Make defer strile offset/bytecount loading available at runtime

... and add per-strile offset/bytecount loading capabilities.

Part of this commit makes the behaviour that was previously met when
libtiff was compiled with -DDEFER_STRILE_LOAD available for default builds
when specifying the new 'D' (Deferred) TIFFOpen() flag. In that mode, the [Tile/Strip][ByteCounts/Offsets]
arrays are only loaded when first accessed. This can speed-up the opening
of files stored on the network when just metadata retrieval is needed.
This mode has been used for years by the GDAL library when compiled with
its embeded libtiff copy.

To avoid potential out-of-tree code (typically codecs) that would use
the td_stripbytecount and td_stripoffset array inconditionnaly assuming they
have been loaded, those have been suffixed with _p (for protected). The
use of the new functions mentionned below is then recommended.

Another addition of this commit is the capability of loading only the
values of the offset/bytecount of the strile of interest instead of the
whole array. This is enabled with the new 'O' (Ondemand) flag of TIFFOpen()
(which implies 'D'). That behaviour has also been used by GDAL, which hacked
into the td_stripoffset/td_stripbytecount arrays directly. The new code
added in the _TIFFFetchStrileValue() and _TIFFPartialReadStripArray() internal
functions is mostly a port of what was in GDAL GTiff driver previously.

Related to that, the public TIFFGetStrileOffset[WithErr]() and TIFFGetStrileByteCount[WithErr]()
functions have been added to API. They are of particular interest when
using sparse files (with offset == bytecount == 0) and you want to detect
if a strile is present or not without decompressing the data, or updating
an existing sparse file.
They will also be used to enable a future enhancement where client code can entirely
skip bytecount loading in some situtations

A new test/defer_strile_loading.c test has been added to test the above
capabilities.

1 files changed, 29 insertions, 58 deletions

diff --git a/libtiff/tif_read.c b/libtiff/tif_read.c
index 79c470cb..c65abcea 100644
--- a/libtiff/tif_read.c
+++ b/libtiff/tif_read.c
@@ -175,17 +175,14 @@ TIFFFillStripPartial( TIFF *tif, int strip, tmsize_t read_ahead, int restart )
         tmsize_t to_read;
         tmsize_t read_ahead_mod;
         /* tmsize_t bytecountm; */
-        
-        if (!_TIFFFillStriles( tif ) || !tif->tif_dir.td_stripbytecount)
-            return 0;
-        
+
         /*
          * Expand raw data buffer, if needed, to hold data
          * strip coming from file (perhaps should set upper
          * bound on the size of a buffer we'll use?).
          */
 
-        /* bytecountm=(tmsize_t) td->td_stripbytecount[strip]; */
+        /* bytecountm=(tmsize_t) TIFFGetStrileByteCount(tif, strip); */
 
         /* Not completely sure where the * 2 comes from, but probably for */
         /* an exponentional growth strategy of tif_rawdatasize */
@@ -229,7 +226,7 @@ TIFFFillStripPartial( TIFF *tif, int strip, tmsize_t read_ahead, int restart )
         /*
         ** Seek to the point in the file where more data should be read.
         */
-        read_offset = td->td_stripoffset[strip]
+        read_offset = TIFFGetStrileOffset(tif, strip)
                 + tif->tif_rawdataoff + tif->tif_rawdataloaded;
 
         if (!SeekOK(tif, read_offset)) {
@@ -246,10 +243,10 @@ TIFFFillStripPartial( TIFF *tif, int strip, tmsize_t read_ahead, int restart )
                 to_read = read_ahead_mod - unused_data;
         else
                 to_read = tif->tif_rawdatasize - unused_data;
-        if( (uint64) to_read > td->td_stripbytecount[strip] 
+        if( (uint64) to_read > TIFFGetStrileByteCount(tif, strip)
             - tif->tif_rawdataoff - tif->tif_rawdataloaded )
         {
-                to_read = (tmsize_t) td->td_stripbytecount[strip]
+                to_read = (tmsize_t) TIFFGetStrileByteCount(tif, strip)
                         - tif->tif_rawdataoff - tif->tif_rawdataloaded;
         }
 
