Johannes Weiss 601e847faa
always @preconcurrency import Glibc (#1175)
Co-authored-by: Johannes Weiss <johannes@jweiss.io>
2025-03-04 09:25:51 -08:00

921 lines
35 KiB
Swift

//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2023 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
//
//===----------------------------------------------------------------------===//
#if canImport(Darwin)
internal import os
#elseif canImport(Android)
@preconcurrency import Android
#elseif canImport(Glibc)
@preconcurrency import Glibc
#elseif canImport(Musl)
@preconcurrency import Musl
#elseif os(Windows)
import WinSDK
#elseif os(WASI)
@preconcurrency import WASILibc
#endif
internal import _FoundationCShims
extension StringProtocol {
fileprivate func _convertingSlashesIfNeeded() -> String {
#if os(Windows)
// The string functions below all assume that the path separator is a forward slash
// Standardize the path to use forward slashes before processing for consistency
return self.replacing(._backslash, with: ._slash)
#else
if let str = _specializingCast(self, to: String.self) {
return str
} else {
return String(self)
}
#endif
}
}
extension String {
// MARK: - Non-filesystem String Extensions
internal var pathComponents: [String] {
_convertingSlashesIfNeeded()._pathComponents
}
private var _pathComponents: [String] {
guard !isEmpty else {
return []
}
var result = [String]()
var start = startIndex
if utf8.first == ._slash {
result.append("/")
start = utf8.firstIndex { $0 != ._slash } ?? endIndex
}
var end = start
while end != endIndex {
end = utf8[end...].firstIndex(of: ._slash) ?? endIndex
if start != end {
result.append(String(self[start..<end]))
}
start = utf8[end...].firstIndex { $0 != ._slash } ?? endIndex
end = start
}
if utf8.count > 1 && utf8.last == ._slash {
result.append("/")
}
return result
}
internal func deletingLastPathComponent() -> String {
_convertingSlashesIfNeeded()._deletingLastPathComponent()
}
private func _deletingLastPathComponent() -> String {
guard let lastSlash = utf8.lastIndex(of: ._slash) else {
// No slash, entire string is deleted
return ""
}
// Skip past consecutive slashes, if any (e.g. find "y" in "/my//path" or "h" in "/path//")
guard let lastNonSlash = self[..<lastSlash].utf8.lastIndex(where: { $0 != ._slash }) else {
// String consists entirely of slashes, return a single slash
return "/"
}
let hasTrailingSlash = (lastSlash == utf8.index(before: endIndex))
guard hasTrailingSlash else {
// No trailing slash, return up to (including) the last non-slash character
return String(self[...lastNonSlash])
}
// We have a trailing slash, find the slash before the last component
guard let previousSlash = self[..<lastNonSlash].utf8.lastIndex(of: ._slash) else {
// No prior slash, deleting the last component removes the entire string (e.g. "path/")
return ""
}
// Again, skip past consecutive slashes, if any (e.g. find "y" in "/my//path/")
guard let previousNonSlash = self[..<previousSlash].utf8.lastIndex(where: { $0 != ._slash }) else {
// String is an absolute path with a single component (e.g. "/path/" or "//path/")
return "/"
}
return String(self[...previousNonSlash])
}
internal func appendingPathComponent(_ component: String) -> String {
_convertingSlashesIfNeeded()._appendingPathComponent(component)
}
private func _appendingPathComponent(_ component: String) -> String {
guard !isEmpty else {
return component._standardizingSlashes
}
if utf8.elementsEqual([._backslash, ._backslash]) {
return self + component._standardizingSlashes
}
return (self + "/" + component)._standardizingSlashes
}
internal var lastPathComponent: String {
_convertingSlashesIfNeeded()._lastPathComponent
}
private var _lastPathComponent: String {
guard utf8.count > 1 else {
return self
}
guard let lastSlash = utf8.lastIndex(of: ._slash) else {
// No slash, just return self
return self
}
guard lastSlash == utf8.index(before: endIndex) else {
// Not a trailing slash, return the component after it
return String(self[utf8.index(after: lastSlash)...])
