iso9660: remove per-reader zero comparison buffer
Check reserved fields by comparing adjacent bytes after confirming the first byte is zero. This preserves the memcmp fast path and removes 2 KiB from each ISO9660 reader state.
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datauwu committed
1 parent
42b2444920
commit
b15a0a0bb5
1 file changed
+34
-42
@@ -379,8 +379,6 @@ struct iso9660 {
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size_t utf16be_path_len;
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unsigned char *utf16be_previous_path;
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size_t utf16be_previous_path_len;
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/* Null buffer used in bidder to improve its performance. */
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unsigned char null[2048];
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};
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static int archive_read_format_iso9660_bid(struct archive_read *, int);
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@@ -403,12 +401,12 @@ static time_t isodate17(const unsigned char *);
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static int isodate17_valid(const unsigned char *);
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static time_t isodate7(const unsigned char *);
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static int isodate7_valid(const unsigned char *);
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static int isBootRecord(struct iso9660 *, const unsigned char *);
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static int isBootRecord(const unsigned char *);
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static int isVolumePartition(struct iso9660 *, const unsigned char *);
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static int isVDSetTerminator(struct iso9660 *, const unsigned char *);
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static int isVDSetTerminator(const unsigned char *);
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static int isJolietSVD(struct iso9660 *, const unsigned char *);
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static int isSVD(struct iso9660 *, const unsigned char *);
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static int isEVD(struct iso9660 *, const unsigned char *);
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static int isSVD(const unsigned char *);
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static int isEVD(const unsigned char *);
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static int isPVD(struct iso9660 *, const unsigned char *);
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static int isRootDirectoryRecord(const unsigned char *);
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static int isValid723Integer(const unsigned char *);
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@@ -547,15 +545,15 @@ archive_read_format_iso9660_bid(struct archive_read *a, int best_bid)
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if (isJolietSVD(iso9660, p))
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continue;
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}
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if (isBootRecord(iso9660, p))
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if (isBootRecord(p))
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continue;
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if (isEVD(iso9660, p))
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if (isEVD(p))
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continue;
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if (isSVD(iso9660, p))
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if (isSVD(p))
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continue;
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if (isVolumePartition(iso9660, p))
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continue;
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if (isVDSetTerminator(iso9660, p)) {
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if (isVDSetTerminator(p)) {
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seenTerminator = 1;
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break;
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}
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@@ -603,26 +601,23 @@ archive_read_format_iso9660_options(struct archive_read *a,
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}
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static int
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isNull(struct iso9660 *iso9660, const unsigned char *h, unsigned offset,
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unsigned bytes)
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isNull(const unsigned char *h, unsigned offset, unsigned bytes)
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{
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while (bytes >= sizeof(iso9660->null)) {
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if (!memcmp(iso9660->null, h + offset, sizeof(iso9660->null)))
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return (0);
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offset += sizeof(iso9660->null);
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bytes -= sizeof(iso9660->null);
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}
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if (bytes)
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return memcmp(iso9660->null, h + offset, bytes) == 0;
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else
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if (bytes == 0)
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return (1);
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/*
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* If the first byte is zero and every byte equals the following
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* byte, the entire range is zero.
