MIPS ABI Conformance Guide 1.1.2 - Chapter 6

Libraries

This chapter describes additions and clarifications to the ABI library specifications. The following areas are defined:

libc.so.1
libm.a
libmutex.so
libsocket.so
libucb.a
X11R5 Support (libX11)
OSF/Motif 1.2 Support (libXm)
mmap
Runtime Dynamic Linking Library
sysinfo

libc.so.1

The C library, libc , contains all the symbols listed in the Generic ABI, as well as the routines listed in the following figures:

libc Contents, Names without Synonyms

_cleanup	_numeric	modf

libc Contents, Names with Synonyms

getitimer gettimeofday makecontext logb nextafter scalb select setlabel setitimer swapcontext sysinfo

Note that the following routines are listed in Generic ABI as Names without Synonyms.

fopen vfprintf vprintf vsprintf

Operating system implementors should note that the SVR4 definition of gettimeofday() differs from the BSD4.3 version.

libc.so.1 must include the entry points _xstat and _lstat which are used to implement the stat interface. Application programmers should not use the _xstat and _lstat interfaces, and should take care to include stat.h. Failure to include stat.h may result in invoking the older (pre-EFT) stat interface leading to erroneous results in the application.

libm.a

Frequently, applications must rely on groups of object files not required to be present on an ABI conforming implementation. These may be provided in static archives provided with the development environment. If each member of the archive is itself ABI conforming, then an ABI conforming application may statically link members from this archive and still be ABI conforming. If extensions to an archive are not ABI conforming, then an ABI conforming application may not include that extension in an executable.

All development environments for ABI applications shall contain ABI conforming versions of libm.a. The MIPS psABI shall define the path to the directory that contains these libraries. The following are entry-points that must be defined for each respective library, as defined in Issue 3 of the SVID.

Required libm Functions

acos	acosh	asin	asinh	atan2	atanh	
cbrt	ceil	cos	cosh	erf	erfc
exp	fabs	floor	fmod	gamma	j0
j1	jn	lgamma	log	log10	pow
remainder	sin	sinh	sqrt	tan	tanh
y0	y1	yn

libmutex.so

libmutex provides ABI entry points for mutual exclusion. It has the following synopsis:

cc [flag ...] file ...  -lmutex [library ...]

#include 

int init_lock(abilock_t *lck)

int acquire_lock(abilock_t *lck)

int release_lock(abilock_t *lck)

int stat_lock(abilock_t *lck)

These functions supply a user-level interface to mutual exclusion. The parameter lck must point to memory shared by all processes wishing to acquire or test the lock. The library routines might not contain checks for the validity (e.g. non-null value) of the lck parameter.

The contents of the structure abilock_t are as follows:

typedef struct {
   unsigned long    abi_lock;
} abilock_t;

The function init_lock must be called on a lock before any of the other functions. It initializes the lock to an unlocked state. A non-zero return status will indicate an error.

acquire_lock tries once to acquire the lock referenced by lck. It returns zero if the lock was acquired, otherwise non-zero.

stat_lock returns the current state of the lock referenced by lck without attempting to acquire the lock. It returns zero if the lock is free, otherwise non-zero.

release_lock unconditionally releases the lock pointed to by lck. The ability for one process to release the lock of another process is permitted. A non-zero return status will indicate an error.

Locks may not be freed automatically by the system. Locks acquired by a process that dies may remain locked.

The user is responsible for implementing a back-off policy if acquire_lock returns failure.

Even though stat_lock returns status indicating that the lock is available, a call to acquire_lock could still fail.

libsocket.so

This definition is derived from the SVR4 specification of sockets. However, applications that rely on assumptions about the underlying implementation of sockets may not be ABI compliant. In particular, stream operations on sockets are not supported. Constants labelled "may not be supported" are included for consistency between vendors but may not be implemented on all ABI compliant platforms. However, the constants are required to be included in the header files. The socket library (-lsocket) must precede the nsl library in the cc command line.

The behavior of a zero queue length (the second argument) to the libsocket routine listen is undefined.

