cosmopolitan/libc/calls/read-nt.c

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney                              │
│                                                                              │
│ Permission to use, copy, modify, and/or distribute this software for         │
│ any purpose with or without fee is hereby granted, provided that the         │
│ above copyright notice and this permission notice appear in all copies.      │
│                                                                              │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
│ PERFORMANCE OF THIS SOFTWARE.                                                │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/calls/calls.h"
#include "libc/calls/internal.h"
#include "libc/calls/sig.internal.h"
#include "libc/calls/struct/fd.internal.h"
#include "libc/calls/struct/iovec.h"
#include "libc/calls/struct/iovec.internal.h"
#include "libc/calls/syscall_support-nt.internal.h"
#include "libc/calls/wincrash.internal.h"
#include "libc/errno.h"
#include "libc/intrin/strace.internal.h"
#include "libc/macros.internal.h"
#include "libc/nt/enum/filetype.h"
#include "libc/nt/enum/wait.h"
#include "libc/nt/errors.h"
#include "libc/nt/events.h"
#include "libc/nt/files.h"
#include "libc/nt/ipc.h"
#include "libc/nt/runtime.h"
#include "libc/nt/struct/overlapped.h"
#include "libc/nt/synchronization.h"
#include "libc/nt/thread.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/o.h"
#include "libc/sysv/errfuns.h"

static textwindows void sys_read_nt_abort(int64_t handle,
                                          struct NtOverlapped *overlapped) {
  unassert(CancelIoEx(handle, overlapped) ||
           GetLastError() == kNtErrorNotFound);
}

static textwindows void MungeTerminalInput(struct Fd *fd, char *p, size_t n) {
  if (!(fd->ttymagic & kFdTtyNoCr2Nl)) {
    size_t i;
    for (i = 0; i < n; ++i) {
      if (p[i] == '\r') {
        p[i] = '\n';
      }
    }
  }
}

// Manual CMD.EXE echoing for when !ICANON && ECHO is the case.
static textwindows void EchoTerminalInput(struct Fd *fd, char *p, size_t n) {
  int64_t hOutput;
  if (fd->kind == kFdConsole) {
    hOutput = fd->extra;
  } else {
    hOutput = g_fds.p[1].handle;
  }
  if (fd->ttymagic & kFdTtyEchoRaw) {
    WriteFile(hOutput, p, n, 0, 0);
  } else {
    size_t i;
    for (i = 0; i < n; ++i) {
      if (isascii(p[i]) && iscntrl(p[i]) && p[i] != '\n' && p[i] != '\t') {
        char ctl[2];
        ctl[0] = '^';
        ctl[1] = p[i] ^ 0100;
        WriteFile(hOutput, ctl, 2, 0, 0);
      } else {
        WriteFile(hOutput, p + i, 1, 0, 0);
      }
    }
  }
}

static textwindows ssize_t sys_read_nt_impl(struct Fd *fd, void *data,
                                            size_t size, int64_t offset) {

  // perform the read i/o operation
  bool32 ok;
  uint32_t got;
  int filetype;
  int64_t handle;
  int abort_errno = EAGAIN;
  size = MIN(size, 0x7ffff000);
  handle = __resolve_stdin_handle(fd->handle);
  filetype = GetFileType(handle);
  if (filetype == kNtFileTypeChar || filetype == kNtFileTypePipe) {
    struct NtOverlapped overlap = {0};
    if (offset != -1) {
      // pread() and pwrite() should not be called on a pipe or tty
      return espipe();
    }
    if ((overlap.hEvent = CreateEvent(0, 0, 0, 0))) {
      // the win32 manual says it's important to *not* put &got here
      // since for overlapped i/o, we always use GetOverlappedResult
      ok = ReadFile(handle, data, size, 0, &overlap);
      if (!ok && GetLastError() == kNtErrorIoPending) {
        // i/o operation is in flight; blocking is unavoidable
        // if we're in non-blocking mode, then immediately abort
        // if an interrupt is pending, then abort before waiting
        // otherwise wait for i/o periodically checking interrupts
        if (fd->flags & O_NONBLOCK) {
          sys_read_nt_abort(handle, &overlap);
        } else if (_check_interrupts(kSigOpRestartable, g_fds.p)) {
        Interrupted:
          abort_errno = errno;
          sys_read_nt_abort(handle, &overlap);
        } else {
          for (;;) {
            uint32_t i;
            i = WaitForSingleObject(overlap.hEvent, __SIG_POLLING_INTERVAL_MS);
            if (i == kNtWaitTimeout) {
              if (_check_interrupts(kSigOpRestartable, g_fds.p)) {
                goto Interrupted;
              }
            } else {
              npassert(!i);
              break;
            }
          }
        }
        ok = true;
      }
      if (ok) {
        // overlapped is allocated on stack, so it's important we wait
        // for windows to acknowledge that it's done using that memory
        ok = GetOverlappedResult(handle, &overlap, &got, true);
      }
      CloseHandle(overlap.hEvent);
    } else {
      ok = false;
    }
  } else if (offset == -1) {
    // perform simple blocking file read
    ok = ReadFile(handle, data, size, &got, 0);
  } else {
    // perform pread()-style file read at particular file offset
    int64_t position;
    // save file pointer which windows clobbers, even for overlapped i/o
    if (!SetFilePointerEx(handle, 0, &position, SEEK_CUR)) {
      return __winerr();  // fd probably isn't seekable?
    }
    struct NtOverlapped overlap = {0};
    overlap.Pointer = (void *)(uintptr_t)offset;
    ok = ReadFile(handle, data, size, 0, &overlap);
    if (!ok && GetLastError() == kNtErrorIoPending) ok = true;
    if (ok) ok = GetOverlappedResult(handle, &overlap, &got, true);
    // restore file pointer which windows clobbers, even on error
    unassert(SetFilePointerEx(handle, position, 0, SEEK_SET));
  }
  if (ok) {
    if (fd->ttymagic & kFdTtyMunging) {
      MungeTerminalInput(fd, data, got);
    }
    if (fd->ttymagic & kFdTtyEchoing) {
      EchoTerminalInput(fd, data, got);
    }
    return got;
  }

  switch (GetLastError()) {
    case kNtErrorBrokenPipe:    // broken pipe
    case kNtErrorNoData:        // closing named pipe
    case kNtErrorHandleEof:     // pread read past EOF
      return 0;                 //
    case kNtErrorAccessDenied:  // read doesn't return EACCESS
      return ebadf();           //
    case kNtErrorOperationAborted:
      errno = abort_errno;
      return -1;
    default:
      return __winerr();
  }
}

textwindows ssize_t sys_read_nt(struct Fd *fd, const struct iovec *iov,
                                size_t iovlen, int64_t opt_offset) {
  ssize_t rc;
  uint32_t size;
  size_t i, total;
  if (opt_offset < -1) return einval();
  if (_check_interrupts(kSigOpRestartable, fd)) return -1;
  while (iovlen && !iov[0].iov_len) iov++, iovlen--;
  if (iovlen) {
    for (total = i = 0; i < iovlen; ++i) {
      if (!iov[i].iov_len) continue;
      rc = sys_read_nt_impl(fd, iov[i].iov_base, iov[i].iov_len, opt_offset);
      if (rc == -1) return -1;
      total += rc;
      if (opt_offset != -1) opt_offset += rc;
      if (rc < iov[i].iov_len) break;
    }
    return total;
  } else {
    return sys_read_nt_impl(fd, NULL, 0, opt_offset);
  }
}