From 9f446be76ee804bcd2f6ff8546612c9fcaf2a73e Mon Sep 17 00:00:00 2001
From: Nat Goodspeed <nat@lindenlab.com>
Date: Mon, 28 Oct 2019 14:21:27 -0400
Subject: [PATCH] DRTVWR-476: Add LLUniqueFile, adding RAII semantics to
LLFILE*.
LLUniqueFile wraps an LLFILE* in a move-only class that closes the wrapped
LLFILE* on destruction. It provides conversion operators to permit idiomatic
usage as an LLFILE* value.
---
indra/llcommon/llfile.h | 63 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 63 insertions(+)
diff --git a/indra/llcommon/llfile.h b/indra/llcommon/llfile.h
index 398938b7291..9de095b45d2 100644
--- a/indra/llcommon/llfile.h
+++ b/indra/llcommon/llfile.h
@@ -86,6 +86,69 @@ class LL_COMMON_API LLFile
static const char * tmpdir();
};
+/// RAII class
+class LLUniqueFile
+{
+public:
+ // empty
+ LLUniqueFile(): mFileHandle(nullptr) {}
+ // wrap (e.g.) result of LLFile::fopen()
+ LLUniqueFile(LLFILE* f): mFileHandle(f) {}
+ // no copy
+ LLUniqueFile(const LLUniqueFile&) = delete;
+ // move construction
+ LLUniqueFile(LLUniqueFile&& other)
+ {
+ mFileHandle = other.mFileHandle;
+ other.mFileHandle = nullptr;
+ }
+ // The point of LLUniqueFile is to close on destruction.
+ ~LLUniqueFile()
+ {
+ close();
+ }
+
+ // simple assignment
+ LLUniqueFile& operator=(LLFILE* f)
+ {
+ close();
+ mFileHandle = f;
+ return *this;
+ }
+ // copy assignment deleted
+ LLUniqueFile& operator=(const LLUniqueFile&) = delete;
+ // move assignment
+ LLUniqueFile& operator=(LLUniqueFile&& other)
+ {
+ close();
+ std::swap(mFileHandle, other.mFileHandle);
+ return *this;
+ }
+
+ // explicit close operation
+ void close()
+ {
+ if (mFileHandle)
+ {
+ // in case close() throws, set mFileHandle null FIRST
+ LLFILE* h{nullptr};
+ std::swap(h, mFileHandle);
+ LLFile::close(h);
+ }
+ }
+
+ // detect whether the wrapped LLFILE is open or not
+ explicit operator bool() const { return bool(mFileHandle); }
+ bool operator!() { return ! mFileHandle; }
+
+ // LLUniqueFile should be usable for any operation that accepts LLFILE*
+ // (or FILE* for that matter)
+ operator LLFILE*() const { return mFileHandle; }
+
+private:
+ LLFILE* mFileHandle;
+};
+
#if LL_WINDOWS
/**
* @brief Controlling input for files.
--
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