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1//= OSLog.h - Analysis of calls to os_log builtins --*- C++ -*-===============//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file defines APIs for determining the layout of the data buffer for
10// os_log() and os_trace().
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_CLANG_AST_OSLOG_H
15#define LLVM_CLANG_AST_OSLOG_H
16
17#include "clang/AST/ASTContext.h"
18#include "clang/AST/Expr.h"
19
20namespace clang {
21namespace analyze_os_log {
22
23/// An OSLogBufferItem represents a single item in the data written by a call
24/// to os_log() or os_trace().
25class OSLogBufferItem {
26public:
27 enum Kind {
28 // The item is a scalar (int, float, raw pointer, etc.). No further copying
29 // is required. This is the only kind allowed by os_trace().
30 ScalarKind = 0,
31
32 // The item is a count, which describes the length of the following item to
33 // be copied. A count may only be followed by an item of kind StringKind,
34 // WideStringKind, or PointerKind.
35 CountKind,
36
37 // The item is a pointer to a C string. If preceded by a count 'n',
38 // os_log() will copy at most 'n' bytes from the pointer.
39 StringKind,
40
41 // The item is a pointer to a block of raw data. This item must be preceded
42 // by a count 'n'. os_log() will copy exactly 'n' bytes from the pointer.
43 PointerKind,
44
45 // The item is a pointer to an Objective-C object. os_log() may retain the
46 // object for later processing.
47 ObjCObjKind,
48
49 // The item is a pointer to wide-char string.
50 WideStringKind,
51
52 // The item is corresponding to the '%m' format specifier, no value is
53 // populated in the buffer and the runtime is loading the errno value.
54 ErrnoKind,
55
56 // The item is a mask type.
57 MaskKind
58 };
59
60 enum {
61 // The item is marked "private" in the format string.
62 IsPrivate = 0x1,
63
64 // The item is marked "public" in the format string.
65 IsPublic = 0x2,
66
67 // The item is marked "sensitive" in the format string.
68 IsSensitive = 0x4 | IsPrivate
69 };
70
71private:
72 Kind TheKind = ScalarKind;
73 const Expr *TheExpr = nullptr;
74 CharUnits ConstValue;
75 CharUnits Size; // size of the data, not including the header bytes
76 unsigned Flags = 0;
77 StringRef MaskType;
78
79public:
80 OSLogBufferItem(Kind kind, const Expr *expr, CharUnits size, unsigned flags,
81 StringRef maskType = StringRef())
82 : TheKind(kind), TheExpr(expr), Size(size), Flags(flags),
83 MaskType(maskType) {
84 assert(((Flags == 0) || (Flags == IsPrivate) || (Flags == IsPublic) ||
85 (Flags == IsSensitive)) &&
86 "unexpected privacy flag");
87 }
88
89 OSLogBufferItem(ASTContext &Ctx, CharUnits value, unsigned flags)
90 : TheKind(CountKind), ConstValue(value),
91 Size(Ctx.getTypeSizeInChars(Ctx.IntTy)), Flags(flags) {}
92
93 unsigned char getDescriptorByte() const {
94 unsigned char result = Flags;
95 result |= ((unsigned)getKind()) << 4;
96 return result;
97 }
98
99 unsigned char getSizeByte() const { return size().getQuantity(); }
100
101 Kind getKind() const { return TheKind; }
102 bool getIsPrivate() const { return (Flags & IsPrivate) != 0; }
103
104 const Expr *getExpr() const { return TheExpr; }
105 CharUnits getConstValue() const { return ConstValue; }
106 CharUnits size() const { return Size; }
107
108 StringRef getMaskType() const { return MaskType; }
109};
110
111class OSLogBufferLayout {
112public:
113 SmallVector<OSLogBufferItem, 4> Items;
114
115 enum Flags { HasPrivateItems = 1, HasNonScalarItems = 1 << 1 };
116
117 CharUnits size() const {
118 CharUnits result;
119 result += CharUnits::fromQuantity(2); // summary byte, num-args byte
120 for (auto &item : Items) {
121 // descriptor byte, size byte
122 result += item.size() + CharUnits::fromQuantity(2);
123 }
124 return result;
125 }
126
127 bool hasPrivateItems() const {
128 return llvm::any_of(
129 Items, [](const OSLogBufferItem &Item) { return Item.getIsPrivate(); });
130 }
131
132 bool hasNonScalarOrMask() const {
133 return llvm::any_of(Items, [](const OSLogBufferItem &Item) {
134 return Item.getKind() != OSLogBufferItem::ScalarKind ||
135 !Item.getMaskType().empty();
136 });
137 }
138
139 unsigned char getSummaryByte() const {
140 unsigned char result = 0;
141 if (hasPrivateItems())
142 result |= HasPrivateItems;
143 if (hasNonScalarOrMask())
144 result |= HasNonScalarItems;
145 return result;
146 }
147
148 unsigned char getNumArgsByte() const { return Items.size(); }
149};
150
151// Given a call 'E' to one of the builtins __builtin_os_log_format() or
152// __builtin_os_log_format_buffer_size(), compute the layout of the buffer that
153// the call will write into and store it in 'layout'. Returns 'false' if there
154// was some error encountered while computing the layout, and 'true' otherwise.
155bool computeOSLogBufferLayout(clang::ASTContext &Ctx, const clang::CallExpr *E,
156 OSLogBufferLayout &layout);
157
158} // namespace analyze_os_log
159} // namespace clang
160#endif
161

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source code of clang/include/clang/AST/OSLog.h