MODULE _unix;   (* connect to unix host *)
IMPORT SYSTEM, API;

(* how to find C declarations:
- gcc -E        preprocess only (to stdout) (preprocessor expand)
- grep -r  name  /usr/include/*
- ldd progfile
- objdump -T progfile  (-t) (-x)
*)

CONST   RTLD_LAZY = 1;
        BIT_DEPTH* = API.BIT_DEPTH;

VAR sym, libc, libdl :INTEGER;

        _dlopen* :PROCEDURE [linux] (name, flags :INTEGER) :INTEGER;
        _dlsym* :PROCEDURE [linux] (p, name :INTEGER) :INTEGER;
        _dlclose* :PROCEDURE [linux] (p :INTEGER) :INTEGER;
        _open* :PROCEDURE [linux] (name, flags, mode :INTEGER) :INTEGER;
        _close* :PROCEDURE [linux] (fd :INTEGER) :INTEGER;
        _read* :PROCEDURE [linux] (fd, buf, sz :INTEGER): INTEGER;
        _write* :PROCEDURE [linux] (fd, buf, sz :INTEGER) :INTEGER;
        _exit* :PROCEDURE [linux] (n :INTEGER);
        _malloc* :PROCEDURE [linux] (sz :INTEGER) :INTEGER;
        _select* :PROCEDURE [linux] (cnt, readfds, writefds, exceptfds, timeout :INTEGER) :INTEGER;

        (* error message to stderr *)
PROCEDURE writeChar (c :CHAR);
VAR ri :INTEGER;
BEGIN ri := _write (2, SYSTEM.ADR(c), 1); ASSERT (ri = 1) END writeChar;

PROCEDURE writeString (s :ARRAY OF CHAR);
VAR i :INTEGER;
BEGIN i := 0; WHILE s[i] # 0X DO writeChar (s[i]); INC(i) END; END writeString;

PROCEDURE nl;
BEGIN writeChar (0AX) END nl;


PROCEDURE getSymAdr (lib :INTEGER; name :ARRAY OF CHAR; adr :INTEGER);
BEGIN
        sym := _dlsym (lib, SYSTEM.ADR(name[0]));
        IF sym = 0 THEN writeString ("error: dlsym: "); writeString (name); nl END;
        ASSERT (sym # 0);
        SYSTEM.PUT (adr, sym)
END getSymAdr;


PROCEDURE finish*;
VAR ri :INTEGER;
BEGIN
        IF libc # 0 THEN ri := _dlclose (libc); libc := 0 END;
        IF libdl # 0 THEN ri := _dlclose (libdl); libdl := 0 END;
END finish;


BEGIN
        _dlopen := API.dlopen;
        _dlsym := API.dlsym;
        libc := _dlopen (SYSTEM.SADR("libc.so.6"), RTLD_LAZY); ASSERT (libc # 0);
                (* getSymAdr is not used for write() to get writeString() error message going *);
        sym := _dlsym (libc, SYSTEM.SADR("write")); ASSERT (sym # 0); SYSTEM.PUT (SYSTEM.ADR(_write), sym);

        libdl := _dlopen (SYSTEM.SADR("libdl.so.2"), RTLD_LAZY); ASSERT (libdl # 0);
        getSymAdr (libdl, "dlclose", SYSTEM.ADR(_dlclose));

        getSymAdr (libc, "open", SYSTEM.ADR(_open));
        getSymAdr (libc, "close", SYSTEM.ADR(_close));
        getSymAdr (libc, "read", SYSTEM.ADR(_read));
        getSymAdr (libc, "exit", SYSTEM.ADR(_exit));
        getSymAdr (libc, "malloc", SYSTEM.ADR(_malloc));
        getSymAdr (libc, "select", SYSTEM.ADR(_select));
END _unix.