From 5c36aeeae6dcf5591a8753ac264a23fa1aac1899 Mon Sep 17 00:00:00 2001
From: Even Rouault <even.rouault@spatialys.com>
Date: Thu, 18 Apr 2024 01:31:38 +0200
Subject: [PATCH] HDF5 multidim: implement GDALMDArray::GetBlockSize() and
 GetStructuralInfo()

---
 autotest/gdrivers/data/hdf5/deflate.h5 | Bin 0 -> 26420 bytes
 autotest/gdrivers/hdf5multidim.py      |  13 ++++
 frmts/hdf5/hdf5multidim.cpp            |  84 +++++++++++++++++++++++++
 3 files changed, 97 insertions(+)
 create mode 100644 autotest/gdrivers/data/hdf5/deflate.h5

diff --git a/autotest/gdrivers/data/hdf5/deflate.h5 b/autotest/gdrivers/data/hdf5/deflate.h5
new file mode 100644
index 0000000000000000000000000000000000000000..f32e29f9c80f23c02829e979d361c415d27d026f
GIT binary patch
literal 26420
zcmeI44RBl4mB;Usli(x@1PCF}KozyamtEIV9NS6?#IfYqu_JpVg$;2)Q7kzTwq=j3
z1TO<yb_bXiC_`y!6YOTXS(?q(thd9qe54&pSr)c+$4fsZFwjZUmPym56KJO&*(F={
zocrE+S33A~ApK(6_rSjI-S@lqo_qf1-Y4tcmyfnb+ZHXjc!9#Bx?0Uqi}fk}deb=?
zcGx*|P4~CaiI8@;M-x8(QD0EsubSgvR1HrT_>_gn1<Sz_rK)_26LjsbL(WouRSo~O
z4i|Rk3Z?vTVHC5~`S3FjespD!wzhpBRM)sz_pSdd$bchmC(6z(z1O}hI=S<f;fXcJ
z=UmTSmnmdJ=THZ1hdK9@T6p-8b-JsIuCpw=q-D3g#9=6{T7pKMyW+jNgGvR|h1Kf9
z4+Ax~8t?dgK3&kZ>XP|(@gq(x<d-?JU+NLHp!eD@T`kEZT%$j*^SWwCqa7P#@nlDL
zJe_Q9>53`;HoRx4xw=%mWn&B=U1}|)R4TPIKN^7lGl4>`)EaFIWb;G0!YFt>uzgo4
zP#7+mTe~yGd}jM#t}fsl;d<q7fc`;kXKU5c@m#4d+usn)59PDa%HnF}`UEcBR`Fb^
ze_Q+fGk**ZUkk0`@z?BOTi?~=`=7Nve67#A0)1lHp{OW!rL@YAVww1=R&(cLj<3pR
zkAgXK@lrRluvwov!^#KohH*E#b60==V9rLcWhXzI>mSUNa(XPIMfRxpqBDZ;!7My<
z&F-WzPaYgSHoXJ_aG9b2Y#kmhX7dGT$DTai5{S-Frm28ZyH%z9EogzI7TUG8<p&3^
z%M9+yY11m)qFZ-rqtcWr|7v@5EYM?caJaA|UC0bMwdk>Up4(NW)<;{q0yrlH;=6{n
z=Zb-lKME5jnBmuE?9L44v*}`{u*0qa)v*o7GcZ`_lu~ah{~8>LmRh7O*-?awhB6}~
z`GS53;9P<~WOxZ08Qq;Lj^@%sxnf_YG+dmiy?K!xO3;oTU<6m`Nsfv;VFFX0zF!t5
z)!0{6Wzlp`<!J)+tEe*tA9m8yG$r4SCEq<qQ}<oj?$-9sd3y9%^Z-%TSf|sed6%KJ
z)|@KG=<{ds=oWmM!Ey3*#)q|4Ux-&#zN+Q5cw(!8`eL0po8yQ(2ZC=|*<9b%kxVId
z5fB&ySOaP!MFQ4TItPBiK{eAgn!4ngi38dcCY2szaNqxg9gpXz5?GOlwZ#&#cxx<e
zTd@?XL@TnHQf4$)g0tU!khSh3$HATHTP!RMW(p`u-6y+KQ})&O?ElN_9rgB-k3Vo*
zTQV6_!G(5zt$$Q1tpm_XSZYd-C2NbN4(PaR`}~id6Fscj674-Yl6+cG2c(hP<V@Do
zlFRrV&`If1ZpXd@1IUaaopl9-`mq}OuBGOmwQOo#syzx8L5Q6T+1V>fPA_q4w2xG{
z_C-z2M{1ExVFHJtj$bwTrM4v0r8YW)lg22eb_q18M~x|bYT7P-!};L$K?k68Z`Z{S