Contents of libsocket

accept	bind	connect
endhostent	endnetent	endprotoent
endservent	ether_aton	ether_hostton
ether_line	ether_ntoa	ether_ntohost
gethostbyaddr	gethostbyname	gethostent	
getnetbyaddr	getnetbyname	getnetent	
getpeername	getprotobyname	getprotobynumber	
getprotoent	getservbyname	getservbyport
getservent	getsockname	getsockopt	
htonl	htons	inet_addr	
inet_lnaof	inet_makeaddr	inet_netof	
inet_network	inet_ntoa	listen
ntohl	ntohs	recv	
recvfrom	recvmsg	send	
sendmsg	sendto	sethostent	
setnetent	setprotoent	setservent
setsockopt	shutdown	socket	
socketpair

Header File: net/if.h

#define IFF_UP           0x1
#define IFF_BROADCAST    0x2
#define IFF_DEBUG        0x4
#define IFF_LOOPBACK     0x8
#define IFF_POINTOPOINT  0x10
#define IFF_NOTRAILERS   0x20
#define IFF_RUNNING      0x40
#define IFF_NOARP        0x80
#define IFF_PROMISC      0x100
#define IFF_ALLMULTI     0x200
#define IFF_INTELLIGENT  0x400
#define IFF_MULTICAST    0x800
#define IFF_PRIVATE      0x8000

struct   ifreq {
#define   IFNAMSIZ   16
   char   ifr_name[IFNAMSIZ];
   union {
      struct  sockaddr ifru_addr;
      struct  sockaddr ifru_dstaddr;
      char    ifru_oname[IFNAMSIZ];
      struct  sockaddr ifru_broadaddr;
      short   ifru_flags;
      int     ifru_metric;
      char    ifru_data[1];
      char    ifru_enaddr[6];
   } ifr_ifru;
#define   ifr_addr      ifr_ifru.ifru_addr
#define   ifr_dstaddr   ifr_ifru.ifru_dstaddr
#define   ifr_oname     ifr_ifru.ifru_oname
#define   ifr_broadaddr ifr_ifru.ifru_broadaddr
#define   ifr_flags     ifr_ifru.ifru_flags
#define   ifr_metric    ifr_ifru.ifru_metric
#define   ifr_data      ifr_ifru.ifru_data
#define   ifr_enaddr    ifr_ifru.ifru_enaddr
};

struct   ifconf {
   int   ifc_len;
   union {
      caddr_t   ifcu_buf;
      struct    ifreq *ifcu_req;
   } ifc_ifcu;
#define   ifc_buf   ifc_ifcu.ifcu_buf
#define   ifc_req   ifc_ifcu.ifcu_req
};

Header File: net/if_arp.h

struct arpreq {
   struct   sockaddr arp_pa;
   struct   sockaddr arp_ha;
   int      arp_flags;
};

#define   ATF_INUSE        0x01
#define   ATF_COM          0x02
#define   ATF_PERM         0x04
#define   ATF_PUBL         0x08
#define   ATF_USETRAILERS  0x10

Header File: netinet/if_ether.h

typedef u_char ether_addr_t[6];

Header File: netinet/in.h

#define ntohl(x) (x)
#define ntohs(x) (x)
#define htonl(x) (x)
#define htons(x) (x)

struct in_addr {
 u_long s_addr;
};

struct sockaddr_in {
 short sin_family;
 u_short sin_port;
 struct in_addr sin_addr;
 char sin_zero[8];
};

#define IPPROTO_IP    0
#define IPPROTO_ICMP  1
#define IPPROTO_IGMP  2
#define IPPROTO_GGP   3
#define IPPROTO_TCP   6
#define IPPROTO_EGP   8
#define IPPROTO_PUP   12
#define IPPROTO_UDP   17
#define IPPROTO_IDP   22
#define IPPROTO_HELLO 63
#define IPPROTO_ND    77

