posix: New function posix_spawn_file_actions_addchdir_np [BZ #17405]

7 files changed, 266 insertions, 2 deletions

diff --git a/posix/Makefile b/posix/Makefile
index 8316212..d67f68d 100644
--- a/posix/Makefile
+++ b/posix/Makefile
@@ -55,6 +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 						      \
 	spawnattr_init spawnattr_destroy				      \
 	spawnattr_getdefault spawnattr_setdefault			      \
 	spawnattr_getflags spawnattr_setflags				      \
@@ -96,7 +97,7 @@ tests		:= test-errno tstgetopt testfnm runtests runptests \
 		   tst-posix_fadvise tst-posix_fadvise64 \
 		   tst-sysconf-empty-chroot tst-glob_symlinks tst-fexecve \
 		   tst-glob-tilde test-ssize-max tst-spawn4 bug-regex37 \
-		   bug-regex38 tst-regcomp-truncated
+		   bug-regex38 tst-regcomp-truncated tst-spawn-chdir
 tests-internal	:= bug-regex5 bug-regex20 bug-regex33 \
 		   tst-rfc3484 tst-rfc3484-2 tst-rfc3484-3 \
 		   tst-glob_lstat_compat tst-spawn4-compat
diff --git a/posix/Versions b/posix/Versions
index cad4c23..56ab921 100644
--- a/posix/Versions
+++ b/posix/Versions
@@ -137,6 +137,9 @@ libc {
   GLIBC_2.27 {
     glob; glob64;
   }
+  GLIBC_2.29 {
+    posix_spawn_file_actions_addchdir_np;
+  }
   GLIBC_PRIVATE {
     __libc_fork; __libc_pread; __libc_pwrite;
     __nanosleep_nocancel; __pause_nocancel;
diff --git a/posix/spawn.h b/posix/spawn.h
index aafb276..c84ee4b 100644
--- a/posix/spawn.h
+++ b/posix/spawn.h
@@ -185,6 +185,13 @@ extern int posix_spawn_file_actions_adddup2 (posix_spawn_file_actions_t *
 					     __file_actions,
 					     int __fd, int __newfd) __THROW;
 
+#ifdef __USE_GNU
+/* Add an action changing the directory to PATH during spawn.  This
+   affects the subsequent file actions.  */
+extern int posix_spawn_file_actions_addchdir_np (posix_spawn_file_actions_t *,
+						 const char *__path) __THROW;
+#endif
+
 __END_DECLS
 
 #endif /* spawn.h */
diff --git a/posix/spawn_faction_addchdir.c b/posix/spawn_faction_addchdir.c
new file mode 100644
index 0000000..0e7a45a
--- /dev/null
+++ b/posix/spawn_faction_addchdir.c
@@ -0,0 +1,53 @@
+/* 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_addchdir_np (posix_spawn_file_actions_t *file_actions,
+                                      const char *path)
+{
+  struct __spawn_action *rec;
+
+  char *path_copy = __strdup (path);
+  if (path_copy == NULL)
+    return ENOMEM;
+
+  /* Allocate more memory if needed.  */
+  if (file_actions->__used == file_actions->__allocated
+      && __posix_spawn_file_actions_realloc (file_actions) != 0)
+    {
+      /* This can only mean we ran out of memory.  */
+      free (path_copy);
+      return ENOMEM;
+    }
+
+  /* Add the new value.  */
+  rec = &file_actions->__actions[file_actions->__used];
+  rec->tag = spawn_do_chdir;
+  rec->action.chdir_action.path = path_copy;
+
+  /* Account for the new entry.  */
+  ++file_actions->__used;
+
+  return 0;
+}
diff --git a/posix/spawn_faction_destroy.c b/posix/spawn_faction_destroy.c
index 2a2de4e..05ca9dc 100644
--- a/posix/spawn_faction_destroy.c
+++ b/posix/spawn_faction_destroy.c
@@ -33,6 +33,9 @@ __posix_spawn_file_actions_destroy (posix_spawn_file_actions_t *file_actions)
 	case spawn_do_open:
 	  free (sa->action.open_action.path);
 	  break;
+	case spawn_do_chdir:
+	  free (sa->action.chdir_action.path);
+	  break;
 	case spawn_do_close:
 	case spawn_do_dup2:
 	  /* No cleanup required.  */
diff --git a/posix/spawn_int.h b/posix/spawn_int.h
index 171f67c..9db3555 100644
--- a/posix/spawn_int.h
+++ b/posix/spawn_int.h
@@ -29,7 +29,8 @@ struct __spawn_action
   {
     spawn_do_close,
     spawn_do_dup2,
-    spawn_do_open
+    spawn_do_open,
+    spawn_do_chdir,
   } tag;
 
