X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Fat-func.c;h=ea456edfb5245b042adbb80b20c2b64d216b8852;hb=2988c8c21303fdadb3a9efe321870d96f6bdc668;hp=c7963fe3d24b67539068947676ec6d3ebbc8fd0b;hpb=57fdfd3f8ec62b105c53bcdf6f127c35c7fe7391;p=gnulib.git

diff --git a/lib/at-func.c b/lib/at-func.c
index c7963fe3d..ea456edfb 100644
--- a/lib/at-func.c
+++ b/lib/at-func.c
@@ -1,5 +1,5 @@
 /* Define an at-style functions like fstatat, unlinkat, fchownat, etc.
-   Copyright (C) 2006 Free Software Foundation, Inc.
+   Copyright (C) 2006, 2009-2010 Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -16,62 +16,106 @@
 
 /* written by Jim Meyering */
 
-#define CALL_FUNC(F)				\
-  (AT_FUNC_USE_F1_COND				\
-    ? AT_FUNC_F1 (F AT_FUNC_POST_FILE_ARGS)	\
+#include "dirname.h" /* solely for definition of IS_ABSOLUTE_FILE_NAME */
+#include "openat.h"
+#include "openat-priv.h"
+#include "save-cwd.h"
+
+#ifdef AT_FUNC_USE_F1_COND
+# define CALL_FUNC(F)                           \
+  (flag == AT_FUNC_USE_F1_COND                  \
+    ? AT_FUNC_F1 (F AT_FUNC_POST_FILE_ARGS)     \
     : AT_FUNC_F2 (F AT_FUNC_POST_FILE_ARGS))
+# define VALIDATE_FLAG(F)                       \
+  if (flag & ~AT_FUNC_USE_F1_COND)              \
+    {                                           \
+      errno = EINVAL;                           \
+      return FUNC_FAIL;                         \
+    }
+#else
+# define CALL_FUNC(F) (AT_FUNC_F1 (F AT_FUNC_POST_FILE_ARGS))
+# define VALIDATE_FLAG(F) /* empty */
+#endif
+
+#ifdef AT_FUNC_RESULT
+# define FUNC_RESULT AT_FUNC_RESULT
+#else
+# define FUNC_RESULT int
+#endif
+
+#ifdef AT_FUNC_FAIL
+# define FUNC_FAIL AT_FUNC_FAIL
+#else
+# define FUNC_FAIL -1
+#endif
 
-/* Call AT_FUNC_F1 or AT_FUNC_F2 (testing AT_FUNC_USE_F1_COND to
-   determine which) to operate on FILE, which is in the directory
-   open on descriptor FD.  If possible, do it without changing the
+/* Call AT_FUNC_F1 to operate on FILE, which is in the directory
+   open on descriptor FD.  If AT_FUNC_USE_F1_COND is defined to a value,
+   AT_FUNC_POST_FILE_PARAM_DECLS must inlude a parameter named flag;
+   call AT_FUNC_F2 if FLAG is 0 or fail if FLAG contains more bits than
+   AT_FUNC_USE_F1_COND.  Return int and fail with -1 unless AT_FUNC_RESULT
+   or AT_FUNC_FAIL are defined.  If possible, do it without changing the
    working directory.  Otherwise, resort to using save_cwd/fchdir,
    then AT_FUNC_F?/restore_cwd.  If either the save_cwd or the restore_cwd
    fails, then give a diagnostic and exit nonzero.  */
-int
+FUNC_RESULT
 AT_FUNC_NAME (int fd, char const *file AT_FUNC_POST_FILE_PARAM_DECLS)
 {
+  /* Be careful to choose names unlikely to conflict with
+     AT_FUNC_POST_FILE_PARAM_DECLS.  */
   struct saved_cwd saved_cwd;
   int saved_errno;
-  int err;
+  FUNC_RESULT err;
+
+  VALIDATE_FLAG (flag);
 
   if (fd == AT_FDCWD || IS_ABSOLUTE_FILE_NAME (file))
     return CALL_FUNC (file);
 
   {
-    char buf[OPENAT_BUFFER_SIZE];
-    char *proc_file = openat_proc_name (buf, fd, file);
+    char proc_buf[OPENAT_BUFFER_SIZE];
+    char *proc_file = openat_proc_name (proc_buf, fd, file);
     if (proc_file)
       {
-	int proc_result = CALL_FUNC (proc_file);
-	int proc_errno = errno;
-	if (proc_file != buf)
-	  free (proc_file);
-	/* If the syscall succeeds, or if it fails with an unexpected
-	   errno value, then return right away.  Otherwise, fall through
-	   and resort to using save_cwd/restore_cwd.  */
-	if (0 <= proc_result)
-	  return proc_result;
-	if (! EXPECTED_ERRNO (proc_errno))
-	  {
-	    errno = proc_errno;
-	    return proc_result;
-	  }
+        FUNC_RESULT proc_result = CALL_FUNC (proc_file);
+        int proc_errno = errno;
+        if (proc_file != proc_buf)
+          free (proc_file);
+        /* If the syscall succeeds, or if it fails with an unexpected
+           errno value, then return right away.  Otherwise, fall through
+           and resort to using save_cwd/restore_cwd.  */
+        if (FUNC_FAIL != proc_result)
+          return proc_result;
+        if (! EXPECTED_ERRNO (proc_errno))
+          {
+            errno = proc_errno;
+            return proc_result;
+          }
       }
   }
 
   if (save_cwd (&saved_cwd) != 0)
     openat_save_fail (errno);
+  if (0 <= fd && fd == saved_cwd.desc)
+    {
+      /* If saving the working directory collides with the user's
+         requested fd, then the user's fd must have been closed to
+         begin with.  */
+      free_cwd (&saved_cwd);
+      errno = EBADF;
+      return FUNC_FAIL;
+    }
 
   if (fchdir (fd) != 0)
     {
       saved_errno = errno;
       free_cwd (&saved_cwd);
       errno = saved_errno;
-      return -1;
+      return FUNC_FAIL;
     }
 
   err = CALL_FUNC (file);
-  saved_errno = (err < 0 ? errno : 0);
+  saved_errno = (err == FUNC_FAIL ? errno : 0);
 
   if (restore_cwd (&saved_cwd) != 0)
     openat_restore_fail (errno);
@@ -83,3 +127,5 @@ AT_FUNC_NAME (int fd, char const *file AT_FUNC_POST_FILE_PARAM_DECLS)
   return err;
 }
 #undef CALL_FUNC
+#undef FUNC_RESULT
+#undef FUNC_FAIL