}
// We have a trailing slash. Ignore it and all slashes that directly precede it
guard let lastNonSlash = self[..<lastSlash].utf8.lastIndex(where: { $0 != ._slash }) else {
// String is all slashes, return a bare slash
return "/"
}
guard let previousSlash = self[..<lastNonSlash].utf8.lastIndex(of: ._slash) else {
return String(self[...lastNonSlash])
}
return String(self[utf8.index(after: previousSlash)...lastNonSlash])
}
// Internal for testing purposes
internal static let invalidExtensionScalars = Set<Unicode.Scalar>([
" ",
"/",
"\u{061c}", // ARABIC LETTER MARK
"\u{200e}", // LEFT-TO-RIGHT MARK
"\u{200f}", // RIGHT-TO-LEFT MARK
"\u{202a}", // LEFT-TO-RIGHT EMBEDDING
"\u{202b}", // RIGHT-TO-LEFT EMBEDDING
"\u{202c}", // POP DIRECTIONAL FORMATTING
"\u{202d}", // LEFT-TO-RIGHT OVERRIDE
"\u{202e}", // RIGHT-TO-LEFT OVERRIDE
"\u{2066}", // LEFT-TO-RIGHT ISOLATE
"\u{2067}", // RIGHT-TO-LEFT ISOLATE
"\u{2068}", // FIRST STRONG ISOLATE
"\u{2069}", // POP DIRECTIONAL ISOLATE
])
internal func deletingPathExtension() -> String {
guard !pathExtension.isEmpty else {
return self
}
guard let lastDot = utf8.lastIndex(of: ._dot) else {
return self
}
var result = String(self[..<lastDot])
if utf8.last == ._slash {
result += "/"
}
return result
}
private func validatePathExtension(_ pathExtension: String) -> Bool {
guard pathExtension.utf8.last != ._dot else {
return false
}
if let lastDot = pathExtension.utf8.lastIndex(of: ._dot) {
let beforeDot = pathExtension[..<lastDot]._convertingSlashesIfNeeded().unicodeScalars
let afterDot = pathExtension[pathExtension.index(after: lastDot)...]._convertingSlashesIfNeeded().unicodeScalars
return beforeDot.allSatisfy { $0 != "/" } && afterDot.allSatisfy { !String.invalidExtensionScalars.contains($0) }
} else {
return pathExtension._convertingSlashesIfNeeded().unicodeScalars.allSatisfy { !String.invalidExtensionScalars.contains($0) }
}
}
internal func appendingPathExtension(_ pathExtension: String) -> String {
guard !pathExtension.isEmpty, validatePathExtension(pathExtension) else {
return self
}
var result = self._droppingTrailingSlashes
guard result != "/" else {
// Path was all slashes
return self + ".\(pathExtension)"
}
result += ".\(pathExtension)"
if utf8.last == ._slash {
result += "/"
}
return result
}
internal var pathExtension: String {
let lastComponent = lastPathComponent.utf8
guard lastComponent.last != ._dot,
!lastComponent.starts(with: [._dot, ._dot]),
let lastDot = lastComponent.lastIndex(of: ._dot),
lastDot != lastComponent.startIndex else {
return ""
}
let result = String(lastPathComponent[lastComponent.index(after: lastDot)...])
guard validatePathExtension(result) else {
return ""
}
return result
}
internal func merging(relativePath: String) -> String {
_convertingSlashesIfNeeded()._merging(relativePath: relativePath)
}
private func _merging(relativePath: String) -> String {
guard relativePath.utf8.first != ._slash else {
return relativePath
}
guard let basePathEnd = self.utf8.lastIndex(of: ._slash) else {
return relativePath
}
return self[...basePathEnd] + relativePath
}
internal var removingDotSegments: String {
_convertingSlashesIfNeeded()._removingDotSegments
}
private var _removingDotSegments: String {
guard !isEmpty else {
return ""
}
enum RemovingDotState {
case initial
case dot
case dotDot
case slash
case slashDot
case slashDotDot
case appendUntilSlash
}
return String(unsafeUninitializedCapacity: utf8.count) { buffer in
// State machine for remove_dot_segments() from RFC 3986
//
// First, remove all "./" and "../" prefixes by moving through
// the .initial, .dot, and .dotDot states (without appending).