#define IPPROTO_RAW   255
#define IPPROTO_MAX   256

#define IP_OPTIONS          1
#define IP_MULTICAST_IF     2   /* may not be supported */
#define IP_MULTICAST_TTL    3   /* may not be supported */
#define IP_MULTICAST_LOOP   4   /* may not be supported */
#define IP_ADD_MEMBERSHIP   5   /* may not be supported */
#define IP_DROP_MEMBERSHIP  6   /* may not be supported */
#define IP_HDRINCL          7   /* may not be supported */
#define IP_TOS              8   /* may not be supported */
#define IP_TTL              9   /* may not be supported */
#define IP_RECVOPTS         10  /* may not be supported */
#define IP_RECVRETOPTS      11  /* may not be supported */
#define IP_RECVDSTADDR      12  /* may not be supported */
#define IP_RETOPTS          13  /* may not be supported */

Header File: netinet/tcp.h

#define TCP_NODELAY     0x01
#define TCP_MAXSEG      0x02

Header File: sys/ioctl.h

#define   IOCPARM_MASK  0xff
#define   IOC_VOID      0x20000000
#define   IOC_OUT       0x40000000
#define   IOC_IN        0x80000000
#define   IOC_INOUT     (IOC_IN|IOC_OUT)
#define   _IO(x,y)      (IOC_VOID|(x<<8)|y)
#define   _IOR(x,y,t)   (IOC_OUT|((((int)sizeof(t))\e
   &IOCPARM_MASK)<<16)|(x<<8)|y)
#define   _IORN(x,y,t)  (IOC_OUT|(((t)\e
   &IOCPARM_MASK)<<16)|(x<<8)|y)
#define   _IOW(x,y,t)   (IOC_IN|((((int)sizeof(t))\e
   &IOCPARM_MASK)<<16)|(x<<8)|y)
#define   _IOWN(x,y,t)  (IOC_IN|(((t)\e
   &IOCPARM_MASK)<<16)|(x<<8)|y)
#define   _IOWR(x,y,t)  (IOC_INOUT|((((int)sizeof(t))\e
   &IOCPARM_MASK)<<16)|(x<<8)|y)

#define   SIOCSHIWAT     _IOW('s',  0, int)
#define   SIOCGHIWAT     _IOR('s',  1, int)
#define   SIOCSLOWAT     _IOW('s',  2, int)
#define   SIOCGLOWAT     _IOR('s',  3, int)
#define   SIOCATMARK     _IOR('s',  7, int)
#define   SIOCSPGRP      _IOW('s',  8, int)
#define   SIOCGPGRP      _IOR('s',  9, int)
#define   SIOCADDRT      _IOW('r', 10, struct rtentry)
#define   SIOCDELRT      _IOW('r', 11, struct rtentry)
#define   SIOCSIFADDR    _IOW('i', 12, struct ifreq)
#define   SIOCGIFADDR    _IOWR('i',13, struct ifreq)
#define   SIOCSIFDSTADDR _IOW('i', 14, struct ifreq)
#define   SIOCGIFDSTADDR _IOWR('i',15, struct ifreq)
#define   SIOCSIFFLAGS   _IOW('i', 16, struct ifreq)
#define   SIOCGIFFLAGS   _IOWR('i',17, struct ifreq)
#define   SIOCSIFMEM     _IOW('i', 18, struct ifreq)
#define   SIOCGIFMEM     _IOWR('i',19, struct ifreq)
#define   SIOCGIFCONF    _IOWR('i',20, struct ifconf)
#define   SIOCSIFMTU     _IOW('i', 21, struct ifreq)
#define   SIOCGIFMTU     _IOWR('i',22, struct ifreq)
#define   SIOCGIFBRDADDR _IOWR('i',23, struct ifreq)
#define   SIOCSIFBRDADDR _IOW('i',24, struct ifreq)
#define   SIOCGIFNETMASK _IOWR('i',25, struct ifreq)
#define   SIOCSIFNETMASK _IOW('i',26, struct ifreq)
#define   SIOCGIFMETRIC  _IOWR('i',27, struct ifreq)
#define   SIOCSIFMETRIC  _IOW('i',28, struct ifreq)
#define   SIOCSARP       _IOW('i', 30, struct arpreq)
#define   SIOCGARP       _IOWR('i',31, struct arpreq)
#define   SIOCDARP       _IOW('i', 32, struct arpreq)
#define   SIOCUPPER      _IOW('i', 40, struct ifreq)
#define   SIOCLOWER      _IOW('i', 41, struct ifreq)
#define   SIOCSETSYNC    _IOW('i',  44, struct ifreq)
#define   SIOCGETSYNC    _IOWR('i', 45, struct ifreq)
#define   SIOCSSDSTATS   _IOWR('i', 46, struct ifreq)
#define   SIOCSSESTATS   _IOWR('i', 47, struct ifreq)
#define   SIOCSPROMISC   _IOW('i', 48, int)
#define   SIOCADDMULTI   _IOW('i', 49, struct ifreq)
#define   SIOCDELMULTI   _IOW('i', 50, struct ifreq)
#define   SIOCPROTO      _IOW('s', 51, struct socknewproto)
#define   SIOCGETNAME    _IOR('s', 52, struct sockaddr)
#define   SIOCGETPEER    _IOR('s', 53, struct sockaddr)
#define   IF_UNITSEL     _IOW('s', 54, int)
#define   SIOCXPROTO     _IO('s', 55)
#define   SIOCIFDETACH   _IOW('i', 56, struct ifreq)
#define   SIOCGENPSTATS  _IOWR('i', 57, struct ifreq)
#define   SIOCX25XMT     _IOWR('i', 59, struct ifreq)
#define   SIOCX25RCV     _IOWR('i', 60, struct ifreq)
#define   SIOCX25TBL     _IOWR('i', 61, struct ifreq)
#define   SIOCSLGETREQ   _IOWR('i', 71, struct ifreq)
#define   SIOCSLSTAT     _IOW('i', 72, struct ifreq)
#define   SIOCSIFNAME    _IOW('i', 73, struct ifreq)
#define   SIOCGENADDR    _IOWR('i', 85, struct ifreq)
#define   SIOCSOCKSYS    _IOW('i', 86, struct socksysreq)

