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-rw-r--r--lib/sh/eaccess.c244
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diff --git a/lib/sh/eaccess.c b/lib/sh/eaccess.c
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+/* eaccess.c - eaccess replacement for the shell, plus other access functions. */
+
+/* Copyright (C) 2006-2020 Free Software Foundation, Inc.
+
+ This file is part of GNU Bash, the Bourne Again SHell.
+
+ Bash 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 3 of the License, or
+ (at your option) any later version.
+
+ Bash 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 Bash. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#if defined (HAVE_CONFIG_H)
+# include <config.h>
+#endif
+
+#include <stdio.h>
+
+#include "bashtypes.h"
+
+#if defined (HAVE_UNISTD_H)
+# include <unistd.h>
+#endif
+
+#include "bashansi.h"
+
+#include <errno.h>
+#if !defined (errno)
+extern int errno;
+#endif /* !errno */
+
+#if !defined (_POSIX_VERSION) && defined (HAVE_SYS_FILE_H)
+# include <sys/file.h>
+#endif /* !_POSIX_VERSION */
+#include "posixstat.h"
+#include "filecntl.h"
+
+#include "shell.h"
+
+#if !defined (R_OK)
+#define R_OK 4
+#define W_OK 2
+#define X_OK 1
+#define F_OK 0
+#endif /* R_OK */
+
+static int path_is_devfd PARAMS((const char *));
+static int sh_stataccess PARAMS((const char *, int));
+#if HAVE_DECL_SETREGID
+static int sh_euidaccess PARAMS((const char *, int));
+#endif
+
+static int
+path_is_devfd (path)
+ const char *path;
+{
+ if (path[0] == '/' && path[1] == 'd' && strncmp (path, "/dev/fd/", 8) == 0)
+ return 1;
+ else if (STREQN (path, "/dev/std", 8))
+ {
+ if (STREQ (path+8, "in") || STREQ (path+8, "out") || STREQ (path+8, "err"))
+ return 1;
+ else
+ return 0;
+ }
+ else
+ return 0;
+}
+
+/* A wrapper for stat () which disallows pathnames that are empty strings
+ and handles /dev/fd emulation on systems that don't have it. */
+int
+sh_stat (path, finfo)
+ const char *path;
+ struct stat *finfo;
+{
+ static char *pbuf = 0;
+
+ if (*path == '\0')
+ {
+ errno = ENOENT;
+ return (-1);
+ }
+ if (path[0] == '/' && path[1] == 'd' && strncmp (path, "/dev/fd/", 8) == 0)
+ {
+ /* If stating /dev/fd/n doesn't produce the same results as fstat of
+ FD N, then define DEV_FD_STAT_BROKEN */
+#if !defined (HAVE_DEV_FD) || defined (DEV_FD_STAT_BROKEN)
+ intmax_t fd;
+ int r;
+
+ if (legal_number (path + 8, &fd) && fd == (int)fd)
+ {
+ r = fstat ((int)fd, finfo);
+ if (r == 0 || errno != EBADF)
+ return (r);
+ }
+ errno = ENOENT;
+ return (-1);
+#else
+ /* If HAVE_DEV_FD is defined, DEV_FD_PREFIX is defined also, and has a
+ trailing slash. Make sure /dev/fd/xx really uses DEV_FD_PREFIX/xx.
