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annotate lib/unlink.c @ 16358:a712776b11ce

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maint: spelling fixes
author Paul Eggert <eggert@cs.ucla.edu>
date Sun, 05 Feb 2012 13:42:03 -0800
parents 8250f2777afc
children e542fd46ad6f
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1 /* Work around unlink bugs.
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2
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3 Copyright (C) 2009-2012 Free Software Foundation, Inc.
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4
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5 This program is free software: you can redistribute it and/or modify
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6 it under the terms of the GNU General Public License as published by
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7 the Free Software Foundation; either version 3 of the License, or
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8 (at your option) any later version.
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9
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10 This program is distributed in the hope that it will be useful,
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11 but WITHOUT ANY WARRANTY; without even the implied warranty of
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12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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13 GNU General Public License for more details.
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14
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15 You should have received a copy of the GNU General Public License
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16 along with this program. If not, see <http://www.gnu.org/licenses/>. */
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17
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18 #include <config.h>
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19
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20 #include <unistd.h>
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21
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22 #include <errno.h>
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23 #include <stdlib.h>
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24 #include <string.h>
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25 #include <sys/stat.h>
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26
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27 #include "dosname.h"
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28
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29 #undef unlink
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30
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31 /* Remove file NAME.
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32 Return 0 if successful, -1 if not. */
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33
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34 int
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35 rpl_unlink (char const *name)
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36 {
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37 /* Work around Solaris 9 bug where unlink("file/") succeeds. */
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38 size_t len = strlen (name);
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39 int result = 0;
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40 if (len && ISSLASH (name[len - 1]))
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41 {
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42 /* We can't unlink(2) something if it doesn't exist. If it does
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43 exist, then it resolved to a directory, due to the trailing
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44 slash, and POSIX requires that the unlink attempt to remove
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45 that directory (which would leave the symlink dangling).
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46 Unfortunately, Solaris 9 is one of the platforms where the
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47 root user can unlink directories, and we don't want to
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48 cripple this behavior on real directories, even if it is
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49 seldom needed (at any rate, it's nicer to let coreutils'
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50 unlink(1) give the correct errno for non-root users). But we
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51 don't know whether name was an actual directory, or a symlink
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52 to a directory; and due to the bug of ignoring trailing
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53 slash, Solaris 9 would end up successfully unlinking the
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54 symlink instead of the directory. Technically, we could use
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55 realpath to find the canonical directory name to attempt
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56 deletion on. But that is a lot of work for a corner case; so
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57 we instead just use an lstat on the shortened name, and
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58 reject symlinks with trailing slashes. The root user of
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59 unlink(1) will just have to live with the rule that they
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60 can't delete a directory via a symlink. */
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61 struct stat st;
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62 result = lstat (name, &st);
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63 if (result == 0)
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64 {
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65 /* Trailing NUL will overwrite the trailing slash. */
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66 char *short_name = malloc (len);
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67 if (!short_name)
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68 {
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69 errno = EPERM;
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70 return -1;
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71 }
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72 memcpy (short_name, name, len);
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73 while (len && ISSLASH (short_name[len - 1]))
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74 short_name[--len] = '\0';
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75 if (len && (lstat (short_name, &st) || S_ISLNK (st.st_mode)))
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76 {
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77 free (short_name);
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78 errno = EPERM;
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79 return -1;
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80 }
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81 free (short_name);
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82 }
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83 }
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84 if (!result)
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85 {
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86 #if UNLINK_PARENT_BUG
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87 if (len >= 2 && name[len - 1] == '.' && name[len - 2] == '.'
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88 && (len == 2 || ISSLASH (name[len - 3])))
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89 {
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90 errno = EISDIR; /* could also use EPERM */
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91 return -1;
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92 }
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93 #endif
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94 result = unlink (name);
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95 }
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96 return result;
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97 }