alter the generator to free strings returned by GEOS.

Author: nraynaud

gen/generator.jl

@@ -1,3 +1,4 @@
+using Clang.LibClang
 using Clang.Generators
 using MacroTools
 using GEOS_jll
@@ -13,7 +14,13 @@ function rewrite(ex::Expr)
         cc = :(@ccall $lib.$cname($(cargs...))::$rettype)
 
         cc′ = if rettype == :Cstring
-            :(unsafe_string($cc))
+            # do not try to free a const char *
+            # this is the only function returning such type
+            if cname == :GEOSversion
+                :(unsafe_string($cc))
+            else
+                :(transform_c_string($cc))
+            end
         else
             cc
         end

src/LibGEOS.jl

@@ -94,6 +94,14 @@ export Point,
     STRtree,
     query
 
+function transform_c_string(s::Cstring)::String
+    @show "freeing string"
+    copy = unsafe_string(s)
+    global _context
+    GEOSFree_r(_context.ptr, Ptr{Cvoid}(s))
+    return copy
+end
+
 include("libgeos_api.jl")
 
 mutable struct GEOSError <: Exception

src/libgeos_api.jl

@@ -1289,7 +1289,7 @@ function GEOSRelatePattern_r(handle, g1, g2, pat)
 end
 
 function GEOSRelate_r(handle, g1, g2)
-    unsafe_string(
+    transform_c_string(
         @ccall(
             libgeos.GEOSRelate_r(
                 handle::GEOSContextHandle_t,
@@ -1309,7 +1309,7 @@ function GEOSRelatePatternMatch_r(handle, mat, pat)
 end
 
 function GEOSRelateBoundaryNodeRule_r(handle, g1, g2, bnr)
-    unsafe_string(
+    transform_c_string(
         @ccall(
             libgeos.GEOSRelateBoundaryNodeRule_r(
                 handle::GEOSContextHandle_t,
@@ -1330,7 +1330,7 @@ function GEOSisValid_r(handle, g)
 end
 
 function GEOSisValidReason_r(handle, g)
-    unsafe_string(
+    transform_c_string(
         @ccall(
             libgeos.GEOSisValidReason_r(
                 handle::GEOSContextHandle_t,
@@ -1408,7 +1408,7 @@ function GEOSRemoveRepeatedPoints_r(handle, g, tolerance)
 end
 
 function GEOSGeomType_r(handle, g)
-    unsafe_string(
+    transform_c_string(
         @ccall(
             libgeos.GEOSGeomType_r(
                 handle::GEOSContextHandle_t,
@@ -1827,7 +1827,7 @@ function GEOSWKTWriter_destroy_r(handle, writer)
 end
 
 function GEOSWKTWriter_write_r(handle, writer, g)
-    unsafe_string(
+    transform_c_string(
         @ccall(
             libgeos.GEOSWKTWriter_write_r(
                 handle::GEOSContextHandle_t,
@@ -2038,7 +2038,7 @@ function GEOSGeoJSONWriter_destroy_r(handle, writer)
 end
 
 function GEOSGeoJSONWriter_writeGeometry_r(handle, writer, g, indent)
-    unsafe_string(
+    transform_c_string(
         @ccall(
             libgeos.GEOSGeoJSONWriter_writeGeometry_r(
                 handle::GEOSContextHandle_t,
@@ -3294,7 +3294,7 @@ function GEOSWKTWriter_destroy(writer)
 end
 
 function GEOSWKTWriter_write(writer, g)
-    unsafe_string(
+    transform_c_string(
         @ccall(
             libgeos.GEOSWKTWriter_write(
                 writer::Ptr{GEOSWKTWriter},
@@ -3450,7 +3450,7 @@ function GEOSGeoJSONWriter_destroy(writer)
 end
 
 function GEOSGeoJSONWriter_writeGeometry(writer, g, indent)
-    unsafe_string(
+    transform_c_string(
         @ccall(
             libgeos.GEOSGeoJSONWriter_writeGeometry(
                 writer::Ptr{GEOSGeoJSONWriter},
@@ -3511,7 +3511,7 @@ function GEOSGeomFromWKT_r(handle, wkt)
 end
 
 function GEOSGeomToWKT_r(handle, g)
-    unsafe_string(
+    transform_c_string(
         @ccall(
             libgeos.GEOSGeomToWKT_r(
                 handle::GEOSContextHandle_t,
@@ -3577,7 +3577,7 @@ function GEOSGeomFromWKT(wkt)
 end
 
 function GEOSGeomToWKT(g)
-    unsafe_string(@ccall(libgeos.GEOSGeomToWKT(g::Ptr{GEOSGeometry})::Cstring))
+    transform_c_string(@ccall(libgeos.GEOSGeomToWKT(g::Ptr{GEOSGeometry})::Cstring))
 end
 
 function GEOS_getWKBOutputDims()