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Use LockedFile struct to enforce safe interface

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Instead of wrong trusted_FUNLOCK.
Note: trusted_FGETC does have a @safe interface.
This commit is contained in:
Nick Treleaven 2022-11-17 11:21:27 +00:00
parent 9f05dd4d4a
commit b036f74ef2
1 changed files with 55 additions and 24 deletions
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79
std/stdio.d
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@ -5455,23 +5455,61 @@ private struct ReadlnAppender
}
}
private struct LockedFile
{
private @system FILE* fps;
this(FILE* fps) @trusted
{
this.fps = fps;
_FLOCK(fps);
}
@disable this();
@disable this(this);
@disable void opAssign(LockedFile);
/* Since fps is now locked, we can create an "unshared" version
* of fp.
*/
@trusted fp() return scope => cast(_iobuf*) fps;
~this() @trusted
{
_FUNLOCK(fps);
}
}
@safe unittest
{
_iobuf* f() @safe
{
FILE* fps;
auto lf = LockedFile(fps);
scope fp = lf.fp;
static assert(!__traits(compiles, lf = LockedFile(fps)));
static assert(!__traits(compiles, { if (fps) return fp; }));
version (ShouldFail)
{
lf.destroy; // fail in @safe because of @system field?
auto x = fp; // demonstrates use after unlock
lf.fps = null; // @system field
}
return null;
}
}
// Private implementation of readln
private size_t readlnImpl(FILE* fps, ref char[] buf, dchar terminator, File.Orientation orientation) @safe
{
alias trusted_FLOCK = (fps) @trusted => _FLOCK(fps);
alias trusted_FUNLOCK = (fps) @trusted => _FUNLOCK(fps);
alias trusted_FGETC = (fp) @trusted => _FGETC(fp);
alias trusted_FGETWC = (fp) @trusted => _FGETWC(fp);
// fp is not shared so these calls are safe
alias trusted_FGETC = (scope _iobuf* fp) @trusted => _FGETC(fp);
alias trusted_FGETWC = (scope _iobuf* fp) @trusted => _FGETWC(fp);
version (DIGITAL_MARS_STDIO)
{
trusted_FLOCK(fps);
scope(exit) trusted_FUNLOCK(fps);
/* Since fps is now locked, we can create an "unshared" version
* of fp.
*/
auto fp = (() @trusted => cast(_iobuf*) fps)();
auto lf = LockedFile(fps);
auto fp = lf.fp;
ReadlnAppender app;
app.initialize(buf);
@ -5586,13 +5624,8 @@ private size_t readlnImpl(FILE* fps, ref char[] buf, dchar terminator, File.Orie
}
else version (MICROSOFT_STDIO)
{
trusted_FLOCK(fps);
scope(exit) trusted_FUNLOCK(fps);
/* Since fps is now locked, we can create an "unshared" version
* of fp.
*/
auto fp = (() @trusted => cast(_iobuf*) fps)();
auto lf = LockedFile(fps);
auto fp = lf.fp;
ReadlnAppender app;
app.initialize(buf);
@ -5621,12 +5654,11 @@ private size_t readlnImpl(FILE* fps, ref char[] buf, dchar terminator, File.Orie
if (orientation == File.Orientation.wide)
{
auto lf = LockedFile(fps);
auto fp = lf.fp;
/* Stream is in wide characters.
* Read them and convert to chars.
*/
trusted_FLOCK(fps);
scope(exit) trusted_FUNLOCK(fps);
auto fp = (() @trusted => cast(_iobuf*) fps)();
version (Windows)
{
buf.length = 0;
@ -5719,9 +5751,8 @@ private size_t readlnImpl(FILE* fps, ref char[] buf, dchar terminator, File.Orie
{
import core.stdc.wchar_ : fwide;
trusted_FLOCK(fps);
scope(exit) trusted_FUNLOCK(fps);
auto fp = (() @trusted => cast(_iobuf*) fps)();
auto lf = LockedFile(fps);
auto fp = lf.fp;
if (orientation == File.Orientation.wide)
{
/* Stream is in wide characters.