[480] Make use of fsfile_ReadInfoNoLen

Update EnsureCanonicalObject so that it can optionally skip reading the
file/object length, based on the new argument R7. Then trace back
through the callers to have them pass in an appropriate value based on
whether they care about the length or not.

TopPath_DoBusinessToPath has also gained a new flag bit to suppress
reading the length, but so far I've only updated DoThePath to use it.

Result: If you have a file in PipeFS which is open for writing, and then
attempt to open it for reading using OS_Find, it'll now open immediately
instead of PipeFS trying to block/sleep until it's no longer open for
writing.

Why: Since at least as far back as RISC OS 3.6, PipeFS tries to sleep
inside fsfile_ReadInfo if the file is open for writing. But a
combination of buggy sleep logic and TaskWindow's lazy approach to
UpCall 6 meant that (prior to TaskWindow 0.65) it wouldn't sleep for
long and would instead allow the open to proceed while the file is still
open for write. The ability to have both a reader & writer active at the
same time is basically the whole point of PipeFS, so this change
restores that pre-TaskWindow 0.65 behaviour without having to remove the
sleep logic from PipeFS (it's a well-intentioned feature, even though
it's been broken for decades)

Tested by performing a ROM build, checking that it works, and running
some PipeFS tests.

This fixes the original issue described in ticket 480:
https://www.riscosopen.org/tracker/tickets/480

Version 2.90. Tagged as 'FileSwitch-2_90'

VersionASM

@@ -9,12 +9,12 @@
                         GBLS    Module_ApplicationDate
                         GBLS    Module_HelpVersion
                         GBLS    Module_ComponentName
-Module_MajorVersion     SETS    "2.89"
-Module_Version          SETA    289
+Module_MajorVersion     SETS    "2.90"
+Module_Version          SETA    290
 Module_MinorVersion     SETS    ""
-Module_Date             SETS    "24 Dec 2022"
-Module_ApplicationDate  SETS    "24-Dec-22"
+Module_Date             SETS    "23 Jan 2023"
+Module_ApplicationDate  SETS    "23-Jan-23"
 Module_ComponentName    SETS    "FileSwitch"
-Module_FullVersion      SETS    "2.89"
-Module_HelpVersion      SETS    "2.89 (24 Dec 2022)"
+Module_FullVersion      SETS    "2.90"
+Module_HelpVersion      SETS    "2.90 (23 Jan 2023)"
                         END

VersionNum

-/* (2.89)
+/* (2.90)
  *
  * This file is automatically maintained by srccommit, do not edit manually.
  *
  */
-#define Module_MajorVersion_CMHG        2.89
+#define Module_MajorVersion_CMHG        2.90
 #define Module_MinorVersion_CMHG
-#define Module_Date_CMHG                24 Dec 2022
+#define Module_Date_CMHG                23 Jan 2023
 
-#define Module_MajorVersion             "2.89"
-#define Module_Version                  289
+#define Module_MajorVersion             "2.90"
+#define Module_Version                  290
 #define Module_MinorVersion             ""
-#define Module_Date                     "24 Dec 2022"
+#define Module_Date                     "23 Jan 2023"
 
-#define Module_ApplicationDate          "24-Dec-22"
+#define Module_ApplicationDate          "23-Jan-23"
 
 #define Module_ComponentName            "FileSwitch"
 
-#define Module_FullVersion              "2.89"
-#define Module_HelpVersion              "2.89 (24 Dec 2022)"
-#define Module_LibraryVersionInfo       "2:89"
+#define Module_FullVersion              "2.90"
+#define Module_HelpVersion              "2.90 (23 Jan 2023)"
+#define Module_LibraryVersionInfo       "2:90"

s/Canonical

@@ -1192,9 +1192,10 @@ ResolveWildcardBySteam Entry "r1,r3,r4,r5,r6,r7"
 ; Out   r2 = RMAlloced resolved wildcard, or NULL if not found
 ;
 
-ResolveWildcard Entry "r0,r1,r2,r3,r4,r5,fscb"
+ResolveWildcard Entry "r0,r1,r2,r3,r4,r5,r7,fscb"
 
         ; Ensure the directory exists, but don't care about it's attributes
+        MOV     r7, #fsfile_ReadInfoNoLen
         BL      EnsureCanonicalObject
         BLVC    AssessDestinationForPathTailForDirRead
         EXIT    VS

s/DirStore

@@ -423,6 +423,7 @@ ReadDir Entry   "r0-r9,fscb", ReadDir_LocalSize
         MOV     r3, #0                  ; @-relativity
         ADR     r6, ReadDir_Special
         LDR     fscb, [sp, #Proc_LocalStack + 10*4]
+        MOV     r7, #fsfile_ReadInfoNoLen
         BL      EnsureObjectCommon
         BVS     %FT90
 

s/Ensure

@@ -33,6 +33,7 @@
 ;
 ; In    r1 = path^ with absolutes resolved and no wildcards
 ;       r6 = special field^/scb^
+;       r7 = Operation to perform (fsfile_ReadInfo or fsfile_ReadInfoNoLen)
 ;       fscb
 ;
 ; Out   r0 = Object type of end object
@@ -85,6 +86,7 @@ EnsureCanonicalObject EntryS "r7,r8,r9"
 01
  ]
 
+        FramLDR r0,,r7
         BL      SimpleReadCatalogueInfo
  [ debugensure
         DSTRING r1, "Resulting tail is "
@@ -161,6 +163,7 @@ EnsureCanonicalObject EntryS "r7,r8,r9"
 ; In    r1 = path^^
 ;       r3 = relativity indicator (0=>@; <>0=>%)
 ;       r6 = special field^^
+;       r7 = Op to perform (fsfile_ReadInfo or fsfile_ReadInfoNoLen)
 ;       fscb
 ;
 ; Out   r0 = Object type of end object
@@ -175,7 +178,7 @@ EnsureCanonicalObject EntryS "r7,r8,r9"
 ; The performs a similar function to AssessDestinationForPath, except it
 ; ensures the end object exists/doesn't exist.
 ;
-EnsureObjectCommon Entry "r7"
+EnsureObjectCommon Entry
 
