6 ms·

Is this just a wrapper around a subset of system calls? Looking at the code it seems to be, not sure.

NobodyNada 6y ago
It looks like it: > a new library for Apple platforms that provides idiomatic interfaces to system calls and low-level currency types In other words, it's a set of native, type-safe Swift APIs that wrap the usual C system calls. > System pervasively uses raw representable structs and option sets. These strong types help catch mistakes at compile time and are trivial to convert to and from the weaker C types. > Errors are thrown using the standard language mechanism and cannot be missed. Further, all system calls interruptible by a signal take a defaulted-true retryOnInterrupt argument, causing them to retry on failure. When combined, these two changes dramatically simplify error and signal handling. > FilePath is a managed, null-terminated bag-of-bytes that conforms to ExpressibleByStringLiteral — far safer to work with than a UnsafePointer<CChar> [Swift's spelling of `char *`].
- layoutIfNeeded 6y ago
  >causing them to retry on failure I hope they meant in case of failure with EINTR.
usmannk 6y ago
Yes, it's a typed, safe wrapper around a subset of Darwin or Glibc (depending on platform) functions. See: https://github.com/apple/swift-system/blob/main/Sources/SystemInternals/Exports.swift https://github.com/apple/swift-system/blob/main/Sources/Syst...
itiman 6y ago
Yes, this is a wrapper. [0] https://github.com/apple/swift-system/blob/main/Sources/System/FileOperations.swift#L29 https://github.com/apple/swift-system/blob/main/Sources/Syst... [1] https://github.com/apple/swift-system/blob/main/Sources/System/FileOperations.swift#L80 https://github.com/apple/swift-system/blob/main/Sources/Syst... [2] https://github.com/apple/swift-system/blob/main/Sources/SystemInternals/Exports.swift#L38 https://github.com/apple/swift-system/blob/main/Sources/Syst...
ChrisMarshallNY 6y ago
Yes, and I'm glad for it. Not sure if it's "ready for prime time," yet (it sounds like it may still be too "nascent" for me), but I'll have to see if I can use it to tweak stuff like this[0]: var md5: String { // The reason we are declaring these here, is so we don't have to actally import the CC module. We will just grope around and find the entry point, ourselves. /// This is a cast for [the MD5 function](https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man3/CC_MD5.3cc.html#//apple_ref/doc/man/3cc/CC_MD5). [The convention attribute](https://docs.swift.org/swift-book/ReferenceManual/Attributes.html#ID600) just says that it's a "raw" C function. typealias CC_MD5_TYPE = @convention(c) (UnsafeRawPointer, UInt32, UnsafeMutableRawPointer) -> UnsafeMutableRawPointer // This is a flag, telling the name lookup to happen in the global scope. No dlopen required. let RTLD_DEFAULT = UnsafeMutableRawPointer(bitPattern: -2) // This loads a function pointer with the CommonCrypto MD5 function. // [dlsym](https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man3/dlsym.3.html) is a symbol lookup. It finds the symbol in our library, and returns a pointer to it. let CC_MD5 = unsafeBitCast(dlsym(RTLD_DEFAULT, "CC_MD5")!, to: CC_MD5_TYPE.self) // This is the length of the hash let CC_MD5_DIGEST_LENGTH = 16 guard let strData = self.data(using: .utf8) else { return "" } /// Creates an array of unsigned 8 bit integers that contains 16 zeros var digest = [UInt8](repeating: 0, count: Int(CC_MD5_DIGEST_LENGTH)) /// CC_MD5 performs digest calculation and places the result in the caller-supplied buffer for digest (md) /// Calls the given closure with a pointer to the underlying unsafe bytes of the strData’s contiguous storage. _ = strData.withUnsafeBytes { (inBytes) -> Int in // CommonCrypto // extern unsigned char *CC_MD5(const void *data, CC_LONG len, unsigned char *md) --| // OpenSSL | // unsigned char *MD5(const unsigned char *d, size_t n, unsigned char *md) <-| if let baseAddr = inBytes.baseAddress { _ = CC_MD5(baseAddr, UInt32(strData.count), &digest) } return 0 } // Convert the numerical response to an uppercase hex string. return digest.reduce("") { (current, new) -> String in String(format: "\(current)%02X", new) } } As a Swift programmer, the above hurts my heart (but it works very well). [0] https://github.com/RiftValleySoftware/RVS_Generic_Swift_Toolbox/blob/fe771c3b577724563852b186b1acf202a89109f8/Sources/RVS_Generic_Swift_Toolbox/Extensions/RVS_String_Extensions.swift#L104 https://github.com/RiftValleySoftware/RVS_Generic_Swift_Tool...

