1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
|
//===----------------- OSLogStringTypes.swift -----------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2020 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
// This file defines extensions for interpolating strings into an OSLogMessage.
// It defines `appendInterpolation` function for String type. It also defines
// extensions for serializing strings into the argument buffer passed to
// os_log ABIs. Note that os_log requires passing a stable pointer to an
// interpolated string.
//
// The `appendInterpolation` function defined in this file accept privacy and
// alignment options along with the interpolated expression as shown below:
//
// 1. "\(x, privacy: .private, align: .right\)"
// 2. "\(x, align: .right(columns: 10)\)"
import ObjectiveC
extension OSLogInterpolation {
/// Defines interpolation for expressions of type String.
///
/// Do not call this function directly. It will be called automatically when interpolating
/// a value of type `String` in the string interpolations passed to the log APIs.
///
/// - Parameters:
/// - argumentString: The interpolated expression of type String, which is autoclosured.
/// - align: Left or right alignment with the minimum number of columns as
/// defined by the type `OSLogStringAlignment`.
/// - privacy: A privacy qualifier which is either private or public.
/// It is auto-inferred by default.
@_semantics("constant_evaluable")
@inlinable
@_optimize(none)
@_semantics("oslog.requires_constant_arguments")
public mutating func appendInterpolation(
_ argumentString: @autoclosure @escaping () -> String,
align: OSLogStringAlignment = .none,
privacy: OSLogPrivacy = .auto
) {
guard argumentCount < maxOSLogArgumentCount else { return }
formatString += getStringFormatSpecifier(align, privacy)
// If minimum column width is specified, append this value first. Note that the
// format specifier would use a '*' for width e.g. %*s.
if let minColumns = align.minimumColumnWidth {
appendAlignmentArgument(minColumns)
}
// If the privacy has a mask, append the mask argument, which is a constant payload.
// Note that this should come after the width but before the precision.
if privacy.hasMask {
appendMaskArgument(privacy)
}
// Append the string argument.
addStringHeaders(privacy)
arguments.append(argumentString)
argumentCount += 1
stringArgumentCount += 1
}
/// Update preamble and append argument headers based on the parameters of
/// the interpolation.
@_semantics("constant_evaluable")
@inlinable
@_optimize(none)
internal mutating func addStringHeaders(_ privacy: OSLogPrivacy) {
// Append argument header.
let header = getArgumentHeader(privacy: privacy, type: .string)
arguments.append(header)
// Append number of bytes needed to serialize the argument.
let byteCount = pointerSizeInBytes()
arguments.append(UInt8(byteCount))
// Increment total byte size by the number of bytes needed for this
// argument, which is the sum of the byte size of the argument and
// two bytes needed for the headers.
totalBytesForSerializingArguments += byteCount + 2
preamble = getUpdatedPreamble(privacy: privacy, isScalar: false)
}
/// Construct an os_log format specifier from the given parameters.
/// This function must be constant evaluable and all its arguments
/// must be known at compile time.
@inlinable
@_semantics("constant_evaluable")
@_effects(readonly)
@_optimize(none)
internal func getStringFormatSpecifier(
_ align: OSLogStringAlignment,
_ privacy: OSLogPrivacy
) -> String {
var specifier = "%"
if let privacySpecifier = privacy.privacySpecifier {
specifier += "{"
specifier += privacySpecifier
specifier += "}"
}
if case .start = align.anchor {
specifier += "-"
}
if let _ = align.minimumColumnWidth {
specifier += "*"
}
specifier += "s"
return specifier
}
}
extension OSLogArguments {
/// Append an (autoclosured) interpolated expression of String type, passed to
/// `OSLogMessage.appendInterpolation`, to the array of closures tracked
/// by this instance.
@_semantics("constant_evaluable")
@inlinable
@_optimize(none)
internal mutating func append(_ value: @escaping () -> String) {
argumentClosures.append({ (position, _, stringArgumentOwners) in
serialize(
value(),
at: &position,
storingStringOwnersIn: &stringArgumentOwners)
})
}
}
/// Return the byte size of a pointer as strings are passed to the C os_log ABIs by
/// a stable pointer to its UTF8 bytes. Since pointers do not have a public
/// bitWidth property, and since MemoryLayout is not supported by the constant
/// evaluator, this function returns the byte size of Int, which must equal the
/// word length of the target architecture and hence the pointer size.
/// This function must be constant evaluable. Note that it is marked transparent
/// instead of @inline(__always) as it is used in optimize(none) functions.
@_transparent
@_alwaysEmitIntoClient
internal func pointerSizeInBytes() -> Int {
return Int.bitWidth &>> logBitsPerByte
}
/// Serialize a stable pointer to the string `stringValue` at the buffer location
/// pointed to by `bufferPosition`.
@_alwaysEmitIntoClient
@inline(__always)
internal func serialize(
_ stringValue: String,
at bufferPosition: inout UnsafeMutablePointer<UInt8>,
storingStringOwnersIn stringArgumentOwners: inout ObjectStorage<Any>
) {
let stringPointer =
getNullTerminatedUTF8Pointer(
stringValue,
storingStringOwnersIn: &stringArgumentOwners)
let byteCount = pointerSizeInBytes()
let dest =
UnsafeMutableRawBufferPointer(start: bufferPosition, count: byteCount)
withUnsafeBytes(of: stringPointer) { dest.copyMemory(from: $0) }
bufferPosition += byteCount
}
/// Return a pointer that points to a contiguous sequence of null-terminated,
/// UTF8 characters. If necessary, extends the lifetime of `stringValue` by
/// using `stringArgumentOwners`.
@_alwaysEmitIntoClient
@inline(never)
internal func getNullTerminatedUTF8Pointer(
_ stringValue: String,
storingStringOwnersIn stringArgumentOwners: inout ObjectStorage<Any>
) -> UnsafeRawPointer {
let (optStorage, bytePointer, _, _, _):
(AnyObject?, UnsafeRawPointer, Int, Bool, Bool) =
stringValue._deconstructUTF8(scratch: nil)
if let storage = optStorage {
initializeAndAdvance(&stringArgumentOwners, to: storage)
} else {
initializeAndAdvance(&stringArgumentOwners, to: stringValue._guts)
}
return bytePointer
}
|
