3 files changed, 40 insertions, 15 deletions

diff --git a/src/base/Exception.cpp b/src/base/Exception.cpp
index 1e3813a9..2bf66fc6 100644
--- a/src/base/Exception.cpp
+++ b/src/base/Exception.cpp
@@ -1,8 +1,10 @@
 #include "cru/base/Exception.h"
 
-#include "cru/base/Format.h"
-
 #include <cerrno>
+#include <format>
+#include <string_view>
+
+constexpr auto NO_MESSAGE = "No message.";
 
 namespace cru {
 Exception::Exception(std::string message, std::unique_ptr<std::exception> inner)
@@ -13,9 +15,7 @@ Exception::Exception(StringView message, std::unique_ptr<std::exception> inner)
 
 Exception::~Exception() {}
 
-const char* Exception::what() const noexcept {
-  return message_.c_str();
-}
+const char* Exception::what() const noexcept { return message_.c_str(); }
 
 void Exception::AppendMessage(StringView additional_message) {
   message_ += " ";
@@ -26,10 +26,21 @@ void Exception::AppendMessage(std::optional<StringView> additional_message) {
   if (additional_message) AppendMessage(*additional_message);
 }
 
-ErrnoException::ErrnoException(String message)
+ErrnoException::ErrnoException() : ErrnoException(NO_MESSAGE) {}
+
+ErrnoException::ErrnoException(int errno_code)
+    : ErrnoException(NO_MESSAGE, errno_code) {}
+
+ErrnoException::ErrnoException(std::string_view message)
     : ErrnoException(message, errno) {}
 
-ErrnoException::ErrnoException(String message, int errno_code)
-    : Exception(Format(u"{}. Errno is {}.", message, errno_code)),
+ErrnoException::ErrnoException(std::string_view message, int errno_code)
+    : Exception(std::format("{} Errno is {}.", message, errno_code)),
       errno_code_(errno_code) {}
+
+ErrnoException::ErrnoException(StringView message)
+    : ErrnoException(message.ToUtf8()) {}
+
+ErrnoException::ErrnoException(StringView message, int errno_code)
+    : ErrnoException(message.ToUtf8(), errno_code) {}
 }  // namespace cru
diff --git a/src/base/platform/unix/PosixSpawnSubProcess.cpp b/src/base/platform/unix/PosixSpawnSubProcess.cpp
index 34ae6622..4471c39c 100644
--- a/src/base/platform/unix/PosixSpawnSubProcess.cpp
+++ b/src/base/platform/unix/PosixSpawnSubProcess.cpp
@@ -56,7 +56,7 @@ void PosixSpawnSubProcessImpl::PlatformCreateProcess(
     const SubProcessStartInfo& start_info) {
   auto check_error = [](int error, String message) {
     if (error == 0) return;
-    std::unique_ptr<ErrnoException> inner(new ErrnoException({}, error));
+    std::unique_ptr<ErrnoException> inner(new ErrnoException(error));
     throw SubProcessFailedToStartException(std::move(message),
                                            std::move(inner));
   };
@@ -145,7 +145,7 @@ SubProcessExitResult PosixSpawnSubProcessImpl::PlatformWaitForProcess() {
       continue;
     }
 
-    std::unique_ptr<ErrnoException> inner(new ErrnoException({}, errno));
+    std::unique_ptr<ErrnoException> inner(new ErrnoException(errno));
 
     throw SubProcessInternalException(
         u"Failed to call waitpid on a subprocess.", std::move(inner));
@@ -163,7 +163,7 @@ SubProcessExitResult PosixSpawnSubProcessImpl::PlatformWaitForProcess() {
 void PosixSpawnSubProcessImpl::PlatformKillProcess() {
   int error = kill(pid_, SIGKILL);
   if (error != 0) {
-    std::unique_ptr<ErrnoException> inner(new ErrnoException({}, errno));
+    std::unique_ptr<ErrnoException> inner(new ErrnoException(errno));
     throw SubProcessInternalException(u"Failed to call kill on a subprocess.",
                                       std::move(inner));
   }
diff --git a/src/base/platform/unix/UnixFile.cpp b/src/base/platform/unix/UnixFile.cpp
index a3c5cc6c..763161ce 100644
--- a/src/base/platform/unix/UnixFile.cpp
+++ b/src/base/platform/unix/UnixFile.cpp
@@ -3,8 +3,9 @@
 #include "cru/base/log/Logger.h"
 
 #include <fcntl.h>
-#include <sys/fcntl.h>
+#include <sys/types.h>
 #include <unistd.h>
+#include <cerrno>
 
 namespace cru::platform::unix {
 
@@ -68,7 +69,7 @@ int UnixFileDescriptor::GetValue() const {
 void UnixFileDescriptor::Close() {
   EnsureValid();
   if (!this->DoClose()) {
-    throw ErrnoException(u"Failed to call close on file descriptor.");
+    throw ErrnoException("Failed to call close on file descriptor.");
   }
   descriptor_ = -1;
   auto_close_ = false;
@@ -82,17 +83,30 @@ bool UnixFileDescriptor::DoClose() {
   }
 }
 
+ssize_t UnixFileDescriptor::Read(void* buffer, size_t size) {
+  EnsureValid();
+  auto result = ::read(GetValue(), buffer, size);
+  if (result == -1) {
+    if (errno == EAGAIN || errno == EWOULDBLOCK) {
+      return -1;
+    } else {
+      throw ErrnoException("Failed to read on file descriptor.");
+    }
+  }
+  return result;
+}
+
 void UnixFileDescriptor::SetFileDescriptorFlags(int flags) {
   EnsureValid();
   if (::fcntl(GetValue(), F_SETFL, flags) != -1) {
-    throw ErrnoException(u"Failed to set flags on file descriptor.");
+    throw ErrnoException("Failed to set flags on file descriptor.");
   }
 }
 
 UniDirectionalUnixPipeResult OpenUniDirectionalPipe(UnixPipeFlag flags) {
   int fds[2];
   if (::pipe(fds) != 0) {
-    throw ErrnoException(u"Failed to create unix pipe.");
+    throw ErrnoException("Failed to create unix pipe.");
   }
 
   UnixFileDescriptor read(fds[0]), write(fds[1]);