//
// Then, move through the remaining states/components, first
// checking if the component is special ("/./" or "/../") so
// that we only append when necessary.
var state = RemovingDotState.initial
var i = 0
for v in utf8 {
switch state {
case .initial:
if v == ._dot {
state = .dot
} else if v == ._slash {
state = .slash
} else {
buffer[i] = v
i += 1
state = .appendUntilSlash
}
case .dot:
if v == ._dot {
state = .dotDot
} else if v == ._slash {
state = .initial
} else {
i = buffer[i...i+1].initialize(fromContentsOf: [._dot, v])
state = .appendUntilSlash
}
case .dotDot:
if v == ._slash {
state = .initial
} else {
i = buffer[i...i+2].initialize(fromContentsOf: [._dot, ._dot, v])
state = .appendUntilSlash
}
case .slash:
if v == ._dot {
state = .slashDot
} else if v == ._slash {
buffer[i] = ._slash
i += 1
} else {
i = buffer[i...i+1].initialize(fromContentsOf: [._slash, v])
state = .appendUntilSlash
}
case .slashDot:
if v == ._dot {
state = .slashDotDot
} else if v == ._slash {
state = .slash
} else {
i = buffer[i...i+2].initialize(fromContentsOf: [._slash, ._dot, v])
state = .appendUntilSlash
}
case .slashDotDot:
if v == ._slash {
// Cheaply remove the previous component by moving i to its start
i = buffer[..<i].lastIndex(of: ._slash) ?? 0
state = .slash
} else {
i = buffer[i...i+3].initialize(fromContentsOf: [._slash, ._dot, ._dot, v])
state = .appendUntilSlash
}
case .appendUntilSlash:
if v == ._slash {
state = .slash
} else {
buffer[i] = v
i += 1
}
}
}
switch state {
case .slash: fallthrough
case .slashDot:
buffer[i] = ._slash
i += 1
case .slashDotDot:
// Note: "/.." is not yet appended to the buffer
i = buffer[..<i].lastIndex(of: ._slash) ?? 0
buffer[i] = ._slash
i += 1
default:
break
}
return i
}
}
/// Replaces any number of sequential `/`
/// characters with a single `/`
/// NOTE: Internal so it's testable
/// - Returns: The replaced String
internal func _compressingSlashes() -> String {
guard utf8.count > 1 else {
return self
}
enum SlashState {
case initial
case slash
}
return String(unsafeUninitializedCapacity: utf8.count) { buffer in
var state = SlashState.initial
var i = 0
for v in utf8 {
switch state {
case .initial:
buffer[i] = v
i += 1
if v == ._slash {
state = .slash
}
case .slash:
if v != ._slash {
buffer[i] = v
i += 1
state = .initial
}
}
}
return i
}
}
internal var _droppingTrailingSlashes: String {
guard !self.isEmpty else {
return self
}
guard let lastNonSlash = utf8.lastIndex(where: { $0 != ._slash }) else {
// It's all /'s so just return a single slash
return "/"
}
return String(self[...lastNonSlash])
}
private var _standardizingSlashes: String {
_compressingSlashes()._droppingTrailingSlashes
}
// MARK: - Filesystem String Extensions
#if !NO_FILESYSTEM
internal static func homeDirectoryPath() -> String {
#if os(Windows)
func fallbackCurrentUserDirectory() -> String {
guard let fallback = ProcessInfo.processInfo.environment["ALLUSERSPROFILE"] else {
fatalError("Unable to find home directory for current user and ALLUSERSPROFILE environment variable is not set")
}
return fallback
}
var hToken: HANDLE? = nil
guard OpenProcessToken(GetCurrentProcess(), TOKEN_QUERY, &hToken) else {
guard let UserProfile = ProcessInfo.processInfo.environment["UserProfile"] else {
return fallbackCurrentUserDirectory()
}
return UserProfile
}
defer { CloseHandle(hToken) }
var dwcchSize: DWORD = 0
_ = GetUserProfileDirectoryW(hToken, nil, &dwcchSize)
return withUnsafeTemporaryAllocation(of: WCHAR.self, capacity: Int(dwcchSize)) {
var dwcchSize: DWORD = DWORD($0.count)
