Add capability to read resource files from the user writable directory

5 files changed, 84 insertions, 37 deletions

diff --git a/src/4D_api.cpp b/src/4D_api.cpp
index cee8262e..9107723d 100644
--- a/src/4D_api.cpp
+++ b/src/4D_api.cpp
@@ -48,6 +48,7 @@
 #include <math.h>
 #include "geodesic.h"
 #include "grids.hpp"
+#include "filemanager.hpp"
 
 #include "proj/common.hpp"
 #include "proj/coordinateoperation.hpp"
@@ -1450,6 +1451,16 @@ PJ_INFO proj_info (void) {
     /* build search path string */
     auto ctx = pj_get_default_ctx();
     if (!ctx || ctx->search_paths.empty()) {
+        // Env var mostly for testing purposes and being independent from
+        // an existing installation
+        const char* ignoreUserWritableDirectory =
+            getenv("PROJ_IGNORE_USER_WRITABLE_DIRECTORY");
+        if( ignoreUserWritableDirectory == nullptr ||
+            ignoreUserWritableDirectory[0] == '\0'  ) {
+            buf = path_append(buf,
+                            pj_context_get_user_writable_directory(ctx, false).c_str(),
+                            &buf_size);
+        }
         const char *envPROJ_LIB = getenv("PROJ_LIB");
         buf = path_append(buf, envPROJ_LIB, &buf_size);
 #ifdef PROJ_LIB
diff --git a/src/filemanager.cpp b/src/filemanager.cpp
index 1a94216d..1c49a16b 100644
--- a/src/filemanager.cpp
+++ b/src/filemanager.cpp
@@ -2294,48 +2294,61 @@ static void CreateDirectory(const std::string &path) {
 
 // ---------------------------------------------------------------------------
 
-std::string pj_context_get_grid_cache_filename(PJ_CONTEXT *ctx) {
-    pj_load_ini(ctx);
-    if (!ctx->gridChunkCache.filename.empty()) {
-        return ctx->gridChunkCache.filename;
-    }
-    std::string path;
+std::string pj_context_get_user_writable_directory(PJ_CONTEXT *ctx,
+                                                   bool create) {
+    if (ctx->user_writable_directory.empty()) {
+        std::string path;
 #ifdef _WIN32
-    std::wstring wPath;
-    wPath.resize(MAX_PATH);
-    if (SHGetFolderPathW(nullptr, CSIDL_LOCAL_APPDATA, nullptr, 0, &wPath[0]) ==
-        S_OK) {
-        wPath.resize(wcslen(wPath.data()));
-        path = WStringToUTF8(wPath);
-    } else {
-        const char *local_app_data = getenv("LOCALAPPDATA");
-        if (!local_app_data) {
-            local_app_data = getenv("TEMP");
+        std::wstring wPath;
+        wPath.resize(MAX_PATH);
+        if (SHGetFolderPathW(nullptr, CSIDL_LOCAL_APPDATA, nullptr, 0,
+                             &wPath[0]) == S_OK) {
+            wPath.resize(wcslen(wPath.data()));
+            path = WStringToUTF8(wPath);
+        } else {
+            const char *local_app_data = getenv("LOCALAPPDATA");
             if (!local_app_data) {
-                local_app_data = "c:/users";
+                local_app_data = getenv("TEMP");
+                if (!local_app_data) {
+                    local_app_data = "c:/users";
+                }
             }
+            path = local_app_data;
         }
-        path = local_app_data;
-    }
 #else
-    const char *xdg_data_home = getenv("XDG_DATA_HOME");
-    if (xdg_data_home != nullptr) {
-        path = xdg_data_home;
-    } else {
-        const char *home = getenv("HOME");
-        if (home) {
+        const char *xdg_data_home = getenv("XDG_DATA_HOME");
+        if (xdg_data_home != nullptr) {
+            path = xdg_data_home;
+        } else {
+            const char *home = getenv("HOME");
+            if (home) {
 #if defined(__MACH__) && defined(__APPLE__)
-            path = std::string(home) + "/Library/Logs";
+                path = std::string(home) + "/Library/Logs";
 #else
-            path = std::string(home) + "/.local/share";
+                path = std::string(home) + "/.local/share";
 #endif
-        } else {
-            path = "/tmp";
+            } else {
+                path = "/tmp";
+            }
         }
-    }
 #endif
-    path += "/proj";
-    CreateDirectory(path);
+        path += "/proj";
+        ctx->user_writable_directory = path;
+    }
+    if (create) {
+        CreateDirectory(ctx->user_writable_directory);
+    }
+    return ctx->user_writable_directory;
+}
+
+// ---------------------------------------------------------------------------
+
+std::string pj_context_get_grid_cache_filename(PJ_CONTEXT *ctx) {
+    pj_load_ini(ctx);
+    if (!ctx->gridChunkCache.filename.empty()) {
+        return ctx->gridChunkCache.filename;
+    }
+    const std::string path(pj_context_get_user_writable_directory(ctx, true));
     ctx->gridChunkCache.filename = path + "/cache.db";
     return ctx->gridChunkCache.filename;
 }
diff --git a/src/filemanager.hpp b/src/filemanager.hpp
index 11fb6356..9793267c 100644
--- a/src/filemanager.hpp
+++ b/src/filemanager.hpp
@@ -33,10 +33,10 @@
 #include "proj.h"
 #include "proj/util.hpp"
 