zuS<2cfpsfzP&L}0Q@aiZ7OS(c(#=X?(awXL1L{evYbTCnr5^hq_yF}JoIpc*I7YYb
z*`Vel0U22Gg=OEmPCbs5LIw_tquW|~)%8ehvwimBzOQXle}e>Mpe(N}YW}QRitHXA
zJie5=;Ri>*u9m`yYQ<kl{l}pf538l<@cVrVqvFWrx4fjT$6MR%zCN>g)&DJzpL!o=
zdB@xFfYyJ0g_|opS|M|V#1(2*ghxd*RcKrh5*0C4p=(7L{L|$#;kVNhk2w<$tZ(h^
z(z66U|KQN)km5MR<6m)v!r>%u$*;0+yZQ7v!pT+#orgAEd#UFE&jX$ZJP&vt@I2so
z!1I9T0nY=T2RsjW9`HQyr}selY5@K1Z~ZO()$iYc-w5C$DK6lq<E=f#;gMXil-H|M
zxN;JNA1a6IF0lT3b+{ImWMMV+>V~?ex|Ov%v;C{C4%LO~>l$u*W8wL2?a_7af{Fg#
z;O~EUY7Z@*kB($Y`OILtnCsWhz&1wU%Li(sC(*s3HQ5`Cw?xBDfe!{Yr8Wj`87|}k
zp-?<nyFS*v-n|>FjkcsVZ3K3>SlXFxfd!#_U#5_bW=gw;(xFJWDOj8AX^$nkJEFb8
z*1=410IF$jYz)>mu54-!*EiNR)P^Gsb&;m##z=EGw6ZzUT-&lK)!v=xNL}9>jP)ef
z2Wx{(_4Uoc8*Z58PGh*S3GehIV2K+HSzpZM3ODEbb_Q$fXTh5z^&!MJ#XC~H!E9~^
z;6T>ZhngBztqe!Pt3r`T!^)Mj6pe(!;n{6yaBb+`5Nl1rGJ9_@Wmd^HI;&(su(Blq
zYwf96qBjWZocYqOY%V?ApB^secjOCTM+MObI~<Cj6FN1U&%pf;ghEXf$Y@_?FqiJn
z^uZz=b|VsrG*$rpnL${m%VkDOu$mXFT~&|AEJOkI(+J$Poimgx6~Q;5*<4X?d$DD6
z2gFH?YLB%fQ=pN~)B&L@jCUte?XyV-UJIcZItaaAe?SjZj(_|%|E1c0&f+3F{?}I=
zP2W6F(u=y@xcA1rH}3y{L+@QtRpt0clNLVuh1)H4o*w_@8$9@y6WXbPWoFryV5v)C
zchEA0yH(t$7k^Gc(Q^aWLQ{CGRSgSO!<)_;2JJndj~bNP=nYTf#~`e~;;{uc&!oQF
z@3^!D_e7Zb=plDz^`VV!|H~fUBgNsHa(%cL(Rq%ap}ltfE401k&-HYsl%B=Kh`(dM
zj7{u+-;<|byVioWU3?VGw(IC@sF!qUO(X-bCo5mbWB)9*{H^Mb6k$`K`x)hotkQ*a
ztBdX4=Z5mI1L>yWVmdRHAAQHYd}#09y^p6hgZk&|`tq<@6t^qk-m+4z;OuL9=ia+#
z)2^=`94@XUd*8KbTYE>@=YKTw*yXmd$DDQhW6t(h+O;w9pTGKXDiMoWuwjYvDAk)o
zen(&LZMSa{huatMz(6WLQrFm5#5tQZoQcAa&n7B4+|z*vt&iGQN}b+HXLd^46`ie9
zZV*>e-j(M8&jX$ZJP&vt@I2so!1KWG>w&R}R}NjEd@HPhv5E1Oun~R63gOvV$~tUC
z;OyToP}XZ!Vr*hyFT4)4&$?)Aq6Yq$um;tsv5D!KdCF>4FIJq@L0+f&{@6q(-d(Bw
zdu*cjjZ2g-X?<>N;*AfVt$Z`q4Al2^xVuZeJ~naUU*POPs~TGSHncH?ZS)?3cdveK
zbz&a8DDjxJ0!kovr=_5^DL6~2AD5pQOHW+CP+8AgtH&lL(b8M7L?>Fc1}&ZZHMFr#
zJqP`WLtdxOI|<w!+Jf)E-KVg%-j|`>m#i?@*8$vZXz43oUaEXoqOVT;1WFvxmTrMJ
zYQBnR10RL5S>1EDwR<)|*^AUu<=*H-tGd+j^1OjO<lSe@hjv$k3P;iU@#G?9eaTuj
zyLXLMrXR-RMx&bhbbrC)lW5g|dJU{c-`|M}o<N&R+LL%!>o$!g!swySDadQZ9@XI8
zUgT;puMcaP+y~sf)?&!Rvs=-Brf)_|qx584*MhNu^=Um!iB41@g?={mnG!~Q6A`^@
zz*nzZ>&h*ioYD4yrKark5r~Kftt-L1<KWZhbrhoox<}J!)f$Xb<Cor7K>g!7hNj@|
zsQL}m=hkc@*7(%;dHP0Z?M`fC8cVS8Vft&z8ud*t%Q&~)@dqH*K8Cs(70ROB<tC?Q
zvDuAS<7cCS>6=lj2J1^|^|3y!xv_5=^Yj=r)|d6@O1OI)S~}^D!5Tc%^M<L#+%>jz
