/** * compress.c - Compressed attribute handling code. Originated from the Linux-NTFS * project. * * Copyright (c) 2004-2005 Anton Altaparmakov * Copyright (c) 2004-2006 Szabolcs Szakacsits * Copyright (c) 2005 Yura Pakhuchiy * Copyright (c) 2009-2011 Jean-Pierre Andre * * This program/include file is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as published * by the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program/include file is distributed in the hope that it will be * useful, but WITHOUT ANY WARRANTY; without even the implied warranty * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program (in the main directory of the NTFS-3G * distribution in the file COPYING); if not, write to the Free Software * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * * A part of the compression algorithm is based on lzhuf.c whose header * describes the roles of the original authors (with no apparent copyright * notice, and according to http://home.earthlink.net/~neilbawd/pall.html * this was put into public domain in 1988 by Haruhiko OKUMURA). * * LZHUF.C English version 1.0 * Based on Japanese version 29-NOV-1988 * LZSS coded by Haruhiko OKUMURA * Adaptive Huffman Coding coded by Haruyasu YOSHIZAKI * Edited and translated to English by Kenji RIKITAKE */ #ifdef HAVE_CONFIG_H #include "config.h" #endif #ifdef HAVE_STDIO_H #include #endif #ifdef HAVE_STRING_H #include #endif #ifdef HAVE_STDLIB_H #include #endif #ifdef HAVE_ERRNO_H #include #endif #include "attrib.h" #include "debug.h" #include "volume.h" #include "types.h" #include "layout.h" #include "runlist.h" #include "compress.h" #include "lcnalloc.h" #include "logging.h" #include "misc.h" #undef le16_to_cpup /* the standard le16_to_cpup() crashes for unaligned data on some processors */ #define le16_to_cpup(p) (*(u8*)(p) + (((u8*)(p))[1] << 8)) /** * enum ntfs_compression_constants - constants used in the compression code */ typedef enum { /* Token types and access mask. */ NTFS_SYMBOL_TOKEN = 0, NTFS_PHRASE_TOKEN = 1, NTFS_TOKEN_MASK = 1, /* Compression sub-block constants. */ NTFS_SB_SIZE_MASK = 0x0fff, NTFS_SB_SIZE = 0x1000, NTFS_SB_IS_COMPRESSED = 0x8000, } ntfs_compression_constants; struct COMPRESS_CONTEXT { const unsigned char *inbuf; int bufsize; int size; int rel; int mxsz; s16 head[256]; s16 lson[NTFS_SB_SIZE]; s16 rson[NTFS_SB_SIZE]; } ; /* * Search for the longest sequence matching current position * * A binary tree is maintained to locate all previously met sequences, * and this function has to be called for all of them. * * This function is heavily used, it has to be optimized carefully * * Returns the size of the longest match, * zero if no match is found. */ static int ntfs_best_match(struct COMPRESS_CONTEXT *pctx, int i) { s16 *prev; int node; register long j; long maxpos; long startj; long bestj; int bufsize; int bestnode; register const unsigned char *p1,*p2; p1 = pctx->inbuf; node = pctx->head[p1[i] & 255]; if (node >= 0) { /* search the best match at current position */ bestnode = node; bufsize = pctx->bufsize; /* restrict matches to the longest allowed sequence */ maxpos = bufsize; if ((i + pctx->mxsz) < maxpos) maxpos = i + pctx->mxsz; startj = i + 1 - maxpos; bestj = startj; /* make indexes relative to end of allowed position */ p1 = &p1[maxpos]; if (startj < 0) { do { /* indexes are negative */ p2 = &p1[node - i]; /* no need to compare the first byte */ j = startj; /* the second byte cannot lead to useful compression */ if (p1[j] == p2[j]) { j++; if (j < 0) { do { } while ((p1[j] == p2[j]) && (++j < 0)); } /* remember the match, if better */ if (j > bestj) { bestj = j; bestnode = node; } } /* walk in the tree in the right direction */ if ((j < 0) && (p1[j] < p2[j])) prev = &pctx->lson[node]; else prev = &pctx->rson[node]; node = *prev; /* stop if reaching a leaf or maximum length */ } while ((node >= 0) && (j < 0)); /* put the node into the tree if we reached a leaf */ if (node < 0) *prev = i; } /* done, return the best match */ pctx->size = bestj + maxpos - i; pctx->rel = bestnode - i; } else { pctx->head[p1[i] & 255] = i; pctx->size = 0; pctx->rel = 0; } return (pctx->size); } /* * Compress a 4096-byte block * * Returns a header of two bytes followed by the compressed data. * If compression is not effective, the header and an uncompressed * block is returned. * * Note : two bytes may be output before output buffer overflow * is detected, so a 4100-bytes output buffer must be reserved. * * Returns the size of the compressed block, including the * header (minimal size is 2, maximum size is 4098) * 0 if an error has been met. */ static unsigned int ntfs_compress_block(const char *inbuf, int bufsize, char *outbuf) { struct COMPRESS_CONTEXT *pctx; int i; /* current position */ int j; /* end of best match from current position */ int k; /* end of best match from next position */ int offs; /* offset to best match */ int n; int bp; /* bits to store offset */ int mxoff; /* max match offset : 1 << bp */ int mxsz2; unsigned int xout; unsigned int q; /* aggregated offset and size */ int done; char *ptag; /* location reserved for a tag */ int tag; /* current value of tag */ int ntag; /* count of bits still undefined in tag */ pctx = (struct COMPRESS_CONTEXT*)ntfs_malloc(sizeof(struct COMPRESS_CONTEXT)); if (pctx) { for (n=0; nlson[n] = pctx->rson[n] = -1; for (n=0; n<256; n++) pctx->head[n] = -1; pctx->inbuf = (const unsigned char*)inbuf; pctx->bufsize = bufsize; xout = 2; n = 0; i = 0; bp = 4; mxoff = 1 << bp; pctx->mxsz = (1 << (16 - bp)) + 2; tag = 0; done = -1; ntag = 8; ptag = &outbuf[xout++]; while ((i < bufsize) && (xout < (NTFS_SB_SIZE + 2))) { /* adjust the longest match we can output */ while (mxoff < i) { bp++; mxoff <<= 1; pctx->mxsz = (pctx->mxsz + 2) >> 1; } /* search the best match at current position */ if (done < i) do { ntfs_best_match(pctx,++done); } while (done < i); j = i + pctx->size; if ((j - i) > pctx->mxsz) j = i + pctx->mxsz; if ((j - i) > 2) { offs = pctx->rel; /* check whether there is a better run at i+1 */ ntfs_best_match(pctx,i+1); done = i+1; k = i + 1 + pctx->size; mxsz2 = pctx->mxsz; if (mxoff <= i) mxsz2 = (pctx->mxsz + 2) >> 1; if ((k - i) > mxsz2) k = i + mxsz2; if (k > (j + 1)) { /* issue a single byte */ outbuf[xout++] = inbuf[i]; i++; } else { q = (~offs << (16 - bp)) + (j - i - 3); outbuf[xout++] = q & 255; outbuf[xout++] = (q >> 8) & 255; tag |= (1 << (8 - ntag)); i = j; } } else { outbuf[xout++] = inbuf[i]; i++; } /* store the tag if fully used */ if (!--ntag) { *ptag = tag; ntag = 8; ptag = &outbuf[xout++]; tag = 0; } } /* store the last tag, if partially used */ if (ntag == 8) xout--; else *ptag = tag; /* uncompressed must be full size, accept if better */ if ((i >= bufsize) && (xout < (NTFS_SB_SIZE + 2))) { outbuf[0] = (xout - 3) & 255; outbuf[1] = 0xb0 + (((xout - 3) >> 8) & 15); } else { memcpy(&outbuf[2],inbuf,bufsize); if (bufsize < NTFS_SB_SIZE) memset(&outbuf[bufsize+2], 0, NTFS_SB_SIZE - bufsize); outbuf[0] = 0xff; outbuf[1] = 0x3f; xout = NTFS_SB_SIZE + 2; } free(pctx); } else { xout = 0; errno = ENOMEM; } return (xout); } /** * ntfs_decompress - decompress a compression block into an array of pages * @dest: buffer to which to write the decompressed data * @dest_size: size of buffer @dest in bytes * @cb_start: compression block to decompress * @cb_size: size of compression block @cb_start in bytes * * This decompresses the compression block @cb_start into the destination * buffer @dest. * * @cb_start is a pointer