1/* Work around unlink bugs. 2 3 Copyright (C) 2009, 2010 Free Software Foundation, Inc. 4 5 This program is free software: you can redistribute it and/or modify 6 it under the terms of the GNU General Public License as published by 7 the Free Software Foundation; either version 3 of the License, or 8 (at your option) any later version. 9 10 This program is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 GNU General Public License for more details. 14 15 You should have received a copy of the GNU General Public License 16 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 17 18#include <config.h> 19 20#include <unistd.h> 21 22#include <errno.h> 23#include <stdlib.h> 24#include <string.h> 25#include <sys/stat.h> 26 27#undef unlink 28 29/* Remove file NAME. 30 Return 0 if successful, -1 if not. */ 31 32int 33rpl_unlink (char const *name) 34{ 35 /* Work around Solaris 9 bug where unlink("file/") succeeds. */ 36 size_t len = strlen (name); 37 int result = 0; 38 if (len && ISSLASH (name[len - 1])) 39 { 40 /* We can't unlink(2) something if it doesn't exist. If it does 41 exist, then it resolved to a directory, due to the trailing 42 slash, and POSIX requires that the unlink attempt to remove 43 that directory (which would leave the symlink dangling). 44 Unfortunately, Solaris 9 is one of the platforms where the 45 root user can unlink directories, and we don't want to 46 cripple this behavior on real directories, even if it is 47 seldom needed (at any rate, it's nicer to let coreutils' 48 unlink(1) give the correct errno for non-root users). But we 49 don't know whether name was an actual directory, or a symlink 50 to a directory; and due to the bug of ignoring trailing 51 slash, Solaris 9 would end up successfully unlinking the 52 symlink instead of the directory. Technically, we could use 53 realpath to find the canonical directory name to attempt 54 deletion on. But that is a lot of work for a corner case; so 55 we instead just use an lstat on the shortened name, and 56 reject symlinks with trailing slashes. The root user of 57 unlink(1) will just have to live with the rule that they 58 can't delete a directory via a symlink. */ 59 struct stat st; 60 result = lstat (name, &st); 61 if (result == 0) 62 { 63 /* Trailing NUL will overwrite the trailing slash. */ 64 char *short_name = malloc (len); 65 if (!short_name) 66 { 67 errno = EPERM; 68 return -1; 69 } 70 memcpy (short_name, name, len); 71 while (len && ISSLASH (short_name[len - 1])) 72 short_name[--len] = '\0'; 73 if (len && (lstat (short_name, &st) || S_ISLNK (st.st_mode))) 74 { 75 free (short_name); 76 errno = EPERM; 77 return -1; 78 } 79 free (short_name); 80 } 81 } 82 if (!result) 83 result = unlink (name); 84 return result; 85} 86