setusercontext(3) - NetBSD Manual Pages

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LOGIN_CAP(3)            NetBSD Library Functions Manual           LOGIN_CAP(3)


NAME

     login_getclass, login_getcapbool, login_getcapnum, login_getcapsize,
     login_getcapstr, login_getcaptime, login_close, setclasscontext,
     setusercontext -- query login.conf database about a user class


LIBRARY

     System Utilities Library (libutil, -lutil)


SYNOPSIS

     #include <sys/types.h>
     #include <login_cap.h>

     login_cap_t *
     login_getclass(char *class);

     int
     login_getcapbool(login_cap_t *lc, const char *cap, u_int def);

     quad_t
     login_getcapnum(login_cap_t *lc, const char *cap, quad_t def,
         quad_t err);

     quad_t
     login_getcapsize(login_cap_t *lc, const char *cap, quad_t def,
         quad_t err);

     char *
     login_getcapstr(login_cap_t *lc, const char *cap, char *def, char *err);

     quad_t
     login_getcaptime(login_cap_t *lc, const char *cap, quad_t def,
         quad_t err);

     void
     login_close(login_cap_t *lc);

     int
     setclasscontext(const char *class, u_int flags);

     int
     setusercontext(login_cap_t *lc, const struct passwd *pwd, uid_t uid,
         u_int flags);


DESCRIPTION

     The login_getclass() function extracts the entry specified by class (or
     default if class is NULL or the empty string) from /etc/login.conf (see
     login.conf(5)).  If the entry is found, a login_cap_t pointer is
     returned.  NULL is returned if the user class is not found.  When the
     login_cap_t structure is no longer needed, it should be freed by the
     login_close() function.

     Once lc has been returned by login_getclass(), any of the other login_*()
     functions may be called.

     The login_getcapnum(), login_getcapsize(), login_getcapstr(), and
     login_getcaptime() functions all query the database entry for a field
     named cap.  If the field is found, its value is returned.  If the field
     is not found, the value specified by def is returned.  If an error is
     encountered while trying to find the field, err is returned.  See
     login.conf(5) for a discussion of the various textual forms the value may
     take.  The login_getcapbool() function is slightly different.  It returns
     def if no capabilities were found for this class (typically meaning that
     the default class was used and the /etc/login.conf file is missing).  It
     returns a non-zero value if cap, with no value, was found, zero other-
     wise.

     The setclasscontext() function takes class, the name of a user class, and
     sets the resources defined by that class according to flags.  Only the
     LOGIN_SETPATH, LOGIN_SETPRIORITY, LOGIN_SETRESOURCES, and LOGIN_SETUMASK
     bits are used.  (See setusercontext() below).  It returns 0 on success
     and -1 on failure.

     The setusercontext() function sets the resources according to flags.  The
     lc argument, if not NULL, contains the class information that should be
     used.  The pwd argument, if not NULL, provides information about the
     user.  Both lc and pwd cannot be NULL.  The uid argument is used in place
     of the user id contained in the pwd structure when calling setuid(2).
     The various bits available to be or-ed together to make up flags are:

     LOGIN_SETGID          Set the group id.  Requires the pwd field be speci-
                           fied.

     LOGIN_SETGROUPS       Set the group membership list by calling
                           initgroups(3).  Requires the pwd field be speci-
                           fied.

     LOGIN_SETGROUP        Set the group id and call initgroups(3).  Requires
                           the pwd field be specified.

     LOGIN_SETLOGIN        Sets the login name by setlogin(2).  Requires the
                           pwd field be specified.

     LOGIN_SETPATH         Sets the PATH environment variable.

     LOGIN_SETPRIORITY     Sets the priority by setpriority(2).

     LOGIN_SETRESOURCES    Sets the various system resources by setrlimit(2).

     LOGIN_SETUMASK        Sets the umask by umask(2).

     LOGIN_SETUSER         Sets the user id to uid by setuid(2).

     LOGIN_SETENV          Sets the environment variables as defined by the
                           setenv keyword, by setenv(3).

     LOGIN_SETALL          Sets all of the above.


SEE ALSO

     setlogin(2), setpriority(2), setrlimit(2), setuid(2), umask(2),
     initgroups(3), secure_path(3), login.conf(5)


HISTORY

     The login_getclass family of functions are largely based on the BSD/OS
     implementation of same, and appeared in NetBSD 1.5 by kind permission.


CAVEATS

     The string returned by login_getcapstr() is allocated via malloc(3) when
     the specified capability is present and thus it is the responsibility of
     the caller to free() this space.  However, if the capability was not
     found or an error occurred and def or err (whichever is relevant) are
     non-NULL the returned value is simply what was passed in to
     login_getcapstr().  Therefore it is not possible to blindly free() the
     return value without first checking it against def and err.

     The same warnings set forth in setlogin(2) apply to setusercontext() when
     the LOGIN_SETLOGIN flag is used.  Specifically, changing the login name
     affects all processes in the current session, not just the current
     process.  See setlogin(2) for more information.

NetBSD 5.0                     December 11, 2004                    NetBSD 5.0