[gh-11363] Fix pipe symbol handling in jvm.config on Windows

Use double nested for loops with eol=# and tokens=1 delims=# to handle comments,
then use delayed expansion only for MAVEN_PROJECTBASEDIR substitution.

The key insight from Maven 3 is that using %%a/%%b directly (parse-time expansion)
works with pipes. We can safely store %%b in a variable for substitution because
the parse-time expansion happens before the set command executes, storing pipes
as literal characters.

Solution: Double nested for loops + safe delayed expansion
- Outer loop: eol=# skips full-line comments, tokens=1 delims=# extracts part before #
- Inner loop: tokens=* trims spaces and skips empty lines
- Store %%b in variable for MAVEN_PROJECTBASEDIR substitution (safe because %%b is parse-time)
- Both loops use parse-time expansion (%%a, %%b), avoiding pipe interpretation

This approach:
- Handles full-line comments (lines starting with #) via eol=#
- Handles end-of-line comments (everything after #) via delims=#
- Trims leading/trailing whitespace via tokens=*
- Replaces ${MAVEN_PROJECTBASEDIR} and $MAVEN_PROJECTBASEDIR placeholders
- Skips empty lines automatically
- Handles pipe symbols correctly (not interpreted as command separators)
- Is simple and maintainable (21 lines)

Author: gnodet

apache-maven/src/assembly/maven/bin/mvn.cmd

@@ -181,63 +181,21 @@ if not exist "%MAVEN_PROJECTBASEDIR%\.mvn\jvm.config" goto endReadJvmConfig
 
 @setlocal EnableExtensions EnableDelayedExpansion
 set "JVM_CONFIG_MAVEN_OPTS="
-rem Read jvm.config line by line and concatenate with spaces
-rem Users must properly quote values containing special characters (pipes, etc.)
-for /F "usebackq tokens=* delims=" %%a in ("%MAVEN_PROJECTBASEDIR%\.mvn\jvm.config") do (
-    set "line=%%a"
-
-    rem Simple comment removal - everything after first # is removed
-    rem This matches the Unix sed behavior: sed -e 's/#.*$//'
-    set "processed=!line:#= !"
-    for /f "tokens=1 delims=#" %%b in ("!line!") do set "processed=%%b"
-
-    rem Trim leading spaces
-    :trimLeading%%a
-    if "!processed:~0,1!"==" " (
-        set "processed=!processed:~1!"
-        goto trimLeading%%a
-    )
-
-    rem Trim trailing spaces
-    :trimTrailing%%a
-    if "!processed:~-1!"==" " (
-        set "processed=!processed:~0,-1!"
-        goto trimTrailing%%a
-    )
-
-    rem Skip empty lines
-    if not "!processed!"=="" (
-        rem Replace MAVEN_PROJECTBASEDIR placeholders
-        set "processed=!processed:${MAVEN_PROJECTBASEDIR}=%MAVEN_PROJECTBASEDIR%!"
-        set "processed=!processed:$MAVEN_PROJECTBASEDIR=%MAVEN_PROJECTBASEDIR%!"
-
-        rem Quote unquoted pipe symbols in -D property values
-        rem Check if line contains unquoted pipes
-        set "testPipe=!processed:|=!"
-        if not "!testPipe!"=="!processed!" (
-            rem Has pipes - check if it's a -D property
-            if "!processed:~0,2!"=="-D" (
-                rem Find the = sign and check if value is already quoted
-                for /f "tokens=1,* delims==" %%p in ("!processed!") do (
-                    set "propName=%%p"
-                    set "propValue=%%q"
-                    if defined propValue (
-                        set "firstChar=!propValue:~0,1!"
-                        set "lastChar=!propValue:~-1!"
-                        if not "!firstChar!"=="^"" if not "!lastChar!"=="^"" (
-                            rem Value is not quoted, quote it
-                            set "processed=!propName!="!propValue!""
-                        )
-                    )
-                )
-            )
-        )
-
-        rem Concatenate with space separator
+rem Read jvm.config line by line, using eol=# and tokens=1 delims=# to strip comments
+rem Then trim whitespace - both %%a and %%b use parse-time expansion to avoid pipe interpretation
+for /F "usebackq eol=# tokens=1 delims=#" %%a in ("%MAVEN_PROJECTBASEDIR%\.mvn\jvm.config") do (
+    rem %%a contains everything before # (comments removed by delims=#, full-line comments skipped by eol=#)
+    rem Trim leading/trailing spaces and skip empty lines
+    for /f "tokens=*" %%b in ("%%a") do (
+        rem %%b has spaces trimmed, empty lines automatically skipped
+        rem Now we need to do MAVEN_PROJECTBASEDIR substitution
+        set "line=%%b"
+        set "line=!line:${MAVEN_PROJECTBASEDIR}=%MAVEN_PROJECTBASEDIR%!"
+        set "line=!line:$MAVEN_PROJECTBASEDIR=%MAVEN_PROJECTBASEDIR%!"
         if "!JVM_CONFIG_MAVEN_OPTS!"=="" (
-            set "JVM_CONFIG_MAVEN_OPTS=!processed!"
+            set "JVM_CONFIG_MAVEN_OPTS=!line!"
         ) else (
-            set "JVM_CONFIG_MAVEN_OPTS=!JVM_CONFIG_MAVEN_OPTS! !processed!"
+            set "JVM_CONFIG_MAVEN_OPTS=!JVM_CONFIG_MAVEN_OPTS! !line!"
         )
     )
 )