Subversion Repositories QNX 8.QNX8 LLVM/Clang compiler suite

//= OSLog.h - Analysis of calls to os_log builtins --*- C++ -*-===============//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

//

// This file defines APIs for determining the layout of the data buffer for

// os_log() and os_trace().

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_AST_OSLOG_H

#define LLVM_CLANG_AST_OSLOG_H

#include "clang/AST/ASTContext.h"

#include "clang/AST/Expr.h"

namespace clang {

namespace analyze_os_log {

/// An OSLogBufferItem represents a single item in the data written by a call

/// to os_log() or os_trace().

class OSLogBufferItem {

public:

  enum Kind {

    // The item is a scalar (int, float, raw pointer, etc.). No further copying

    // is required. This is the only kind allowed by os_trace().

    ScalarKind = 0,

    // The item is a count, which describes the length of the following item to

    // be copied. A count may only be followed by an item of kind StringKind,

    // WideStringKind, or PointerKind.

    CountKind,

    // The item is a pointer to a C string. If preceded by a count 'n',

    // os_log() will copy at most 'n' bytes from the pointer.

    StringKind,

    // The item is a pointer to a block of raw data. This item must be preceded

    // by a count 'n'. os_log() will copy exactly 'n' bytes from the pointer.

    PointerKind,

    // The item is a pointer to an Objective-C object. os_log() may retain the

    // object for later processing.

    ObjCObjKind,

    // The item is a pointer to wide-char string.

    WideStringKind,

    // The item is corresponding to the '%m' format specifier, no value is

    // populated in the buffer and the runtime is loading the errno value.

    ErrnoKind,

    // The item is a mask type.

    MaskKind

  };

  enum {

    // The item is marked "private" in the format string.

    IsPrivate = 0x1,

    // The item is marked "public" in the format string.

    IsPublic = 0x2,

    // The item is marked "sensitive" in the format string.

    IsSensitive = 0x4 | IsPrivate

  };

private:

  Kind TheKind = ScalarKind;

  const Expr *TheExpr = nullptr;

  CharUnits ConstValue;

  CharUnits Size; // size of the data, not including the header bytes

  unsigned Flags = 0;

  StringRef MaskType;

public:

  OSLogBufferItem(Kind kind, const Expr *expr, CharUnits size, unsigned flags,

                  StringRef maskType = StringRef())

      : TheKind(kind), TheExpr(expr), Size(size), Flags(flags),

        MaskType(maskType) {

    assert(((Flags == 0) || (Flags == IsPrivate) || (Flags == IsPublic) ||

            (Flags == IsSensitive)) &&

           "unexpected privacy flag");

  }

  OSLogBufferItem(ASTContext &Ctx, CharUnits value, unsigned flags)

      : TheKind(CountKind), ConstValue(value),

        Size(Ctx.getTypeSizeInChars(Ctx.IntTy)), Flags(flags) {}

  unsigned char getDescriptorByte() const {

    unsigned char result = Flags;

    result |= ((unsigned)getKind()) << 4;

    return result;

  }

  unsigned char getSizeByte() const { return size().getQuantity(); }

  Kind getKind() const { return TheKind; }

  bool getIsPrivate() const { return (Flags & IsPrivate) != 0; }

  const Expr *getExpr() const { return TheExpr; }

  CharUnits getConstValue() const { return ConstValue; }

  CharUnits size() const { return Size; }

  StringRef getMaskType() const { return MaskType; }

};

class OSLogBufferLayout {

public:

  SmallVector<OSLogBufferItem, 4> Items;

  enum Flags { HasPrivateItems = 1, HasNonScalarItems = 1 << 1 };

  CharUnits size() const {

    CharUnits result;

    result += CharUnits::fromQuantity(2); // summary byte, num-args byte

    for (auto &item : Items) {

      // descriptor byte, size byte

      result += item.size() + CharUnits::fromQuantity(2);

    }

    return result;

  }

  bool hasPrivateItems() const {

    return llvm::any_of(

        Items, [](const OSLogBufferItem &Item) { return Item.getIsPrivate(); });

  }

  bool hasNonScalarOrMask() const {

    return llvm::any_of(Items, [](const OSLogBufferItem &Item) {

      return Item.getKind() != OSLogBufferItem::ScalarKind ||

             !Item.getMaskType().empty();

    });

  }

  unsigned char getSummaryByte() const {

    unsigned char result = 0;

    if (hasPrivateItems())

      result |= HasPrivateItems;

    if (hasNonScalarOrMask())

      result |= HasNonScalarItems;

    return result;

  }

  unsigned char getNumArgsByte() const { return Items.size(); }

};

// Given a call 'E' to one of the builtins __builtin_os_log_format() or

// __builtin_os_log_format_buffer_size(), compute the layout of the buffer that

// the call will write into and store it in 'layout'. Returns 'false' if there

// was some error encountered while computing the layout, and 'true' otherwise.

bool computeOSLogBufferLayout(clang::ASTContext &Ctx, const clang::CallExpr *E,

                              OSLogBufferLayout &layout);

} // namespace analyze_os_log

} // namespace clang

#endif