posix: New function posix_spawn_file_actions_addfchdir_np [BZ #17405]

Along with posix_spawn_file_actions_addchdir,
posix_spawn_file_actions_addfchdir is the subject of a change proposal
for POSIX: <http://austingroupbugs.net/view.php?id=1208>

7 files changed, 180 insertions, 95 deletions

diff --git a/posix/Makefile b/posix/Makefile
index a8fb1e1839..d5a6844c88 100644
--- a/posix/Makefile
+++ b/posix/Makefile
@@ -55,7 +55,7 @@ routines :=								      \
 	pread pwrite pread64 pwrite64					      \
 	spawn_faction_init spawn_faction_destroy spawn_faction_addclose	      \
 	spawn_faction_addopen spawn_faction_adddup2 spawn_valid_fd	      \
-	spawn_faction_addchdir 						      \
+	spawn_faction_addchdir spawn_faction_addfchdir			      \
 	spawnattr_init spawnattr_destroy				      \
 	spawnattr_getdefault spawnattr_setdefault			      \
 	spawnattr_getflags spawnattr_setflags				      \
diff --git a/posix/Versions b/posix/Versions
index 56ab921562..ad693ae9a7 100644
--- a/posix/Versions
+++ b/posix/Versions
@@ -139,6 +139,7 @@ libc {
   }
   GLIBC_2.29 {
     posix_spawn_file_actions_addchdir_np;
+    posix_spawn_file_actions_addfchdir_np;
   }
   GLIBC_PRIVATE {
     __libc_fork; __libc_pread; __libc_pwrite;
diff --git a/posix/spawn.h b/posix/spawn.h
index c84ee4bf72..8c40b4d28b 100644
--- a/posix/spawn.h
+++ b/posix/spawn.h
@@ -190,6 +190,12 @@ extern int posix_spawn_file_actions_adddup2 (posix_spawn_file_actions_t *
    affects the subsequent file actions.  */
 extern int posix_spawn_file_actions_addchdir_np (posix_spawn_file_actions_t *,
 						 const char *__path) __THROW;
+
+/* Add an action changing the directory to FD during spawn.  This
+   affects the subsequent file actions.  FD is not duplicated and must
+   be open when the file action is executed.  */
+extern int posix_spawn_file_actions_addfchdir_np (posix_spawn_file_actions_t *,
+						  int __fd) __THROW;
 #endif
 
 __END_DECLS
diff --git a/posix/spawn_faction_addfchdir.c b/posix/spawn_faction_addfchdir.c
new file mode 100644
index 0000000000..6f069df29e
--- /dev/null
+++ b/posix/spawn_faction_addfchdir.c
@@ -0,0 +1,46 @@
+/* Add a directory change to a file action list for posix_spawn.
+   Copyright (C) 2000-2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <spawn.h>
+#include <string.h>
+
+#include "spawn_int.h"
+
+int
+posix_spawn_file_actions_addfchdir_np (posix_spawn_file_actions_t *actions,
+                                       int fd)
+{
+  struct __spawn_action *rec;
+
+  /* Allocate more memory if needed.  */
+  if (actions->__used == actions->__allocated
+      && __posix_spawn_file_actions_realloc (actions) != 0)
+    /* This can only mean we ran out of memory.  */
+    return ENOMEM;
+
+  /* Add the new value.  */
+  rec = &actions->__actions[actions->__used];
+  rec->tag = spawn_do_fchdir;
+  rec->action.fchdir_action.fd = fd;
+
+  /* Account for the new entry.  */
+  ++actions->__used;
+
+  return 0;
+}
diff --git a/posix/spawn_faction_destroy.c b/posix/spawn_faction_destroy.c
index 05ca9dc13b..da172a894e 100644
--- a/posix/spawn_faction_destroy.c
+++ b/posix/spawn_faction_destroy.c
@@ -38,6 +38,7 @@ __posix_spawn_file_actions_destroy (posix_spawn_file_actions_t *file_actions)
 	  break;
 	case spawn_do_close:
 	case spawn_do_dup2:
+	case spawn_do_fchdir:
 	  /* No cleanup required.  */
 	  break;
 	}
diff --git a/posix/spawn_int.h b/posix/spawn_int.h
index 9db35553c2..0d0e438ff6 100644
--- a/posix/spawn_int.h
+++ b/posix/spawn_int.h
@@ -31,6 +31,7 @@ struct __spawn_action
     spawn_do_dup2,
     spawn_do_open,
     spawn_do_chdir,
+    spawn_do_fchdir,
   } tag;
 
   union
@@ -55,6 +56,10 @@ struct __spawn_action
     {
       char *path;
     } chdir_action;
+    struct
+    {
+      int fd;
+    } fchdir_action;
   } action;
 };
 
diff --git a/posix/tst-spawn-chdir.c b/posix/tst-spawn-chdir.c
index dc14f2059b..8f447955c1 100644
--- a/posix/tst-spawn-chdir.c
+++ b/posix/tst-spawn-chdir.c
@@ -20,11 +20,13 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <spawn.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 #include <support/check.h>
 #include <support/support.h>
 #include <support/temp_file.h>
+#include <support/test-driver.h>
 #include <support/xstdio.h>
 #include <support/xunistd.h>
 #include <unistd.h>
@@ -64,6 +66,24 @@ get_pwd_program (void)
   FAIL_EXIT1 ("cannot find pwd program");
 }
 
