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__)
34 static 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 
42 static int
simple_copy(const char * from,const char * to)43 simple_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 
90 void
set_times(const char * destination,const struct stat * statbuf)91 set_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 
137 int
smart_rename(const char * from,const char * to,int preserve_dates ATTRIBUTE_UNUSED)138 smart_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