Allow double quotes in an environment variable

This came up at CRAN on some platforms by BDR using
R_KNITR_OPTIONS='knitr.chunk.optipng="-quiet"'

Author: eddelbuettel

ChangeLog

@@ -1,3 +1,7 @@
+2025-04-08  Dirk Eddelbuettel  <[email protected]>
+
+	* src/tools/RInsideEnvVars.r: Allow double quotes in env.var
+
 2025-03-19  Dirk Eddelbuettel  <[email protected]>
 
 	* inst/examples/sandboxed_server/example_server.cpp: Remove obsolete

src/tools/RInsideEnvVars.r

@@ -14,6 +14,8 @@ cat("    const char *R_VARS[] = {\n")
 for (i in 1:length(IncludeVars)){
     if (names(IncludeVars)[i] %in% ExcludeVars)
         next
-    cat('        "',names(IncludeVars)[i],'","',IncludeVars[i],'",\n',sep='')
+    cat('        "', names(IncludeVars)[i], '", "',
+        gsub('"', r"(\\")", IncludeVars[i], perl=TRUE),
+        '",\n', sep='')
 }
 cat("        NULL\n    };\n")