It looks like it: > a new library for Apple platforms that provides idiomatic interfaces to system calls and low-level currency types In other words, it's a set of native, type-safe Swift APIs that wrap the usual C system calls. > System pervasively uses raw representable structs and option sets. These strong types help catch mistakes at compile time and are trivial to convert to and from the weaker C types. > Errors are thrown using the standard language mechanism and cannot be missed. Further, all system calls interruptible by a signal take a defaulted-true retryOnInterrupt argument, causing them to retry on failure. When combined, these two changes dramatically simplify error and signal handling. > FilePath is a managed, null-terminated bag-of-bytes that conforms to ExpressibleByStringLiteral — far safer to work with than a UnsafePointer<CChar> [Swift's spelling of `char *`].

layoutIfNeeded 6y ago
>causing them to retry on failure I hope they meant in case of failure with EINTR.

usmannk 6y ago

Yes, it's a typed, safe wrapper around a subset of Darwin or Glibc (depending on platform) functions. See: https://github.com/apple/swift-system/blob/main/Sources/SystemInternals/Exports.swift https://github.com/apple/swift-system/blob/main/Sources/Syst...

itiman 6y ago

Yes, this is a wrapper. [0] https://github.com/apple/swift-system/blob/main/Sources/System/FileOperations.swift#L29 https://github.com/apple/swift-system/blob/main/Sources/Syst... [1] https://github.com/apple/swift-system/blob/main/Sources/System/FileOperations.swift#L80 https://github.com/apple/swift-system/blob/main/Sources/Syst... [2] https://github.com/apple/swift-system/blob/main/Sources/SystemInternals/Exports.swift#L38 https://github.com/apple/swift-system/blob/main/Sources/Syst...

ChrisMarshallNY 6y ago

Yes, and I'm glad for it. Not sure if it's "ready for prime time," yet (it sounds like it may still be too "nascent" for me), but I'll have to see if I can use it to tweak stuff like this[0]: var md5: String { // The reason we are declaring these here, is so we don't have to actally import the CC module. We will just grope around and find the entry point, ourselves. /// This is a cast for [the MD5 function](https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man3/CC_MD5.3cc.html#//apple_ref/doc/man/3cc/CC_MD5). [The convention attribute](https://docs.swift.org/swift-book/ReferenceManual/Attributes.html#ID600) just says that it's a "raw" C function. typealias CC_MD5_TYPE = @convention(c) (UnsafeRawPointer, UInt32, UnsafeMutableRawPointer) -> UnsafeMutableRawPointer // This is a flag, telling the name lookup to happen in the global scope. No dlopen required. let RTLD_DEFAULT = UnsafeMutableRawPointer(bitPattern: -2) // This loads a function pointer with the CommonCrypto MD5 function. // [dlsym](https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man3/dlsym.3.html) is a symbol lookup. It finds the symbol in our library, and returns a pointer to it. let CC_MD5 = unsafeBitCast(dlsym(RTLD_DEFAULT, "CC_MD5")!, to: CC_MD5_TYPE.self) // This is the length of the hash let CC_MD5_DIGEST_LENGTH = 16 guard let strData = self.data(using: .utf8) else { return "" } /// Creates an array of unsigned 8 bit integers that contains 16 zeros var digest = [UInt8](repeating: 0, count: Int(CC_MD5_DIGEST_LENGTH)) /// CC_MD5 performs digest calculation and places the result in the caller-supplied buffer for digest (md) /// Calls the given closure with a pointer to the underlying unsafe bytes of the strData’s contiguous storage. _ = strData.withUnsafeBytes { (inBytes) -> Int in // CommonCrypto // extern unsigned char *CC_MD5(const void *data, CC_LONG len, unsigned char *md) --| // OpenSSL | // unsigned char *MD5(const unsigned char *d, size_t n, unsigned char *md) <-| if let baseAddr = inBytes.baseAddress { _ = CC_MD5(baseAddr, UInt32(strData.count), &digest) } return 0 } // Convert the numerical response to an uppercase hex string. return digest.reduce("") { (current, new) -> String in String(format: "\(current)%02X", new) } } As a Swift programmer, the above hurts my heart (but it works very well). [0] https://github.com/RiftValleySoftware/RVS_Generic_Swift_Toolbox/blob/fe771c3b577724563852b186b1acf202a89109f8/Sources/RVS_Generic_Swift_Toolbox/Extensions/RVS_String_Extensions.swift#L104 https://github.com/RiftValleySoftware/RVS_Generic_Swift_Tool...