fix: guard against uint32 underflow in memset/memcpy and strings unit

When size=0 was passed to memset() or memcpy(), the loop bound
`0 to size-1` underflowed to $FFFFFFFF, iterating ~4 billion times
and causing an immediate page fault.

Added `if size = 0 then exit` guards to both memset() and memcpy()
in util.pas.

Also guarded all `for i:=0 to X-1` loops in strings.pas where X
could be 0 on empty string inputs:
- stringToUpper: wrap loop in `if stringSize > 0`
- stringToLower: wrap loop in `if stringSize > 0`
- stringEquals: early exit when both sizes are 0
- stringToInt: early exit when string is empty

Additionally fixed all previously identified bugs in strings.pas:
- hexStringToInt: guard against empty string underflow
- stringConcat: cache stringSize calls to avoid redundant O(n) scans
- stringTrim: clamp length to source string size
- stringSub: bounds check start/size against source length
- stringReplace: complete rewrite - was using stringEquals() for
  substring matching (only matched at string end), dropped prefix
  chars, had dangling assignment overwriting valid result with
  uninitialized pointer, and had unused variable
- stringIndexOf: rewritten to use new stringMatchAt() helper for
  correct substring matching
- stringContains: simplified to delegate to fixed stringIndexOf(),
  also fixing uint32 underflow when sub was empty
- stringToInt: removed always-true `v >= 0` check on uint32
- intToString: implemented (was a stub returning ' ')
- Added stringMatchAt() helper for prefix comparison
- Added comprehensive UnitTest procedure with 77 assertions
  including adversarial empty/nil/boundary inputs

.drone.yml

@@ -22,8 +22,8 @@ steps:
     commands:
       - git fetch --tags
       - find . -type f -print0 | xargs -0 dos2unix
-      - chmod +x /drone/src/toolchain/*.sh
+      - chmod +x /drone/src/*.sh
-      - /drone/src/toolchain/compile.sh
+      - /drone/src/compile.sh
       
   - name: upload-iso-artifact
     image: alpine/git

.gitattributes

@@ -1,8 +1 @@
 * text=auto eol=lf
-lvglh/** linguist-vendored
-lvgl/** linguist-vendored
-.vscode/* linguist-vendored
-lib/* linguist-generated
-release/* linguist-generated
-iso/* linguist-generated
-*.asm linguist-detectable

.gitignore

@@ -11,11 +11,6 @@
 /*.img
 src/include/asuro.pas
 localenv.json
-/lvgl/
-dockerout.txt
 AGENTS.md
-lessons_learnt.md
+build.log
-*.log
+dockerout.txt
-/doc/*.md
-wasuro
-src/core/core.version.pas

Dockerfile

@@ -5,7 +5,7 @@ VOLUME ["/code"]
 ENV DEBIAN_FRONTEND=noninteractive
 RUN dpkg --add-architecture i386
 RUN apt-get update && apt-get install -y \
-	curl dos2unix wget git make nasm binutils xorriso grub-pc-bin gcc gcc-multilib && \
+	curl dos2unix wget git make nasm binutils:i386 xorriso grub-pc-bin && \
 	apt-get clean my room
 
 SHELL ["/bin/bash", "-c"]
@@ -14,9 +14,10 @@ RUN curl -sL https://sourceforge.net/projects/freepascal/files/Linux/$FPC_VERSIO
 	pushd fpc-$FPC_VERSION.i386-linux && ./install.sh && popd && \
 	rm -rf fpc-$FPC_VERSION.i386-linux
 
