poll_darwin.go

Documentation: github.com/tetratelabs/wazero/internal/sysfs

     1  package sysfs
     2  
     3  import (
     4  	"unsafe"
     5  
     6  	"github.com/tetratelabs/wazero/experimental/sys"
     7  )
     8  
     9  // pollFd is the struct to query for file descriptor events using poll.
    10  type pollFd struct {
    11  	// fd is the file descriptor.
    12  	fd int32
    13  	// events is a bitmap containing the requested events.
    14  	events int16
    15  	// revents is a bitmap containing the returned events.
    16  	revents int16
    17  }
    18  
    19  // newPollFd is a constructor for pollFd that abstracts the platform-specific type of file descriptors.
    20  func newPollFd(fd uintptr, events, revents int16) pollFd {
    21  	return pollFd{fd: int32(fd), events: events, revents: revents}
    22  }
    23  
    24  // _POLLIN subscribes a notification when any readable data is available.
    25  const _POLLIN = 0x0001
    26  
    27  // _poll implements poll on Darwin via the corresponding libc function.
    28  func _poll(fds []pollFd, timeoutMillis int32) (n int, errno sys.Errno) {
    29  	var fdptr *pollFd
    30  	nfds := len(fds)
    31  	if nfds > 0 {
    32  		fdptr = &fds[0]
    33  	}
    34  	n1, _, err := syscall_syscall6(
    35  		libc_poll_trampoline_addr,
    36  		uintptr(unsafe.Pointer(fdptr)),
    37  		uintptr(nfds),
    38  		uintptr(int(timeoutMillis)),
    39  		uintptr(unsafe.Pointer(nil)),
    40  		uintptr(unsafe.Pointer(nil)),
    41  		uintptr(unsafe.Pointer(nil)))
    42  	return int(n1), sys.UnwrapOSError(err)
    43  }
    44  
    45  // libc_poll_trampoline_addr is the address of the
    46  // `libc_poll_trampoline` symbol, defined in `poll_darwin.s`.
    47  //
    48  // We use this to invoke the syscall through syscall_syscall6 imported below.
    49  var libc_poll_trampoline_addr uintptr
    50  
    51  // Imports the select symbol from libc as `libc_poll`.
    52  //
    53  // Note: CGO mechanisms are used in darwin regardless of the CGO_ENABLED value
    54  // or the "cgo" build flag. See /RATIONALE.md for why.
    55  //go:cgo_import_dynamic libc_poll poll "/usr/lib/libSystem.B.dylib"
    56
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