  [ debugensure
  Push "r1,r6"
@@ -515,7 +518,8 @@ AssessDestinationForPathTailForDirRead Entry "r2,r3,scb"
 ;
 ; SimpleReadCatalogueInfo
 ;
-; In    r1 = path^ to perform action on
+; In    r0 = operation to perform (fsfile_ReadInfo or fsfile_ReadInfoNoLen)
+;       r1 = path^ to perform action on
 ;       r6 = special field^/scb^
 ;       fscb for path
 ;
@@ -542,7 +546,11 @@ SimpleReadCatalogueInfo Entry
         ; Get ifscb and file handle as necessary
         BL      AssessDestinationForPath
 
-        MOV     r0, #fsfile_ReadInfo
+        ; Fall back to fsfile_ReadInfo if fsfile_ReadInfoNoLen not supported
+        TEQ     r0, #fsfile_ReadInfoNoLen
+        LDREQ   lr, [fscb, #fscb_info]
+        TSTEQ   lr, #fsinfo_fsfilereadinfonolen
+        MOVEQ   r0, #fsfile_ReadInfo
         BL      CallFSFile_Given
 
         ; If all OK, then adjust the objecttype

s/FSUtils

@@ -1356,7 +1356,10 @@ CopyDirectory Entry
 
         ; Ensure we're set up for this object
         BL      Copy_PromptDest
+        Push    "r7"
+        MOV     r7, #fsfile_ReadInfoNoLen
         BL      EnsureCanonicalObject
+        Pull    "r7"
 
         CMP     r0, #object_file
         BHI     %FT20                   ; If a dir, don't ask to recreate
@@ -1459,7 +1462,7 @@ CopyDirectory Entry
 ;       VC, EQ: copy file
 ;       VC, NE: don't copy file
 
-CopyFile_EnsureDestFileWriteable Entry
+CopyFile_EnsureDestFileWriteable Entry "r7"
 
  [ debugcopy
  BL %FT00
@@ -1491,6 +1494,7 @@ CopyFile_EnsureDestFileWriteable Entry
         DREG    r6, "scb/special is "
         DREG    fscb, "fscb is "
  ]
+        MOVVC   r7, #fsfile_ReadInfoNoLen
         BLVC    EnsureCanonicalObject
         EXIT    VS
 

s/FSUtils3

@@ -945,7 +945,10 @@ Util_IntoDirectory ROUT
         STR     r14, util_totalsize + 4
 
         LDMIA   r7, {r1,r6,fscb}
+        Push    "r7"
+        MOV     r7, #fsfile_ReadInfoNoLen
         BL      EnsureCanonicalObject
+        Pull    "r7"
         BLVC    AssessDestinationForPathTailForDirRead
         EXIT    VS
         STMIB   r7, {r6, fscb}

s/OSFind

@@ -347,7 +347,7 @@ DoTheOpen
 
         ADR     r0, PassedFilename
         ADR     r4, FullFilename
-        MOV     r5, #0
+        MOV     r5, #TopPath_NoLen
         AND     r14, r7, #open_write :OR: open_read
         TEQ     r14, #open_write
         ORREQ   r5, r5, #TopPath_NoMultiParts

s/TopPath

@@ -59,6 +59,8 @@
 ;               7       For EnsureThingIsDirectory. This causes entry into a partition
 ;                       if a partition itself is specified. DoBusinessToPath ignores
 ;                       this flag bit.
+;               8       File length not required (use fsfile_ReadInfoNoLen if
+;                       possible)
 ;       r6 = Place to put linked special field
 ;
 ; Out
@@ -82,6 +84,7 @@ TopPath_DontMindNuls    *       1:SHL:4
 TopPath_Canonicalise    *       1:SHL:5
 TopPath_NoWildCards     *       1:SHL:6
 TopPath_WantPartition   *       1:SHL:7
+TopPath_NoLen           *       1:SHL:8
 
         ^       0, sp
 FSPath_Context  #       4
@@ -323,7 +326,13 @@ TopPath_DoBusinessToPathFSPrefix Entry "r0-r9",:INDEX:TopPath_ContextSize
         B       %FT60
 
 40
+        LDR     r14, [sp, #Proc_LocalStack + 5*4]
+        TST     r14, #TopPath_NoLen
+        Push    "r7"
+        MOVEQ   r7, #fsfile_ReadInfo
+        MOVNE   r7, #fsfile_ReadInfoNoLen
         BL      EnsureObjectCommon      ; (r1,r6,fscb)->(r0-r6,fscb)
+        Pull    "r7"
  [ debugpath
         BVC     %FT01
         DLINE   "Error from EnsureObjectCommon"
@@ -383,7 +392,13 @@ TopPath_DoBusinessToPathFSPrefix Entry "r0-r9",:INDEX:TopPath_ContextSize
  [ debugheapK
         CheckLinkedHeapBlock r1,F
  ]
+        LDR     r14, [sp, #Proc_LocalStack + 5*4]
+        TST     r14, #TopPath_NoLen
+        Push    "r7"
+        MOVEQ   r7, #fsfile_ReadInfo
+        MOVNE   r7, #fsfile_ReadInfoNoLen
         BL      EnsureCanonicalObject
+        Pull    "r7"
         BVS     %FT70                   ; Once again go around for another go if bad
 
         ; Reject anything but pure files