Header File: netdb.h

struct hostent {
   char   *h_name;
   char   **h_aliases;
   int    h_addrtype;
   int    h_length;
   char   **h_addr_list;
#define   h_addr   h_addr_list[0]
};

struct netent {
   char           *n_name;
   char           **n_aliases;
   int            n_addrtype;
   unsigned long  n_net;
};

struct protoent {
   char  *p_name;
   char  **p_aliases;
   int   p_proto;
};

struct servent {
   char   *s_name;
   char   **s_aliases;
   int    s_port;
   char   *s_proto;
};

Header File: net/route.h

struct rtentry {
   u_long   rt_hash;
   struct   sockaddr rt_dst;
   struct   sockaddr rt_gateway;
   short    rt_flags;
   short    rt_refcnt;
   u_long   rt_use;
   union {
      struct  ip_provider *rtu_prov;
      struct  ifnet *rtu_ifp;
   } rt_u;
#define rt_prov rt_u.rtu_prov
#define rt_ifp rt_u.rtu_ifp
};

#define RTF_UP         0x1
#define RTF_GATEWAY    0x2
#define RTF_HOST       0x4
#define RTF_REINSTATE  0x8
#define RTF_DYNAMIC    0x10
#define RTF_MODIFIED   0x20

#define RTF_SWITCHED   0x40
#define RTF_SLAVE      0x80
#define RTF_REMOTE     0x100
#define RTF_TOSWITCH   0x200

Header File: sys/socket.h

#define  AF_UNSPEC     0
#define  AF_UNIX       1
#define  AF_INET       2
#define  AF_IMPLINK    3
#define  AF_PUP        4
#define  AF_CHAOS      5
#define  AF_NS         6
#define  AF_NBS        7
#define  AF_ECMA       8
#define  AF_DATAKIT    9
#define  AF_CCITT      10
#define  AF_SNA        11
#define  AF_DECnet     12
#define  AF_DLI        13
#define  AF_LAT        14
#define  AF_HYLINK     15
#define  AF_APPLETALK  16
#define  AF_NIT        17
#define  AF_802        18
#define  AF_OSI        19
#define  AF_X25        20
#define  AF_OSINET     21
#define  AF_GOSIP      22

struct sockaddr {
   u_short  sa_family;
   char     sa_data[14];
};

