createFromPROJString: avoid repeated openings of proj.db and proj.ini and lookup of 'epsg'

src/ctx.cpp

@@ -129,6 +129,7 @@ projCppContext *pj_ctx::get_cpp_context() {
 /************************************************************************/
 
 void pj_ctx::set_search_paths(const std::vector<std::string> &search_paths_in) {
+    lookupedFiles.clear();
     search_paths = search_paths_in;
     delete[] c_compat_paths;
     c_compat_paths = nullptr;

src/filemanager.cpp

@@ -1779,6 +1779,16 @@ NS_PROJ::FileManager::open_resource_file(PJ_CONTEXT *ctx, const char *name,
  */
 int pj_find_file(PJ_CONTEXT *ctx, const char *short_filename,
                  char *out_full_filename, size_t out_full_filename_size) {
+    const auto iter = ctx->lookupedFiles.find(short_filename);
+    if (iter != ctx->lookupedFiles.end()) {
+        if (iter->second.empty()) {
+            out_full_filename[0] = 0;
+            return 0;
+        }
+        snprintf(out_full_filename, out_full_filename_size, "%s",
+                 iter->second.c_str());
+        return 1;
+    }
     const bool old_network_enabled =
         proj_context_is_network_enabled(ctx) != FALSE;
     if (old_network_enabled)
@@ -1787,6 +1797,11 @@ int pj_find_file(PJ_CONTEXT *ctx, const char *short_filename,
         ctx, short_filename, out_full_filename, out_full_filename_size);
     if (old_network_enabled)
         proj_context_set_enable_network(ctx, true);
+    if (file) {
+        ctx->lookupedFiles[short_filename] = out_full_filename;
+    } else {
+        ctx->lookupedFiles[short_filename] = std::string();
+    }
     return file != nullptr;
 }
 

src/iso19111/io.cpp

@@ -12244,25 +12244,35 @@ PROJStringParser::createFromPROJString(const std::string &projString) {
     if (d->steps_.size() == 1 && d->steps_[0].isInit &&
         !d->steps_[0].inverted) {
 
+        auto ctx = d->ctx_ ? d->ctx_ : proj_context_create();
+        if (!ctx) {
+            throw ParsingException("out of memory");
+        }
+        PJContextHolder contextHolder(ctx, ctx != d->ctx_);
+
         // Those used to come from a text init file
         // We only support them in compatibility mode
         const std::string &stepName = d->steps_[0].name;
         if (ci_starts_with(stepName, "epsg:") ||
             ci_starts_with(stepName, "IGNF:")) {
 
-            /* We create a new context so as to avoid messing up with the */
-            /* errorno of the main context, when trying to find the likely */
-            /* missing epsg file */
-            auto ctx = proj_context_create();
-            if (!ctx) {
-                throw ParsingException("out of memory");
-            }
-            PJContextHolder contextHolder(ctx, true);
-            if (d->ctx_) {
-                ctx->set_search_paths(d->ctx_->search_paths);
-                ctx->file_finder = d->ctx_->file_finder;
-                ctx->file_finder_user_data = d->ctx_->file_finder_user_data;
-            }
+            struct BackupContextErrno {
+                PJ_CONTEXT *m_ctxt = nullptr;
+                int m_last_errno = 0;
+
+                explicit BackupContextErrno(PJ_CONTEXT *ctxtIn)
+                    : m_ctxt(ctxtIn), m_last_errno(m_ctxt->last_errno) {
+                    m_ctxt->debug_level = PJ_LOG_ERROR;
+                }
+
+                ~BackupContextErrno() { m_ctxt->last_errno = m_last_errno; }
+
+                BackupContextErrno(const BackupContextErrno &) = delete;
+                BackupContextErrno &
+                operator=(const BackupContextErrno &) = delete;
+            };
+
+            BackupContextErrno backupContextErrno(ctx);
 
             bool usePROJ4InitRules = d->usePROJ4InitRules_;
             if (!usePROJ4InitRules) {
@@ -12369,12 +12379,6 @@ PROJStringParser::createFromPROJString(const std::string &projString) {
             }
         }
 
-        auto ctx = d->ctx_ ? d->ctx_ : proj_context_create();
-        if (!ctx) {
-            throw ParsingException("out of memory");
-        }
-        PJContextHolder contextHolder(ctx, ctx != d->ctx_);
-
         paralist *init = pj_mkparam(("init=" + d->steps_[0].name).c_str());
         if (!init) {
             throw ParsingException("out of memory");

src/proj_internal.h

@@ -806,6 +806,9 @@ struct pj_ctx {
                                void *user_data) = nullptr;
     void *file_finder_user_data = nullptr;
 
+    // Cache result of pj_find_file()
+    std::map<std::string, std::string> lookupedFiles{};
+
     bool defer_grid_opening = false; // set transiently by pj_obj_create()
 
     projFileApiCallbackAndData fileApi{};