+ On most systems, with the notable exception of linux, this is
+ effectively a no-op. */
+ pbuf = xrealloc (pbuf, sizeof (DEV_FD_PREFIX) + strlen (path + 8));
+ strcpy (pbuf, DEV_FD_PREFIX);
+ strcat (pbuf, path + 8);
+ return (stat (pbuf, finfo));
+#endif /* !HAVE_DEV_FD */
+ }
+#if !defined (HAVE_DEV_STDIN)
+ else if (STREQN (path, "/dev/std", 8))
+ {
+ if (STREQ (path+8, "in"))
+ return (fstat (0, finfo));
+ else if (STREQ (path+8, "out"))
+ return (fstat (1, finfo));
+ else if (STREQ (path+8, "err"))
+ return (fstat (2, finfo));
+ else
+ return (stat (path, finfo));
+ }
+#endif /* !HAVE_DEV_STDIN */
+ return (stat (path, finfo));
+}
+
+/* Do the same thing access(2) does, but use the effective uid and gid,
+ and don't make the mistake of telling root that any file is
+ executable. This version uses stat(2). */
+static int
+sh_stataccess (path, mode)
+ const char *path;
+ int mode;
+{
+ struct stat st;
+
+ if (sh_stat (path, &st) < 0)
+ return (-1);
+
+ if (current_user.euid == 0)
+ {
+ /* Root can read or write any file. */
+ if ((mode & X_OK) == 0)
+ return (0);
+
+ /* Root can execute any file that has any one of the execute
+ bits set. */
+ if (st.st_mode & S_IXUGO)
+ return (0);
+ }
+
+ if (st.st_uid == current_user.euid) /* owner */
+ mode <<= 6;
+ else if (group_member (st.st_gid))
+ mode <<= 3;
+
+ if (st.st_mode & mode)
+ return (0);
+
+ errno = EACCES;
+ return (-1);
+}
+
+#if HAVE_DECL_SETREGID
+/* Version to call when uid != euid or gid != egid. We temporarily swap
+ the effective and real uid and gid as appropriate. */
+static int
+sh_euidaccess (path, mode)
+ const char *path;
+ int mode;
+{
+ int r, e;
+
+ if (current_user.uid != current_user.euid)
+ setreuid (current_user.euid, current_user.uid);
+ if (current_user.gid != current_user.egid)
+ setregid (current_user.egid, current_user.gid);
+
+ r = access (path, mode);
+ e = errno;
+
+ if (current_user.uid != current_user.euid)
+ setreuid (current_user.uid, current_user.euid);
+ if (current_user.gid != current_user.egid)
+ setregid (current_user.gid, current_user.egid);
+
+ errno = e;
+ return r;
+}
+#endif
+
+int
+sh_eaccess (path, mode)
+ const char *path;
+ int mode;
+{
+ int ret;
+
+ if (path_is_devfd (path))
+ return (sh_stataccess (path, mode));
+
+#if (defined (HAVE_FACCESSAT) && defined (AT_EACCESS)) || defined (HAVE_EACCESS)
+# if defined (HAVE_FACCESSAT) && defined (AT_EACCESS)
+ ret = faccessat (AT_FDCWD, path, mode, AT_EACCESS);
+# else /* HAVE_EACCESS */ /* FreeBSD */
+ ret = eaccess (path, mode); /* XXX -- not always correct for X_OK */
+# endif /* HAVE_EACCESS */
+# if defined (__FreeBSD__) || defined (SOLARIS) || defined (_AIX)
+ if (ret == 0 && current_user.euid == 0 && mode == X_OK)
+ return (sh_stataccess (path, mode));
+# endif /* __FreeBSD__ || SOLARIS || _AIX */
+ return ret;
+#elif defined (EFF_ONLY_OK) /* SVR4(?), SVR4.2 */
+ return access (path, mode|EFF_ONLY_OK);
+#else
+ if (mode == F_OK)
+ return (sh_stataccess (path, mode));
+
+# if HAVE_DECL_SETREGID
+ if (current_user.uid != current_user.euid || current_user.gid != current_user.egid)
+ return (sh_euidaccess (path, mode));
+# endif
+
+ if (current_user.uid == current_user.euid && current_user.gid == current_user.egid)
+ {
+ ret = access (path, mode);
+#if defined (__FreeBSD__) || defined (SOLARIS)
+ if (ret == 0 && current_user.euid == 0 && mode == X_OK)
+ return (sh_stataccess (path, mode));
+#endif
+ return ret;
+ }
+
+ return (sh_stataccess (path, mode));
+#endif
+}
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