guard GetUserProfileDirectoryW(hToken, $0.baseAddress, &dwcchSize) else {
return fallbackCurrentUserDirectory()
}
return String(decodingCString: $0.baseAddress!, as: UTF16.self)
}
#else
#if targetEnvironment(simulator)
// Simulator checks these environment variables first for the current user
if let envValue = getenv("CFFIXED_USER_HOME") ?? getenv("HOME") {
return String(cString: envValue).standardizingPath
}
#endif
// First check CFFIXED_USER_HOME if the environment is not considered tainted
if let envVar = Platform.getEnvSecure("CFFIXED_USER_HOME") {
return envVar.standardizingPath
}
#if !os(WASI) // WASI does not have user concept
// Next, attempt to find the home directory via getpwuid
// We use the real UID instead of the EUID here when the EUID is the root user (i.e. a process has called seteuid(0))
// In this instance, we historically do this to ensure a stable home directory location for processes that call seteuid(0)
if let dir = Platform.homeDirectory(forUID: Platform.getUGIDs(allowEffectiveRootUID: false).uid) {
return dir.standardizingPath
}
#endif
// Fallback to HOME for the current user if possible
if let home = getenv("HOME") {
return String(cString: home).standardizingPath
}
// If all else fails, fall back to /var/empty
return "/var/empty"
#endif
}
internal static func homeDirectoryPath(forUser user: String) -> String? {
#if os(Windows)
guard !user.isEmpty else {
return nil
}
return user.withCString(encodedAs: UTF16.self) { pwszUserName in
var cbSID: DWORD = 0
var cchReferencedDomainName: DWORD = 0
var eUse: SID_NAME_USE = SidTypeUnknown
LookupAccountNameW(nil, pwszUserName, nil, &cbSID, nil, &cchReferencedDomainName, &eUse)
guard cbSID > 0 else {
return nil
}
return withUnsafeTemporaryAllocation(of: CChar.self, capacity: Int(cbSID)) { pSID in
return withUnsafeTemporaryAllocation(of: WCHAR.self, capacity: Int(cchReferencedDomainName)) { pwszReferencedDomainName in
guard LookupAccountNameW(nil, pwszUserName, pSID.baseAddress, &cbSID, pwszReferencedDomainName.baseAddress, &cchReferencedDomainName, &eUse) else {
return nil
}
var pwszSID: LPWSTR? = nil
guard ConvertSidToStringSidW(pSID.baseAddress, &pwszSID) else {
fatalError("unable to convert SID to string for user \(user)")
}
return #"SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList\\#(String(decodingCString: pwszSID!, as: UTF16.self))"#.withCString(encodedAs: UTF16.self) { pwszKeyPath in
return "ProfileImagePath".withCString(encodedAs: UTF16.self) { pwszKey in
var cbData: DWORD = 0
RegGetValueW(HKEY_LOCAL_MACHINE, pwszKeyPath, pwszKey, RRF_RT_REG_SZ, nil, nil, &cbData)
guard cbData > 0 else {
fatalError("unable to query ProfileImagePath for user \(user)")
}
return withUnsafeTemporaryAllocation(of: WCHAR.self, capacity: Int(cbData)) { pwszData in
guard RegGetValueW(HKEY_LOCAL_MACHINE, pwszKeyPath, pwszKey, RRF_RT_REG_SZ, nil, pwszData.baseAddress, &cbData) == ERROR_SUCCESS else {
fatalError("unable to query ProfileImagePath for user \(user)")
}
return String(decodingCString: pwszData.baseAddress!, as: UTF16.self)
}
}
}
}
}
}
#else
// First check CFFIXED_USER_HOME if the environment is not considered tainted
if let envVar = Platform.getEnvSecure("CFFIXED_USER_HOME") {
return envVar.standardizingPath
}
#if !os(WASI) // WASI does not have user concept
// Next, attempt to find the home directory via getpwnam
return Platform.homeDirectory(forUserName: user)?.standardizingPath
#else
return nil
#endif
#endif
}
// From swift-corelibs-foundation's NSTemporaryDirectory. Internal for now, pending a better public API.
