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Fix Issue 24165 - Failed readf leaves File in inconsistent state #8826

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Fix Issue 24165 - Failed readf leaves File in inconsistent state #8826

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153 changes: 100 additions & 53 deletions std/stdio.d
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Original file line number Diff line number Diff line change
Expand Up @@ -3993,79 +3993,103 @@ enum LockType

struct LockingTextReader
{
private File _f;
private char _front;
private bool _hasChar;

this(File f)
private static struct Impl
{
import std.exception : enforce;
enforce(f.isOpen, "LockingTextReader: File must be open");
_f = f;
_FLOCK(_f._p.handle);
}
private File _f;
private char _front;
private bool _hasChar;

this(this)
{
_FLOCK(_f._p.handle);
}
this(File f)
{
import std.exception : enforce;
enforce(f.isOpen, "LockingTextReader: File must be open");
_f = f;
_FLOCK(_f._p.handle);
}

~this()
{
if (_hasChar)
ungetc(_front, cast(FILE*)_f._p.handle);
@disable this(this);

// File locking has its own reference count
if (_f.isOpen) _FUNLOCK(_f._p.handle);
}
~this()
{
if (_hasChar)
ungetc(_front, cast(FILE*)_f._p.handle);

void opAssign(LockingTextReader r)
{
import std.algorithm.mutation : swap;
swap(this, r);
}
// File locking has its own reference count
if (_f.isOpen) _FUNLOCK(_f._p.handle);
}

@property bool empty()
{
if (!_hasChar)
void opAssign(typeof(this) r)
{
import std.algorithm.mutation : swap;
swap(this, r);
}

@property bool empty()
{
if (!_f.isOpen || _f.eof)
return true;
immutable int c = _FGETC(cast(_iobuf*) _f._p.handle);
if (c == EOF)
if (!_hasChar)
{
.destroy(_f);
return true;
if (!_f.isOpen || _f.eof)
return true;
immutable int c = _FGETC(cast(_iobuf*) _f._p.handle);
if (c == EOF)
{
.destroy(_f);
return true;
}
_front = cast(char) c;
_hasChar = true;
}
_front = cast(char) c;
_hasChar = true;
return false;
}
return false;
}

@property char front()
{
if (!_hasChar)
@property char front()
{
version (assert)
if (!_hasChar)
{
import core.exception : RangeError;
if (empty)
throw new RangeError();
version (assert)
{
import core.exception : RangeError;
if (empty)
throw new RangeError();
}
else
{
empty;
}
}
else
{
return _front;
}

void popFront()
{
if (!_hasChar)
empty;
}
_hasChar = false;
}
return _front;
}

import std.typecons : SafeRefCounted, borrow;

private SafeRefCounted!Impl impl;

this(File f)
{
impl = SafeRefCounted!Impl(f);
}

@property bool empty()
{
return impl.borrow!((ref r) => r.empty);
}

@property char front()
{
return impl.borrow!((ref r) => r.front);
}

void popFront()
{
if (!_hasChar)
empty;
_hasChar = false;
impl.borrow!((ref r) { r.popFront; });
}
}

Expand Down Expand Up @@ -4143,6 +4167,29 @@ struct LockingTextReader
fr.readf("%s;%s;%s;%s\n", &nom, &fam, &nam, &ot);
}

// https://issues.dlang.org/show_bug.cgi?id=24165
@system unittest
{
// @system due to readf
static import std.file;
import std.algorithm.iteration : joiner, map;
import std.algorithm.searching : canFind;
import std.array : array;
import std.utf : byChar;

string content = "-hello";
auto deleteme = testFilename();
std.file.write(deleteme, content);
scope(exit) std.file.remove(deleteme);
File f = File(deleteme);
int n;
try f.readf("%d", n);
catch (Exception e) {}
// Data read must match what was written
char[] result = f.byLine(Yes.keepTerminator).map!byChar.joiner.array;
assert(content.canFind(result));
}

/**
* Indicates whether `T` is a file handle, i.e. the type
* is implicitly convertable to $(LREF File) or a pointer to a
Expand Down