zV$C}02HaYVE#nDL@N*b-;|cJ_XY{Cb^Ncdnbx@0rXH$#GGi`JpSpb%zTAedcLeE!g
z4#7B&Sfk~$&j}o%`>b=zW8C!D+#SH#VhBgK>E!^<NRQ)OVoI2~#6<CIJ(@<ZZPlZ~
z_22j>bkAX4GxZr2)_i)A^3BKC9oP#|d_d2gsQ#zWdc)PAhuD}l-tFC@M+(lnI9uqM
z+Sp>|CNs`W)Xk=J4XUbR$ec~P8jU{ytv!e{b<Ihzw4~46{+jxXpH0urs6B!4@-ZxH
zd~a+vabTjU?96R#8ZFh4ZS?4MXL-|_>2D{N)ie4ep6Mr!@pI=sPytqO%AZ!o7Q>mo
znLJ~?IWu|~AJDV=oqitB-y5ljqVIwD_czk_LH9M=Ez$Qu#5vpKT{HFwoPH0@rIgyw
zIQkx_4AG~L2ps=@=`n$GUq^B(ep=vo``-{adJll?{I0-}pNKmmaP-a-amNLYe?RvN
zf#Z6d7C5fQyohZ9+3ma-MrOI`Vu9m&Tr6;0kM|24*P~A0xE{>{NByFXtP?n{N0-2H
zJ+2ctuE#ck<9gi0INnd{M@itg9)BlrT#t_k9M|Ikf#Y^g2prerfWUD*z94X1k3#~-
z^>|j`xE?c%b6z1N8Qk<Gf#Z7oP~f;8KNC2v$FBvB>!IL9c09=c)DOD0@4|h7<9aL+
zIIhQ~0>|~ZLg2U_Va9R$sUIH_IIc&Vz;Qi#1di*mMc}v|S%KsIDF__bV@%+<9{(V4
zT#tJNj_dI$#?g8a=|Jgc1&-_Sd4c14d{N-I9#07z*Mscz(n=4|=SEs*<m-c#w7E*b
zOVoJqc;<TFC~#cwodU=8E(#pi`&NPD_TD9MeEi)naD4ndByfEEJuGm1{7o^AHU-$;
zH@}|{IIhPt0>}0EroeGM4htOD<EX%KJ$@>1T#sK09M|Kw0>|~JZnAwz_K=^s9_KNR
z`<E11E^wT`OyIa4^#aHBSS@f|kEp;=|EV8wf#Z5?7C5fQc7fx13<@0AV>jdIJ#Dg|
z(%S`&>v6ZhaXmgMa9odl0>||@C~#blM+J`S@fCsNdORm^T#pw7j_dI<<G9~Qk5>hb
z>v2-xc)h0tj_cuLe>YP-To1p%aXpp_9M>Zta9oe81di*`AaGodYZyo0?~o3ZwhJ8B
zBO!3)N2+hDz;QkL1&-@6B5+)fTLg~lafiThJ*YokTIm7$+(@4nX&)HrL4PN39sf)C
zyiVn)m2V3i*YSG-$8|g=aC}_7E^vHY{V(IVUDS^`@Xxy8LH#3+kE^o<j*qKl0>{Ty
zP~f;8wE{=>+SbFrnIv%3AL7;u9M@xmz;QiN0>|~Zk#WvHD@A6x=}v*;dK3kY>v5~V
zaXs!5IIhS20>|}uNZ`004+|XEV@lw-9#04y*W($+@%BiNZwegO<FLSSJ&p<-*W;%G
z$MyK7z;Qi(D{x$o>JQmHr}E?%O35$h2^`mBxxjHfE@PbZ&lS}R9M@yDz;QjI0>|};
z3mn&Dv%rx*$$#4gj_WZfa9oew0>|~ZUEsJLcQcOHL;d)qz;QkH2^`nspullG9u+vQ
z$5#Z7>+zhxaXnrTIIhRb0>}OMs=#qQPBM=6yOR!-o)S2&2k~B7=>hw5<0XpLr|Ek~
ziWl-b_owe_yB^N*`1T7NkME@d$KyL7aAXJd?ka)f@!cSBJif0HI3C~a0>|S!!8m@O
z`mt5uxE}oi$MqNyIIhPn0>|~ZL*Td`_X!-=V~@abJ@yM6*W(d^<Nkh(arn;PY{%0A
z$MyJzz;QjkD{x$oBLc_uI4*Epk6#EJ*W<LnaXsd-_n63kT#v;9$Mv|_;Yb7TJtp#m
QmwF!XJm7iY&+CEz2OMWc{Qv*}

literal 0
HcmV?d00001

diff --git a/autotest/gdrivers/hdf5multidim.py b/autotest/gdrivers/hdf5multidim.py
index 64dac532c916..6f1f003c326f 100755
--- a/autotest/gdrivers/hdf5multidim.py
+++ b/autotest/gdrivers/hdf5multidim.py
@@ -827,3 +827,16 @@ def test_hdf5_multidim_eos_swath_no_explicit_dimension_map():
         coordinates[1].GetFullName()
         == "/HDFEOS/SWATHS/MySwath/Geolocation Fields/Latitude"