@@ -288,7 +285,7 @@ TIFFFillStripPartial( TIFF *tif, int strip, tmsize_t read_ahead, int restart )
             /* For JPEG, if there are multiple scans (can generally be known */
             /* with the  read_ahead used), we need to read the whole strip */
             if( tif->tif_dir.td_compression==COMPRESSION_JPEG &&
-                (uint64)tif->tif_rawcc < td->td_stripbytecount[strip] )
+                (uint64)tif->tif_rawcc < TIFFGetStrileByteCount(tif, strip) )
             {
                 if( TIFFJPEGIsFullStripRequired(tif) )
                 {
@@ -347,9 +344,7 @@ TIFFSeek(TIFF* tif, uint32 row, uint16 sample )
          * read it a few lines at a time?
          */
 #if defined(CHUNKY_STRIP_READ_SUPPORT)
-        if (!_TIFFFillStriles( tif ) || !tif->tif_dir.td_stripbytecount)
-            return 0;
-        whole_strip = tif->tif_dir.td_stripbytecount[strip] < 10
+        whole_strip = TIFFGetStrileByteCount(tif, strip) < 10
                 || isMapped(tif);
         if( td->td_compression == COMPRESSION_LERC ||
             td->td_compression == COMPRESSION_JBIG )
@@ -402,7 +397,7 @@ TIFFSeek(TIFF* tif, uint32 row, uint16 sample )
         else if( !whole_strip )
         {
                 if( ((tif->tif_rawdata + tif->tif_rawdataloaded) - tif->tif_rawcp) < read_ahead 
-                    && (uint64) tif->tif_rawdataoff+tif->tif_rawdataloaded < td->td_stripbytecount[strip] )
+                    && (uint64) tif->tif_rawdataoff+tif->tif_rawdataloaded < TIFFGetStrileByteCount(tif, strip) )
                 {
                         if( !TIFFFillStripPartial(tif,strip,read_ahead,0) )
                                 return 0;
@@ -599,16 +594,11 @@ static tmsize_t
 TIFFReadRawStrip1(TIFF* tif, uint32 strip, void* buf, tmsize_t size,
     const char* module)
 {
-	TIFFDirectory *td = &tif->tif_dir;
-
-    if (!_TIFFFillStriles( tif ))
-        return ((tmsize_t)(-1));
-        
 	assert((tif->tif_flags&TIFF_NOREADRAW)==0);
 	if (!isMapped(tif)) {
 		tmsize_t cc;
 
-		if (!SeekOK(tif, td->td_stripoffset[strip])) {
+		if (!SeekOK(tif, TIFFGetStrileOffset(tif, strip))) {
 			TIFFErrorExt(tif->tif_clientdata, module,
 			    "Seek error at scanline %lu, strip %lu",
 			    (unsigned long) tif->tif_row, (unsigned long) strip);
@@ -634,8 +624,8 @@ TIFFReadRawStrip1(TIFF* tif, uint32 strip, void* buf, tmsize_t size,
 	} else {
 		tmsize_t ma = 0;
 		tmsize_t n;
-		if ((td->td_stripoffset[strip] > (uint64)TIFF_TMSIZE_T_MAX)||
-                    ((ma=(tmsize_t)td->td_stripoffset[strip])>tif->tif_size))
+		if ((TIFFGetStrileOffset(tif, strip) > (uint64)TIFF_TMSIZE_T_MAX)||
+                    ((ma=(tmsize_t)TIFFGetStrileOffset(tif, strip))>tif->tif_size))
                 {
                     n=0;
                 }
@@ -679,12 +669,10 @@ static tmsize_t
 TIFFReadRawStripOrTile2(TIFF* tif, uint32 strip_or_tile, int is_strip,
                         tmsize_t size, const char* module)
 {
-        TIFFDirectory *td = &tif->tif_dir;
-
         assert( !isMapped(tif) );
         assert((tif->tif_flags&TIFF_NOREADRAW)==0);
 
-        if (!SeekOK(tif, td->td_stripoffset[strip_or_tile])) {
+        if (!SeekOK(tif, TIFFGetStrileOffset(tif, strip_or_tile))) {
             if( is_strip )
             {
                 TIFFErrorExt(tif->tif_clientdata, module,
@@ -738,7 +726,7 @@ TIFFReadRawStrip(TIFF* tif, uint32 strip, void* buf, tmsize_t size)
 		    "Compression scheme does not support access to raw uncompressed data");
 		return ((tmsize_t)(-1));
 	}
-	bytecount = td->td_stripbytecount[strip];
+	bytecount = TIFFGetStrileByteCount(tif, strip);
 	if ((int64)bytecount <= 0) {
 #if defined(__WIN32__) && (defined(_MSC_VER) || defined(__MINGW32__))
 		TIFFErrorExt(tif->tif_clientdata, module,
@@ -773,12 +761,9 @@ TIFFFillStrip(TIFF* tif, uint32 strip)
 	static const char module[] = "TIFFFillStrip";
 	TIFFDirectory *td = &tif->tif_dir;
 
