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127 lines
3.2 KiB
C
127 lines
3.2 KiB
C
/* chown() compatibility.
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Copyright (C) 1998, 2000, 2002, 2003 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library 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 GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#include <errno.h>
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#include <string.h>
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#include <unistd.h>
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#include <limits.h>
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#include <sysdep.h>
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#include <stdlib.h>
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/*
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In Linux 2.1.x the chown functions have been changed. A new function lchown
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was introduced. The new chown now follows symlinks - the old chown and the
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new lchown do not follow symlinks.
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This file emulates chown() under the old kernels.
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*/
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int
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__chown (const char *file, uid_t owner, gid_t group)
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{
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int err;
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int old_errno;
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char link[PATH_MAX+2];
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char path[2*PATH_MAX+4];
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int loopct;
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size_t filelen;
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static int libc_old_chown = 0 /* -1=old linux, 1=new linux, 0=unknown */;
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if (libc_old_chown == 1)
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return INLINE_SYSCALL (chown, 3, __ptrvalue (file), owner, group);
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old_errno = errno;
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#ifdef __NR_lchown
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if (libc_old_chown == 0)
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{
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err = INLINE_SYSCALL (chown, 3, __ptrvalue (file), owner, group);
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if (err != -1 || errno != ENOSYS)
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{
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libc_old_chown = 1;
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return err;
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}
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libc_old_chown = -1;
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}
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#endif
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err = __readlink (file, link, PATH_MAX+1);
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if (err == -1)
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{
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errno = old_errno;
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return __lchown(file, owner, group);
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}
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filelen = strlen (file) + 1;
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if (filelen > sizeof(path))
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{
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errno = ENAMETOOLONG;
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return -1;
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}
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memcpy (path, file, filelen);
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/* 'The system has an arbitrary limit...' In practise, we'll hit
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ENAMETOOLONG before this, usually. */
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for (loopct = 0; loopct < 128; loopct++)
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{
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size_t linklen;
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if (err >= PATH_MAX+1)
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{
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errno = ENAMETOOLONG;
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return -1;
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}
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link[err] = 0; /* Null-terminate string, just-in-case. */
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linklen = strlen (link) + 1;
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if (link[0] == '/')
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memcpy (path, link, linklen);
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else
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{
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filelen = strlen (path);
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while (filelen > 1 && path[filelen-1] == '/')
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filelen--;
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while (filelen > 0 && path[filelen-1] != '/')
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filelen--;
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if (filelen + linklen > sizeof(path))
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{
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errno = ENAMETOOLONG;
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return -1;
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}
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memcpy (path+filelen, link, linklen);
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}
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err = __readlink(path, link, PATH_MAX+1);
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if (err == -1)
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{
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errno = old_errno;
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return __lchown(path, owner, group);
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}
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}
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errno = ELOOP;
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return -1;
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}
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libc_hidden_def (__chown)
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#include <shlib-compat.h>
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versioned_symbol (libc, __chown, chown, GLIBC_2_1);
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