4 files changed, 110 insertions, 1 deletions

diff --git a/include/cru/common/platform/unix/PosixSpawnSubProcess.h b/include/cru/common/platform/unix/PosixSpawnSubProcess.h
index 02b9e7e2..a55c2c1c 100644
--- a/include/cru/common/platform/unix/PosixSpawnSubProcess.h
+++ b/include/cru/common/platform/unix/PosixSpawnSubProcess.h
@@ -6,6 +6,9 @@
 
 #include "../../SubProcess.h"
 
+#include "UnixFileStream.h"
+#include "UnixPipe.h"
+
 #include <spawn.h>
 
 namespace cru::platform::unix {
@@ -17,6 +20,14 @@ class PosixSpawnSubProcess : public PlatformSubProcessBase {
  private:
   pid_t pid_;
   int exit_code_;
+
+  UnixPipe stdin_pipe_;
+  UnixPipe stdout_pipe_;
+  UnixPipe stderr_pipe_;
+
+  std::unique_ptr<UnixFileStream> stdin_stream_;
+  std::unique_ptr<UnixFileStream> stdout_stream_;
+  std::unique_ptr<UnixFileStream> stderr_stream_;
 };
 }  // namespace cru::platform::unix
 
diff --git a/include/cru/common/platform/unix/UnixPipe.h b/include/cru/common/platform/unix/UnixPipe.h
new file mode 100644
index 00000000..153c52bf
--- /dev/null
+++ b/include/cru/common/platform/unix/UnixPipe.h
@@ -0,0 +1,59 @@
+#pragma once
+
+#include "../../PreConfig.h"
+
+#ifdef CRU_PLATFORM_UNIX
+
+#include "../../Base.h"
+
+namespace cru::platform::unix {
+/**
+ * @brief an unix pipe, commonly for communication of parent process and child
+ * process.
+ *
+ * There are two types of pipes sorted by its usage. For stdin, parent process
+ * SEND data to child process. For stdout and stderr, parent process RECEIVE
+ * data from child process. Each pipe has two ends, one for read and the other
+ * for write. But for send and receive, they are reversed. It is a little
+ * confused to consider which end should be used by parent and which end should
+ * be used by child. So this class help you make it clear. You specify SEND or
+ * RECEIVE, and this class give you a parent used end and a child used end.
+ *
+ * This class will only close the end used by parent when it is destructed. It
+ * is the user's duty to close the one used by child.
+ */
+class UnixPipe : public Object {
+ private:
+  constexpr static auto kLogTag = u"cru::platform::unix::UnixPipe";
+
+ public:
+  enum class Usage {
+    Send,
+    Receive,
+  };
+
+  explicit UnixPipe(Usage usage);
+
+  CRU_DELETE_COPY(UnixPipe)
+  CRU_DELETE_MOVE(UnixPipe)
+
+  ~UnixPipe();
+
+  /**
+   * @brief aka, the one used by parent process.
+   */
+  int GetSelfFileDescriptor();
+
+  /**
+   * @brief aka, the one used by child process.
+   */
+  int GetOtherFileDescriptor();
+
+ private:
+  Usage usage_;
+  int read_fd_;
+  int write_fd_;
+};
+}  // namespace cru::platform::unix
+
+#endif
diff --git a/src/common/CMakeLists.txt b/src/common/CMakeLists.txt
index 2414831b..aaff70fe 100644
--- a/src/common/CMakeLists.txt
+++ b/src/common/CMakeLists.txt
@@ -22,8 +22,9 @@ target_compile_definitions(CruBase PUBLIC $<$<CONFIG:Debug>:CRU_DEBUG>)
 
 if (UNIX AND NOT EMSCRIPTEN)
 	target_sources(CruBase PRIVATE
+		platform/unix/PosixSpawnSubProcess.cpp
 		platform/unix/UnixFileStream.cpp
-		platform/unix/UnixFileStream.cpp
+		platform/unix/UnixPipe.cpp
 	)
 
 	if (NOT APPLE)
diff --git a/src/common/platform/unix/UnixPipe.cpp b/src/common/platform/unix/UnixPipe.cpp
new file mode 100644
index 00000000..8393f022
--- /dev/null
+++ b/src/common/platform/unix/UnixPipe.cpp
@@ -0,0 +1,38 @@
+#include "cru/common/platform/unix/UnixPipe.h"
+#include "cru/common/Exception.h"
+#include "cru/common/log/Logger.h"
+
+#include <unistd.h>
+
+namespace cru::platform::unix {
+UnixPipe::UnixPipe(Usage usage) : usage_(usage) {
+  int fds[2];
+  if (pipe(fds) != 0) {
+    throw ErrnoException(u"Failed to create unix pipe.");
+  }
+  read_fd_ = fds[0];
+  write_fd_ = fds[1];
+}
+
+int UnixPipe::GetSelfFileDescriptor() {
+  if (usage_ == Usage::Send) {
+    return write_fd_;
+  } else {
+    return read_fd_;
+  }
+}
+
+int UnixPipe::GetOtherFileDescriptor() {
+  if (usage_ == Usage::Send) {
+    return read_fd_;
+  } else {
+    return write_fd_;
+  }
+}
+
+UnixPipe::~UnixPipe() {
+  if (close(GetSelfFileDescriptor()) != 0) {
+    CRU_LOG_ERROR(u"Failed to close unix pipe file descriptor.");
+  }
+}
+}  // namespace cru::platform::unix