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*/
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return (h[offset] == 0 &&
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(bytes == 1 ||
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memcmp(h + offset, h + offset + 1, bytes - 1) == 0));
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}
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static int
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isBootRecord(struct iso9660 *iso9660, const unsigned char *h)
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isBootRecord(const unsigned char *h)
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{
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(void)iso9660; /* UNUSED */
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/* Type of the Volume Descriptor Boot Record must be 0. */
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if (h[0] != 0)
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@@ -662,9 +657,8 @@ isVolumePartition(struct iso9660 *iso9660, const unsigned char *h)
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}
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static int
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isVDSetTerminator(struct iso9660 *iso9660, const unsigned char *h)
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isVDSetTerminator(const unsigned char *h)
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{
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(void)iso9660; /* UNUSED */
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/* Type of the Volume Descriptor Set Terminator must be 255. */
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if (h[0] != 255)
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@@ -675,7 +669,7 @@ isVDSetTerminator(struct iso9660 *iso9660, const unsigned char *h)
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return (0);
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/* Reserved field must be 0. */
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if (!isNull(iso9660, h, 7, 2048-7))
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if (!isNull(h, 7, 2048-7))
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return (0);
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return (1);
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@@ -690,7 +684,7 @@ isJolietSVD(struct iso9660 *iso9660, const unsigned char *h)
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/* Check if current sector is a kind of Supplementary Volume
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* Descriptor. */
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if (!isSVD(iso9660, h))
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if (!isSVD(h))
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return (0);
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/* FIXME: do more validations according to joliet spec. */
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@@ -731,25 +725,24 @@ isJolietSVD(struct iso9660 *iso9660, const unsigned char *h)
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}
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static int
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isSVD(struct iso9660 *iso9660, const unsigned char *h)
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isSVD(const unsigned char *h)
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{
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const unsigned char *p;
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ssize_t logical_block_size;
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int32_t volume_block;
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int32_t location;
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(void)iso9660; /* UNUSED */
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/* Type 2 means it's a SVD. */
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if (h[SVD_type_offset] != 2)
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return (0);
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/* Reserved field must be 0. */
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if (!isNull(iso9660, h, SVD_reserved1_offset, SVD_reserved1_size))
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if (!isNull(h, SVD_reserved1_offset, SVD_reserved1_size))
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return (0);
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if (!isNull(iso9660, h, SVD_reserved2_offset, SVD_reserved2_size))
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if (!isNull(h, SVD_reserved2_offset, SVD_reserved2_size))
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return (0);
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if (!isNull(iso9660, h, SVD_reserved3_offset, SVD_reserved3_size))
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if (!isNull(h, SVD_reserved3_offset, SVD_reserved3_size))
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return (0);
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/* File structure version must be 1 for ISO9660/ECMA119. */
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@@ -791,14 +784,13 @@ isSVD(struct iso9660 *iso9660, const unsigned char *h)
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}
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static int
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isEVD(struct iso9660 *iso9660, const unsigned char *h)
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isEVD(const unsigned char *h)
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{
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const unsigned char *p;
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ssize_t logical_block_size;
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int32_t volume_block;
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int32_t location;
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(void)iso9660; /* UNUSED */
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/* Type of the Enhanced Volume Descriptor must be 2. */
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if (h[PVD_type_offset] != 2)
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@@ -813,11 +805,11 @@ isEVD(struct iso9660 *iso9660, const unsigned char *h)
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return (0);
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/* Reserved field must be 0. */
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if (!isNull(iso9660, h, PVD_reserved2_offset, PVD_reserved2_size))
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if (!isNull(h, PVD_reserved2_offset, PVD_reserved2_size))
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return (0);
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/* Reserved field must be 0. */
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if (!isNull(iso9660, h, PVD_reserved3_offset, PVD_reserved3_size))
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if (!isNull(h, PVD_reserved3_offset, PVD_reserved3_size))
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return (0);
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/* Logical block size must be > 0. */
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@@ -853,11 +845,11 @@ isEVD(struct iso9660 *iso9660, const unsigned char *h)
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return (0);
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/* Reserved field must be 0. */
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if (!isNull(iso9660, h, PVD_reserved4_offset, PVD_reserved4_size))
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if (!isNull(h, PVD_reserved4_offset, PVD_reserved4_size))
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return (0);
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/* Reserved field must be 0. */
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if (!isNull(iso9660, h, PVD_reserved5_offset, PVD_reserved5_size))
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if (!isNull(h, PVD_reserved5_offset, PVD_reserved5_size))
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return (0);
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/* Read Root Directory Record in Volume Descriptor. */
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@@ -891,7 +883,7 @@ isPVD(struct iso9660 *iso9660, const unsigned char *h)
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return (0);
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/* Reserved field must be 0. */
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if (!isNull(iso9660, h, PVD_reserved2_offset, PVD_reserved2_size))
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if (!isNull(h, PVD_reserved2_offset, PVD_reserved2_size))
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return (0);
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/* Volume space size must be encoded according to 7.3.3 */
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@@ -903,7 +895,7 @@ isPVD(struct iso9660 *iso9660, const unsigned char *h)
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return (0);
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/* Reserved field must be 0. */
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if (!isNull(iso9660, h, PVD_reserved3_offset, PVD_reserved3_size))
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if (!isNull(h, PVD_reserved3_offset, PVD_reserved3_size))
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return (0);
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/* Volume set size must be encoded according to 7.2.3 */
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@@ -961,7 +953,7 @@ isPVD(struct iso9660 *iso9660, const unsigned char *h)
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return (0);
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/* Reserved field must be 0. */
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if (!isNull(iso9660, h, PVD_reserved5_offset, PVD_reserved5_size))
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if (!isNull(h, PVD_reserved5_offset, PVD_reserved5_size))
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return (0);
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/* XXX TODO: Check other values for sanity; reject more
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