internal static var temporaryDirectoryPath: String {
func normalizedPath(with path: String) -> String {
let result = path._convertingSlashesIfNeeded()
guard result.utf8.last != ._slash else {
return result
}
return result + "/"
}
#if os(Windows)
let cchLength: DWORD = GetTempPathW(0, nil)
var wszPath: [WCHAR] = Array<WCHAR>(repeating: 0, count: Int(cchLength + 1))
guard GetTempPathW(DWORD(wszPath.count), &wszPath) <= cchLength else {
preconditionFailure("GetTempPathW mutation race")
}
return normalizedPath(with: String(decodingCString: wszPath, as: UTF16.self).standardizingPath)
#else // os(Windows)
#if canImport(Darwin)
// If confstr returns 0 it either failed or the variable had no content
// If the variable had no content, we should continue on below
// If it fails, we should also silently ignore the error and continue on below. This API can fail for non-programmer reasons such as the device being out of storage space when libSystem attempts to create the directory
let length: Int = confstr(_CS_DARWIN_USER_TEMP_DIR, nil, 0)
if length > 0 {
return withUnsafeTemporaryAllocation(of: UInt8.self, capacity: length) { buffer in
buffer.initialize(repeating: 0)
defer { buffer.deinitialize() }
let finalLength = confstr(_CS_DARWIN_USER_TEMP_DIR, buffer.baseAddress!, buffer.count)
assert(length == finalLength, "Value of _CS_DARWIN_USER_TEMP_DIR changed?")
return String(cString: buffer.baseAddress!)
}
}
#endif // canImport(Darwin)
#if !os(WASI)
if let envValue = Platform.getEnvSecure("TMPDIR") {
return normalizedPath(with: envValue)
}
#endif
#if os(Android)
// Bionic uses /data/local/tmp/ as temporary directory. TMPDIR is rarely
// defined.
return "/data/local/tmp/"
#else
return "/tmp/"
#endif
#endif // os(Windows)
}
private static let NETWORK_PREFIX: [UInt8] = [._backslash, ._backslash]
private static let _automountPrefixes = {
let prefixes: [[UInt8]] = [
Array("/private/var/automount/".utf8),
Array("/var/automount/".utf8),
Array("/private/".utf8)
]
return prefixes
}()
private static let _automountExclusionList = {
let exclusions: [[UInt8]] = [
Array("/Applications".utf8),
Array("/Library".utf8),
Array("/System".utf8),
Array("/Users".utf8),
Array("/Volumes".utf8),
Array("/bin".utf8),
Array("/cores".utf8),
Array("/dev".utf8),
Array("/opt".utf8),
Array("/private".utf8),
Array("/sbin".utf8),
Array("/usr".utf8)
]
return exclusions
}()
private var _standardizingPath: String {
var result = _convertingSlashesIfNeeded()._standardizingSlashes
let postNetStart = if result.utf8.starts(with: String.NETWORK_PREFIX) {
result.utf8.firstIndex(of: ._slash) ?? result.endIndex
} else {
result.startIndex
}
let hasDotDot = result[postNetStart...]._hasDotDotComponent()
if hasDotDot, let resolved = result._resolvingSymlinksInPath() {
result = resolved
}
result = result._removingDotSegments
// Automounted paths need to be stripped for various flavors of paths
for prefix in String._automountPrefixes {
if result.utf8.starts(with: prefix) {
let prefixEndSlash = result.utf8.index(result.startIndex, offsetBy: prefix.count - 1)
let newPath = result[prefixEndSlash...]
let isExcluded = String._automountExclusionList.contains {
newPath._hasPathPrefix($0)
}
if !isExcluded && FileManager.default.fileExists(atPath: String(newPath)) {
result = String(newPath)
}
break
}
}
return result
}
var standardizingPath: String {
expandingTildeInPath._standardizingPath
}
var abbreviatingWithTildeInPath: String {
_convertingSlashesIfNeeded()._abbreviatingWithTildeInPath
}
private var _abbreviatingWithTildeInPath: String {
guard !self.isEmpty && self != "/" else { return self }
let homeDir = String.homeDirectoryPath().utf8
guard utf8.starts(with: homeDir) else { return self }
let nextIdxInOriginal = utf8.index(startIndex, offsetBy: homeDir.count)
guard nextIdxInOriginal == endIndex || utf8[nextIdxInOriginal] == ._slash else { return self }
return "~" + self[nextIdxInOriginal...]
