From eff841f1294c5d1f606501c08049104ff37c1e8f Mon Sep 17 00:00:00 2001
From: Even Rouault <even.rouault@spatialys.com>
Date: Tue, 17 Sep 2024 18:56:51 +0200
Subject: [PATCH] /vsitar/: fix support of /vsitar/ of /vsitar/

Fixes #10821
---
 autotest/gcore/data/tar_of_tar_gzip.tar | Bin 0 -> 10240 bytes
 autotest/gcore/vsifile.py               |   9 +++++++++
 port/cpl_vsil_gzip.cpp                  |   8 +++++---
 3 files changed, 14 insertions(+), 3 deletions(-)
 create mode 100644 autotest/gcore/data/tar_of_tar_gzip.tar

diff --git a/autotest/gcore/data/tar_of_tar_gzip.tar b/autotest/gcore/data/tar_of_tar_gzip.tar
new file mode 100644
index 0000000000000000000000000000000000000000..ed18401a2bc5a28e5819161eaeba64436925c9e9
GIT binary patch
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diff --git a/autotest/gcore/vsifile.py b/autotest/gcore/vsifile.py
index 4b648807a813..bf57128f21f7 100755
--- a/autotest/gcore/vsifile.py
+++ b/autotest/gcore/vsifile.py
@@ -701,6 +701,15 @@ def test_vsifile_14():
         )
 
 
+###############################################################################
+# Test bugfix for https://github.com/OSGeo/gdal/issues/10821
+
+
+def test_vsifile_vsitar_of_vsitar():
+
+    gdal.Open("/vsitar/{/vsitar/data/tar_of_tar_gzip.tar}/byte_tif.tar.gz/byte.tif")
+
+
 ###############################################################################
 # Test issue with Error() not detecting end of corrupted gzip stream (#6944)
 
diff --git a/port/cpl_vsil_gzip.cpp b/port/cpl_vsil_gzip.cpp
index 6bf160e7feeb..1e36d1645847 100644
--- a/port/cpl_vsil_gzip.cpp
+++ b/port/cpl_vsil_gzip.cpp
@@ -960,10 +960,12 @@ bool VSIGZipHandle::gzseek(vsi_l_offset offset, int whence)
     {
         m_uncompressed_size = out;
 
-        if (m_pszBaseFileName &&
-            !STARTS_WITH_CI(m_pszBaseFileName, "/vsicurl/") &&
-            m_bWriteProperties)
+        if (m_pszBaseFileName && !STARTS_WITH(m_pszBaseFileName, "/vsicurl/") &&
+            !STARTS_WITH(m_pszBaseFileName, "/vsitar/") &&
+            !STARTS_WITH(m_pszBaseFileName, "/vsizip/") && m_bWriteProperties)
         {
+            CPLErrorStateBackuper oErrorStateBackuper(CPLQuietErrorHandler);
+
             CPLString osCacheFilename(m_pszBaseFileName);
             osCacheFilename += ".properties";