#define  SO_DEBUG       0x0001
#define  SO_ACCEPTCONN  0x0002
#define  SO_REUSEADDR   0x0004
#define  SO_KEEPALIVE   0x0008
#define  SO_DONTROUTE   0x0010
#define  SO_BROADCAST   0x0020
#define  SO_USELOOPBACK 0x0040
#define  SO_LINGER      0x0080
#define  SO_OOBINLINE   0x0100
#define  SO_IMASOCKET   0x0400

#define  SOL_SOCKET   0xffff

struct   linger {
   int   l_onoff;
   int   l_linger;
};

#define  SOCK_DGRAM     1
#define  SOCK_STREAM    2
#define  SOCK_RAW       4
#define  SOCK_RDM       5
#define  SOCK_SEQPACKET 6

#define  PF_UNSPEC     AF_UNSPEC
#define  PF_UNIX       AF_UNIX
#define  PF_INET       AF_INET
#define  PF_IMPLINK    AF_IMPLINK
#define  PF_PUP        AF_PUP
#define  PF_CHAOS      AF_CHAOS
#define  PF_NS         AF_NS
#define  PF_NBS        AF_NBS
#define  PF_ECMA       AF_ECMA
#define  PF_DATAKIT    AF_DATAKIT
#define  PF_CCITT      AF_CCITT
#define  PF_SNA        AF_SNA
#define  PF_DECnet     AF_DECnet
#define  PF_DLI        AF_DLI
#define  PF_LAT        AF_LAT
#define  PF_HYLINK     AF_HYLINK
#define  PF_APPLETALK  AF_APPLETALK
#define  PF_NIT        AF_NIT
#define  PF_802        AF_802
#define  PF_OSI        AF_OSI
#define  PF_X25        AF_X25
#define  PF_OSINET     AF_OSINET
#define  PF_GOSIP      AF_GOSIP

struct msghdr {
   caddr_t  msg_name;
   int      msg_namelen;
   struct   iovec *msg_iov;
   int      msg_iovlen;
   caddr_t  msg_accrights;
   int      msg_accrightslen;
};

#define  MSG_OOB       0x1
#define  MSG_PEEK      0x2
#define  MSG_DONTROUTE 0x4

struct socknewproto {
   int     family;
   int     type;
   int     proto;
   dev_t   dev;
   int     flags;
};

struct socksysreq {
   int     args[7];
};

Header File: sys/types.h

#ifndef   FD_SETSIZE
#define   FD_SETSIZE   1024
#endif

#ifndef NBBY
#define NBBY 8
#endif

typedef   long     fd_mask;
#define   NFDBITS  (sizeof(fd_mask) * NBBY)
#ifndef   howmany
#define   howmany(x, y)  (((x)+((y)-1))/(y))
#endif

typedef   struct fd_set {
   fd_mask   fds_bits[howmany(FD_SETSIZE, NFDBITS)];
} fd_set;

#define  FD_SET(n, p)   ((p)->fds_bits[(n)/NFDBITS] \e
                     |= (1 << ((n) % NFDBITS)))
#define  FD_CLR(n, p)   ((p)->fds_bits[(n)/NFDBITS] \e
                     &= ~(1 << ((n) % NFDBITS)))
#define  FD_ISSET(n, p) ((p)->fds_bits[(n)/NFDBITS] \e
                     &  (1 << ((n) % NFDBITS)))
#define  FD_ZERO(p)     memset((char *)(p), 0, sizeof(*(p)))

libucb.a

libucb.a provides many of the popular interfaces from BSD UNIX. It is intended to be used as a migration path for ISVs moving applications from BSD UNIX to SVR4. Over time all ISVs are encouraged to move to the SVR4 ABI interfaces since they may not be supported in the future. It is also important to note that use of libucb.a pulls in all of its BSD interfaces. This can result in subtle problems for applications which mix BSD and SVR4 interfaces, for example using the BSD printf and SVR4 readdir. In the previous case, both the printf and readdir calls would use the BSD version. This class of problem will be exposed at runtime rather than compile time.