to the compression block which needs decompressing * and @cb_size is the size of @cb_start in bytes (8-64kiB). * * Return 0 if success or -EOVERFLOW on error in the compressed stream. */ static int ntfs_decompress(u8 *dest, const u32 dest_size, u8 *const cb_start, const u32 cb_size) { /* * Pointers into the compressed data, i.e. the compression block (cb), * and the therein contained sub-blocks (sb). */ u8 *cb_end = cb_start + cb_size; /* End of cb. */ u8 *cb = cb_start; /* Current position in cb. */ u8 *cb_sb_start = cb; /* Beginning of the current sb in the cb. */ u8 *cb_sb_end; /* End of current sb / beginning of next sb. */ /* Variables for uncompressed data / destination. */ u8 *dest_end = dest + dest_size; /* End of dest buffer. */ u8 *dest_sb_start; /* Start of current sub-block in dest. */ u8 *dest_sb_end; /* End of current sb in dest. */ /* Variables for tag and token parsing. */ u8 tag; /* Current tag. */ int token; /* Loop counter for the eight tokens in tag. */ ntfs_log_trace("Entering, cb_size = 0x%x.\n", (unsigned)cb_size); do_next_sb: ntfs_log_debug("Beginning sub-block at offset = %d in the cb.\n", (int)(cb - cb_start)); /* * Have we reached the end of the compression block or the end of the * decompressed data? The latter can happen for example if the current * position in the compression block is one byte before its end so the * first two checks do not detect it. */ if (cb == cb_end || !le16_to_cpup((le16*)cb) || dest == dest_end) { ntfs_log_debug("Completed. Returning success (0).\n"); return 0; } /* Setup offset for the current sub-block destination. */ dest_sb_start = dest; dest_sb_end = dest + NTFS_SB_SIZE; /* Check that we are still within allowed boundaries. */ if (dest_sb_end > dest_end) goto return_overflow; /* Does the minimum size of a compressed sb overflow valid range? */ if (cb + 6 > cb_end) goto return_overflow; /* Setup the current sub-block source pointers and validate range. */ cb_sb_start = cb; cb_sb_end = cb_sb_start + (le16_to_cpup((le16*)cb) & NTFS_SB_SIZE_MASK) + 3; if (cb_sb_end > cb_end) goto return_overflow; /* Now, we are ready to process the current sub-block (sb). */ if (!(le16_to_cpup((le16*)cb) & NTFS_SB_IS_COMPRESSED)) { ntfs_log_debug("Found uncompressed sub-block.\n"); /* This sb is not compressed, just copy it into destination. */ /* Advance source position to first data byte. */ cb += 2; /* An uncompressed sb must be full size. */ if (cb_sb_end - cb != NTFS_SB_SIZE) goto return_overflow; /* Copy the block and advance the source position. */ memcpy(dest, cb, NTFS_SB_SIZE); cb += NTFS_SB_SIZE; /* Advance destination position to next sub-block. */ dest += NTFS_SB_SIZE; goto do_next_sb; } ntfs_log_debug("Found compressed sub-block.\n"); /* This sb is compressed, decompress it into destination. */ /* Forward to the first tag in the sub-block. */ cb += 2; do_next_tag: if (cb == cb_sb_end) { /* Check if the decompressed sub-block was not full-length. */ if (dest < dest_sb_end) { int nr_bytes = dest_sb_end - dest; ntfs_log_debug("Filling incomplete sub-block with zeroes.\n"); /* Zero remainder and update destination position. */ memset(dest, 0, nr_bytes); dest += nr_bytes; } /* We have finished the current sub-block. */ goto do_next_sb; } /* Check we are still in range. */ if (cb > cb_sb_end || dest > dest_sb_end) goto return_overflow; /* Get the next tag and advance to first token. */ tag = *cb++; /* Parse the eight tokens described by the tag. */ for (token = 0; token < 8; token++, tag >>= 1) { u16 lg, pt, length, max_non_overlap; register u16 i; u8 *dest_back_addr; /* Check if we are done / still in range. */ if (cb >= cb_sb_end || dest > dest_sb_end) break; /* Determine token type and parse appropriately.