X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Frename.c;h=3e463ea86a92ee8d5e27ba429043e94e142c4bd0;hb=23eecb48e39afd0d267d64d40ba6bf97aa865e13;hp=b27fd9100d02a5bb7ac62c75e1a92a03ebc75b69;hpb=533b27747fe3d0d67f727d4d7ba6c97f8a5b4060;p=gnulib.git

diff --git a/lib/rename.c b/lib/rename.c
index b27fd9100..3e463ea86 100644
--- a/lib/rename.c
+++ b/lib/rename.c
@@ -1,9 +1,6 @@
-/* Work around rename bugs in some systems.  On SunOS 4.1.1_U1
-   and mips-dec-ultrix4.4, rename fails when the source file has
-   a trailing slash.  On mingw, rename fails when the destination
-   exists.
+/* Work around rename bugs in some systems.
 
-   Copyright (C) 2001, 2002, 2003, 2005, 2006, 2009 Free Software Foundation, Inc.
+   Copyright (C) 2001-2003, 2005-2006, 2009-2013 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
@@ -18,19 +15,29 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-/* written by Volker Borchert */
+/* Written by Volker Borchert, Eric Blake.  */
 
 #include <config.h>
+
+#include <stdio.h>
+
 #undef rename
 
-#if RENAME_DEST_EXISTS_BUG
-/* This replacement must come first, otherwise when cross
- * compiling to Windows we will guess that it has the trailing
- * slash bug and entirely miss this one. */
-#include <errno.h>
+#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+/* The mingw rename has problems with trailing slashes; it also
+   requires use of native Windows calls to allow atomic renames over
+   existing files.  */
+
+# include <errno.h>
+# include <stdbool.h>
+# include <stdlib.h>
+# include <sys/stat.h>
+# include <unistd.h>
+
+# define WIN32_LEAN_AND_MEAN
+# include <windows.h>
 
-#define WIN32_LEAN_AND_MEAN
-#include <windows.h>
+# include "dirname.h"
 
 /* Rename the file SRC to DST.  This replacement is necessary on
    Windows, on which the system rename function will not replace
@@ -39,15 +46,140 @@ int
 rpl_rename (char const *src, char const *dst)
 {
   int error;
+  size_t src_len = strlen (src);
+  size_t dst_len = strlen (dst);
+  char *src_base = last_component (src);
+  char *dst_base = last_component (dst);
+  bool src_slash;
+  bool dst_slash;
+  bool dst_exists;
+  struct stat src_st;
+  struct stat dst_st;
+
+  /* Filter out dot as last component.  */
+  if (!src_len || !dst_len)
+    {
+      errno = ENOENT;
+      return -1;
+    }
+  if (*src_base == '.')
+    {
+      size_t len = base_len (src_base);
+      if (len == 1 || (len == 2 && src_base[1] == '.'))
+        {
+          errno = EINVAL;
+          return -1;
+        }
+    }
+  if (*dst_base == '.')
+    {
+      size_t len = base_len (dst_base);
+      if (len == 1 || (len == 2 && dst_base[1] == '.'))
+        {
+          errno = EINVAL;
+          return -1;
+        }
+    }
 