Symbols Contained in libucb.a

alloca	alphasort	bcmp
bcopy	bzero	dbm_close
dbm_delete	dbm_do_nextkey	dbm_fetch
dbm_firsthash	dbm_firstkey	dbm_forder
dbm_nextkey	dbm_open	dbm_store
dc	endusershell	fopen
fp_accrued_exceptions	fp_class_d	fp_class_f
fp_direction	fp_precision	fprintf
ftime	getdtablesize	gethostid
gethostname	getpagesize	getrusage
getusershell	getwd	ieee_handlers
index	initstate	isnan
killpg	longjmp	mctl
mkstemp	printf	psignal
rand	random	re_comp
re_exec	readdir	rindex
scandir	sethostname	setjmp
setstate	setusershell	sigblock
sigfpe	siginterrupt	signal
sigpause	sigsetmask	sigstack
sigvec	sleep	sprintf
srand	srandom	strcasecmp
strncasecmp	sys_siglist	times
timezone	ualarm	usleep
utimes	vfprintf	vprintf
vsprintf	wait3

X11R5 Support (libX11)

Graphical MIPS ABI conformant applications may be constructed using the X Window System, Version 11, Release 5 (X11R5). The gABI specifies X11R4 but indicates an intent to track upward compatible future releases of the X Window System. Prior versions of this document relied on the gABI specification of X11R4 and did not have MIPS ABI extensions in this area.

The basic X11 support library, libX11 shall be supported as a DSO, libX11.so.2, by ABI-conforming systems. (libX11.so.1 is reserved for implementations that may have had X11R4 versions.) The X Toolkit Intrinsics library, libXt, is supplied as a static archive in the ABI build environment. An ABI-conforming system shall provide the following include files whose content is defined by the X11R5 Reference Manual.

X11R5 Include Files

X11/cursorfont.h	X11/keysymdef.h	X11/X.h
X11/Xatom.h	X11/Xcms.h	X11/Xlib.h
X11/Xproto.h	X11/Xresource.h	X11/Xutil.h

X11R5 X Toolkit Intrinsics Include Files

X11/Intrinsic.h	X11/IntrinsicP.h	X11/Shell.h
X11/ShellP.h	X11/StringDefs.h	X11/Vendor.h
X11/VendorP.h

OSF/Motif 1.2 Support (libXm)

An ABI-conforming system shall support Release 1.2 of the OSF/Motif software as a static library in the ABI build environment, libXm.a. Previously, the RISC/os reference platform supported OSF/Motif 1.1 as a static library that was bound into the application at build time.

An ABI-conforming system shall provide the following include files whose content is defined by the OSF/Motif Programmer's Reference Manual.

OSF/Motif 1.2 Include Files

Xm/ArrowB.h	Xm/ArrowBG.h	Xm/BulletinB.h
Xm/CascadeB.h	Xm/CascadeBG.h	Xm/Command.h
Xm/CutPaste.h	Xm/DialogS.h	Xm/DrawingA.h
Xm/DrawnB.h	Xm/FileSB.h	Xm/Form.h
Xm/Frame.h	Xm/Label.h	Xm/LabelG.h
Xm/List.h	Xm/MainW.h	Xm/MenuShell.h
Xm/MessageB.h	Xm/PanedW.h	Xm/Protocols.h
Xm/PushB.h	Xm/PushBG.h	Xm/RowColumn.h
Xm/Scale.h	Xm/ScrollBar.h	Xm/ScrolledW.h
Xm/SelectioB.h	Xm/SeparatoG.h	Xm/Separator.h
Xm/Text.h	Xm/ToggleB.h	Xm/ToggleBG.h
Xm/Xm.h	Xm/XmP.h

mmap

A group of programs may need to specify the address of shared memory and mapped file regions in order to use the same addresses to access these regions. The address range from 0x30000000 to 0x3fff0000 is reserved for this purpose; additional contiguous space above this range is recommended and may be supported. A MIPS ABI conforming system guarantees that shared memory and mapped file regions placed by the system will not fall in this range.

