From fd66eeefaf18f00c5460ab7c329677644c8b7f15 Mon Sep 17 00:00:00 2001
From: Timothy E Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
Date: Mon, 25 Jan 2021 18:19:44 +0000
Subject: [PATCH] Fix OS_EvaluateExpression
OS_EvaluateExpression is documented as applying GSTrans to any strings
within the expression, but did instead GSTrans the entire expression.
This would result in a sequence such as:
*Set Alias$@RunType_FD1 "Basic -quit ""%0"" %*1"
*If "<Alias$@RunType_FD1>"="" Then Set Alias$@RunType_FD1 @RunType_FFB %*0
raising a "Unknown operand" error as the quote in the variable
were interpreted as expression syntax. See
https://www.riscosopen.org/forum/forums/5/topics/16127
Unfortunately skipping the initial GSTrans breaks common code such as:
If "<StrED_cfg$Dir>" = "" AND <Ctrl$Pressed> = 0 Then ...
If "<Zap$OSVsn>" <> "" Then SetEval ZapFonts$OSVsn <Zap$OSVsn>
Fix by applying a GSTrans transformation over unquoted parts of the
expression, then applying GSTrans over the quoted strings.
Version 6.51. Tagged as 'Kernel-6_51'
---
VersionASM | 12 +++---
VersionNum | 20 +++++-----
s/Arthur2 | 3 ++
s/Arthur3 | 107 +++++++++++++++++++++++++++++++++++++++--------------
4 files changed, 99 insertions(+), 43 deletions(-)
diff --git a/VersionASM b/VersionASM
index 06e742a..5f3ed41 100644
--- a/VersionASM
+++ b/VersionASM
@@ -9,12 +9,12 @@
GBLS Module_ApplicationDate
GBLS Module_HelpVersion
GBLS Module_ComponentName
-Module_MajorVersion SETS "6.50"
-Module_Version SETA 650
+Module_MajorVersion SETS "6.51"
+Module_Version SETA 651
Module_MinorVersion SETS ""
-Module_Date SETS "30 Jan 2021"
-Module_ApplicationDate SETS "30-Jan-21"
+Module_Date SETS "10 Feb 2021"
+Module_ApplicationDate SETS "10-Feb-21"
Module_ComponentName SETS "Kernel"
-Module_FullVersion SETS "6.50"
-Module_HelpVersion SETS "6.50 (30 Jan 2021)"
+Module_FullVersion SETS "6.51"
+Module_HelpVersion SETS "6.51 (10 Feb 2021)"
END
diff --git a/VersionNum b/VersionNum
index c0a5771..1e72e5a 100644
--- a/VersionNum
+++ b/VersionNum
@@ -1,21 +1,21 @@
-/* (6.50)
+/* (6.51)
*
* This file is automatically maintained by srccommit, do not edit manually.
*
*/
-#define Module_MajorVersion_CMHG 6.50
+#define Module_MajorVersion_CMHG 6.51
#define Module_MinorVersion_CMHG
-#define Module_Date_CMHG 30 Jan 2021
+#define Module_Date_CMHG 10 Feb 2021
-#define Module_MajorVersion "6.50"
-#define Module_Version 650
+#define Module_MajorVersion "6.51"
+#define Module_Version 651
#define Module_MinorVersion ""
-#define Module_Date "30 Jan 2021"
+#define Module_Date "10 Feb 2021"
-#define Module_ApplicationDate "30-Jan-21"
+#define Module_ApplicationDate "10-Feb-21"
#define Module_ComponentName "Kernel"
-#define Module_FullVersion "6.50"
-#define Module_HelpVersion "6.50 (30 Jan 2021)"
-#define Module_LibraryVersionInfo "6:50"
+#define Module_FullVersion "6.51"
+#define Module_HelpVersion "6.51 (10 Feb 2021)"
+#define Module_LibraryVersionInfo "6:51"
diff --git a/s/Arthur2 b/s/Arthur2
index 3d7a062..947a5ee 100644
--- a/s/Arthur2
+++ b/s/Arthur2
@@ -465,6 +465,9 @@ GS_StackLimitPos * 19 ; The bit position of the LSB of the byte
; After GSINIT, R2 has these flags, and if expanding a count in the low byte
+; The flags GS_ReadingString and GS_Macroing returned by GSREAD are used by
+; ReadExpression in Arthur3.