-  /* MoveFileEx works if SRC is a directory without any flags,
-     but fails with MOVEFILE_REPLACE_EXISTING, so try without
-     flags first. */
+  /* Presence of a trailing slash requires directory semantics.  If
+     the source does not exist, or if the destination cannot be turned
+     into a directory, give up now.  Otherwise, strip trailing slashes
+     before calling rename.  There are no symlinks on mingw, so stat
+     works instead of lstat.  */
+  src_slash = ISSLASH (src[src_len - 1]);
+  dst_slash = ISSLASH (dst[dst_len - 1]);
+  if (stat (src, &src_st))
+    return -1;
+  if (stat (dst, &dst_st))
+    {
+      if (errno != ENOENT || (!S_ISDIR (src_st.st_mode) && dst_slash))
+        return -1;
+      dst_exists = false;
+    }
+  else
+    {
+      if (S_ISDIR (dst_st.st_mode) != S_ISDIR (src_st.st_mode))
+        {
+          errno = S_ISDIR (dst_st.st_mode) ? EISDIR : ENOTDIR;
+          return -1;
+        }
+      dst_exists = true;
+    }
+
+  /* There are no symlinks, so if a file existed with a trailing
+     slash, it must be a directory, and we don't have to worry about
+     stripping strip trailing slash.  However, mingw refuses to
+     replace an existing empty directory, so we have to help it out.
+     And canonicalize_file_name is not yet ported to mingw; however,
+     for directories, getcwd works as a viable alternative.  Ensure
+     that we can get back to where we started before using it; later
+     attempts to return are fatal.  Note that we can end up losing a
+     directory if rename then fails, but it was empty, so not much
+     damage was done.  */
+  if (dst_exists && S_ISDIR (dst_st.st_mode))
+    {
+      char *cwd = getcwd (NULL, 0);
+      char *src_temp;
+      char *dst_temp;
+      if (!cwd || chdir (cwd))
+        return -1;
+      if (IS_ABSOLUTE_FILE_NAME (src))
+        {
+          dst_temp = chdir (dst) ? NULL : getcwd (NULL, 0);
+          src_temp = chdir (src) ? NULL : getcwd (NULL, 0);
+        }
+      else
+        {
+          src_temp = chdir (src) ? NULL : getcwd (NULL, 0);
+          if (!IS_ABSOLUTE_FILE_NAME (dst) && chdir (cwd))
+            abort ();
+          dst_temp = chdir (dst) ? NULL : getcwd (NULL, 0);
+        }
+      if (chdir (cwd))
+        abort ();
+      free (cwd);
+      if (!src_temp || !dst_temp)
+        {
+          free (src_temp);
+          free (dst_temp);
+          errno = ENOMEM;
+          return -1;
+        }
+      src_len = strlen (src_temp);
+      if (strncmp (src_temp, dst_temp, src_len) == 0
+          && (ISSLASH (dst_temp[src_len]) || dst_temp[src_len] == '\0'))
+        {
+          error = dst_temp[src_len];
+          free (src_temp);
+          free (dst_temp);
+          if (error)
+            {
+              errno = EINVAL;
+              return -1;
+            }
+          return 0;
+        }
+      if (rmdir (dst))
+        {
+          error = errno;
+          free (src_temp);
+          free (dst_temp);
+          errno = error;
+          return -1;
+        }
+      free (src_temp);
+      free (dst_temp);
+    }
+
+  /* MoveFileEx works if SRC is a directory without any flags, but
+     fails with MOVEFILE_REPLACE_EXISTING, so try without flags first.
+     Thankfully, MoveFileEx handles hard links correctly, even though
+     rename() does not.  */
   if (MoveFileEx (src, dst, 0))
     return 0;
 
   /* Retry with MOVEFILE_REPLACE_EXISTING if the move failed
-   * due to the destination already existing. */
+     due to the destination already existing.  */
   error = GetLastError ();
   if (error == ERROR_FILE_EXISTS || error == ERROR_ALREADY_EXISTS)
     {
@@ -114,10 +246,10 @@ rpl_rename (char const *src, char const *dst)
       errno = EPERM;        /* ? */
       break;
 
-#ifndef ERROR_FILE_TOO_LARGE
-/* This value is documented but not defined in all versions of windows.h. */
-#define ERROR_FILE_TOO_LARGE 223
-#endif
+# ifndef ERROR_FILE_TOO_LARGE
+/* This value is documented but not defined in all versions of windows.h.  */
+#  define ERROR_FILE_TOO_LARGE 223
+# endif
     case ERROR_FILE_TOO_LARGE:
       errno = EFBIG;
       break;
@@ -129,37 +261,213 @@ rpl_rename (char const *src, char const *dst)
 
   return -1;
 }
-#elif RENAME_TRAILING_SLASH_BUG
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
 
