Merge pull request #1589 from rouault/fix_1574

PROJStringParser::createFromPROJString(): avoid potential infinite recursion (fixes #1574)

2 files changed, 49 insertions, 25 deletions

diff --git a/src/iso19111/io.cpp b/src/iso19111/io.cpp
index 4d8fe285..eccb034d 100644
--- a/src/iso19111/io.cpp
+++ b/src/iso19111/io.cpp
@@ -8638,6 +8638,21 @@ static const metadata::ExtentPtr &getExtent(const crs::CRS *crs) {
 
 //! @endcond
 
+namespace {
+struct PJContextHolder {
+    PJ_CONTEXT *ctx_;
+    bool bFree_;
+
+    PJContextHolder(PJ_CONTEXT *ctx, bool bFree) : ctx_(ctx), bFree_(bFree) {}
+    ~PJContextHolder() {
+        if (bFree_)
+            proj_context_destroy(ctx_);
+    }
+    PJContextHolder(const PJContextHolder &) = delete;
+    PJContextHolder &operator=(const PJContextHolder &) = delete;
+};
+} // namespace
+
 // ---------------------------------------------------------------------------
 
 /** \brief Instantiate a sub-class of BaseObject from a PROJ string.
@@ -8652,8 +8667,10 @@ PROJStringParser::createFromPROJString(const std::string &projString) {
 
     // In some abnormal situations involving init=epsg:XXXX syntax, we could
     // have infinite loop
-    if (d->ctx_ && d->ctx_->curStringInCreateFromPROJString == projString) {
-        throw ParsingException("invalid PROJ string");
+    if (d->ctx_ &&
+        d->ctx_->projStringParserCreateFromPROJStringRecursionCounter == 2) {
+        throw ParsingException(
+            "Infinite recursion in PROJStringParser::createFromPROJString()");
     }
 
     d->steps_.clear();
@@ -8701,27 +8718,38 @@ PROJStringParser::createFromPROJString(const std::string &projString) {
         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_legacy = d->ctx_->file_finder_legacy;
+                ctx->file_finder_user_data = d->ctx_->file_finder_user_data;
+            }
+
             bool usePROJ4InitRules = d->usePROJ4InitRules_;
             if (!usePROJ4InitRules) {
-                PJ_CONTEXT *ctx = proj_context_create();
-                if (ctx) {
-                    usePROJ4InitRules = proj_context_get_use_proj4_init_rules(
-                                            ctx, FALSE) == TRUE;
-                    proj_context_destroy(ctx);
-                }
+                usePROJ4InitRules =
+                    proj_context_get_use_proj4_init_rules(ctx, FALSE) == TRUE;
             }
             if (!usePROJ4InitRules) {
                 throw ParsingException("init=epsg:/init=IGNF: syntax not "
                                        "supported in non-PROJ4 emulation mode");
             }
 
-            PJ_CONTEXT *ctx = proj_context_create();
             char unused[256];
             std::string initname(stepName);
             initname.resize(initname.find(':'));
             int file_found =
                 pj_find_file(ctx, initname.c_str(), unused, sizeof(unused));
-            proj_context_destroy(ctx);
+
             if (!file_found) {
                 auto obj = createFromUserInput(stepName, d->dbContext_, true);
                 auto crs = dynamic_cast<CRS *>(obj.get());
@@ -8790,19 +8818,19 @@ PROJStringParser::createFromPROJString(const std::string &projString) {
             }
         }
 
-        paralist *init = pj_mkparam(("init=" + d->steps_[0].name).c_str());
-        if (!init) {
+        auto ctx = d->ctx_ ? d->ctx_ : proj_context_create();
+        if (!ctx) {
             throw ParsingException("out of memory");
         }
-        PJ_CONTEXT *ctx = d->ctx_ ? d->ctx_ : proj_context_create();
-        if (!ctx) {
-            pj_dealloc(init);
+        PJContextHolder contextHolder(ctx, ctx != d->ctx_);
+
+        paralist *init = pj_mkparam(("init=" + d->steps_[0].name).c_str());
+        if (!init) {
             throw ParsingException("out of memory");
         }
+        ctx->projStringParserCreateFromPROJStringRecursionCounter++;
         paralist *list = pj_expand_init(ctx, init);
-        if (ctx != d->ctx_) {
-            proj_context_destroy(ctx);
-        }
+        ctx->projStringParserCreateFromPROJStringRecursionCounter--;
         if (!list) {
             pj_dealloc(init);
             throw ParsingException("cannot expand " + projString);
@@ -8933,18 +8961,14 @@ PROJStringParser::createFromPROJString(const std::string &projString) {
         proj_log_func(pj_context, &logger, Logger::log);
         proj_context_use_proj4_init_rules(pj_context, d->usePROJ4InitRules_);
     }
-    if (d->ctx_) {
-        d->ctx_->curStringInCreateFromPROJString = projString;
-    }
+    pj_context->projStringParserCreateFromPROJStringRecursionCounter++;
     auto log_level = proj_log_level(pj_context, PJ_LOG_NONE);
     auto pj = pj_create_internal(
         pj_context, (projString.find("type=crs") != std::string::npos
                          ? projString + " +disable_grid_presence_check"
                          : projString)
                         .c_str());
-    if (d->ctx_) {
-        d->ctx_->curStringInCreateFromPROJString.clear();
-    }
+    pj_context->projStringParserCreateFromPROJStringRecursionCounter--;
     valid = pj != nullptr;
     proj_log_level(pj_context, log_level);
 
diff --git a/src/proj_internal.h b/src/proj_internal.h
index 761746c1..4a126e98 100644
--- a/src/proj_internal.h
+++ b/src/proj_internal.h
@@ -706,7 +706,7 @@ struct projCtx_t {
     const char* (*file_finder) (PJ_CONTEXT *, const char*, void* user_data) = nullptr;
     void* file_finder_user_data = nullptr;
 
-    std::string curStringInCreateFromPROJString{};
+    int projStringParserCreateFromPROJStringRecursionCounter = 0; // to avoid potential infinite recursion in PROJStringParser::createFromPROJString()
 
     projCtx_t() = default;
     projCtx_t(const projCtx_t&);