Merge pull request #1215 from hartbit/posix-exec

Wrap POSIX’s exec for future swift run PR

Sources/Basic/misc.swift

@@ -8,6 +8,21 @@
  See http://swift.org/CONTRIBUTORS.txt for Swift project authors
 */
 
+import libc
+import POSIX
+
+/// Replace the current process image with a new process image.
+///
+/// - Parameters:
+///   - path: Absolute path to the executable.
+///   - args: The executable arguments.
+public func exec(path: String, args: [String]) throws {
+    let cArgs = CStringArray(args)
+    guard execv(path, cArgs.cArray) != -1 else {
+        throw POSIX.SystemError.exec(errno, path: path, args: args)
+    }
+}
+
 // MARK: Utility function for searching for executables
 
 /// Create a list of AbsolutePath search paths from a string, such as the PATH environment variable.

Sources/POSIX/Error.swift

@@ -12,6 +12,7 @@ public enum SystemError: Swift.Error {
     case chdir(Int32, String)
     case close(Int32)
     case dirfd(Int32, String)
+    case exec(Int32, path: String, args: [String])
     case fgetc(Int32)
     case fread(Int32)
     case getcwd(Int32)
@@ -68,6 +69,9 @@ extension SystemError: CustomStringConvertible {
             return "close error: \(strerror(errno))"
         case .dirfd(let errno, _):
             return "dirfd error: \(strerror(errno))"
+        case .exec(let errno, let path, let args):
+            let joinedArgs = args.joined(separator: " ")
+            return "exec error: \(strerror(errno)): \(path) \(joinedArgs)"
         case .fgetc(let errno):
             return "fgetc error: \(strerror(errno))"
         case .fread(let errno):