-#include "dirname.h"
-#include "xalloc.h"
+#else /* ! W32 platform */
+
+# include <errno.h>
+# include <stdio.h>
+# include <stdlib.h>
+# include <string.h>
+# include <sys/stat.h>
+# include <unistd.h>
+
+# include "dirname.h"
+# include "same-inode.h"
 
-/* Rename the file SRC to DST, removing any trailing
-   slashes from SRC.  Needed for SunOS 4.1.1_U1.  */
+/* Rename the file SRC to DST, fixing any trailing slash bugs.  */
 
 int
 rpl_rename (char const *src, char const *dst)
 {
-  char *src_temp;
-  int ret_val;
-  size_t s_len = strlen (src);
-
-  if (s_len && src[s_len - 1] == '/')
+  size_t src_len = strlen (src);
+  size_t dst_len = strlen (dst);
+  char *src_temp = (char *) src;
+  char *dst_temp = (char *) dst;
+  bool src_slash;
+  bool dst_slash;
+  bool dst_exists;
+  int ret_val = -1;
+  int rename_errno = ENOTDIR;
+  struct stat src_st;
+  struct stat dst_st;
+
+  if (!src_len || !dst_len)
+    return rename (src, dst); /* Let strace see the ENOENT failure.  */
+
+# if RENAME_DEST_EXISTS_BUG
+  {
+    char *src_base = last_component (src);
+    char *dst_base = last_component (dst);
+    if (*src_base == '.')
+      {
+        size_t len = base_len (src_base);
+        if (len == 1 || (len == 2 && src_base[1] == '.'))
+          {
+            errno = EINVAL;
+            return -1;
+          }
+      }
+    if (*dst_base == '.')
+      {
+        size_t len = base_len (dst_base);
+        if (len == 1 || (len == 2 && dst_base[1] == '.'))
+          {
+            errno = EINVAL;
+            return -1;
+          }
+      }
+  }
+# endif /* RENAME_DEST_EXISTS_BUG */
+
+  src_slash = src[src_len - 1] == '/';
+  dst_slash = dst[dst_len - 1] == '/';
+
+# if !RENAME_HARD_LINK_BUG && !RENAME_DEST_EXISTS_BUG
+  /* If there are no trailing slashes, then trust the native
+     implementation unless we also suspect issues with hard link
+     detection or file/directory conflicts.  */
+  if (!src_slash && !dst_slash)
+    return rename (src, dst);
+# endif /* !RENAME_HARD_LINK_BUG && !RENAME_DEST_EXISTS_BUG */
+
+  /* Presence of a trailing slash requires directory semantics.  If
+     the source does not exist, or if the destination cannot be turned
+     into a directory, give up now.  Otherwise, strip trailing slashes
+     before calling rename.  */
+  if (lstat (src, &src_st))
+    return -1;
+  if (lstat (dst, &dst_st))
     {
-      src_temp = xstrdup (src);
-      strip_trailing_slashes (src_temp);
+      if (errno != ENOENT || (!S_ISDIR (src_st.st_mode) && dst_slash))
+        return -1;
+      dst_exists = false;
     }
   else
-    src_temp = (char *) src;
+    {
+      if (S_ISDIR (dst_st.st_mode) != S_ISDIR (src_st.st_mode))
+        {
+          errno = S_ISDIR (dst_st.st_mode) ? EISDIR : ENOTDIR;
+          return -1;
+        }
+# if RENAME_HARD_LINK_BUG
+      if (SAME_INODE (src_st, dst_st))
+        return 0;
+# endif /* RENAME_HARD_LINK_BUG */
+      dst_exists = true;
+    }
 
