<()>;
+}
+
+impl UnixCompatibility for PipeStream {
+    fn try_clone(&self) -> Option<Self> {
+        Some(unsafe { Self::from_raw_handle(self.as_raw_handle()) })
+    }
+
+    fn set_read_timeout(&self, timeout: Option<Duration>) -> io::Result<()> {
+        // NOTE(qix-): Technically, this shouldn't work (and probably doesn't).
+        // NOTE(qix-): The documentation states:
+        // NOTE(qix-):
+        // NOTE(qix-): > This parameter must be NULL if . . . client and server
+        // NOTE(qix-): > processes are on the same computer.
+        // NOTE(qix-):
+        // NOTE(qix-): This is indeed the case here, but we try to make it work
+        // NOTE(qix-): anyway.
+        #[allow(unused_assignments)]
+        let mut timeout_ms: winapi::shared::minwindef::DWORD = 0;
+        let timeout_ptr: winapi::shared::minwindef::LPDWORD = if let Some(timeout) = timeout {
+            timeout_ms = timeout.as_millis() as winapi::shared::minwindef::DWORD;
+            &mut timeout_ms as *mut _
+        } else {
+            std::ptr::null_mut()
+        };
+
+        let r = unsafe {
+            winapi::um::namedpipeapi::SetNamedPipeHandleState(
+                self.as_raw_handle(),
+                std::ptr::null_mut(),
+                std::ptr::null_mut(),
+                timeout_ptr,
+            )
+        };
+
+        if r == 0 {
+            Err(io::Error::last_os_error())
+        } else {
+            Ok(())
+        }
+    }
+}

gitbutler-git/src/bin/setsid.rs

@@ -0,0 +1,10 @@
+// NOTE(qix-): Cargo doesn't let us specify binaries based on the platform,
+// NOTE(qix-): unfortunately. This utility is not used on Windows but is
+// NOTE(qix-): build anyway. We'll address this at a later time.
+// NOTE(qix-):
+// NOTE(qix-): For now, we just stub out the main function on windows and panic.
+
+#[cfg(unix)]
+include!("setsid/unix.rs");
+#[cfg(windows)]
+include!("setsid/windows.rs");

gitbutler-git/src/cli/bin/setsid.rs → gitbutler-git/src/bin/setsid/unix.rs

@@ -1,16 +1,9 @@
-#[cfg(not(target_os = "windows"))]
 use nix::{
     libc::{c_int, wait, EXIT_FAILURE, WEXITSTATUS, WIFEXITED, WIFSIGNALED, WTERMSIG},
     unistd::{fork, setsid, ForkResult},
 };
 use std::{os::unix::process::CommandExt, process};
 
-#[cfg(target_os = "windows")]
-pub fn main() {
-    panic!("This binary is only meant to be run on Unix-like systems. It exists on Windows only because Cargo cannot switch off bins based on target platform.");
-}
-
-#[cfg(not(target_os = "windows"))]
 pub fn main() {
     let has_pipe_var = std::env::var("GITBUTLER_ASKPASS_PIPE")
         .map(|v| !v.is_empty())

gitbutler-git/src/bin/setsid/windows.rs

@@ -0,0 +1,3 @@
+pub fn main() {
+    panic!("This binary is only meant to be run on Unix-like systems. It exists on Windows only because Cargo cannot switch off bins based on target platform.");
+}