*/ if ((tag & NTFS_TOKEN_MASK) == NTFS_SYMBOL_TOKEN) { /* * We have a symbol token, copy the symbol across, and * advance the source and destination positions. */ *dest++ = *cb++; /* Continue with the next token. */ continue; } /* * We have a phrase token. Make sure it is not the first tag in * the sb as this is illegal and would confuse the code below. */ if (dest == dest_sb_start) goto return_overflow; /* * Determine the number of bytes to go back (p) and the number * of bytes to copy (l). We use an optimized algorithm in which * we first calculate log2(current destination position in sb), * which allows determination of l and p in O(1) rather than * O(n). We just need an arch-optimized log2() function now. */ lg = 0; for (i = dest - dest_sb_start - 1; i >= 0x10; i >>= 1) lg++; /* Get the phrase token into i. */ pt = le16_to_cpup((le16*)cb); /* * Calculate starting position of the byte sequence in * the destination using the fact that p = (pt >> (12 - lg)) + 1 * and make sure we don't go too far back. */ dest_back_addr = dest - (pt >> (12 - lg)) - 1; if (dest_back_addr < dest_sb_start) goto return_overflow; /* Now calculate the length of the byte sequence. */ length = (pt & (0xfff >> lg)) + 3; /* Verify destination is in range. */ if (dest + length > dest_sb_end) goto return_overflow; /* The number of non-overlapping bytes. */ max_non_overlap = dest - dest_back_addr; if (length <= max_non_overlap) { /* The byte sequence doesn't overlap, just copy it. */ memcpy(dest, dest_back_addr, length); /* Advance destination pointer. */ dest += length; } else { /* * The byte sequence does overlap, copy non-overlapping * part and then do a slow byte by byte copy for the * overlapping part. Also, advance the destination * pointer. */ memcpy(dest, dest_back_addr, max_non_overlap); dest += max_non_overlap; dest_back_addr += max_non_overlap; length -= max_non_overlap; while (length--) *dest++ = *dest_back_addr++; } /* Advance source position and continue with the next token. */ cb += 2; } /* No tokens left in the current tag. Continue with the next tag. */ goto do_next_tag; return_overflow: errno = EOVERFLOW; ntfs_log_perror("Failed to decompress file"); return -1; } /** * ntfs_is_cb_compressed - internal function, do not use * * This is a very specialised function determining if a cb is compressed or * uncompressed. It is assumed that checking for a sparse cb has already been * performed and that the cb is not sparse. It makes all sorts of other * assumptions as well and hence it is not useful anywhere other than where it * is used at the moment. Please, do not make this function available for use * outside of compress.c as it is bound to confuse people and not do what they * want. * * Return TRUE on errors so that the error will be detected later on in the * code. Might be a bit confusing to debug but there really should never be * errors coming from here. */ static BOOL ntfs_is_cb_compressed(ntfs_attr *na, runlist_element *rl, VCN cb_start_vcn, int cb_clusters) { /* * The simplest case: the run starting at @cb_start_vcn contains * @cb_clusters clusters which are all not sparse, thus the cb is not * compressed. */ restart: cb_clusters -= rl->length - (cb_start_vcn - rl->vcn); while (cb_clusters > 0) { /* Go to the next run. */ rl++; /* Map the next runlist fragment if it is not mapped. */ if (rl->lcn < LCN_HOLE || !rl->length) { cb_start_vcn = rl->vcn; rl = ntfs_attr_find_vcn(na, rl->vcn); if (!rl || rl->lcn < LCN_HOLE || !rl->length) return TRUE; /* * If the runs were merged need to deal with the * resulting partial run so simply restart. */ if (rl->vcn < cb_start_vcn) goto restart; } /* If the current run is sparse, the cb is compressed. */ if (rl->lcn == LCN_HOLE) return TRUE; /* If the whole cb is not