1 /* rename.c -- rename a file, preserving symlinks.
2    Copyright 1999, 2002, 2003 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 2 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 "bfd.h"
22 #include "bucomm.h"
23 
24 #include <sys/stat.h>
25 
26 #ifdef HAVE_GOOD_UTIME_H
27 #include <utime.h>
28 #else /* ! HAVE_GOOD_UTIME_H */
29 #ifdef HAVE_UTIMES
30 #include <sys/time.h>
31 #endif /* HAVE_UTIMES */
32 #endif /* ! HAVE_GOOD_UTIME_H */
33 
34 /* We need to open the file in binary modes on system where that makes
35    a difference.  */
36 #ifndef O_BINARY
37 #define O_BINARY 0
38 #endif
39 
40 #if ! defined (_WIN32) || defined (__CYGWIN32__)
41 static int simple_copy (const char *, const char *);
42 
43 /* The number of bytes to copy at once.  */
44 #define COPY_BUF 8192
45 
46 /* Copy file FROM to file TO, performing no translations.
47    Return 0 if ok, -1 if error.  */
48 
49 static int
50 simple_copy (const char *from, const char *to)
51 {
52   int fromfd, tofd, nread;
53   int saved;
54   char buf[COPY_BUF];
55 
56   fromfd = open (from, O_RDONLY | O_BINARY);
57   if (fromfd < 0)
58     return -1;
59 #ifdef O_CREAT
60   tofd = open (to, O_CREAT | O_WRONLY | O_TRUNC | O_BINARY, 0777);
61 #else
62   tofd = creat (to, 0777);
63 #endif
64   if (tofd < 0)
65     {
66       saved = errno;
67       close (fromfd);
68       errno = saved;
69       return -1;
70     }
71   while ((nread = read (fromfd, buf, sizeof buf)) > 0)
72     {
73       if (write (tofd, buf, nread) != nread)
74 	{
75 	  saved = errno;
76 	  close (fromfd);
77 	  close (tofd);
78 	  errno = saved;
79 	  return -1;
80 	}
81     }
82   saved = errno;
83   close (fromfd);
84   close (tofd);
85   if (nread < 0)
86     {
87       errno = saved;
88       return -1;
89     }
90   return 0;
91 }
92 #endif /* __CYGWIN32__ or not _WIN32 */
93 
94 /* Set the times of the file DESTINATION to be the same as those in
95    STATBUF.  */
96 
97 void
98 set_times (const char *destination, const struct stat *statbuf)
99 {
100   int result;
101 
102   {
103 #ifdef HAVE_GOOD_UTIME_H
104     struct utimbuf tb;
105 
106     tb.actime = statbuf->st_atime;
107     tb.modtime = statbuf->st_mtime;
108     result = utime (destination, &tb);
109 #else /* ! HAVE_GOOD_UTIME_H */
110 #ifndef HAVE_UTIMES
111     long tb[2];
112 
113     tb[0] = statbuf->st_atime;
114     tb[1] = statbuf->st_mtime;
115     result = utime (destination, tb);
116 #else /* HAVE_UTIMES */
117     struct timeval tv[2];
118 
119     tv[0].tv_sec = statbuf->st_atime;
120     tv[0].tv_usec = 0;
121     tv[1].tv_sec = statbuf->st_mtime;
122     tv[1].tv_usec = 0;
123     result = utimes (destination, tv);
124 #endif /* HAVE_UTIMES */
125 #endif /* ! HAVE_GOOD_UTIME_H */
126   }
127 
128   if (result != 0)
129     non_fatal (_("%s: cannot set time: %s"), destination, strerror (errno));
130 }
131 
132 #ifndef S_ISLNK
133 #ifdef S_IFLNK
134 #define S_ISLNK(m) (((m) & S_IFMT) == S_IFLNK)
135 #else
136 #define S_ISLNK(m) 0
137 #define lstat stat
138 #endif
139 #endif
140 
141 /* Rename FROM to TO, copying if TO is a link.
142    Return 0 if ok, -1 if error.  */
143 
144 int
145 smart_rename (const char *from, const char *to, int preserve_dates ATTRIBUTE_UNUSED)
146 {
147   bfd_boolean exists;
148   struct stat s;
149   int ret = 0;
150 
151   exists = lstat (to, &s) == 0;
152 
153 #if defined (_WIN32) && !defined (__CYGWIN32__)
154   /* Win32, unlike unix, will not erase `to' in `rename(from, to)' but
155      fail instead.  Also, chown is not present.  */
156 
157   if (exists)
158     remove (to);
159 
160   ret = rename (from, to);
161   if (ret != 0)
162     {
163       /* We have to clean up here.  */
164       non_fatal (_("unable to rename '%s' reason: %s"), to, strerror (errno));
165       unlink (from);
166     }
167 #else
168   /* Use rename only if TO is not a symbolic link and has
169      only one hard link, and we have permission to write to it.  */
170   if (! exists
171       || (!S_ISLNK (s.st_mode)
172 	  && S_ISREG (s.st_mode)
173 	  && (s.st_mode & S_IWUSR)
174 	  && s.st_nlink == 1)
175       )
176     {
177       ret = rename (from, to);
178       if (ret == 0)
179 	{
180 	  if (exists)
181 	    {
182 	      /* Try to preserve the permission bits and ownership of
183 		 TO.  First get the mode right except for the setuid
184 		 bit.  Then change the ownership.  Then fix the setuid
185 		 bit.  We do the chmod before the chown because if the
186 		 chown succeeds, and we are a normal user, we won't be
187 		 able to do the chmod afterward.  We don't bother to
188 		 fix the setuid bit first because that might introduce
189 		 a fleeting security problem, and because the chown
190 		 will clear the setuid bit anyhow.  We only fix the
191 		 setuid bit if the chown succeeds, because we don't
192 		 want to introduce an unexpected setuid file owned by
193 		 the user running objcopy.  */
194 	      chmod (to, s.st_mode & 0777);
195 	      if (chown (to, s.st_uid, s.st_gid) >= 0)
196 		chmod (to, s.st_mode & 07777);
197 	    }
198 	}
199       else
200 	{
201 	  /* We have to clean up here.  */
202 	  non_fatal (_("unable to rename '%s' reason: %s"), to, strerror (errno));
203 	  unlink (from);
204 	}
205     }
206   else
207     {
208       ret = simple_copy (from, to);
209       if (ret != 0)
210 	non_fatal (_("unable to copy file '%s' reason: %s"), to, strerror (errno));
211 
212       if (preserve_dates)
213 	set_times (to, &s);
214       unlink (from);
215     }
216 #endif /* _WIN32 && !__CYGWIN32__ */
217 
218   return ret;
219 }
220