1/* rename.c -- rename a file, preserving symlinks.
2   Copyright (C) 1999-2020 Free Software Foundation, Inc.
3
4   This file is part of GNU Binutils.
5
6   This program is free software; you can redistribute it and/or modify
7   it under the terms of the GNU General Public License as published by
8   the Free Software Foundation; either version 3 of the License, or
9   (at your option) any later version.
10
11   This program is distributed in the hope that it will be useful,
12   but WITHOUT ANY WARRANTY; without even the implied warranty of
13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14   GNU General Public License for more details.
15
16   You should have received a copy of the GNU General Public License
17   along with this program; if not, write to the Free Software
18   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA
19   02110-1301, USA.  */
20
21#include "sysdep.h"
22#include "bfd.h"
23#include "bucomm.h"
24
25#ifdef HAVE_GOOD_UTIME_H
26#include <utime.h>
27#else /* ! HAVE_GOOD_UTIME_H */
28#ifdef HAVE_UTIMES
29#include <sys/time.h>
30#endif /* HAVE_UTIMES */
31#endif /* ! HAVE_GOOD_UTIME_H */
32
33#if ! defined (_WIN32) || defined (__CYGWIN32__)
34static int simple_copy (const char *, const char *);
35
36/* The number of bytes to copy at once.  */
37#define COPY_BUF 8192
38
39/* Copy file FROM to file TO, performing no translations.
40   Return 0 if ok, -1 if error.  */
41
42static int
43simple_copy (const char *from, const char *to)
44{
45  int fromfd, tofd, nread;
46  int saved;
47  char buf[COPY_BUF];
48
49  fromfd = open (from, O_RDONLY | O_BINARY);
50  if (fromfd < 0)
51    return -1;
52#ifdef O_CREAT
53  tofd = open (to, O_CREAT | O_WRONLY | O_TRUNC | O_BINARY, 0777);
54#else
55  tofd = creat (to, 0777);
56#endif
57  if (tofd < 0)
58    {
59      saved = errno;
60      close (fromfd);
61      errno = saved;
62      return -1;
63    }
64  while ((nread = read (fromfd, buf, sizeof buf)) > 0)
65    {
66      if (write (tofd, buf, nread) != nread)
67	{
68	  saved = errno;
69	  close (fromfd);
70	  close (tofd);
71	  errno = saved;
72	  return -1;
73	}
74    }
75  saved = errno;
76  close (fromfd);
77  close (tofd);
78  if (nread < 0)
79    {
80      errno = saved;
81      return -1;
82    }
83  return 0;
84}
85#endif /* __CYGWIN32__ or not _WIN32 */
86
87/* Set the times of the file DESTINATION to be the same as those in
88   STATBUF.  */
89
90void
91set_times (const char *destination, const struct stat *statbuf)
92{
93  int result;
94
95  {
96#ifdef HAVE_GOOD_UTIME_H
97    struct utimbuf tb;
98
99    tb.actime = statbuf->st_atime;
100    tb.modtime = statbuf->st_mtime;
101    result = utime (destination, &tb);
102#else /* ! HAVE_GOOD_UTIME_H */
103#ifndef HAVE_UTIMES
104    long tb[2];
105
106    tb[0] = statbuf->st_atime;
107    tb[1] = statbuf->st_mtime;
108    result = utime (destination, tb);
109#else /* HAVE_UTIMES */
110    struct timeval tv[2];
111
112    tv[0].tv_sec = statbuf->st_atime;
113    tv[0].tv_usec = 0;
114    tv[1].tv_sec = statbuf->st_mtime;
115    tv[1].tv_usec = 0;
116    result = utimes (destination, tv);
117#endif /* HAVE_UTIMES */
118#endif /* ! HAVE_GOOD_UTIME_H */
119  }
120
121  if (result != 0)
122    non_fatal (_("%s: cannot set time: %s"), destination, strerror (errno));
123}
124
125#ifndef S_ISLNK
126#ifdef S_IFLNK
127#define S_ISLNK(m) (((m) & S_IFMT) == S_IFLNK)
128#else
129#define S_ISLNK(m) 0
130#define lstat stat
131#endif
132#endif
133
134/* Rename FROM to TO, copying if TO is a link.
135   Return 0 if ok, -1 if error.  */
136
137int
138smart_rename (const char *from, const char *to, int preserve_dates ATTRIBUTE_UNUSED)
139{
140  bfd_boolean exists;
141  struct stat s;
142  int ret = 0;
143
144  exists = lstat (to, &s) == 0;
145
146#if defined (_WIN32) && !defined (__CYGWIN32__)
147  /* Win32, unlike unix, will not erase `to' in `rename(from, to)' but
148     fail instead.  Also, chown is not present.  */
149
150  if (exists)
151    remove (to);
152
153  ret = rename (from, to);
154  if (ret != 0)
155    {
156      /* We have to clean up here.  */
157      non_fatal (_("unable to rename '%s'; reason: %s"), to, strerror (errno));
158      unlink (from);
159    }
160#else
161  /* Use rename only if TO is not a symbolic link and has
162     only one hard link, and we have permission to write to it.  */
163  if (! exists
164      || (!S_ISLNK (s.st_mode)
165	  && S_ISREG (s.st_mode)
166	  && (s.st_mode & S_IWUSR)
167	  && s.st_nlink == 1)
168      )
169    {
170      ret = rename (from, to);
171      if (ret == 0)
172	{
173	  if (exists)
174	    {
175	      /* Try to preserve the permission bits and ownership of
176		 TO.  First get the mode right except for the setuid
177		 bit.  Then change the ownership.  Then fix the setuid
178		 bit.  We do the chmod before the chown because if the
179		 chown succeeds, and we are a normal user, we won't be
180		 able to do the chmod afterward.  We don't bother to
181		 fix the setuid bit first because that might introduce
182		 a fleeting security problem, and because the chown
183		 will clear the setuid bit anyhow.  We only fix the
184		 setuid bit if the chown succeeds, because we don't
185		 want to introduce an unexpected setuid file owned by
186		 the user running objcopy.  */
187	      chmod (to, s.st_mode & 0777);
188	      if (chown (to, s.st_uid, s.st_gid) >= 0)
189		chmod (to, s.st_mode & 07777);
190	    }
191	}
192      else
193	{
194	  /* We have to clean up here.  */
195	  non_fatal (_("unable to rename '%s'; reason: %s"), to, strerror (errno));
196	  unlink (from);
197	}
198    }
199  else
200    {
201      ret = simple_copy (from, to);
202      if (ret != 0)
203	non_fatal (_("unable to copy file '%s'; reason: %s"), to, strerror (errno));
204
205      if (preserve_dates)
206	set_times (to, &s);
207      unlink (from);
208    }
209#endif /* _WIN32 && !__CYGWIN32__ */
210
211  return ret;
212}
213