1 //= OSLog.h - Analysis of calls to os_log builtins --*- C++ -*-===============//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines APIs for determining the layout of the data buffer for
11 // os_log() and os_trace().
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_CLANG_ANALYSIS_ANALYSES_OSLOG_H
16 #define LLVM_CLANG_ANALYSIS_ANALYSES_OSLOG_H
18 #include "clang/AST/ASTContext.h"
19 #include "clang/AST/Expr.h"
22 namespace analyze_os_log {
24 /// An OSLogBufferItem represents a single item in the data written by a call
25 /// to os_log() or os_trace().
26 class OSLogBufferItem {
29 // The item is a scalar (int, float, raw pointer, etc.). No further copying
30 // is required. This is the only kind allowed by os_trace().
33 // The item is a count, which describes the length of the following item to
34 // be copied. A count may only be followed by an item of kind StringKind,
35 // WideStringKind, or PointerKind.
38 // The item is a pointer to a C string. If preceded by a count 'n',
39 // os_log() will copy at most 'n' bytes from the pointer.
42 // The item is a pointer to a block of raw data. This item must be preceded
43 // by a count 'n'. os_log() will copy exactly 'n' bytes from the pointer.
46 // The item is a pointer to an Objective-C object. os_log() may retain the
47 // object for later processing.
50 // The item is a pointer to wide-char string.
53 // The item is corresponding to the '%m' format specifier, no value is
54 // populated in the buffer and the runtime is loading the errno value.
57 // The item is a mask type.
62 // The item is marked "private" in the format string.
65 // The item is marked "public" in the format string.
68 // The item is marked "sensitive" in the format string.
69 IsSensitive = 0x4 | IsPrivate
73 Kind TheKind = ScalarKind;
74 const Expr *TheExpr = nullptr;
76 CharUnits Size; // size of the data, not including the header bytes
81 OSLogBufferItem(Kind kind, const Expr *expr, CharUnits size, unsigned flags,
82 StringRef maskType = StringRef())
83 : TheKind(kind), TheExpr(expr), Size(size), Flags(flags),
85 assert(((Flags == 0) || (Flags == IsPrivate) || (Flags == IsPublic) ||
86 (Flags == IsSensitive)) &&
87 "unexpected privacy flag");
90 OSLogBufferItem(ASTContext &Ctx, CharUnits value, unsigned flags)
91 : TheKind(CountKind), ConstValue(value),
92 Size(Ctx.getTypeSizeInChars(Ctx.IntTy)), Flags(flags) {}
94 unsigned char getDescriptorByte() const {
95 unsigned char result = Flags;
96 result |= ((unsigned)getKind()) << 4;
100 unsigned char getSizeByte() const { return size().getQuantity(); }
102 Kind getKind() const { return TheKind; }
103 bool getIsPrivate() const { return (Flags & IsPrivate) != 0; }
105 const Expr *getExpr() const { return TheExpr; }
106 CharUnits getConstValue() const { return ConstValue; }
107 CharUnits size() const { return Size; }
109 StringRef getMaskType() const { return MaskType; }
112 class OSLogBufferLayout {
114 SmallVector<OSLogBufferItem, 4> Items;
116 enum Flags { HasPrivateItems = 1, HasNonScalarItems = 1 << 1 };
118 CharUnits size() const {
120 result += CharUnits::fromQuantity(2); // summary byte, num-args byte
121 for (auto &item : Items) {
122 // descriptor byte, size byte
123 result += item.size() + CharUnits::fromQuantity(2);
128 bool hasPrivateItems() const {
130 Items, [](const OSLogBufferItem &Item) { return Item.getIsPrivate(); });
133 bool hasNonScalarOrMask() const {
134 return llvm::any_of(Items, [](const OSLogBufferItem &Item) {
135 return Item.getKind() != OSLogBufferItem::ScalarKind ||
136 !Item.getMaskType().empty();
140 unsigned char getSummaryByte() const {
141 unsigned char result = 0;
142 if (hasPrivateItems())
143 result |= HasPrivateItems;
144 if (hasNonScalarOrMask())
145 result |= HasNonScalarItems;
149 unsigned char getNumArgsByte() const { return Items.size(); }
152 // Given a call 'E' to one of the builtins __builtin_os_log_format() or
153 // __builtin_os_log_format_buffer_size(), compute the layout of the buffer that
154 // the call will write into and store it in 'layout'. Returns 'false' if there
155 // was some error encountered while computing the layout, and 'true' otherwise.
156 bool computeOSLogBufferLayout(clang::ASTContext &Ctx, const clang::CallExpr *E,
157 OSLogBufferLayout &layout);
159 } // namespace analyze_os_log