Depend on kj/miniposix.h instead of unistd.h in most places

This is necessary to get things working in MSVC. Note I swapped unistd.h
for miniposix.h in the compiler, too, which will be necessary to port the
compiler to MSVC.

This commit also pulls capnp/compiler/capnp.c++'s pipe() implementation
details (i.e., 8k reserved memory, _O_BINARY mode) into kj/miniposix.h.

c++/src/capnp/compiler/capnp.c++

@@ -28,7 +28,7 @@
 #include <capnp/schema.capnp.h>
 #include <kj/vector.h>
 #include <kj/io.h>
-#include <unistd.h>
+#include <kj/miniposix.h>
 #include <kj/debug.h>
 #include "../message.h"
 #include <iostream>
@@ -43,9 +43,6 @@
 
 #if _WIN32
 #include <process.h>
-#include <io.h>
-#include <fcntl.h>
-#define pipe(fds) _pipe(fds, 8192, _O_BINARY)
 #else
 #include <sys/wait.h>
 #endif
@@ -447,7 +444,7 @@ public:
       }
 
       int pipeFds[2];
-      KJ_SYSCALL(pipe(pipeFds));
+      KJ_SYSCALL(kj::miniposix::pipe(pipeFds));
 
       kj::String exeName;
       bool shouldSearchPath = true;

c++/src/capnp/compiler/capnpc-c++.c++

@@ -30,7 +30,7 @@
 #include <kj/vector.h>
 #include "../schema-loader.h"
 #include "../dynamic.h"
-#include <unistd.h>
+#include <kj/miniposix.h>
 #include <unordered_map>
 #include <unordered_set>
 #include <map>
@@ -50,10 +50,6 @@
 #define VERSION "(unknown)"
 #endif
 
-#if _WIN32
-#define mkdir(path, mode) mkdir(path)
-#endif
-
 namespace capnp {
 namespace {
 
@@ -2917,7 +2913,7 @@ private:
       makeDirectory(kj::str(path.slice(0, *slashpos)));
     }
 
-    if (mkdir(path.cStr(), 0777) < 0) {
+    if (kj::miniposix::mkdir(path.cStr(), 0777) < 0) {
       int error = errno;
       if (error != EEXIST) {
         KJ_FAIL_SYSCALL("mkdir(path)", error, path);

c++/src/capnp/compiler/capnpc-capnp.c++

@@ -30,7 +30,7 @@
 #include <kj/vector.h>
 #include "../schema-loader.h"
 #include "../dynamic.h"
-#include <unistd.h>
+#include <kj/miniposix.h>
 #include <unordered_map>
 #include <kj/main.h>
 #include <algorithm>

c++/src/capnp/compiler/evolution-test.c++

@@ -37,7 +37,7 @@
 #include <time.h>
 #include <kj/main.h>
 #include <kj/io.h>
-#include <unistd.h>
+#include <kj/miniposix.h>
 
 namespace capnp {
 namespace compiler {

c++/src/capnp/compiler/module-loader.c++

@@ -28,7 +28,7 @@
 #include <kj/io.h>
 #include <capnp/message.h>
 #include <map>
-#include <unistd.h>
+#include <kj/miniposix.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
@@ -99,7 +99,7 @@ kj::Array<const byte> mmapForRead(kj::StringPtr filename) {
 
     byte buffer[4096];
     for (;;) {
-      ssize_t n;
+      kj::miniposix::ssize_t n;
       KJ_SYSCALL(n = read(fd, buffer, sizeof(buffer)));
       if (n == 0) break;
       data.addAll(buffer, buffer + n);

c++/src/capnp/fuzz-test.c++

@@ -25,7 +25,7 @@
 #include "serialize.h"
 #include <kj/test.h>
 #include <stdlib.h>
-#include <unistd.h>
+#include <kj/miniposix.h>
 #include "test-util.h"
 
 namespace capnp {

c++/src/capnp/schema-parser.c++

@@ -31,7 +31,7 @@
 #include <kj/vector.h>
 #include <kj/debug.h>
 #include <kj/io.h>
-#include <unistd.h>
+#include <kj/miniposix.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
@@ -400,7 +400,7 @@ kj::Array<const char> SchemaFile::DiskFileReader::read(kj::StringPtr path) const
 
     char buffer[4096];
     for (;;) {
-      ssize_t n;
+      kj::miniposix::ssize_t n;
       KJ_SYSCALL(n = ::read(fd, buffer, sizeof(buffer)));
       if (n == 0) break;
       data.addAll(buffer, buffer + n);

c++/src/kj/main.c++

@@ -22,17 +22,15 @@
 #include "main.h"
 #include "debug.h"
 #include "arena.h"
+#include "miniposix.h"
 #include <map>
 #include <set>
 #include <stdlib.h>
-#include <unistd.h>
 #include <errno.h>
 #include <limits.h>
 
 #if _WIN32
 #include <windows.h>
-#include <io.h>
-#include <fcntl.h>
 #else
 #include <sys/uio.h>
 #endif

c++/src/kj/miniposix.h

@@ -19,8 +19,8 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
 
-#ifndef KJ_PORTABLE_FD_H_
-#define KJ_PORTABLE_FD_H_
+#ifndef KJ_MINIPOSIX_H_
+#define KJ_MINIPOSIX_H_
 
 // This header provides a small subset of the POSIX API which also happens to be available on
 // Windows under slightly-different names.
@@ -32,6 +32,7 @@
 #if _WIN32
 #include <io.h>
 #include <direct.h>
+#include <fcntl.h>  // _O_BINARY
 #else
 #include <limits.h>
 #include <errno.h>
@@ -61,6 +62,17 @@ inline int close(int fd) {
   return ::_close(fd);
 }
 
+#ifndef F_OK
+#define F_OK 0  // access() existence test
+#endif
+
+#ifndef S_ISREG
+#define S_ISREG(mode) (((mode) & S_IFMT) ==  S_IFREG)  // stat() regular file test
+#endif
+#ifndef S_ISDIR
+#define S_ISDIR(mode) (((mode) & S_IFMT) ==  S_IFDIR)  // stat() directory test
+#endif
+
 #ifndef STDIN_FILENO
 #define STDIN_FILENO 0
 #endif
@@ -85,7 +97,7 @@ using ::close;
 // We're on Windows, including MinGW. pipe() and mkdir() are non-standard even on MinGW.
 
 inline int pipe(int fds[2]) {
-  return ::_pipe(fds, 4096, false);
+  return ::_pipe(fds, 8192, _O_BINARY);
 }
 inline int mkdir(const char* path, int mode) {
   return ::_mkdir(path);
@@ -133,4 +145,4 @@ inline size_t iovMax(size_t count) {
 }  // namespace miniposix
 }  // namespace kj
 
-#endif  // KJ_WIN32_FD_H_
+#endif  // KJ_MINIPOSIX_H_