mirror of https://gitee.com/openkylin/wget.git
98 lines
3.3 KiB
C
98 lines
3.3 KiB
C
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/* Work around unlink bugs.
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Copyright (C) 2009-2019 Free Software Foundation, Inc.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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#include <config.h>
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#include <unistd.h>
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#include <errno.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/stat.h>
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#include "dosname.h"
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#undef unlink
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/* Remove file NAME.
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Return 0 if successful, -1 if not. */
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int
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rpl_unlink (char const *name)
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{
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/* Work around Solaris 9 bug where unlink("file/") succeeds. */
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size_t len = strlen (name);
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int result = 0;
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if (len && ISSLASH (name[len - 1]))
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{
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/* We can't unlink(2) something if it doesn't exist. If it does
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exist, then it resolved to a directory, due to the trailing
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slash, and POSIX requires that the unlink attempt to remove
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that directory (which would leave the symlink dangling).
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Unfortunately, Solaris 9 is one of the platforms where the
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root user can unlink directories, and we don't want to
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cripple this behavior on real directories, even if it is
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seldom needed (at any rate, it's nicer to let coreutils'
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unlink(1) give the correct errno for non-root users). But we
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don't know whether name was an actual directory, or a symlink
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to a directory; and due to the bug of ignoring trailing
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slash, Solaris 9 would end up successfully unlinking the
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symlink instead of the directory. Technically, we could use
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realpath to find the canonical directory name to attempt
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deletion on. But that is a lot of work for a corner case; so
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we instead just use an lstat on the shortened name, and
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reject symlinks with trailing slashes. The root user of
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unlink(1) will just have to live with the rule that they
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can't delete a directory via a symlink. */
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struct stat st;
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result = lstat (name, &st);
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if (result == 0)
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{
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/* Trailing NUL will overwrite the trailing slash. */
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char *short_name = malloc (len);
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if (!short_name)
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{
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errno = EPERM;
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return -1;
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}
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memcpy (short_name, name, len);
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while (len && ISSLASH (short_name[len - 1]))
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short_name[--len] = '\0';
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if (len && (lstat (short_name, &st) || S_ISLNK (st.st_mode)))
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{
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free (short_name);
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errno = EPERM;
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return -1;
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}
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free (short_name);
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}
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}
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if (!result)
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{
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#if UNLINK_PARENT_BUG
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if (len >= 2 && name[len - 1] == '.' && name[len - 2] == '.'
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&& (len == 2 || ISSLASH (name[len - 3])))
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{
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errno = EISDIR; /* could also use EPERM */
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return -1;
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}
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#endif
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result = unlink (name);
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}
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return result;
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}
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