From 6cd1d68baf219b5d3c742ba5fb3a9ee04e830999 Mon Sep 17 00:00:00 2001
From: crupest <crupest@outlook.com>
Date: Thu, 5 Oct 2023 20:56:07 +0800
Subject: ...

---
 src/common/io/CFileStream.cpp           | 25 ++++++++++++++++++++++---
 src/common/io/FileNotExistException.cpp | 12 ++++++++++++
 src/common/io/OpenFileFlag.cpp          | 19 +++++++++++++++++++
 3 files changed, 53 insertions(+), 3 deletions(-)
 create mode 100644 src/common/io/FileNotExistException.cpp
 create mode 100644 src/common/io/OpenFileFlag.cpp

(limited to 'src/common/io')

diff --git a/src/common/io/CFileStream.cpp b/src/common/io/CFileStream.cpp
index 68fb137d..133cd8f6 100644
--- a/src/common/io/CFileStream.cpp
+++ b/src/common/io/CFileStream.cpp
@@ -46,22 +46,41 @@ CFileStream::CFileStream(std::FILE* file, bool readable, bool writable,
 }
 
 namespace {
-std::string ConvertOpenFileFlagToCFileFlag(OpenFileFlag flags) {
+/**
+ *  Generally the fopen will return a NULL ptr if the file does not exist. Then
+ * we must throw FileNotExistException. However, there are cases we have to
+ * check existence explicitly before. The case is OpenFileFlags::Write is
+ * specified but OpenFileFlags::Create is not, in which fopen usually create a
+ * new file automatically but we want a FileNotExistException to be thrown.
+ */
+std::string ConvertOpenFileFlagToCFileFlag(OpenFileFlag flags,
+                                           bool* explicit_check_exist) {
+  *explicit_check_exist = false;
+
   std::string result;
+
   bool need_read = flags & OpenFileFlags::Read;
   bool need_write = flags & OpenFileFlags::Write;
-  bool append = flags & OpenFileFlags::Append;
 
   if (!need_write) {
     // No need to write? The simplest
+    // Note even OpenFileFlags::Create is set, we still have to check exist.
     return "r";
   }
 
   // Now we need writing.
-  if (!need_read) {
 
+  bool create = OpenFileFlags::Create;
+
+  if (!create) {
+    *explicit_check_exist = true;
   }
 
+  bool append = flags & OpenFileFlags::Append;
+
+  if (!need_read) {
+    return "w";
+  }
 }
 }  // namespace
 
diff --git a/src/common/io/FileNotExistException.cpp b/src/common/io/FileNotExistException.cpp
new file mode 100644
index 00000000..a2e1fdb1
--- /dev/null
+++ b/src/common/io/FileNotExistException.cpp
@@ -0,0 +1,12 @@
+#include "cru/common/io/FileNotExistException.h"
+
+#include "cru/common/Exception.h"
+#include "cru/common/Format.h"
+
+#include <utility>
+
+namespace cru::io {
+  FileNotExistException::FileNotExistException(String path): Exception(), path_(std::move(path)) {
+    SetMessage(Format(u"File {} does not exist.", path_));
+  }
+}
diff --git a/src/common/io/OpenFileFlag.cpp b/src/common/io/OpenFileFlag.cpp
new file mode 100644
index 00000000..6b9957fe
--- /dev/null
+++ b/src/common/io/OpenFileFlag.cpp
@@ -0,0 +1,19 @@
+#include "cru/common/io/OpenFileFlag.h"
+
+namespace cru::io {
+bool CheckOpenFileFlag(OpenFileFlag flags) {
+  auto has = [flags](OpenFileFlag flag) { return flags & flag; };
+
+  if ((has(OpenFileFlags::Append) || has(OpenFileFlags::Truncate) ||
+       has(OpenFileFlags::Create)) &&
+      !has(OpenFileFlags::Write)) {
+    return false;
+  }
+
+  if (has(OpenFileFlags::Truncate) && has(OpenFileFlags::Append)) {
+    return false;
+  }
+
+  return true;
+}
+}  // namespace cru::io
-- 
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