Fix vCont on Redox

Cargo.lock

@@ -89,7 +89,7 @@ dependencies = [
  "libc 0.2.71 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "memchr 2.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "redox_syscall 0.1.56 (git+https://gitlab.redox-os.org/redox-os/syscall)",
+ "redox_syscall 0.1.56 (git+https://gitlab.redox-os.org/jD91mZM2/syscall?branch=ptrace-fexec)",
  "strace 0.1.0 (git+https://gitlab.redox-os.org/redox-os/strace-redox)",
  "structopt 0.2.18 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -183,6 +183,14 @@ dependencies = [
  "bitflags 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "redox_syscall"
+version = "0.1.56"
+source = "git+https://gitlab.redox-os.org/jD91mZM2/syscall?branch=ptrace-fexec#c23d36e8923b8087039c26fcde3c359b5e0accc7"
+dependencies = [
+ "bitflags 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "regex"
 version = "1.3.9"
@@ -373,6 +381,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum quick-error 1.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "a1d01941d82fa2ab50be1e79e6714289dd7cde78eba4c074bc5a4374f650dfe0"
 "checksum quote 0.3.15 (registry+https://github.com/rust-lang/crates.io-index)" = "7a6e920b65c65f10b2ae65c831a81a073a89edd28c7cce89475bff467ab4167a"
 "checksum quote 0.6.13 (registry+https://github.com/rust-lang/crates.io-index)" = "6ce23b6b870e8f94f81fb0a363d65d86675884b34a09043c81e5562f11c1f8e1"
+"checksum redox_syscall 0.1.56 (git+https://gitlab.redox-os.org/jD91mZM2/syscall?branch=ptrace-fexec)" = "<none>"
 "checksum redox_syscall 0.1.56 (git+https://gitlab.redox-os.org/redox-os/syscall)" = "<none>"
 "checksum regex 1.3.9 (registry+https://github.com/rust-lang/crates.io-index)" = "9c3780fcf44b193bc4d09f36d2a3c87b251da4a046c87795a0d35f4f927ad8e6"
 "checksum regex-syntax 0.6.18 (registry+https://github.com/rust-lang/crates.io-index)" = "26412eb97c6b088a6997e05f69403a802a92d520de2f8e63c2b65f9e0f47c4e8"

src/os/redox.rs

@@ -50,6 +50,13 @@ impl FromOsError<syscall::Error> for Box<dyn std::error::Error> {
     }
 }
 
+fn stopped() -> usize {
+    let status = (SIGSTOP << 8) | 0x7f;
+    assert!(syscall::wifstopped(status));
+    assert_eq!(syscall::wstopsig(status), SIGSTOP);
+    status
+}
+
 macro_rules! e {
     ($result:expr) => {{
         match $result {
@@ -326,40 +333,29 @@ impl super::Target for Os {
         let mut tracer = self.tracer.borrow_mut();
         e!(tracer.next(strace::Flags::STOP_SINGLESTEP));
 
+        let rip = e!(tracer.regs.get_int()).rip;
+
         // Just pretend ptrace SIGSTOP:ped this
-        let status = (SIGSTOP << 8) | 0x7f;
-        assert!(syscall::wifstopped(status));
-        assert_eq!(syscall::wstopsig(status), SIGSTOP);
-        self.last_status.set(status);
-
-        Ok(None)
-        // unsafe {
-        //     Ok(
-        //         if libc::WIFSTOPPED(self.last_status.get())
-        //             && libc::WSTOPSIG(self.last_status.get()) == libc::SIGTRAP
-        //         {
-        //             let rip = e!(libc::ptrace(
-        //                 libc::PTRACE_PEEKUSER,
-        //                 self.pid,
-        //                 libc::RIP as usize * mem::size_of::<usize>()
-        //             ));
-        //             Some(rip as u64)
-        //         } else {
-        //             None
-        //         },
-        //     )
-        // }
+        self.last_status.set(stopped());
+
+        Ok(Some(rip as _))
     }
 
     fn cont(&self, _signal: Option<u8>) -> Result<()> {
         let mut tracer = self.tracer.borrow_mut();
-        e!(tracer.next(strace::Flags::STOP_BREAKPOINT));
 
-        // Just pretend ptrace SIGSTOP:ped this
-        let status = (SIGSTOP << 8) | 0x7f;
-        assert!(syscall::wifstopped(status));
-        assert_eq!(syscall::wstopsig(status), SIGSTOP);
-        self.last_status.set(status);
+        match tracer.next(strace::Flags::STOP_BREAKPOINT) {
+            Ok(_) => {
+                // Just pretend ptrace SIGSTOP:ped this
+                self.last_status.set(stopped());
+            },
+            Err(err) if err.raw_os_error() == Some(syscall::ESRCH) => {
+                let mut status = 0;
+                e!(syscall::waitpid(0, &mut status, WNOHANG));
+                self.last_status.set(status);
+            },
+            Err(err) => e!(Err(err)),
+        };
 
         Ok(())
     }