Add support for posix_spawn_file_actions_addchdir_np on available Linux platforms

Author: sergiocampama

Sources/TSCBasic/Process.swift

@@ -121,6 +121,9 @@ public final class Process: ObjectIdentifierProtocol {
     public enum Error: Swift.Error {
         /// The program requested to be executed cannot be found on the existing search paths, or is not executable.
         case missingExecutableProgram(program: String)
+
+        /// The current OS does not support the workingDirectory API.
+        case workingDirectoryNotSupported
     }
 
     public enum OutputRedirection {
@@ -226,7 +229,6 @@ public final class Process: ObjectIdentifierProtocol {
     /// Value: Path to the executable, if found.
     static private var validatedExecutablesMap = [String: AbsolutePath?]()
 
-  #if os(macOS)
     /// Create a new process instance.
     ///
     /// - Parameters:
@@ -254,7 +256,6 @@ public final class Process: ObjectIdentifierProtocol {
         self.verbose = verbose
         self.startNewProcessGroup = startNewProcessGroup
     }
-  #endif
 
     /// Create a new process instance.
     ///
@@ -404,16 +405,24 @@ public final class Process: ObjectIdentifierProtocol {
         posix_spawn_file_actions_init(&fileActions)
         defer { posix_spawn_file_actions_destroy(&fileActions) }
 
-      #if os(macOS)
         if let workingDirectory = workingDirectory?.pathString {
+          #if os(macOS)
             // The only way to set a workingDirectory is using an availability-gated initializer, so we don't need
             // to handle the case where the posix_spawn_file_actions_addchdir_np method is unavailable. This check only
             // exists here to make the compiler happy.
             if #available(macOS 10.15, *) {
                 posix_spawn_file_actions_addchdir_np(&fileActions, workingDirectory)
             }
+          #elseif os(Linux)
+            guard SPM_posix_spawn_file_actions_addchdir_np_supported() else {
+                throw Process.Error.workingDirectoryNotSupported
+            }
+
+            SPM_posix_spawn_file_actions_addchdir_np(&fileActions, workingDirectory)
+          #else
+            throw Process.Error.workingDirectoryNotSupported
+          #endif
         }
-      #endif
 
         // Workaround for https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=89e435f3559c53084498e9baad22172b64429362
         // Change allowing for newer version of glibc
@@ -691,6 +700,8 @@ extension Process.Error: CustomStringConvertible {
         switch self {
         case .missingExecutableProgram(let program):
             return "could not find executable for '\(program)'"
+        case .workingDirectoryNotSupported:
+            return "workingDirectory is not supported in this platform"
         }
     }
 }

Sources/TSCclibc/CMakeLists.txt

@@ -7,7 +7,7 @@
 # See http://swift.org/CONTRIBUTORS.txt for Swift project authors
 
 add_library(TSCclibc STATIC
-  libc.c)
+  libc.c process.c)
 target_include_directories(TSCclibc PUBLIC
   include)
 

Sources/TSCclibc/include/module.modulemap

@@ -1,5 +1,6 @@
 module TSCclibc {
     header "TSCclibc.h"
     header "indexstore_functions.h"
+    header "process.h"
     export *
 }

Sources/TSCclibc/include/process.h

@@ -0,0 +1,12 @@
+#if defined(__linux__)
+
+#include <spawn.h>
+#include <stdbool.h>
+
+// Wrapper method for posix_spawn_file_actions_addchdir_np that fails on Linux versions that do not have this method available.
+int SPM_posix_spawn_file_actions_addchdir_np(posix_spawn_file_actions_t *restrict file_actions, const char *restrict path);
+
+// Runtime check for the availability of posix_spawn_file_actions_addchdir_np. Returns 0 if the method is available, -1 if not.
+bool SPM_posix_spawn_file_actions_addchdir_np_supported();
+
+#endif

Sources/TSCclibc/process.c

@@ -0,0 +1,23 @@
+#if defined(__linux__)
+
+#include <errno.h>
+
+#include "process.h"
+
+int SPM_posix_spawn_file_actions_addchdir_np(posix_spawn_file_actions_t *restrict file_actions, const char *restrict path) {
+#if __GLIBC_PREREQ(2, 29)
+    return posix_spawn_file_actions_addchdir_np(file_actions, path);
+#else
+    return ENOSYS;
+#endif
+}
+
+bool SPM_posix_spawn_file_actions_addchdir_np_supported() {
+#if __GLIBC_PREREQ(2, 29)
+    return true;
+#else
+    return false;
+#endif
+}
+
+#endif

Tests/TSCBasicTests/ProcessTests.swift

@@ -211,32 +211,40 @@ class ProcessTests: XCTestCase {
         }
     }
 
-  #if os(macOS)
     func testWorkingDirectory() throws {
-        if #available(macOS 10.15, *) {
-            try! withTemporaryDirectory(removeTreeOnDeinit: true) { tempDirPath in
-                let parentPath = tempDirPath.appending(component: "file")
-                let childPath = tempDirPath.appending(component: "subdir").appending(component: "file")
+        guard #available(macOS 10.15, *) else {
+            // Skip this test since it's not supported in this OS.
+            return
+        }
 
-                try localFileSystem.writeFileContents(parentPath, bytes: ByteString("parent"))
-                try localFileSystem.createDirectory(childPath.parentDirectory, recursive: true)
-                try localFileSystem.writeFileContents(childPath, bytes: ByteString("child"))
+      #if os(Linux)
+        guard SPM_posix_spawn_file_actions_addchdir_np_supported() else {
+            // Skip this test since it's not supported in this OS.
+            return
+        }
+      #endif
 
-                do {
-                    let process = Process(arguments: ["cat", "file"], workingDirectory: tempDirPath)
-                    try process.launch()
-                    let result = try process.waitUntilExit()
-                    XCTAssertEqual(try result.utf8Output(), "parent")
-                }
+        try withTemporaryDirectory(removeTreeOnDeinit: true) { tempDirPath in
+            let parentPath = tempDirPath.appending(component: "file")
+            let childPath = tempDirPath.appending(component: "subdir").appending(component: "file")
 
-                do {
-                    let process = Process(arguments: ["cat", "file"], workingDirectory: childPath.parentDirectory)
-                    try process.launch()
-                    let result = try process.waitUntilExit()
-                    XCTAssertEqual(try result.utf8Output(), "child")
-                }
+            try localFileSystem.writeFileContents(parentPath, bytes: ByteString("parent"))
+            try localFileSystem.createDirectory(childPath.parentDirectory, recursive: true)
+            try localFileSystem.writeFileContents(childPath, bytes: ByteString("child"))
+
+            do {
+                let process = Process(arguments: ["cat", "file"], workingDirectory: tempDirPath)
+                try process.launch()
+                let result = try process.waitUntilExit()
+                XCTAssertEqual(try result.utf8Output(), "parent")
+            }
+
+            do {
+                let process = Process(arguments: ["cat", "file"], workingDirectory: childPath.parentDirectory)
+                try process.launch()
+                let result = try process.waitUntilExit()
+                XCTAssertEqual(try result.utf8Output(), "child")
             }
         }
     }
-  #endif
 }