From 10f89852c8c868b779e78b433a9e6cf872a01849 Mon Sep 17 00:00:00 2001
From: Even Rouault <even.rouault@spatialys.com>
Date: Wed, 13 Nov 2024 17:26:11 +0100
Subject: [PATCH] Do not turn on 'TPsot==TNsot detection fix' when TNsot==1,
 and add a OPJ_DPARAMETERS_DISABLE_TPSOT_FIX flag to disable it

Adresses the use case of https://lists.osgeo.org/pipermail/gdal-dev/2024-November/059805.html
where Sentinel2 L1C JPEG2000 files are made of a single tile-part per
tile.
---
 src/lib/openjp2/j2k.c      | 20 +++++++++++++++++---
 src/lib/openjp2/openjpeg.h |  7 ++++++-
 2 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/src/lib/openjp2/j2k.c b/src/lib/openjp2/j2k.c
index 7dc389fa2..94d775d7c 100644
--- a/src/lib/openjp2/j2k.c
+++ b/src/lib/openjp2/j2k.c
@@ -6752,6 +6752,9 @@ void opj_j2k_setup_decoder(opj_j2k_t *j2k, opj_dparameters_t *parameters)
         j2k->m_cp.m_specific_param.m_dec.m_reduce = parameters->cp_reduce;
 
         j2k->dump_state = (parameters->flags & OPJ_DPARAMETERS_DUMP_FLAG);
+        if (parameters->flags & OPJ_DPARAMETERS_DISABLE_TPSOT_FIX) {
+            j2k->m_specific_param.m_decoder.m_nb_tile_parts_correction_checked = 1;
+        }
 #ifdef USE_JPWL
         j2k->m_cp.correct = parameters->jpwl_correct;
         j2k->m_cp.exp_comps = parameters->jpwl_exp_comps;
@@ -9961,14 +9964,25 @@ OPJ_BOOL opj_j2k_read_tile_header(opj_j2k_t * p_j2k,
                 }
             }
 
+            printf("p_j2k->m_specific_param.m_decoder.m_nb_tile_parts_correction_checked = %d\n", p_j2k->m_specific_param.m_decoder.m_nb_tile_parts_correction_checked);
             if (p_j2k->m_specific_param.m_decoder.m_can_decode &&
                     !p_j2k->m_specific_param.m_decoder.m_nb_tile_parts_correction_checked) {
                 /* Issue 254 */
-                OPJ_BOOL l_correction_needed;
+                OPJ_BOOL l_correction_needed = OPJ_FALSE;
 
                 p_j2k->m_specific_param.m_decoder.m_nb_tile_parts_correction_checked = 1;
-                if (!opj_j2k_need_nb_tile_parts_correction(p_stream,
-                        p_j2k->m_current_tile_number, &l_correction_needed, p_manager)) {
+                if (p_j2k->m_cp.tcps[p_j2k->m_current_tile_number].m_nb_tile_parts == 1) {
+                    /* Skip opj_j2k_need_nb_tile_parts_correction() if there is
+                     * only a single tile part declared. The
+                     * opj_j2k_need_nb_tile_parts_correction() hack was needed
+                     * for files with 5 declared tileparts (where they were
+                     * actually 6).
+                     * Doing it systematically hurts performance when reading
+                     * Sentinel2 L1C JPEG2000 files as explained in
+                     * https://lists.osgeo.org/pipermail/gdal-dev/2024-November/059805.html
+                     */
+                } else if (!opj_j2k_need_nb_tile_parts_correction(p_stream,
+                           p_j2k->m_current_tile_number, &l_correction_needed, p_manager)) {
                     opj_event_msg(p_manager, EVT_ERROR,
                                   "opj_j2k_apply_nb_tile_parts_correction error\n");
                     return OPJ_FALSE;
diff --git a/src/lib/openjp2/openjpeg.h b/src/lib/openjp2/openjpeg.h
index 113481bbb..05cec0e3c 100644
--- a/src/lib/openjp2/openjpeg.h
+++ b/src/lib/openjp2/openjpeg.h
@@ -546,7 +546,12 @@ typedef struct opj_cparameters {
 } opj_cparameters_t;
 
 #define OPJ_DPARAMETERS_IGNORE_PCLR_CMAP_CDEF_FLAG  0x0001
-#define OPJ_DPARAMETERS_DUMP_FLAG 0x0002
+#define OPJ_DPARAMETERS_DUMP_FLAG                   0x0002
+
+/** Disable at runtime the check for invalid TPSOT values added in
+ * https://github.com/uclouvain/openjpeg/pull/514.
+ */
+#define OPJ_DPARAMETERS_DISABLE_TPSOT_FIX           0x0004
 
 /**
  * Decompression parameters