     )
+
+
+###############################################################################
+# Test GetBlockSize() and GetStructuralInfo()
+
+
+def test_hdf5_multidim_block_size_structural_info():
+
+    ds = gdal.OpenEx("data/hdf5/deflate.h5", gdal.OF_MULTIDIM_RASTER)
+    rg = ds.GetRootGroup()
+    var = rg.OpenMDArray("Band1")
+    assert var.GetBlockSize() == [1, 2]
+    assert var.GetStructuralInfo() == {"COMPRESSION": "DEFLATE", "FILTER": "SHUFFLE"}
diff --git a/frmts/hdf5/hdf5multidim.cpp b/frmts/hdf5/hdf5multidim.cpp
index 07d6be6c4e25..22623602ab7b 100644
--- a/frmts/hdf5/hdf5multidim.cpp
+++ b/frmts/hdf5/hdf5multidim.cpp
@@ -293,6 +293,7 @@ class HDF5Array final : public GDALMDArray
     mutable bool m_bHasDimensionLabels = false;
     std::shared_ptr<OGRSpatialReference> m_poSRS{};
     haddr_t m_nOffset;
+    mutable CPLStringList m_aosStructuralInfo{};
 
     HDF5Array(const std::string &osParentName, const std::string &osName,
               const std::shared_ptr<HDF5SharedResources> &poShared,
@@ -365,6 +366,10 @@ class HDF5Array final : public GDALMDArray
     std::vector<std::shared_ptr<GDALAttribute>>
     GetAttributes(CSLConstList papszOptions = nullptr) const override;
 
+    std::vector<GUInt64> GetBlockSize() const override;
+
+    CSLConstList GetStructuralInfo() const override;
+
     const void *GetRawNoDataValue() const override
     {
         return m_abyNoData.empty() ? nullptr : m_abyNoData.data();
@@ -1808,6 +1813,85 @@ HDF5Array::GetAttributes(CSLConstList papszOptions) const
     return m_oListAttributes;
 }
 
+/************************************************************************/
+/*                           GetBlockSize()                             */
+/************************************************************************/
+
+std::vector<GUInt64> HDF5Array::GetBlockSize() const
+{
+    HDF5_GLOBAL_LOCK();
+
+    const auto nDimCount = GetDimensionCount();
+    std::vector<GUInt64> res(nDimCount);
+    if (res.empty())
+        return res;
+
+    const hid_t nListId = H5Dget_create_plist(m_hArray);
+    if (nListId > 0)
+    {
+        if (H5Pget_layout(nListId) == H5D_CHUNKED)
+        {
+            std::vector<hsize_t> anChunkDims(nDimCount);