-  ret_val = rename (src_temp, dst);
+# if (RENAME_TRAILING_SLASH_SOURCE_BUG || RENAME_DEST_EXISTS_BUG        \
+      || RENAME_HARD_LINK_BUG)
+  /* If the only bug was that a trailing slash was allowed on a
+     non-existing file destination, as in Solaris 10, then we've
+     already covered that situation.  But if there is any problem with
+     a trailing slash on an existing source or destination, as in
+     Solaris 9, or if a directory can overwrite a symlink, as on
+     Cygwin 1.5, or if directories cannot be created with trailing
+     slash, as on NetBSD 1.6, then we must strip the offending slash
+     and check that we have not encountered a symlink instead of a
+     directory.
+
+     Stripping a trailing slash interferes with POSIX semantics, where
+     rename behavior on a symlink with a trailing slash operates on
+     the corresponding target directory.  We prefer the GNU semantics
+     of rejecting any use of a symlink with trailing slash, but do not
+     enforce them, since Solaris 10 is able to obey POSIX semantics
+     and there might be clients expecting it, as counter-intuitive as
+     those semantics are.
+
+     Technically, we could also follow the POSIX behavior by chasing a
+     readlink trail, but that is harder to implement.  */
+  if (src_slash)
+    {
+      src_temp = strdup (src);
+      if (!src_temp)
+        {
+          /* Rather than rely on strdup-posix, we set errno ourselves.  */
+          rename_errno = ENOMEM;
+          goto out;
+        }
+      strip_trailing_slashes (src_temp);
+      if (lstat (src_temp, &src_st))
+        {
+          rename_errno = errno;
+          goto out;
+        }
+      if (S_ISLNK (src_st.st_mode))
+        goto out;
+    }
+  if (dst_slash)
+    {
+      dst_temp = strdup (dst);
+      if (!dst_temp)
+        {
+          rename_errno = ENOMEM;
+          goto out;
+        }
+      strip_trailing_slashes (dst_temp);
+      if (lstat (dst_temp, &dst_st))
+        {
+          if (errno != ENOENT)
+            {
+              rename_errno = errno;
+              goto out;
+            }
+        }
+      else if (S_ISLNK (dst_st.st_mode))
+        goto out;
+    }
+# endif /* RENAME_TRAILING_SLASH_SOURCE_BUG || RENAME_DEST_EXISTS_BUG
+           || RENAME_HARD_LINK_BUG */
+
+# if RENAME_DEST_EXISTS_BUG
+  /* Cygwin 1.5 sometimes behaves oddly when moving a non-empty
+     directory on top of an empty one (the old directory name can
+     reappear if the new directory tree is removed).  Work around this
+     by removing the target first, but don't remove the target if it
+     is a subdirectory of the source.  Note that we can end up losing
+     a directory if rename then fails, but it was empty, so not much
+     damage was done.  */
+  if (dst_exists && S_ISDIR (dst_st.st_mode))
+    {
+      if (src_st.st_dev != dst_st.st_dev)
+        {
+          rename_errno = EXDEV;
+          goto out;
+        }
+      if (src_temp != src)
+        free (src_temp);
+      src_temp = canonicalize_file_name (src);
+      if (dst_temp != dst)
+        free (dst_temp);
+      dst_temp = canonicalize_file_name (dst);
+      if (!src_temp || !dst_temp)
+        {
+          rename_errno = ENOMEM;
+          goto out;
+        }
+      src_len = strlen (src_temp);
+      if (strncmp (src_temp, dst_temp, src_len) == 0
+          && dst_temp[src_len] == '/')
+        {
+          rename_errno = EINVAL;
+          goto out;
+        }
+      if (rmdir (dst))
+        {
+          rename_errno = errno;
+          goto out;
+        }
+    }
+# endif /* RENAME_DEST_EXISTS_BUG */
 
+  ret_val = rename (src_temp, dst_temp);
+  rename_errno = errno;
+ out:
   if (src_temp != src)
     free (src_temp);
-
+  if (dst_temp != dst)
+    free (dst_temp);
+  errno = rename_errno;
   return ret_val;
 }
-#endif /* RENAME_TRAILING_SLASH_BUG */
+#endif /* ! W32 platform */