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 | |
20 | namespace clang { |
21 | namespace 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(). |
25 | class OSLogBufferItem { |
26 | public: |
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 | |
71 | private: |
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 | |
79 | public: |
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 | |
111 | class OSLogBufferLayout { |
112 | public: |
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(Quantity: 2); // summary byte, num-args byte |
120 | for (auto &item : Items) { |
121 | // descriptor byte, size byte |
122 | result += item.size() + CharUnits::fromQuantity(Quantity: 2); |
123 | } |
124 | return result; |
125 | } |
126 | |
127 | bool hasPrivateItems() const { |
128 | return llvm::any_of( |
129 | Range: Items, P: [](const OSLogBufferItem &Item) { return Item.getIsPrivate(); }); |
130 | } |
131 | |
132 | bool hasNonScalarOrMask() const { |
133 | return llvm::any_of(Range: Items, P: [](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. |
155 | bool computeOSLogBufferLayout(clang::ASTContext &Ctx, const clang::CallExpr *E, |
156 | OSLogBufferLayout &layout); |
157 | |
158 | } // namespace analyze_os_log |
159 | } // namespace clang |
160 | #endif |
161 | |