ifp1
 use ..../defs/os9defs.a
 endc
Carry equ %00000001
Write. equ 2 write access
FD.Att equ 0 FD offset to attr
FD.Own equ 1 FD offset to owner

Bufsize equ 16 FD info bytes

 psect change,0,0,2,0,0

* chown(fname,owner)
chown:
 pshs y,u save registers
 leas -Bufsize,s reserve buffer space
 os9 F$ID get user ID
 bcs chexit bra if error
 ldb #E$FNA prime for error
 cmpy #0 superuser?
 orcc #Carry prime the carry
 bne chexit bra if not

 bsr openfile open file and read FD
 bcs chexit bra if error

 pshs a save path number
 ldd Bufsize+9,s get the new owner id
 std FD.Own,x modify the FD
 puls a restore path number
 ldb #SS.FD write FD code
 os9 I$SETSTT write the FD
 bcs chexit bra if error
 os9 I$CLOSE close the file

* carry set is error exit, clear for normal
chexit
 leas Bufsize,s return scratch
 puls y,u restore regs
 lbra _sysret return to caller

*
* open file and fetch file FD
* Bufsize buffer is at 2,s
*
openfile
 lda #Write. access mode
 ldx Bufsize+8,s address of name
 os9 I$OPEN open the file
 bcc openf10 exit if error
 rts

openf10
 leax 2,s get buffer address
 ldy #Bufsize and size
 ldb #SS.FD read FD code
 os9 I$GETSTT read the FD
 rts

* chmod(fname,perm)
chmod:
 pshs y,u save registers
 leas -Bufsize,s reserve buffer space

 bsr openfile open file and read FD
 bcs chexit bra if error

 pshs a,y save regs
 os9 F$ID get user id
 cmpy #0 super-user?
 beq chmod10 yes, he can do it
 ldb #E$FNA prime for error
 cmpy FD.Own,x user's own file?
 orcc #Carry prime the carry
 bne chexit no, return error

chmod10
 ldb Bufsize+12,s get the new attributes
 stb FD.Att,x update FD
 puls a,y restore path number
 ldb #SS.FD write FD code
 os9 I$SETSTT write the FD
 bcs chexit bra if error
 os9 I$CLOSE close the file
 bra chexit and exit

 endsect