From 2d04cacc5322951f187bb17e017c12920ac8ebe2 Mon Sep 17 00:00:00 2001
From: Mark Zbikowski
Date: Thu, 25 Apr 2024 21:24:10 +0100
Subject: MZ is back!

---
 v4.0/src/DOS/SHARE.ASM | 151 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 151 insertions(+)
 create mode 100644 v4.0/src/DOS/SHARE.ASM

(limited to 'v4.0/src/DOS/SHARE.ASM')

diff --git a/v4.0/src/DOS/SHARE.ASM b/v4.0/src/DOS/SHARE.ASM
new file mode 100644
index 0000000..ded4cd7
--- /dev/null
+++ b/v4.0/src/DOS/SHARE.ASM
@@ -0,0 +1,151 @@
+;	SCCSID = @(#)share.asm	1.1 85/04/10
+TITLE   SHARING ROUTINES - Routines for file Sharing
+NAME    SHARE
+
+include dosseg.asm
+
+CODE    SEGMENT BYTE PUBLIC  'CODE'
+	ASSUME  SS:DOSGROUP,CS:DOSGROUP
+
+.xlist
+.xcref
+INCLUDE DOSSYM.INC
+INCLUDE DEVSYM.INC
+.cref
+.list
+
+AsmVars <IBM, Installed>
+
+Installed = True
+
+	i_need  THISDPB,DWORD
+	i_need  EXTERR,WORD
+	i_need  ReadOp,BYTE
+	i_need  ThisSFT,DWORD
+	i_need  ALLOWED,BYTE
+	I_need  RetryCount,WORD
+	i_need  JShare,DWORD
+
+; Inputs:
+;       [THISSFT] Points to filled in local file/device SFT for new
+;               instance of file sf_mode ALWAYS has mode (even on FCB SFTs)
+;       [WFP_START] has full path of name
+;       [USER_ID] Set
+;       [PROC_ID] Set
+; Function:
+;       Check for sharing violations on local file/device access
+; Outputs:
+;    Carry clear
+;       Sharing approved
+;    Carry set
+;       A sharing violation detected
+;           AX is error code
+; USES    ALL but DS
+
+	procedure   SHARE_CHECK,NEAR
+	DOSAssume   CS,<DS>,"Share_Check"
+	ASSUME  ES:NOTHING
+
+if installed
+	call    JShare + 1 * 4
+else
+	Call    MFT_Enter
+endif
+	return
+
+EndProc SHARE_CHECK
+
+; Inputs:
+;       [THISDPB] Set
+;       AX has error code
+; Function:
+;       Handle Sharing errors
+; Outputs:
+;       Carry set if user says FAIL, causes error_sharing_violation
+;       Carry clear if user wants a retry
+;
+; DS, ES, DI preserved, others destroyed
+
+	procedure   SHARE_VIOLATION,NEAR
+	DOSAssume   CS,<DS>,"Share_Violation"
+	ASSUME  ES:NOTHING
+
+	PUSH    DS
+	PUSH    ES
+	PUSH    DI
+	MOV     [READOP],0                      ; All share errors are reading
+	MOV     [ALLOWED],allowed_FAIL + allowed_RETRY
+	LES     BP,[THISDPB]
+	MOV     DI,1                            ; Fake some registers
+	MOV     CX,DI
+	MOV     DX,ES:[BP.dpb_dir_sector]
+	invoke  HARDERR
+	POP     DI
+	POP     ES
+	POP     DS
+	CMP     AL,1
+	retz                    ; 1 = retry, carry clear
+	STC
+	return
+
+EndProc SHARE_VIOLATION
+
+;   ShareEnd - terminate sharing info on a particular SFT/UID/PID.  This does
+;       NOT perform a close, it merely asserts that the sharing information
+;       for the SFT/UID/PID may be safely released.
+;
+;   Inputs:     ES:DI points to an SFT
+;   Outputs:    None
+;   Registers modified: all except DS,ES,DI
+
+	procedure   ShareEnd,Near
+	DOSAssume   CS,<DS>,"ShareEnd"
+	ASSUME  ES:NOTHING
+
+if installed
+	Call    JShare + 2 * 4
+else
+	Call    MFTClose
+endif
+	return
+
+EndProc ShareEnd
+
+break <ShareEnter - attempt to enter a node into the sharing set>
+
+;
+;   ShareEnter - perform a retried entry of a nodde into the sharing set.  If
+;   the max number of retries is exceeded, we notify the user via int 24.
+;
+;   Inputs:     ThisSFT points to the SFT
+;               WFP_Start points to the WFP
+;   Outputs:    Carry clear => successful entry
+;               Carry set => failed system call
+;   Registers modified: all
+
+Procedure   ShareEnter,NEAR
+	DOSAssume   CS,<DS>,"ShareEnter"
+	assume  es:nothing
+
+	SaveReg <CX>
+retry:
+	mov     cx,RetryCount
+attempt:
+	les     di,ThisSFT              ; grab sft
+	XOR     AX,AX
+	MOV     ES:[DI.sf_MFT],AX       ; indicate free SFT
+	SaveReg <CX>
+	call    Share_Check             ; attempt to enter into the sharing set
+	RestoreReg  <CX>
+	jnc     done                    ; success, let the user see this
+	invoke  Idle                    ; wait a while
+	loop    attempt                 ; go back for another attempt
+	call    Share_violation         ; signal the problem to the user
+	jnc     retry                   ; user said to retry, go do it
+done:
+	RestoreReg  <CX>
+	return
+EndProc ShareEnter
+
+CODE    ENDS
+    END
-- 
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