+/* Adds chdir operations to ACTIONS, using PATH.  If DO_FCHDIR, use
+   the open function and TMPFD to emulate chdir using fchdir.  */
+static void
+add_chdir (posix_spawn_file_actions_t *actions, const char *path,
+           bool do_fchdir, int tmpfd)
+{
+  if (do_fchdir)
+    {
+      TEST_COMPARE (posix_spawn_file_actions_addopen
+                    (actions, tmpfd, path, O_DIRECTORY | O_RDONLY, 0), 0);
+      TEST_COMPARE (posix_spawn_file_actions_addfchdir_np
+                    (actions, tmpfd), 0);
+      TEST_COMPARE (posix_spawn_file_actions_addclose (actions, tmpfd), 0);
+    }
+  else
+    TEST_COMPARE (posix_spawn_file_actions_addchdir_np (actions, path), 0);
+}
+
 static int
 do_test (void)
 {
@@ -87,103 +107,109 @@ do_test (void)
   int iteration = 0;
   for (int do_spawnp = 0; do_spawnp < 2; ++do_spawnp)
     for (int do_overwrite = 0; do_overwrite < 2; ++do_overwrite)
-      {
-        ++iteration;
-        printf ("info: iteration=%d do_spawnp=%d do_overwrite=%d\n",
-                iteration, do_spawnp, do_overwrite);
-
-        /* The "pwd" program runs in this directory.  */
-        char *iteration_directory = xasprintf ("%s/%d", directory, iteration);
-        add_temp_file (iteration_directory);
-        xmkdir (iteration_directory, 0777);
-
-        /* This file receives output from "pwd".  */
-        char *output_file_path
-          = xasprintf ("%s/output-file", iteration_directory);
-        add_temp_file (output_file_path);
-
-        /* This subdirectory is used for chdir ordering checks.  */
-        char *subdir_path = xasprintf ("%s/subdir", iteration_directory);
-        add_temp_file (subdir_path);
-        xmkdir (subdir_path, 0777);
-
-        /* Also used for checking the order of actions.  */
-        char *probe_file_path
-          = xasprintf ("%s/subdir/probe-file", iteration_directory);
-        add_temp_file (probe_file_path);
-        TEST_COMPARE (access (probe_file_path, F_OK), -1);
-        TEST_COMPARE (errno, ENOENT);
-
-        /* This symbolic link is used in a relative path with
-           posix_spawn.  */
-        char *pwd_symlink_path
-          = xasprintf ("%s/subdir/pwd-symlink", iteration_directory);
-        xsymlink (get_pwd_program (), pwd_symlink_path);
-        add_temp_file (pwd_symlink_path);
-
-        posix_spawn_file_actions_t actions;
-        TEST_COMPARE (posix_spawn_file_actions_init (&actions), 0);
-        TEST_COMPARE (posix_spawn_file_actions_addchdir_np
-                      (&actions, subdir_path), 0);
-        TEST_COMPARE (posix_spawn_file_actions_addopen
-                      (&actions, 3, /* Arbitrary unused descriptor.  */
-                       "probe-file",
-                       O_WRONLY | O_CREAT | O_EXCL, 0777), 0);
-        TEST_COMPARE (posix_spawn_file_actions_addclose (&actions, 3), 0);
-        /* Run the actual in iteration_directory.  */
-        TEST_COMPARE (posix_spawn_file_actions_addchdir_np (&actions, ".."), 0);
-        TEST_COMPARE (posix_spawn_file_actions_addopen
-                      (&actions, STDOUT_FILENO, "output-file",
-                       O_WRONLY | O_CREAT | O_EXCL, 0777), 0);
-
-        /* Check that posix_spawn_file_actions_addchdir_np made a copy
-           of the path.  */
-        if (do_overwrite)
-          subdir_path[0] = '\0';
-
-        char *const argv[] = { (char *) "pwd", NULL };
-        char *const envp[] = { NULL } ;
-        pid_t pid;
-        if (do_spawnp)
-          TEST_COMPARE (posix_spawnp (&pid, "pwd", &actions,
-                                      NULL, argv, envp), 0);
-        else
-          TEST_COMPARE (posix_spawn (&pid, "subdir/pwd-symlink", &actions,
-                                     NULL, argv, envp), 0);
-        TEST_VERIFY (pid > 0);
-        int status;
-        xwaitpid (pid, &status, 0);
-        TEST_COMPARE (status, 0);
-
-        /* Check that the current directory did not change.  */
+      for (int do_fchdir = 0; do_fchdir < 2; ++do_fchdir)
         {
-          char *cwd = get_current_dir_name ();
-          if (cwd == NULL)
-            FAIL_EXIT1 ("get_current_dir_name: %m");
-          TEST_COMPARE_BLOB (original_cwd, strlen (original_cwd),
-                             cwd, strlen (cwd));
-          free (cwd);
+          /* This subtest does not make sense for fchdir.  */
+          if (do_overwrite && do_fchdir)
+            continue;
+
+          ++iteration;
+          if (test_verbose > 0)
+            printf ("info: iteration=%d do_spawnp=%d do_overwrite=%d"
+                    " do_fchdir=%d\n",
