Merge pull request #9166 from rouault/fix_9165

Doc: OpenFileGDB: document OPENFILEGDB_DEFAULT_STRING_WIDTH configuration option (fixes #9165)

doc/source/drivers/vector/openfilegdb.rst

@@ -92,6 +92,13 @@ available:
       using the native spatial index. See `Spatial filtering`_.
 
 
+-  .. config:: OPENFILEGDB_DEFAULT_STRING_WIDTH
+      :choices: <integer>
+
+      Width of string fields to use on creation, when the width specified to
+      CreateField() is the unspecified value 0. This defaults to 65536.
+
+
 Dataset open options
 --------------------
 

ogr/ogrsf_frmts/openfilegdb/ogr_openfilegdb.h

@@ -48,6 +48,18 @@ std::string OFGDBGenerateUUID();
 
 int OGROpenFileGDBIsComparisonOp(int op);
 
+// The FileGeodatabase format does not really allow strings of arbitrary width
+// in the XML and .gdbtable header declaration. They must have a non-zero
+// maximum width. But if we put it to a huge value (let's say 1 billion), this
+// causes crashes in some Esri products (cf #5952, perhaps they allocate
+// std::string's to that maximum size?).
+// Hence this default of a relative large but not too large
+// width when creating a OGR string field width of unspecified width.
+// Note that when opening a FileGeodatabase with string fields of that width,
+// we do not advertise it in OGRFieldDefn::GetWidth() but we advertise 0 instead,
+// to allow round-tripping.
+constexpr int DEFAULT_STRING_WIDTH = 65536;
+
 // UUID of object type
 constexpr const char *pszFolderTypeUUID =
     "{f3783e6f-65ca-4514-8315-ce3985dad3b1}";

ogr/ogrsf_frmts/openfilegdb/ogropenfilegdblayer.cpp

@@ -661,10 +661,11 @@ int OGROpenFileGDBLayer::BuildLayerDefinition()
         oFieldDefn.SetAlternativeName(poGDBField->GetAlias().c_str());
         oFieldDefn.SetSubType(eSubType);
         // On creation in the FileGDB driver (GDBFieldTypeToLengthInBytes) if
-        // string width is 0, we pick up 65536 by default to mean unlimited
-        // string length, but we do not want to advertise such a big number.
+        // string width is 0, we pick up DEFAULT_STRING_WIDTH=65536 by default
+        // to mean unlimited string length, but we do not want to advertise
+        // such a big number.
         if (eType == OFTString &&
-            (nWidth < 65536 ||
+            (nWidth < DEFAULT_STRING_WIDTH ||
              CPLTestBool(CPLGetConfigOption(
                  "OPENFILEGDB_REPORT_GENUINE_FIELD_WIDTH", "NO"))))
         {

ogr/ogrsf_frmts/openfilegdb/ogropenfilegdblayer_write.cpp

@@ -1350,11 +1350,23 @@ OGRErr OGROpenFileGDBLayer::CreateField(const OGRFieldDefn *poFieldIn,
         nWidth = poField->GetWidth();
         if (nWidth == 0)
         {
-            // We can't use a 0 width value since that prevents ArcMap
-            // from editing (#5952)
-            nWidth = atoi(CPLGetConfigOption("OPENFILEGDB_DEFAULT_STRING_WIDTH",
-                                             "65536"));
-            if (nWidth < 65536)
+            // Hard-coded non-zero default string width if the user doesn't
+            // override it with the below configuration option.
+            // See comment at declaration of DEFAULT_STRING_WIDTH for more
+            // details
+            nWidth = DEFAULT_STRING_WIDTH;
+            if (const char *pszVal = CPLGetConfigOption(
+                    "OPENFILEGDB_DEFAULT_STRING_WIDTH", nullptr))
+            {
+                const int nVal = atoi(pszVal);
+                if (nVal >= 0)
+                    nWidth = nVal;
+            }
+            // Advertise a non-zero user-modified width back to the created
+            // OGRFieldDefn, only if it is less than the hard-coded default
+            // value (this will avoid potential issues with excessively large
+            // field width afterwards)
+            if (nWidth < DEFAULT_STRING_WIDTH)
                 poField->SetWidth(nWidth);
         }
     }