-NS_PROJ_START
-
 //! @cond Doxygen_Suppress
 
+NS_PROJ_START
+
 class File;
 
 class FileManager {
@@ -74,8 +74,8 @@ class File {
     const std::string &name() const { return name_; }
 };
 
-//! @endcond Doxygen_Suppress
-
 NS_PROJ_END
 
+//! @endcond Doxygen_Suppress
+
 #endif // FILEMANAGER_HPP_INCLUDED
\ No newline at end of file
diff --git a/src/open_lib.cpp b/src/open_lib.cpp
index 222dd757..ae387281 100644
--- a/src/open_lib.cpp
+++ b/src/open_lib.cpp
@@ -224,6 +224,16 @@ static bool is_rel_or_absolute_filename(const char *name)
             || (name[0] != '\0' && name[1] == ':' && strchr(dir_chars,name[2]));
 }
 
+static bool ignoreUserWritableDirectory()
+{
+    // Env var mostly for testing purposes and being independent from
+    // an existing installation
+    const char* envVarIgnoreUserWritableDirectory =
+        getenv("PROJ_IGNORE_USER_WRITABLE_DIRECTORY");
+    return envVarIgnoreUserWritableDirectory != nullptr &&
+           envVarIgnoreUserWritableDirectory[0] != '\0';
+}
+
 static void*
 pj_open_lib_internal(projCtx ctx, const char *name, const char *mode,
                      void* (*open_file)(projCtx, const char*, const char*),
@@ -279,6 +289,17 @@ pj_open_lib_internal(projCtx ctx, const char *name, const char *mode,
                     break;
             }
         }
+
+        else if( !ignoreUserWritableDirectory() &&
+                 (fid = open_file(ctx,
+                    (pj_context_get_user_writable_directory(ctx, false) +
+                     DIR_CHAR + name).c_str(), mode)) != nullptr ) {
+            fname = pj_context_get_user_writable_directory(ctx, false);
+            fname += DIR_CHAR;
+            fname += name;
+            sysname = fname.c_str();
+        }
+
         /* if is environment PROJ_LIB defined */
         else if ((sysname = getenv("PROJ_LIB")) != nullptr) {
             auto paths = NS_PROJ::internal::split(std::string(sysname), dirSeparator);
diff --git a/src/proj_internal.h b/src/proj_internal.h
index 63c53551..ce7b9d74 100644
--- a/src/proj_internal.h
+++ b/src/proj_internal.h
@@ -709,6 +709,7 @@ struct projCtx_t {
     bool iniFileLoaded = false;
     std::string endpoint{};
 
+    std::string user_writable_directory{};
     projGridChunkCache gridChunkCache{};
 
     int projStringParserCreateFromPROJStringRecursionCounter = 0; // to avoid potential infinite recursion in PROJStringParser::createFromPROJString()
@@ -844,8 +845,9 @@ std::string pj_context_get_url_endpoint(PJ_CONTEXT* ctx);
 
 void pj_load_ini(PJ_CONTEXT* ctx);
 
-// For testing purposes
+// Exported for testing purposes only
 std::string PROJ_DLL pj_context_get_grid_cache_filename(PJ_CONTEXT *ctx);
+std::string PROJ_DLL pj_context_get_user_writable_directory(PJ_CONTEXT *ctx, bool create);
 
 /* classic public API */
 #include "proj_api.h"