Add compat module to provide openpty/forkpty on aix

src/unix/aix/compat.rs

@@ -0,0 +1,198 @@
+// Common functions that are unfortunately missing on AIX
+
+use crate::unix::aix::*;
+use crate::{c_char, c_int};
+
+#[cfg(target_os = "aix")]
+unsafe fn bail(fdm: c_int, fds: c_int) -> c_int {
+    let e = *_Errno();
+    if fds >= 0 {
+        crate::close(fds);
+    }
+    if fdm >= 0 {
+        crate::close(fdm);
+    }
+    *_Errno() = e;
+    -1
+}
+
+#[cfg(target_os = "aix")]
+pub unsafe fn openpty(
+    amain: *mut c_int,
+    asubord: *mut c_int,
+    name: *mut c_char,
+    termp: *const termios,
+    winp: *const crate::winsize,
+) -> c_int {
+    const PTEM: &[u8] = b"ptem\0";
+    const LDTERM: &[u8] = b"ldterm\0";
+
+    // Open the main pseudo-terminal device, making sure not to set it as the
+    // controlling terminal for this process:
+    let fdm = crate::posix_openpt(O_RDWR | O_NOCTTY);
+    if fdm < 0 {
+        return -1;
+    }
+
+    // Set permissions and ownership on the subordinate device and unlock it:
+    if crate::grantpt(fdm) < 0 || crate::unlockpt(fdm) < 0 {
+        return bail(fdm, -1);
+    }
+
+    // Get the path name of the subordinate device:
+    let subordpath = crate::ptsname(fdm);
+    if subordpath.is_null() {
+        return bail(fdm, -1);
+    }
+
+    // Open the subordinate device without setting it as the controlling
+    // terminal for this process:
+    let fds = crate::open(subordpath, O_RDWR | O_NOCTTY);
+    if fds < 0 {
+        return bail(fdm, -1);
+    }
+
+    // Check if the STREAMS modules are already pushed:
+    let setup = crate::ioctl(fds, I_FIND, LDTERM.as_ptr());
+    if setup < 0 {
+        return bail(fdm, fds);
+    } else if setup == 0 {
+        // The line discipline is not present, so push the appropriate STREAMS
+        // modules for the subordinate device:
+        if crate::ioctl(fds, I_PUSH, PTEM.as_ptr()) < 0
+            || crate::ioctl(fds, I_PUSH, LDTERM.as_ptr()) < 0
+        {
+            return bail(fdm, fds);
+        }
+    }
+
+    // If provided, set the terminal parameters:
+    if !termp.is_null() && crate::tcsetattr(fds, TCSAFLUSH, termp) != 0 {
+        return bail(fdm, fds);
+    }
+
+    // If provided, set the window size:
+    if !winp.is_null() && crate::ioctl(fds, TIOCSWINSZ, winp) < 0 {
+        return bail(fdm, fds);
+    }
+
+    // If the caller wants the name of the subordinate device, copy it out.
+    //
+    // Note that this is a terrible interface: there appears to be no standard
+    // upper bound on the copy length for this pointer.  Nobody should pass
+    // anything but NULL here, preferring instead to use ptsname(3C) directly.
+    if !name.is_null() {
+        crate::strcpy(name, subordpath);
+    }
+
+    *amain = fdm;
+    *asubord = fds;
+    0
+}
+
+#[cfg(target_os = "aix")]
+pub unsafe fn forkpty(
+    amain: *mut c_int,
+    name: *mut c_char,
+    termp: *const termios,
+    winp: *const crate::winsize,
+) -> crate::pid_t {
+    const PTEM: &[u8] = b"ptem\0";
+    const LDTERM: &[u8] = b"ldterm\0";
+    let fds = -1;
+
+    let fdm = crate::posix_openpt(O_RDWR);
+    if fdm < 0 {
+        return -1;
+    }
+
+    // Set permissions and ownership on the subordinate device and unlock it:
+    if crate::grantpt(fdm) < 0 || crate::unlockpt(fdm) < 0 {
+        return bail(fdm, -1);
+    }
+
+    *amain = fdm;
+
+    let pid = crate::fork();
+    if pid < 0 {
+        return bail(*amain, fds);
+    } else if pid > 0 {
+        // In the parent process, we close the subordinate device and return the
+        // process ID of the new child:
+        crate::close(fds);
+        return pid;
+    }
+
+    // The rest of this function executes in the child process.
+
+    // Get the path name of the subordinate device:
+    let subordpath = crate::ptsname(fdm);
+    if subordpath.is_null() {
+        return bail(fdm, -1);
+    }
+
+    // Open the subordinate device without setting it as the controlling
+    // terminal for this process:
+    let fds = crate::open(subordpath, O_RDWR);
+    if fds < 0 {
+        return bail(fdm, -1);
+    }
+
+    // Check if the STREAMS modules are already pushed:
+    let setup = crate::ioctl(fds, I_FIND, LDTERM.as_ptr());
+    if setup < 0 {
+        return bail(fdm, fds);
+    } else if setup == 0 {
+        // The line discipline is not present, so push the appropriate STREAMS
+        // modules for the subordinate device:
+        if crate::ioctl(fds, I_PUSH, PTEM.as_ptr()) < 0
+            || crate::ioctl(fds, I_PUSH, LDTERM.as_ptr()) < 0
+        {
+            return bail(fdm, fds);
+        }
+    }
+
+    // If provided, set the terminal parameters:
+    if !termp.is_null() && crate::tcsetattr(fds, TCSAFLUSH, termp) != 0 {
+        return bail(fdm, fds);
+    }
+
+    // If provided, set the window size:
+    if !winp.is_null() && crate::ioctl(fds, TIOCSWINSZ, winp) < 0 {
+        return bail(fdm, fds);
+    }
+
+    // If the caller wants the name of the subordinate device, copy it out.
+    //
+    // Note that this is a terrible interface: there appears to be no standard
+    // upper bound on the copy length for this pointer.  Nobody should pass
+    // anything but NULL here, preferring instead to use ptsname(3C) directly.
+    if !name.is_null() {
+        crate::strcpy(name, subordpath);
+    }
+
+    // Close the main side of the pseudo-terminal pair:
+    crate::close(*amain);
+
+    // Use TIOCSCTTY to set the subordinate device as our controlling
+    // terminal.  This will fail (with ENOTTY) if we are not the leader in
+    // our own session, so we call setsid() first.  Finally, arrange for
+    // the pseudo-terminal to occupy the standard I/O descriptors.
+    if crate::setsid() < 0
+        || crate::dup2(fds, 0) < 0
+        || crate::dup2(fds, 1) < 0
+        || crate::dup2(fds, 2) < 0
+    {
+        // At this stage there are no particularly good ways to handle failure.
+        // Exit as abruptly as possible, using _exit() to avoid messing with any
+        // state still shared with the parent process.
+        crate::_exit(EXIT_FAILURE);
+    }
+    // Close the inherited descriptor, taking care to avoid closing the standard
+    // descriptors by mistake:
+    if fds > 2 {
+        crate::close(fds);
+    }
+
+    0
+}

src/unix/aix/mod.rs

@@ -3352,6 +3352,9 @@ extern "C" {
     pub fn _Errno() -> *mut c_int;
 }
 
+mod compat;
+pub use self::compat::*;
+
 cfg_if! {
     if #[cfg(target_arch = "powerpc64")] {
         mod powerpc64;