Fix background task execution.

.github/workflows/unit-tests.yml

@@ -37,6 +37,9 @@ jobs:
     runs-on: ubuntu-22.04
     needs: ubuntu-base
     steps:
+    - name: Update Packages
+      run: |
+        sudo apt-get update
     - name: Install Dependencies
       run: |
         sudo apt-get install -y \
@@ -75,6 +78,9 @@ jobs:
       matrix:
         config_flag: ["--with-xmlrpc-c", "--with-xmlrpc-tinyxml2"]
     steps:
+    - name: Update Packages
+      run: |
+        sudo apt-get update
     - name: Install Dependencies
       run: |
         sudo apt-get install -y \

src/rpc/exec_file.cc

@@ -38,24 +38,10 @@ ExecFile::execute(const char* file, char* const* argv, int flags) {
     result = write(m_log_fd, "\n---\n", sizeof("\n---\n"));
   }
 
-  int pipe_fd[2];
-
-  if ((flags & flag_capture) && pipe(pipe_fd))
-    throw torrent::input_error("ExecFile::execute(...) Pipe creation failed.");
-
-  auto clean_fn = [pipe_fd, flags]() {
-      if (flags & flag_capture) {
-        ::close(pipe_fd[0]);
-        ::close(pipe_fd[1]);
-      }
-    };
-
   posix_spawn_file_actions_t actions{};
 
-  if (posix_spawn_file_actions_init(&actions) != 0) {
+  if (posix_spawn_file_actions_init(&actions) != 0)
-    clean_fn();
     throw torrent::internal_error("ExecFile::execute(...) posix_spawn_file_actions_init failed.");
-  }
 
   // Handle standard input redirection (/dev/null), posix_spawn_file_actions_addopen handles opening
   // and dup2 natively
@@ -64,6 +50,11 @@ ExecFile::execute(const char* file, char* const* argv, int flags) {
     posix_spawn_file_actions_addclose(&actions, 0);
   }
 
+  int pipe_fd[2] = {-1, -1};
+
+  if ((flags & flag_capture) && pipe(pipe_fd))
+    throw torrent::input_error("ExecFile::execute(...) Pipe creation failed.");
+
   // Handle standard output redirection
   if (flags & flag_capture) {
     posix_spawn_file_actions_adddup2(&actions, pipe_fd[1], 1);
@@ -88,23 +79,36 @@ ExecFile::execute(const char* file, char* const* argv, int flags) {
   posix_spawnattr_t attr;
   posix_spawnattr_init(&attr);
 
-  // If you are using standard close-on-exec (O_CLOEXEC) across rtorrent, posix_spawn honors it
+  short spawn_flags = 0;
-  // automatically. If you want to explicitly enforce a clean slate, modern systems support
-  // POSIX_SPAWN_CLOEXEC_DEFAULT.
 
 #ifdef POSIX_SPAWN_CLOEXEC_DEFAULT
-  posix_spawnattr_setflags(&attr, POSIX_SPAWN_CLOEXEC_DEFAULT);
+  spawn_flags |= POSIX_SPAWN_CLOEXEC_DEFAULT;
 #endif
 
-  pid_t child_pid{};
+  if (flags & flag_background) {
+#ifdef POSIX_SPAWN_SETSID
+    spawn_flags |= POSIX_SPAWN_SETSID;
+#else
+    spawn_flags |= POSIX_SPAWN_SETPGROUP;
+    posix_spawnattr_setpgroup(&attr, 0);
+#endif
+  }
 
-  int spawn_status = posix_spawnp(&child_pid, file, &actions, &attr, argv, environ);
+  posix_spawnattr_setflags(&attr, spawn_flags);
+
+  pid_t child_pid{};
+  int   spawn_status = posix_spawnp(&child_pid, file, &actions, &attr, argv, environ);
 
   posix_spawn_file_actions_destroy(&actions);
   posix_spawnattr_destroy(&attr);
 
   if (spawn_status != 0) {
-    clean_fn();
+    if (pipe_fd[0] != -1)
+      ::close(pipe_fd[0]);
+
+    if (pipe_fd[1] != -1)
+      ::close(pipe_fd[1]);
+
     throw torrent::input_error("ExecFile::execute(...) posix_spawn failed: " + std::string(std::strerror(spawn_status)));
   }
 
@@ -131,6 +135,13 @@ ExecFile::execute(const char* file, char* const* argv, int flags) {
     }
   }
 
+  if (flags & flag_background) {
+    if (m_log_fd != -1)
+      result = write(m_log_fd, "\n--- Running in Background ---\n", sizeof("\n--- Running in Background ---\n"));
+
+    return 0;
+  }
+
   int status;
 
   while (waitpid(child_pid, &status, 0) == -1) {

src/signal_handler.cc

@@ -81,6 +81,18 @@ SignalHandler::set_unblock(unsigned int signum) {
     throw std::logic_error("Could not unblock signal: " + std::string(std::strerror(errno)));
 }
 
+void
+SignalHandler::set_sigchild_ignore() {
+  struct sigaction sa;
+  sa.sa_handler = SIG_IGN;
+  sa.sa_flags   = SA_NOCLDWAIT | SA_RESTART;
+
+  sigemptyset(&sa.sa_mask);
+
+  if (sigaction(SIGCHLD, &sa, NULL) == -1)
+    throw std::logic_error("Could not set sigaction (ignore) for SIGCHLD: " + std::string(std::strerror(errno)));
+}
+
 void
 SignalHandler::set_sigaction_handler(unsigned int signum, handler_slot slot) {
   if (signum >= HIGHEST_SIGNAL)

src/signal_handler.h

@@ -25,6 +25,8 @@ public:
   static void         set_block(unsigned int signum);
   static void         set_unblock(unsigned int signum);
 
+  static void         set_sigchild_ignore();
+
   static void         set_sigaction_handler(unsigned int signum, handler_slot slot);
 
   static const char*  as_string(unsigned int signum);