posix_spawn(): dup2() again this time on file_action_dup2.

* fixes #14322.

src/system/libroot/posix/spawn.cpp

@@ -408,7 +408,7 @@ process_file_actions(const posix_spawn_file_actions_t *_actions, int *errfd)
 					return errno;
 			}
 		} else if (action->type == file_action_dup2) {
-			if (dup2(action->action.dup2_action.srcfd, action->fd) != 0)
+			if (dup2(action->action.dup2_action.srcfd, action->fd) == -1)
 				return errno;
 		}
 	}

src/tests/system/libroot/posix/Jamfile

@@ -42,6 +42,8 @@ SimpleTest pthread_barrier_test : pthread_barrier_test.cpp ;
 SimpleTest posix_spawn_test : posix_spawn_test.cpp ;
 SimpleTest posix_spawn_redir_test : posix_spawn_redir_test.c ;
 SimpleTest posix_spawn_redir_err : posix_spawn_redir_err.c ;
+SimpleTest posix_spawn_pipe_test : posix_spawn_pipe_test.c ;
+SimpleTest posix_spawn_pipe_err : posix_spawn_pipe_err.c ;
 
 # XSI tests
 SimpleTest xsi_msg_queue_test1 : xsi_msg_queue_test1.cpp ;

src/tests/system/libroot/posix/posix_spawn_pipe_err.c

@@ -0,0 +1,10 @@
+#include "posix_spawn_pipe_test.h"
+
+#include <stdio.h>
+#include <string.h>
+
+ int main() {
+  puts(testOut);
+  fputs(testErr, stderr);
+  return 0;
+}

src/tests/system/libroot/posix/posix_spawn_pipe_test.c

@@ -0,0 +1,56 @@
+#include "posix_spawn_pipe_test.h"
+
+#include <errno.h>
+#include <unistd.h>
+#include <spawn.h>
+#include <stdio.h>
+#include <string.h>
+
+#define panic(n, str) if (n != 0) { perror(str); return 1; }
+#define readIdx 0
+#define writeIdx 1
+
+int main() {
+  int out[2], err[2];
+  posix_spawn_file_actions_t fdops;
+  pid_t pid;
+  char* const argv[] = { "./posix_spawn_pipe_err", NULL };
+
+  panic(pipe(out), "pipe stdout");
+  panic(pipe(err), "pipe stderr");
+
+  errno = posix_spawn_file_actions_init(&fdops);
+  panic(errno, "init");
+  errno = posix_spawn_file_actions_addclose(&fdops, out[readIdx]);
+  panic(errno, "close stdout read");
+  errno = posix_spawn_file_actions_adddup2(&fdops, out[writeIdx], 1);
+  panic(errno, "dup2 stdout write");
+  errno = posix_spawn_file_actions_addclose(&fdops, err[readIdx]);
+  panic(errno, "close stderr read");
+  errno = posix_spawn_file_actions_adddup2(&fdops, err[writeIdx], 2);
+  panic(errno, "dup2 stderr write");
+  errno = posix_spawn(&pid, "./posix_spawn_pipe_err", &fdops, NULL, argv, NULL);
+  panic(errno, "spawn");
+
+  FILE *cOut = fdopen(out[readIdx], "r");
+  if (cOut == NULL) panic(-1, "cOut");
+  FILE *cErr = fdopen(err[readIdx], "r");
+  if (cErr == NULL) panic(-1, "cErr");
+
+  char *buf = NULL;
+  size_t bufsize = 0;
+  getline(&buf, &bufsize, cOut);
+  panic(ferror(cOut), "getline cOut");
+  if (strcmp(buf, testOut) != 0) {
+    printf("stdout got: %s", buf);
+    printf("stdout exp: %s", testOut);
+  }
+  getline(&buf, &bufsize, cErr);
+  panic(ferror(cErr), "getline cErr");
+  if (strcmp(buf, testErr) != 0) {
+    printf("stderr got: %s", buf);
+    printf("stderr exp: %s", testErr);
+  }
+
+  return 0;
+}

src/tests/system/libroot/posix/posix_spawn_pipe_test.h

@@ -0,0 +1,5 @@
+#ifndef t_h
+#define t_h
+#define testOut "test out\n"
+#define testErr "test err\n"
+#endif