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authorJim Meyering <jim@meyering.net>2005-11-20 08:51:10 +0000
committerJim Meyering <jim@meyering.net>2005-11-20 08:51:10 +0000
commite88132fa068ea949837d0aeaf36aa9004b4ef528 (patch)
treed36445f5affb12fe684ae8380fdd511f00cd7ed9 /lib
parentc0c83656d258e4b09f914104ff9d25ee58b2480f (diff)
downloadcoreutils-e88132fa068ea949837d0aeaf36aa9004b4ef528.tar.xz
New file, mostly from euidaccess.c.
Diffstat (limited to 'lib')
-rw-r--r--lib/euidaccess-stat.c145
1 files changed, 145 insertions, 0 deletions
diff --git a/lib/euidaccess-stat.c b/lib/euidaccess-stat.c
new file mode 100644
index 000000000..8d39fa1c3
--- /dev/null
+++ b/lib/euidaccess-stat.c
@@ -0,0 +1,145 @@
+/* euidaccess-stat -- check if effective user id can access lstat'd file
+ This function is probably useful only for choosing whether to issue
+ a prompt in an implementation of POSIX-specified rm.
+
+ Copyright (C) 2005 Free Software Foundation, Inc.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2, or (at your option)
+ any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License along
+ with this program; if not, write to the Free Software Foundation,
+ Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
+
+/* Adapted for use in GNU remove.c by Jim Meyering. */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "euidaccess-stat.h"
+
+#include <unistd.h>
+
+#ifndef F_OK
+# define F_OK 0
+# define X_OK 1
+# define W_OK 2
+# define R_OK 4
+#endif
+
+#include "group-member.h"
+#include "stat-macros.h"
+
+/* Return true if the current user has permission of type MODE
+ on the file from which stat buffer *ST was obtained, ignoring
+ ACLs, attributes, `read-only'ness, etc...
+ Otherwise, return false.
+
+ Like the reentrant version of euidaccess, but starting with
+ a stat buffer rather than a file name. Hence, this function
+ never calls access or accessx, and doesn't take into account
+ whether the file has ACLs or other attributes, or resides on
+ a read-only file system. */
+
+bool
+euidaccess_stat (struct stat const *st, int mode)
+{
+ uid_t euid;
+ unsigned int granted;
+
+ /* Convert the mode to traditional form, clearing any bogus bits. */
+ if (R_OK == 4 && W_OK == 2 && X_OK == 1 && F_OK == 0)
+ mode &= 7;
+ else
+ mode = ((mode & R_OK ? 4 : 0)
+ + (mode & W_OK ? 2 : 0)
+ + (mode & X_OK ? 1 : 0));
+
+ if (mode == 0)
+ return true; /* The file exists. */
+
+ euid = geteuid ();
+
+ /* The super-user can read and write any file, and execute any file
+ that anyone can execute. */
+ if (euid == 0 && ((mode & X_OK) == 0
+ || (st->st_mode & (S_IXUSR | S_IXGRP | S_IXOTH))))
+ return true;
+
+ /* Convert the file's permission bits to traditional form. */
+ if ( S_IRUSR == (4 << 6)
+ && S_IWUSR == (2 << 6)
+ && S_IXUSR == (1 << 6)
+ && S_IRGRP == (4 << 3)
+ && S_IWGRP == (2 << 3)
+ && S_IXGRP == (1 << 3)
+ && S_IROTH == (4 << 0)
+ && S_IWOTH == (2 << 0)
+ && S_IXOTH == (1 << 0))
+ granted = st->st_mode;
+ else
+ granted = ( (st->st_mode & S_IRUSR ? 4 << 6 : 0)
+ + (st->st_mode & S_IWUSR ? 2 << 6 : 0)
+ + (st->st_mode & S_IXUSR ? 1 << 6 : 0)
+ + (st->st_mode & S_IRGRP ? 4 << 3 : 0)
+ + (st->st_mode & S_IWGRP ? 2 << 3 : 0)
+ + (st->st_mode & S_IXGRP ? 1 << 3 : 0)
+ + (st->st_mode & S_IROTH ? 4 << 0 : 0)
+ + (st->st_mode & S_IWOTH ? 2 << 0 : 0)
+ + (st->st_mode & S_IXOTH ? 1 << 0 : 0));
+
+ if (euid == st->st_uid)
+ granted >>= 6;
+ else
+ {
+ gid_t egid = getegid ();
+ if (egid == st->st_gid || group_member (st->st_gid))
+ granted >>= 3;
+ }
+
+ if ((mode & ~granted) == 0)
+ return true;
+
+ return false;
+}
+
+
+#ifdef TEST
+# include <errno.h>
+# include <stdio.h>
+# include <stdlib.h>
+
+# include "error.h"
+# define _(msg) msg
+
+char *program_name;
+
+int
+main (int argc, char **argv)
+{
+ char *file;
+ int mode;
+ bool ok;
+ struct stat st;
+
+ program_name = argv[0];
+ if (argc < 3)
+ abort ();
+ file = argv[1];
+ mode = atoi (argv[2]);
+ if (lstat (file, &st) != 0)
+ error (EXIT_FAILURE, errno, _("cannot stat %s"), file);
+
+ ok = euidaccess_stat (&st, mode);
+ printf ("%s: %s\n", file, ok ? "y" : "n");
+ exit (0);
+}
+#endif