The placement of a shared memory or mapped file region by a program must follow these rules:

The address range of the reserved region will at least lie between 0x30000000 to 0x3fff0000.
No two fixed regions may occupy the same chunk of memory, modulo 256K.
The address of a mapped file region and the corresponding file offset must be congruent modulo 256K.

For example, if a program wants to create a 0x3000-byte shared memory region and map a file with an offset of 0x2000 and length of 0x1000, both regions will have fixed addresses. One possible placement of these regions puts the shared memory region at [0x30000000, 0x30000fff] and the mapped file at [0x30042000, 0x30042fff].

Implementors using mmap() are advised that the gABI requires

the system will zero fill any partial page at the end of an mmap()'ed object
the system will never write out any modified portions of the last page of an object which are beyond its end, i.e. mmap() cannot be used to extend the size of a file.
references to whole pages following the end of an object will result in the delivery of a SIGBUS signal.

The RunTime Dynamic Linking Library

The libdl library allows users to dynamically link shared libraries after a program is launched. Shared libraries are accessed with dlopen() and released with dlclose(). Symbols in shared libraries opened via dlopen() can be located by calling dlsym(). If an error occurs, dlerror() provides a formatted error message that describes the problem.

libdl provides the following routines:

cc  [flag ...] file  ...  -ldl [library ...]

void *dlopen(char *pathname, int mode);
   /* returns a handle for future dlclose() 
    * and dlsym() calls */

int dlclose(void *handle);
   /* returns zero on success, non-zero otherwise */

void *dlsym(void *handle, char *name);
   /* returns the address of the symbol , 
    * else NULL if not found  */

char *dlerror(void);
   /* returns formatted string of last error */

Complete information is provided in the UNIX SVR4 Programmer's Reference Manual.

Implementation notes:

dlopen() looks for DT_NEEDED entries in the \&.dynamic section of the shared library it opens and, for each entry, invokes dlopen() on the shared library entry names. This process recurses until all libraries specified by DT_NEEDED entries have been loaded. In no case will the dynamic linker link in a shared library twice.
dlclose() unmaps the shared library associated with the handle passed to it and any other libraries that were linked via the recursive process described above. It guarantees that a library is not unlinked until all the references to it are closed.
dlsym() restricts its search to the shared libraries linked by the dlopen() that created its handle. The search looks first in the shared library referenced by the handle and then recursively traverses libraries named in DT_NEEDED entries in a breadth-first order.
dlerror() returns an English message; it is not internationalized.
The libdl library is implemented as shared library, libdl.so. It is installed in /usr/lib.

sysinfo

The following are additions to commands supported by sysinfo. The new and recommended routines are described below, along with examples. A sysinfo header file, including the additional commands, follows. See vendor release notes for vendor values.

_MIPS_SI_VENDOR
_MIPS_SI_OS_PROVIDER
_MIPS_SI_OS_NAME
_MIPS_SI_HW_NAME
_MIPS_SI_NUM_PROCESSORS
_MIPS_SI_HOSTID
_MIPS_SI_OSREL_MAJ
_MIPS_SI_OSREL_MIN
_MIPS_SI_OSREL_PATCH
_MIPS_SI_PROCESSORS

There are no additions to the system level commands.

The following figure shows the systeminfo.h file.

Header File: systeminfo.h

#define SI_SYSNAME               1    
#define SI_HOSTNAME              2   
#define SI_RELEASE               3   
#define SI_VERSION               4  
#define SI_MACHINE               5  
#define SI_ARCHITECTURE          6 
#define SI_HW_SERIAL             7 
#define SI_HW_PROVIDER           8 
#define SI_SRPC_DOMAIN           9 
#define _MIPS_SI_VENDOR          100 
#define _MIPS_SI_OS_PROVIDER     101 
#define _MIPS_SI_OS_NAME         102 
#define _MIPS_SI_HW_NAME         103 
#define _MIPS_SI_NUM_PROCESSORS  104 
#define _MIPS_SI_HOSTID          105 
#define _MIPS_SI_OSREL_MAJ       106 
#define _MIPS_SI_OSREL_MIN       107 
#define _MIPS_SI_OSREL_PATCH     108 
#define _MIPS_SI_PROCESSORS      109

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last modified on August 17, 1995