-        if (!_TIFFFillStriles( tif ) || !tif->tif_dir.td_stripbytecount)
-            return 0;
-
 	if ((tif->tif_flags&TIFF_NOREADRAW)==0)
 	{
-		uint64 bytecount = td->td_stripbytecount[strip];
+		uint64 bytecount = TIFFGetStrileByteCount(tif, strip);
 		if ((int64)bytecount <= 0) {
 #if defined(__WIN32__) && (defined(_MSC_VER) || defined(__MINGW32__))
 			TIFFErrorExt(tif->tif_clientdata, module,
@@ -831,13 +816,13 @@ TIFFFillStrip(TIFF* tif, uint32 strip)
 			 * We must check for overflow, potentially causing
 			 * an OOB read. Instead of simple
 			 *
-			 *  td->td_stripoffset[strip]+bytecount > tif->tif_size
+			 *  TIFFGetStrileOffset(tif, strip)+bytecount > tif->tif_size
 			 *
 			 * comparison (which can overflow) we do the following
 			 * two comparisons:
 			 */
 			if (bytecount > (uint64)tif->tif_size ||
-			    td->td_stripoffset[strip] > (uint64)tif->tif_size - bytecount) {
+			    TIFFGetStrileOffset(tif, strip) > (uint64)tif->tif_size - bytecount) {
 				/*
 				 * This error message might seem strange, but
 				 * it's what would happen if a read were done
@@ -849,7 +834,7 @@ TIFFFillStrip(TIFF* tif, uint32 strip)
 					"Read error on strip %lu; "
 					"got %I64u bytes, expected %I64u",
 					(unsigned long) strip,
-					(unsigned __int64) tif->tif_size - td->td_stripoffset[strip],
+					(unsigned __int64) tif->tif_size - TIFFGetStrileOffset(tif, strip),
 					(unsigned __int64) bytecount);
 #else
 				TIFFErrorExt(tif->tif_clientdata, module,
@@ -857,7 +842,7 @@ TIFFFillStrip(TIFF* tif, uint32 strip)
 					"Read error on strip %lu; "
 					"got %llu bytes, expected %llu",
 					(unsigned long) strip,
-					(unsigned long long) tif->tif_size - td->td_stripoffset[strip],
+					(unsigned long long) tif->tif_size - TIFFGetStrileOffset(tif, strip),
 					(unsigned long long) bytecount);
 #endif
 				tif->tif_curstrip = NOSTRIP;
@@ -886,7 +871,7 @@ TIFFFillStrip(TIFF* tif, uint32 strip)
 			}
 			tif->tif_flags &= ~TIFF_MYBUFFER;
 			tif->tif_rawdatasize = (tmsize_t)bytecount;
-			tif->tif_rawdata = tif->tif_base + (tmsize_t)td->td_stripoffset[strip];
+			tif->tif_rawdata = tif->tif_base + (tmsize_t)TIFFGetStrileOffset(tif, strip);
                         tif->tif_rawdataoff = 0;
                         tif->tif_rawdataloaded = (tmsize_t) bytecount;
 
@@ -1101,16 +1086,11 @@ _TIFFReadEncodedTileAndAllocBuffer(TIFF* tif, uint32 tile,
 static tmsize_t
 TIFFReadRawTile1(TIFF* tif, uint32 tile, void* buf, tmsize_t size, const char* module)
 {
-	TIFFDirectory *td = &tif->tif_dir;
-
-    if (!_TIFFFillStriles( tif ))
-        return ((tmsize_t)(-1));
-
 	assert((tif->tif_flags&TIFF_NOREADRAW)==0);
 	if (!isMapped(tif)) {
 		tmsize_t cc;
 
-		if (!SeekOK(tif, td->td_stripoffset[tile])) {
+		if (!SeekOK(tif, TIFFGetStrileOffset(tif, tile))) {
 			TIFFErrorExt(tif->tif_clientdata, module,
 			    "Seek error at row %lu, col %lu, tile %lu",
 			    (unsigned long) tif->tif_row,
@@ -1140,9 +1120,9 @@ TIFFReadRawTile1(TIFF* tif, uint32 tile, void* buf, tmsize_t size, const char* m
 	} else {
 		tmsize_t ma,mb;
 		tmsize_t n;
-		ma=(tmsize_t)td->td_stripoffset[tile];
+		ma=(tmsize_t)TIFFGetStrileOffset(tif, tile);
 		mb=ma+size;
-		if ((td->td_stripoffset[tile] > (uint64)TIFF_TMSIZE_T_MAX)||(ma>tif->tif_size))
+		if ((TIFFGetStrileOffset(tif, tile) > (uint64)TIFF_TMSIZE_T_MAX)||(ma>tif->tif_size))
 			n=0;
 		else if ((mb<ma)||(mb<size)||(mb>tif->tif_size))
 			n=tif->tif_size-ma;
@@ -1198,7 +1178,7 @@ TIFFReadRawTile(TIFF* tif, uint32 tile, void* buf, tmsize_t size)
 		"Compression scheme does not support access to raw uncompressed data");
 		return ((tmsize_t)(-1));
 	}
-	bytecount64 = td->td_stripbytecount[tile];
+	bytecount64 = TIFFGetStrileByteCount(tif, tile);
 	if (size != (tmsize_t)(-1) && (uint64)size < bytecount64)
 		bytecount64 = (uint64)size;
 	bytecountm = (tmsize_t)bytecount64;
@@ -1220,12 +1200,9 @@ TIFFFillTile(TIFF* tif, uint32 tile)
 	static const char module[] = "TIFFFillTile";
 	TIFFDirectory *td = &tif->tif_dir;
 