+                    iteration, do_spawnp, do_overwrite, do_fchdir);
+
+          /* The "pwd" program runs in this directory.  */
+          char *iteration_directory = xasprintf ("%s/%d", directory, iteration);
+          add_temp_file (iteration_directory);
+          xmkdir (iteration_directory, 0777);
+
+          /* This file receives output from "pwd".  */
+          char *output_file_path
+            = xasprintf ("%s/output-file", iteration_directory);
+          add_temp_file (output_file_path);
+
+          /* This subdirectory is used for chdir ordering checks.  */
+          char *subdir_path = xasprintf ("%s/subdir", iteration_directory);
+          add_temp_file (subdir_path);
+          xmkdir (subdir_path, 0777);
+
+          /* Also used for checking the order of actions.  */
+          char *probe_file_path
+            = xasprintf ("%s/subdir/probe-file", iteration_directory);
+          add_temp_file (probe_file_path);
+          TEST_COMPARE (access (probe_file_path, F_OK), -1);
+          TEST_COMPARE (errno, ENOENT);
+
+          /* This symbolic link is used in a relative path with
+             posix_spawn.  */
+          char *pwd_symlink_path
+            = xasprintf ("%s/subdir/pwd-symlink", iteration_directory);
+          xsymlink (get_pwd_program (), pwd_symlink_path);
+          add_temp_file (pwd_symlink_path);
+
+          posix_spawn_file_actions_t actions;
+          TEST_COMPARE (posix_spawn_file_actions_init (&actions), 0);
+          add_chdir (&actions, subdir_path, do_fchdir, 4);
+          TEST_COMPARE (posix_spawn_file_actions_addopen
+                        (&actions, 3, /* Arbitrary unused descriptor.  */
+                         "probe-file",
+                         O_WRONLY | O_CREAT | O_EXCL, 0777), 0);
+          TEST_COMPARE (posix_spawn_file_actions_addclose (&actions, 3), 0);
+          /* Run the actual in iteration_directory.  */
+          add_chdir (&actions, "..", do_fchdir, 5);
+          TEST_COMPARE (posix_spawn_file_actions_addopen
+                        (&actions, STDOUT_FILENO, "output-file",
+                         O_WRONLY | O_CREAT | O_EXCL, 0777), 0);
+
+          /* Check that posix_spawn_file_actions_addchdir_np made a copy
+             of the path.  */
+          if (do_overwrite)
+            subdir_path[0] = '\0';
+
+          char *const argv[] = { (char *) "pwd", NULL };
+          char *const envp[] = { NULL } ;
+          pid_t pid;
+          if (do_spawnp)
+            TEST_COMPARE (posix_spawnp (&pid, "pwd", &actions,
+                                        NULL, argv, envp), 0);
+          else
+            TEST_COMPARE (posix_spawn (&pid, "subdir/pwd-symlink", &actions,
+                                       NULL, argv, envp), 0);
+          TEST_VERIFY (pid > 0);
+          int status;
+          xwaitpid (pid, &status, 0);
+          TEST_COMPARE (status, 0);
+
+          /* Check that the current directory did not change.  */
+          {
+            char *cwd = get_current_dir_name ();
+            if (cwd == NULL)
+              FAIL_EXIT1 ("get_current_dir_name: %m");
+            TEST_COMPARE_BLOB (original_cwd, strlen (original_cwd),
+                               cwd, strlen (cwd));
+            free (cwd);
+          }
+
+
+          /* Check the output from "pwd".  */
+          {
+            char *pwd = read_one_line (output_file_path);
+            TEST_COMPARE_BLOB (iteration_directory, strlen (iteration_directory),
+                               pwd, strlen (pwd));
+            free (pwd);
+          }
+
+          /* This file must now exist.  */
+          TEST_COMPARE (access (probe_file_path, F_OK), 0);
+
+          TEST_COMPARE (posix_spawn_file_actions_destroy (&actions), 0);
+          free (pwd_symlink_path);
+          free (probe_file_path);
+          free (subdir_path);
+          free (output_file_path);
         }
 
-
-        /* Check the output from "pwd".  */
-        {
-          char *pwd = read_one_line (output_file_path);
-          TEST_COMPARE_BLOB (iteration_directory, strlen (iteration_directory),
-                             pwd, strlen (pwd));
-          free (pwd);
-        }
-
-        /* This file must now exist.  */
-        TEST_COMPARE (access (probe_file_path, F_OK), 0);
-
-        TEST_COMPARE (posix_spawn_file_actions_destroy (&actions), 0);
-        free (pwd_symlink_path);
-        free (probe_file_path);
-        free (subdir_path);
-        free (output_file_path);
-      }
-
   free (directory);
 
   return 0;