}
var expandingTildeInPath: String {
_convertingSlashesIfNeeded()._expandingTildeInPath
}
private var _expandingTildeInPath: String {
guard utf8.first == UInt8(ascii: "~") else { return self }
let firstSlash = utf8.firstIndex(of: ._slash) ?? endIndex
let indexAfterTilde = utf8.index(after: startIndex)
var userDir: String
if firstSlash != indexAfterTilde {
guard let dir = String.homeDirectoryPath(forUser: String(self[indexAfterTilde ..< firstSlash])) else {
return self
}
userDir = dir
} else {
userDir = String.homeDirectoryPath()
}
return userDir + self[firstSlash...]
}
private static func _resolvingSymlinksInPathUsingFullPathAttribute(_ fsRep: UnsafePointer<CChar>) -> String? {
#if canImport(Darwin)
var attrs = attrlist()
attrs.bitmapcount = u_short(ATTR_BIT_MAP_COUNT)
attrs.commonattr = attrgroup_t(ATTR_CMN_FULLPATH)
var buffer = FullPathAttributes()
guard getattrlist(fsRep, &attrs, &buffer, MemoryLayout<FullPathAttributes>.size, 0) == 0, buffer.fullPathAttr.attr_length > 0 else {
return nil
}
let length = Int(buffer.fullPathAttr.attr_length) // Includes null byte
return withUnsafePointer(to: buffer.fullPathBuf) { pathPtr in
pathPtr.withMemoryRebound(to: CChar.self, capacity: length) { ccharPtr in
String(cString: ccharPtr)
}
}
#else
return nil
#endif // canImport(Darwin)
}
func _resolvingSymlinksInPath() -> String? {
guard !isEmpty else { return nil }
#if os(Windows)
return try? self.withNTPathRepresentation {
let hFile: HANDLE = CreateFileW($0, GENERIC_READ, FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, nil, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, nil)
if hFile == INVALID_HANDLE_VALUE {
return nil
}
defer { CloseHandle(hFile) }
let dwLength: DWORD = GetFinalPathNameByHandleW(hFile, nil, 0, VOLUME_NAME_DOS)
return withUnsafeTemporaryAllocation(of: WCHAR.self, capacity: Int(dwLength)) {
guard GetFinalPathNameByHandleW(hFile, $0.baseAddress, dwLength, VOLUME_NAME_DOS) == dwLength - 1 else {
return nil
}
let pathBaseAddress: UnsafePointer<WCHAR>
if Array($0.prefix(4)) == Array(#"\\?\"#.utf16) {
// When using `VOLUME_NAME_DOS`, the returned path uses `\\?\`.
pathBaseAddress = UnsafePointer($0.baseAddress!.advanced(by: 4))
} else {
pathBaseAddress = UnsafePointer($0.baseAddress!)
}
return String(decodingCString: pathBaseAddress, as: UTF16.self)
}
}
#else // os(Windows)
return self.withFileSystemRepresentation { fsPtr -> String? in
guard let fsPtr else { return nil }
// If not using the cache (which may not require hitting the disk at all if it's warm), try getting the full path from getattrlist.
// If it succeeds, this approach always returns an absolute path starting from the root. Since this function returns relative paths when given a relative path to a relative symlink, dont use this approach unless the path is absolute.
var path = self
if URL.isAbsolute(standardizing: &path), let resolved = Self._resolvingSymlinksInPathUsingFullPathAttribute(fsPtr) {
return resolved
}
return withUnsafeTemporaryAllocation(of: CChar.self, capacity: FileManager.MAX_PATH_SIZE) { buffer -> String? in
buffer.initialize(repeating: 0)
defer { buffer.deinitialize() }
var fullLength = Platform.copyCString(dst: buffer.baseAddress!, src: fsPtr, size: FileManager.MAX_PATH_SIZE) + 1 // Includes null byte
return withUnsafeTemporaryAllocation(of: CChar.self, capacity: FileManager.MAX_PATH_SIZE) { linkBuffer -> String? in
linkBuffer.initialize(repeating: 0)
defer { linkBuffer.deinitialize() }
var scanLoc = buffer.baseAddress!
