Content-type: text/html Man page of getdvagent


Section: C Library Functions (3)
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getdvagent, getdvagnam, putdvagnam, copydvagent - Manipulate device assignment database entry (Enhanced Security)  


Security Library (libsecurity.a)  


#include <sys/types.h> #include <sys/security.h> #include <prot.h>

struct dev_asg *getdvagent(void);

struct dev_asg *getdvagnam(        char *name);

void setdvagent(void);

void enddvagent(void);

int putdvagnam(        char *name,
       struct dev_asg *dv);

struct dev_asg *copydvagent(        struct dev_asg *dv);


A cross-reference to the terminal control database. Contains a device assignment structure.  


The getdvagent(), getdvagnam(), and copydvagent() functions each return a pointer to an object with the following structure containing the separated-out fields of an entry in the device assignment database. Each database entry is returned as a dev_asg structure, declared in the prot.h header file as follows: struct dev_field {         char           *fd_name;       /* external name */
        char           **fd_devs;      /* device list */
        mask_t          fd_type[1];     /* tape, printer, terminal */
        mask_t          fd_assign[1];   /* single-lvl, multlvl, etc. */
        char           **fd_users;     /* authorized user list */

/* Device Assignment Database entry */

#define AUTH_DEV_TYPE "device type" #define AUTH_DEV_PRINTER     0

#define AUTH_DEV_ASSIGN "device assignment"

#define AUTH_DEV_IMPORT 4 /* enabled for import */ #define AUTH_DEV_EXPORT 5 /* enabled for export */ #define AUTH_DEV_PASS 6 /* *internal* to mltape */ #define AUTH_MAX_DEV_ASSIGN 6 #define AUTH_DEV_ASSIGN_SIZE (WORD_OF_BIT (AUTH_MAX_DEV_ASSIGN) + 1)

/* this structure tells which of the corresponding fields in dev_field
 * are valid (filled).
 */ struct dev_flag {
        unsigned short
                        fg_name : 1,
                        fg_devs : 1,
                        fg_type   : 1,
                        fg_assign : 1,
                        fg_users  : 1,
                        ; };

struct dev_asg {
        struct dev_field ufld;
        struct dev_flag  uflg;
        struct dev_field sfld;
        struct dev_flag  sflg; };

The device assignment database stores device characteristics that are related to synonyms. On systems supporting network connections, the device assignment database stores information about hosts initiating connections.

Each entry contains a name, which is a cross-reference to the terminal control database, and a list of devices, each of which is a pathname that corresponds to that device. This list allows the device assignment software to invalidate all references to a device when reassigning it. The list is a table of character string pointers, whose last entry is a null pointer.

The fd_type fields are bit masks that can be manipulated with the ADDBIT(), RMBIT(), and ISBITSET() macros. The fd_users field is a pointer to a null-terminated table of character string pointers referring to user allowed access.

For system versions supporting network connections, the device name can be a 12 character host name, where the first 8 characters are the ASCII hex address of the device, and the last 4 characters are ASCII zeros. For example, a host with Internet address has device name 814b00030000. The trailing four zeros are for compatibility with ports on terminal concentrators.

When the getdvagent() function is first called, it returns a pointer to the first device assignment entry. Thereafter, it returns a pointer to the next entry, so successive calls can be used to search the database. The getdvagnam() function searches from the beginning of the database until an entry with device name matching name is found, and returns a pointer to that entry. If an end-of-file or an error is encountered on reading, these functions return a null pointer.

The copydvagent() function copies dv, and the fields to which it refers, to a newly allocated data area. Because the getdvagent(), getdvagnam(), and putdvagent() functions reuse a static structure when accessing the database, the values of any entry must be saved if the database routines are used again. The dev_asg structure returned by copydvagent() can be freed using the free() function.

A call to the setdvagent() function has the effect of setting the device assignment database back to the first entry, to allow repeated searches of the database. The enddvagent() function frees all memory and closes all files used to support the database routines.

The putdvagnam() function rewrites or adds an entry to the database. If there is an entry whose fd_name field matches the name argument, that entry is replaced with the contents of the dv structure. Otherwise, that entry is added to the database.  


Programs using the database routines must be compiled with -lsecurity.  


Structures returned by the database routines contain pointers to character strings and lists rather than being self-contained. The copydvagent() function must be used rather than doing a structure assignment to save a returned structure.

The value returned by the getdvagent() and getdvagnam() functions refers to a structure that is overwritten by calls to these functions. To retrieve an entry, modify it, and replace it in the database, you must copy the entry using the copydvagent() function and supply the modified buffer to the putdvagent() function.  


The getdvagent() and getdvagnam() functions return a pointer to a static structure on success, or a null pointer on failure. This static structure is overwritten by the getdvagent(), getdvagnam(), and putdvagnam() functions. The putdvagnam() function returns a value of 1 on success, or a value of 0 (zero) on failure. The copydvagent() function returns a pointer to the newly allocated structure on success, or a null pointer if there was a memory allocation error.  


File containing device assignment entries.  


Files: authcap(4). delim off




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Time: 02:41:10 GMT, October 02, 2010