+            const int nDimSize =
+                H5Pget_chunk(nListId, nDimCount, &anChunkDims[0]);
+            if (static_cast<size_t>(nDimSize) == nDimCount)
+            {
+                for (size_t i = 0; i < nDimCount; ++i)
+                {
+                    res[i] = anChunkDims[i];
+                }
+            }
+        }
+
+        H5Pclose(nListId);
+    }
+
+    return res;
+}
+
+/************************************************************************/
+/*                         GetStructuralInfo()                          */
+/************************************************************************/
+
+CSLConstList HDF5Array::GetStructuralInfo() const
+{
+    if (m_aosStructuralInfo.empty())
+    {
+        HDF5_GLOBAL_LOCK();
+        const hid_t nListId = H5Dget_create_plist(m_hArray);
+        if (nListId > 0)
+        {
+            const int nFilters = H5Pget_nfilters(nListId);
+            for (int i = 0; i < nFilters; ++i)
+            {
+                unsigned int flags = 0;
+                size_t cd_nelmts = 0;
+                char szName[64 + 1] = {0};
+                const auto eFilter = H5Pget_filter(
+                    nListId, i, &flags, &cd_nelmts, nullptr, 64, szName);
+                if (eFilter == H5Z_FILTER_DEFLATE)
+                {
+                    m_aosStructuralInfo.SetNameValue("COMPRESSION", "DEFLATE");
+                }
+                else if (eFilter == H5Z_FILTER_SZIP)
+                {
+                    m_aosStructuralInfo.SetNameValue("COMPRESSION", "SZIP");
+                }
+                else if (eFilter == H5Z_FILTER_SHUFFLE)
+                {
+                    m_aosStructuralInfo.SetNameValue("FILTER", "SHUFFLE");
+                }
+                else
+                {
+                    CPLDebug("HDF5", "Filter used: %s", szName);
+                }
+            }
+            H5Pclose(nListId);
+        }
+    }
+    return m_aosStructuralInfo.List();
+}
+
 /************************************************************************/
 /*                           CopyBuffer()                               */
 /************************************************************************/