+
GSINIT ROUT
; In : R0 pointer to string to expand
; R2 has flags :
diff --git a/s/Arthur3 b/s/Arthur3
index 69a2ed0..09f0974 100644
--- a/s/Arthur3
+++ b/s/Arthur3
@@ -267,20 +267,82 @@ ExprBuffOFlo ROUT
Pull "R0-R4, lr"
B SLVK_SetV
+ReadExpression_Error
+ LDR R5, [stack], #8
+ [ International
+ BL TranslateError
+ ]
+ Pull "R1-R4, lr"
+ B SLVK_SetV
+
ReadExpression ROUT
Push "R0-R4, lr"
CLRPSR I_bit, R12 ; interrupts on, ta.
LDR R12, =ExprWSpace
STR R13, ExprSVCstack
- LDR R1, =ExprBuff
- MOV R2, #LongCLISize
- ORR R2, R2, #(1 :SHL: 30) :OR: (1 :SHL: 31)
- SWI XOS_GSTrans ; No | transformation, no " or space termination.
- ; so can never go wrong!
- BCS ExprBuffOFlo
+
+ ; Historically in violation of the behaviour documented in the
+ ; Programmer's Reference Manual the expression was passed to
+ ; OS_GSTrans, which would transform a reasonable expression such as
+ ; "<Alias$@RunType_FFB>"="" into "Basic -quit "%0" %*1"="" which
+ ; is not a valid expression.
+ ;
+ ; Unfortunately merely removing this transformation breaks
+ ; software that references system variable using angle brackets
+ ; but not quote marks. eg. SetEval ZapFonts$OSVsn <Zap$OSVsn>
+ ;
+ ; Instead process the unquoted parts of the expression using
+ ; OS_GSRead, using the internal flags to detect when a variable
+ ; is being expanded.
+
+ ; Register allocation for code below:
+ ; R0 = Pointer to expression passed by caller
+ ; R1 = Character read
+ ; R2 = GSRead flags
+ ; R3 = pointer into ExprBuff
+ ; R4 = bytes remaining in output buffer - 1
+ ; R5 = flag to indicate not in quoted string
+
+ Push "R5"
+ LDR R3, =ExprBuff
+ MOV R4, #LongCLISize
+ MOV R2, #GS_NoQuoteMess | GS_NoVBarStuff
+ SUBS R4, R4, #2
+ SWI XOS_GSInit
+ BVS ReadExpression_Error
+ MOV R5, #0x100
+
+00 ; If OS_GSRead is reading a system variable, or outside quotes
+ ; then use OS_GSRead, else read directly.
+ TST R2, #GS_ReadingString | GS_Macroing
+ TSTEQ R5, #0x100 ; Clears C
+ LDREQB R1, [R0], #1
+ SWINE XOS_GSRead
+ BVS ReadExpression_Error
+
+ ; Check for end of expression
+ BCS %FT00
+ CMP R1, #13
+ CMPNE R1, #10
+ CMPNE R1, #0
+ BEQ %FT00
+
+ ; Write character into buffer, check for overflow.
+ STRB R1, [R3], #1
+ SUBS R4, R4, #1
+ BMI ExprBuffOFlo
+
+ ; Toggle quote flag if needed and continue loop
+ TEQ R1, #""""
+ EOREQ R5, R5, #0x100
+ B %BT00
+
+00 ; Write terminator
MOV R0, #13
- STRB R0, [R1, R2]
+ STRB R0, [R3]
+ LDR R1, =ExprBuff
+ Pull "R5"
LDR R11, =ExprStackStart
LDR R10, =ExprStackLimit
MOV R0, #0
@@ -1085,28 +1147,19 @@ DivZeroErr
B ExprErrCommon
MakeErrorBlock DivZero
-04
- LDR R2, =exprSTRACC
-05
- LDRB R0, [R1], #1
- CMP R0, #13
- CMPNE R0, #10
- CMPNE R0, #0
- BEQ BadStringErr
- CMP R0, #""""
- BEQ %FT06
-07
- STRB R0, [R2], #1 ; can't overflow - comes from buffer
- B %BT05
+05 LDR R13, ExprSVCstack
+ B BumNumber2
-06
- LDRB R0, [R1], #1
- CMP R0, #""""
- BEQ %BT07
- SUB R1, R1, #1
- LDR R0, =exprSTRACC
- SUB R2, R2, R0 ; length to R2
+04
Push "lr"
+ SUB R0, R1, #1
+ LDR R1, =exprSTRACC
+ MOV R2, #LongCLISize
+ ORR R2, R2, #GS_NoVBarStuff | GS_Spc_term
+ SWI XOS_GSTrans
+ BCS ExprBuffOFlo
+ BVS %BT05
+ MOV R1, R0
BL Push_String
ePush "R0, R2"
Pull "PC"
--
GitLab