   union
@@ -50,6 +51,10 @@ struct __spawn_action
       int oflag;
       mode_t mode;
     } open_action;
+    struct
+    {
+      char *path;
+    } chdir_action;
   } action;
 };
 
diff --git a/posix/tst-spawn-chdir.c b/posix/tst-spawn-chdir.c
new file mode 100644
index 0000000..dc14f20
--- /dev/null
+++ b/posix/tst-spawn-chdir.c
@@ -0,0 +1,192 @@
+/* Test the posix_spawn_file_actions_addchdir_np function.
+   Copyright (C) 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 <array_length.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <spawn.h>
+#include <stdlib.h>
+#include <string.h>
+#include <support/check.h>
+#include <support/support.h>
+#include <support/temp_file.h>
+#include <support/xstdio.h>
+#include <support/xunistd.h>
+#include <unistd.h>
+
+/* Reads the file at PATH, which must consist of exactly one line.
+   Removes the line terminator at the end of the file.  */
+static char *
+read_one_line (const char *path)
+{
+  FILE *fp = xfopen (path, "r");
+  char *buffer = NULL;
+  size_t length = 0;
+  ssize_t ret = getline (&buffer, &length, fp);
+  if (ferror (fp))
+    FAIL_EXIT1 ("getline: %m");
+  if (ret < 1)
+    FAIL_EXIT1 ("getline returned %zd", ret);
+  if (fgetc (fp) != EOF)
+    FAIL_EXIT1 ("trailing bytes in %s", path);
+  if (ferror (fp))
+    FAIL_EXIT1 ("fgetc: %m");
+  xfclose (fp);
+  if (buffer[ret - 1] != '\n')
+    FAIL_EXIT1 ("missing line terminator in %s", path);
+  buffer[ret - 1] = 0;
+  return buffer;
+}
+
+/* Return the path to the "pwd" program.  */
+const char *
+get_pwd_program (void)
+{
+  const char *const paths[] = { "/bin/pwd", "/usr/bin/pwd" };
+  for (size_t i = 0; i < array_length (paths); ++i)
+    if (access (paths[i], X_OK) == 0)
+      return paths[i];
+  FAIL_EXIT1 ("cannot find pwd program");
+}
+
+static int
+do_test (void)
+{
+  /* Directory for temporary file data.  Each subtest uses a numeric
+     subdirectory.  */
+  char *directory = support_create_temp_directory ("tst-spawn-chdir-");
+  {
+    /* Avoid symbolic links, to get more consistent behavior from the
+       pwd command.  */
+    char *tmp = realpath (directory, NULL);
+    if (tmp == NULL)
+      FAIL_EXIT1 ("realpath: %m");
+    free (directory);
+    directory = tmp;
+  }
+
+  char *original_cwd = get_current_dir_name ();
+  if (original_cwd == NULL)
+    FAIL_EXIT1 ("get_current_dir_name: %m");
+
+  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.  */
+        {
+          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);
+      }
+
+  free (directory);
+
+  return 0;
+}
+
+#include <support/test-driver.c>