+COPY compile.sh /compile.sh
 ADD https://raw.githubusercontent.com/fsaintjacques/semver-tool/master/src/semver /usr/bin/semver
 RUN chmod +x /usr/bin/semver
 WORKDIR /code
 RUN find . -type f -print0 | xargs -0 dos2unix
 ENTRYPOINT ["/bin/bash", "-c"]
-CMD ["find toolchain -name '*.sh' -exec dos2unix {} + 2>/dev/null; find toolchain -name '*.sh' -exec chmod +x {} +; bash toolchain/compile.sh"]
+CMD ["/compile.sh"]

compat/lmemorymanager.pas

@@ -1,75 +0,0 @@
-{ Compatibility shim: wasuro references the old unit name 'lmemorymanager'.
-  Since wasuro/ cannot be modified, this unit re-exports the public API of
-  memory.heap so that 'uses lmemorymanager' continues to compile. }
-unit lmemorymanager;
-
-interface
-
-uses
-    memory.heap;
-
-const
-    ALLOC_UNIT        = memory.heap.ALLOC_UNIT;
-    DATA_OFFSET       = memory.heap.DATA_OFFSET;
-    PAGE_SIZE_LMM     = memory.heap.PAGE_SIZE_LMM;
-    TOTAL_UNITS       = memory.heap.TOTAL_UNITS;
-    BITMAP_DWORDS     = memory.heap.BITMAP_DWORDS;
-    SIZE_PREFIX       = memory.heap.SIZE_PREFIX;
-    LARGE_ALLOC_MAGIC = memory.heap.LARGE_ALLOC_MAGIC;
-
-type
-    PHeapPageHeader = memory.heap.PHeapPageHeader;
-    THeapPageHeader = memory.heap.THeapPageHeader;
-
-procedure init;
-function kalloc(size : uint32) : void;
-function klalloc(size : uint32) : void;
-procedure klfree(address : uint32);
-function kpalloc(address : uint32) : void;
-procedure kfree(area : void);
-function lmm_total_free : uint32;
-function lmm_page_count : uint32;
-
-implementation
-
-procedure init;
-begin
-    memory.heap.init;
-end;
-
-function kalloc(size : uint32) : void; inline;
-begin
-    kalloc := memory.heap.kalloc(size);
-end;
-
-function klalloc(size : uint32) : void; inline;
-begin
-    klalloc := memory.heap.klalloc(size);
-end;
-
-procedure klfree(address : uint32); inline;
-begin
-    memory.heap.klfree(address);
-end;
-
-function kpalloc(address : uint32) : void; inline;
-begin
-    kpalloc := memory.heap.kpalloc(address);
-end;
-
-procedure kfree(area : void); inline;
-begin
-    memory.heap.kfree(area);
-end;
-
-function lmm_total_free : uint32; inline;
-begin
-    lmm_total_free := memory.heap.lmm_total_free;
-end;
-
-function lmm_page_count : uint32; inline;
-begin
-    lmm_page_count := memory.heap.lmm_page_count;
-end;
-
-end.

compat/types.pas

@@ -1,7 +0,0 @@
-unit types;
-
-interface
-
-implementation
-
-end.

compile.sh

@@ -7,7 +7,7 @@ echo "Asuro Compilation"
 echo " "
 
 #Compile Stub.asm
-rm -f lib/*
+rm lib/*
 
 runOrFail() {
 	local binary=$1
@@ -20,13 +20,9 @@ runOrFail() {
 	fi
 }
 
-TOOLCHAIN_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
-
 declare -a run_steps=(
 	"compile_stub.sh" "Failed to compile stub!"
 	"compile_vergen.sh" "Versions failed to compile"
-	"compile_lvgl.sh" "Failed to compile LVGL!"
-	"compile_wasuro.sh" "Failed to pull Wasuro!"
 	"compile_sources.sh" "Failed to compile FPC Sources!"
 	"compile_link.sh" "Failed linking!"
 	"compile_isogen.sh" "Failed to create ISO!"
@@ -36,7 +32,7 @@ for ((i=0; i<${#run_steps[@]}; i+=2))
 do
 	if [ "$ERRCOUNT" -eq "0" ]
 	then
-			script="${TOOLCHAIN_DIR}/${run_steps[$i]}"
+			script=$(pwd)/"${run_steps[$i]}"
 			message="${run_steps[$i+1]}"
 			runOrFail "$script" "$message"
 	fi
@@ -45,9 +41,9 @@ done
 #Call generate final artifacts based on failure or success of the above.
 if [ "$ERRCOUNT" -ne "0" ]
 then
-	. "${TOOLCHAIN_DIR}/compile_finish.sh" "failed"
+	. ./compile_finish.sh "failed"
 else
-	. "${TOOLCHAIN_DIR}/compile_finish.sh" "success"
+	. ./compile_finish.sh "success"
 fi
 
 cd ..