-        if (!_TIFFFillStriles( tif ) || !tif->tif_dir.td_stripbytecount)
-            return 0;
-
 	if ((tif->tif_flags&TIFF_NOREADRAW)==0)
 	{
-		uint64 bytecount = td->td_stripbytecount[tile];
+		uint64 bytecount = TIFFGetStrileByteCount(tif, tile);
 		if ((int64)bytecount <= 0) {
 #if defined(__WIN32__) && (defined(_MSC_VER) || defined(__MINGW32__))
 			TIFFErrorExt(tif->tif_clientdata, module,
@@ -1278,13 +1255,13 @@ TIFFFillTile(TIFF* tif, uint32 tile)
 			 * We must check for overflow, potentially causing
 			 * an OOB read. Instead of simple
 			 *
-			 *  td->td_stripoffset[tile]+bytecount > tif->tif_size
+			 *  TIFFGetStrileOffset(tif, tile)+bytecount > tif->tif_size
 			 *
 			 * comparison (which can overflow) we do the following
 			 * two comparisons:
 			 */
 			if (bytecount > (uint64)tif->tif_size ||
-			    td->td_stripoffset[tile] > (uint64)tif->tif_size - bytecount) {
+			    TIFFGetStrileOffset(tif, tile) > (uint64)tif->tif_size - bytecount) {
 				tif->tif_curtile = NOTILE;
 				return (0);
 			}
@@ -1313,7 +1290,7 @@ TIFFFillTile(TIFF* tif, uint32 tile)
 
 			tif->tif_rawdatasize = (tmsize_t)bytecount;
 			tif->tif_rawdata =
-				tif->tif_base + (tmsize_t)td->td_stripoffset[tile];
+				tif->tif_base + (tmsize_t)TIFFGetStrileOffset(tif, tile);
                         tif->tif_rawdataoff = 0;
                         tif->tif_rawdataloaded = (tmsize_t) bytecount;
 			tif->tif_flags |= TIFF_BUFFERMMAP;
@@ -1440,9 +1417,6 @@ TIFFStartStrip(TIFF* tif, uint32 strip)
 {
 	TIFFDirectory *td = &tif->tif_dir;
 
-        if (!_TIFFFillStriles( tif ) || !tif->tif_dir.td_stripbytecount)
-            return 0;
-
 	if ((tif->tif_flags & TIFF_CODERSETUP) == 0) {
 		if (!(*tif->tif_setupdecode)(tif))
 			return (0);
@@ -1463,7 +1437,7 @@ TIFFStartStrip(TIFF* tif, uint32 strip)
 		if( tif->tif_rawdataloaded > 0 )
 			tif->tif_rawcc = tif->tif_rawdataloaded;
 		else
-			tif->tif_rawcc = (tmsize_t)td->td_stripbytecount[strip];
+			tif->tif_rawcc = (tmsize_t)TIFFGetStrileByteCount(tif, strip);
 	}
 	return ((*tif->tif_predecode)(tif,
 			(uint16)(strip / td->td_stripsperimage)));
@@ -1480,9 +1454,6 @@ TIFFStartTile(TIFF* tif, uint32 tile)
 	TIFFDirectory *td = &tif->tif_dir;
         uint32 howmany32;
 
-        if (!_TIFFFillStriles( tif ) || !tif->tif_dir.td_stripbytecount)
-                return 0;
-
 	if ((tif->tif_flags & TIFF_CODERSETUP) == 0) {
 		if (!(*tif->tif_setupdecode)(tif))
 			return (0);
@@ -1513,7 +1484,7 @@ TIFFStartTile(TIFF* tif, uint32 tile)
 		if( tif->tif_rawdataloaded > 0 )
 			tif->tif_rawcc = tif->tif_rawdataloaded;
 		else
-			tif->tif_rawcc = (tmsize_t)td->td_stripbytecount[tile];
+			tif->tif_rawcc = (tmsize_t)TIFFGetStrileByteCount(tif, tile);
 	}
 	return ((*tif->tif_predecode)(tif,
 			(uint16)(tile/td->td_stripsperimage)));