var links = 0
while true {
var linkResultLen = 0
let lastScanLoc = scanLoc
while scanLoc.pointee == 0x2F /* U+002F Solidus (/) */ {
scanLoc = scanLoc.advanced(by: 1)
}
while scanLoc.pointee != 0x2F && scanLoc.pointee != 0 {
scanLoc = scanLoc.advanced(by: 1)
}
let slash = scanLoc.pointee
scanLoc.pointee = 0
var statBuf = stat()
if lstat(buffer.baseAddress!, &statBuf) < 0 {
return nil
}
if mode_t(statBuf.st_mode) & S_IFMT == S_IFLNK {
/* Examples:
* fspath == /foo/bar0baz/quux/froboz
* linkx == /tic/tac/toe
* result == /tic/tac/toe/baz/quux/froboz
*
* fspath == /foo/bar0baz/quux/froboz
* linkx == tic/tac/toe
* result == /foo/tic/tac/toe/baz/quux/froboz
*/
if links > MAXSYMLINKS {
return nil
}
linkResultLen = readlink(buffer.baseAddress!, linkBuffer.baseAddress!, FileManager.MAX_PATH_SIZE - 1)
if linkResultLen < 0 {
return nil
}
linkBuffer[linkResultLen] = 0
}
scanLoc.pointee = slash
if linkResultLen > 0 {
links += 1
// If the link is not an absolute path, preserve the prefix
let preservedPrefixLength = linkBuffer[0] == 0x2F ? 0 : (buffer.baseAddress!.distance(to: lastScanLoc) + 1)
let scanLocIdx = buffer.baseAddress!.distance(to: scanLoc)
let suffixLength = fullLength - scanLocIdx // Includes null byte
if preservedPrefixLength + linkResultLen + suffixLength > FileManager.MAX_PATH_SIZE {
return nil
}
// Shift the suffix + null byte to the correct location
let afterSuffixIdx = buffer[(preservedPrefixLength + linkResultLen)...].update(fromContentsOf: buffer[scanLocIdx ..< (fullLength)])
// Replace the component with the link
_ = buffer[preservedPrefixLength ..< (preservedPrefixLength + linkResultLen)].update(fromContentsOf: linkBuffer[..<linkResultLen])
fullLength = afterSuffixIdx
scanLoc = linkBuffer[0] == 0x2F ? buffer.baseAddress! : lastScanLoc
} else {
if scanLoc.pointee == 0 {
break
}
}
}
return String(cString: buffer.baseAddress!)
}
}
}
#endif // os(Windows)
}
var resolvingSymlinksInPath: String {
var result = expandingTildeInPath
if let resolved = result._resolvingSymlinksInPath() {
result = resolved
}
return result._standardizingPath
}
#endif // !NO_FILESYSTEM
}
// MARK: - StringProtocol Helper Extensions
fileprivate enum DotDotState {
case initial
case dot
case dotDot
case lookingForSlash
}
extension StringProtocol {
internal func replacing(_ a: UInt8, with b: UInt8) -> String {
var utf8Array = Array(self.utf8)
var didReplace = false
// ~300x faster than Array.replace([UInt8], with: [UInt8]) for one element
for i in 0..<utf8Array.count {
if utf8Array[i] == a {
utf8Array[i] = b
didReplace = true
}
}
guard didReplace else {
return String(self)
}
return String(unsafeUninitializedCapacity: utf8Array.count) { buffer in
buffer.initialize(fromContentsOf: utf8Array)
}
}
// Internal for testing purposes
internal func _hasDotDotComponent() -> Bool {
guard utf8.count >= 2 else {
return false
}
var state = DotDotState.initial
for v in utf8 {
switch state {
case .initial:
if v == ._dot {
state = .dot
} else if v == ._slash {
continue
} else {
state = .lookingForSlash
}
case .dot:
if v == ._dot {
state = .dotDot
} else if v == ._slash {
state = .initial
} else {
state = .lookingForSlash
}
case .dotDot:
if v == ._slash {
return true // Starts with "../" or contains "/../"
} else {
state = .lookingForSlash
}
case .lookingForSlash:
if v == ._slash {
state = .initial
} else {
continue
}
}
}
return state == .dotDot // Is ".." or ends with "/.."
}
// Returns true if self == prefix or self starts with (prefix + "/")
internal func _hasPathPrefix(_ prefix: some Collection<UInt8>) -> Bool {
guard utf8.starts(with: prefix) else {
return false
}
let prefixEnd = utf8.index(startIndex, offsetBy: prefix.count)
return prefixEnd == endIndex || utf8[prefixEnd] == ._slash
}
}