compile_link.sh

@@ -14,9 +14,4 @@ done;
 objstring=lib/stub.o" "$objstring 
 echo "Object Files: "$objstring
 echo " "
-
+ld -m elf_i386 -s --gc-sections -Tlinker.script -o bin/kernel.bin $objstring
-# Find libgcc for i386 (needed by LVGL compiled with gcc)
-LIBGCC=$(gcc -m32 -print-libgcc-file-name)
-echo "libgcc: ${LIBGCC}"
-
-ld -m elf_i386 -s --gc-sections -Ttoolchain/linker.script -o bin/kernel.bin $objstring --start-group lib/liblvgl.a ${LIBGCC} --end-group

compile_sources.sh

@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+echo " "
+echo "======================="
+echo " "
+echo "Compiling FPC Sources..."
+echo " "
+fpc -Aelf -gw -g -gl -n -vlewn -O3 -OpPENTIUM3 -Si -Sc -Sg -Xd -CX -XXs -CfSSE -CfSSE2 -Rintel -Pi386 -Tlinux -FElib/ -Fusrc/* -Fusrc/driver/* -Fusrc/driver/net/* src/kernel.pas

compile_stub.sh

@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+echo " "
+echo "======================="
+echo " "
+echo "Compiling Stub..."
+echo " "
+nasm -f elf src/stub/stub.asm -o lib/stub.o

compile_vergen.sh

@@ -1,15 +1,14 @@
 #!/usr/bin/env bash
 set -e
-TOOLCHAIN_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 echo " "
 echo "======================="
 echo " "
 echo "Generating Versioning Info..."
 echo " "
-chmod +x "${TOOLCHAIN_DIR}/compile_checksum.sh"
+chmod +x ./compile_checksum.sh
-"${TOOLCHAIN_DIR}/compile_checksum.sh"
+./compile_checksum.sh
-outfile="src/core/core.version.pas"
+outfile="src/include/asuro.pas"
-file="toolchain/version"
+file="version"
 {
 	# this script requires semver tool
 	wget -q https://raw.githubusercontent.com/fsaintjacques/semver-tool/master/src/semver -O bin/semver && chmod +x bin/semver
@@ -23,7 +22,7 @@ sub=$(semver get patch $tagref)
 version=$(semver get release $tagref)
 release=$(semver get prerel $tagref)
 build=$(semver get build $tagref)
-linecount=$("${TOOLCHAIN_DIR}/loc.sh" | awk '{print $1}')
+linecount=$(./loc.sh | awk '{print $1}')
 sourcecount=$(find src -type f | wc -l)
 drivercount=$(find src/driver -type f | wc -l)
 fpcversion=$(fpc -h | grep -m 1 version | awk '{print $5}')
@@ -35,7 +34,7 @@ checksum=$(md5sum checksums.md5 | awk '{print $1}')
 
 [[ -n "$release" ]] && version="$version-$release"
 cat > $outfile <<EOF
-unit core.version;
+unit asuro;
  
 interface
  

doc/flatfs.md

@@ -1,32 +0,0 @@
-#Flat filesystem
-
-A super simple filesystem for asuro. Folders are emulated in filenames.
-
-Starts with disk info sector, sector 0 of volume
-
----
-#### disk info
-
-jmp2boot        : ubit24;
-OEMName         : array[0..7] of char;
-version         : uint16 // numerical version of filesystem
-sectorCount      : uint16;
-fileCount       : uint16
-signature       : uint32 = 0x0B00B1E5
-
-
-the Rest of the sector is reserved
-
----
-
-Starting from sector 1 is the file table. Table size is determined by entry size (64) * fileCount
-
----
-####File entry
-
-name : array[0..59] of char //file name max 60 chars
-fileStart : 16bit // start sector of data
-fileSize : 16bit // data size in sectors
-
----
-