CSV: fix parsing files with double-quote inside a field value

Fixes OSGeo#11660

autotest/ogr/data/csv/double_quotes_in_middle_of_field_bis.csv

@@ -0,0 +1,3 @@
+first,second,third
+1,two"with quote,3
+10,twenty"with quote,30

autotest/ogr/ogr_csv.py

@@ -2800,6 +2800,26 @@ def test_ogr_csv_double_quotes_in_middle_of_field():
     assert f["str"] == "foo"
 
 
+###############################################################################
+# Test bugfix for https://github.com/OSGeo/gdal/issues/11660
+
+
+def test_ogr_csv_double_quotes_in_middle_of_field_bis():
+
+    ds = ogr.Open("data/csv/double_quotes_in_middle_of_field_bis.csv")
+    lyr = ds.GetLayer(0)
+
+    f = lyr.GetNextFeature()
+    assert f["first"] == "1"
+    assert f["second"] == """two"with quote"""
+    assert f["third"] == "3"
+
+    f = lyr.GetNextFeature()
+    assert f["first"] == "10"
+    assert f["second"] == """twenty"with quote"""
+    assert f["third"] == "30"
+
+
 ###############################################################################
 
 

port/cpl_csv.cpp

@@ -647,45 +647,68 @@ CSVReadParseLineGeneric(void *fp, const char *(*pfnReadLine)(void *, size_t),
         return CSVSplitLine(pszLine, pszDelimiter, bKeepLeadingAndClosingQuotes,
                             bMergeDelimiter);
 
+    const size_t nDelimiterLength = strlen(pszDelimiter);
+    bool bInString = false;  // keep in that scope !
+    std::string osWorkLine;  // keep in that scope !
+    size_t i = 0;            // keep in that scope !
+
     try
     {
-        // We must now count the quotes in our working string, and as
-        // long as it is odd, keep adding new lines.
-        std::string osWorkLine(pszLine);
-
-        size_t i = 0;
-        int nCount = 0;
-
         while (true)
         {
-            for (; i < osWorkLine.size(); i++)
+            for (; pszLine[i]; ++i)
             {
-                if (osWorkLine[i] == '\"')
-                    nCount++;
+                if (pszLine[i] == '\"')
+                {
+                    if (!bInString)
+                    {
+                        // Only consider " as the start of a quoted string
+                        // if it is the first character of the line, or
+                        // if it is immediately after the field delimiter.
+                        if (i == 0 ||
+                            (i >= nDelimiterLength &&
+                             memcmp(pszLine + (i - nDelimiterLength),
+                                    pszDelimiter, nDelimiterLength) == 0))
+                        {
+                            bInString = true;
+                        }
+                    }
+                    else if (pszLine[i + 1] == '"')
+                    {
+                        // Escaped double quote in a quoted string
+                        ++i;
+                    }
+                    else
+                    {
+                        bInString = false;
+                    }
+                }
             }
 
-            if (nCount % 2 == 0)
-                break;
+            if (!bInString)
+            {
+                return CSVSplitLine(pszLine, pszDelimiter,
+                                    bKeepLeadingAndClosingQuotes,
+                                    bMergeDelimiter);
+            }
+
+            if (osWorkLine.empty())
+                osWorkLine = pszLine;
 
             pszLine = pfnReadLine(fp, nMaxLineSize);
             if (pszLine == nullptr)
                 break;
 
             osWorkLine.append("\n");
             osWorkLine.append(pszLine);
+            pszLine = osWorkLine.c_str();
         }
-
-        char **papszReturn =
-            CSVSplitLine(osWorkLine.c_str(), pszDelimiter,
-                         bKeepLeadingAndClosingQuotes, bMergeDelimiter);
-
-        return papszReturn;
     }
     catch (const std::exception &e)
     {
         CPLError(CE_Failure, CPLE_OutOfMemory, "%s", e.what());
-        return nullptr;
     }
+    return nullptr;
 }
 
 /************************************************************************/