sparse, it is not compressed. */ if (rl->length >= cb_clusters) return FALSE; cb_clusters -= rl->length; }; /* All cb_clusters were not sparse thus the cb is not compressed. */ return FALSE; } /** * ntfs_compressed_attr_pread - read from a compressed attribute * @na: ntfs attribute to read from * @pos: byte position in the attribute to begin reading from * @count: number of bytes to read * @b: output data buffer * * NOTE: You probably want to be using attrib.c::ntfs_attr_pread() instead. * * This function will read @count bytes starting at offset @pos from the * compressed ntfs attribute @na into the data buffer @b. * * On success, return the number of successfully read bytes. If this number * is lower than @count this means that the read reached end of file or that * an error was encountered during the read so that the read is partial. * 0 means end of file or nothing was read (also return 0 when @count is 0). * * On error and nothing has been read, return -1 with errno set appropriately * to the return code of ntfs_pread(), or to EINVAL in case of invalid * arguments. */ s64 ntfs_compressed_attr_pread(ntfs_attr *na, s64 pos, s64 count, void *b) { s64 br, to_read, ofs, total, total2; u64 cb_size_mask; VCN start_vcn, vcn, end_vcn; ntfs_volume *vol; runlist_element *rl; u8 *dest, *cb, *cb_pos, *cb_end; u32 cb_size; int err; ATTR_FLAGS data_flags; FILE_ATTR_FLAGS compression; unsigned int nr_cbs, cb_clusters; ntfs_log_trace("Entering for inode 0x%llx, attr 0x%x, pos 0x%llx, count 0x%llx.\n", (unsigned long long)na->ni->mft_no, na->type, (long long)pos, (long long)count); data_flags = na->data_flags; compression = na->ni->flags & FILE_ATTR_COMPRESSED; if (!na || !na->ni || !na->ni->vol || !b || ((data_flags & ATTR_COMPRESSION_MASK) != ATTR_IS_COMPRESSED) || pos < 0 || count < 0) { errno = EINVAL; return -1; } /* * Encrypted attributes are not supported. We return access denied, * which is what Windows NT4 does, too. */ if (NAttrEncrypted(na)) { errno = EACCES; return -1; } if (!count) return 0; /* Truncate reads beyond end of attribute. */ if (pos + count > na->data_size) { if (pos >= na->data_size) { return 0; } count = na->data_size - pos; } /* If it is a resident attribute, simply use ntfs_attr_pread(). */ if (!NAttrNonResident(na)) return ntfs_attr_pread(na, pos, count, b); total = total2 = 0; /* Zero out reads beyond initialized size. */ if (pos + count > na->initialized_size) { if (pos >= na->initialized_size) { memset(b, 0, count); return count; } total2 = pos + count - na->initialized_size; count -= total2; memset((u8*)b + count, 0, total2); } vol = na->ni->vol; cb_size = na->compression_block_size; cb_size_mask = cb_size - 1UL; cb_clusters = na->compression_block_clusters; /* Need a temporary buffer for each loaded compression block. */ cb = (u8*)ntfs_malloc(cb_size); if (!cb) return -1; /* Need a temporary buffer for each uncompressed block. */ dest = (u8*)ntfs_malloc(cb_size); if (!dest) { free(cb); return -1; } /* * The first vcn in the first compression block (cb) which we need to * decompress. */ start_vcn = (pos & ~cb_size_mask) >> vol->cluster_size_bits; /* Offset in the uncompressed cb at which to start reading data. */ ofs = pos & cb_size_mask; /* * The first vcn in the cb after the last cb which we need to * decompress. */ end_vcn = ((pos + count + cb_size - 1) & ~cb_size_mask) >> vol->cluster_size_bits; /* Number of compression blocks (cbs) in the wanted vcn range. */ nr_cbs = (end_vcn - start_vcn) << vol->cluster_size_bits >> na->compression_block_size_bits; cb_end = cb + cb_size; do_next_cb: nr_cbs--; cb_pos = cb; vcn = start_vcn; start_vcn += cb_clusters; /* Check whether the compression block is sparse. */ rl = ntfs_attr_find_vcn(na, vcn); if (!rl || rl->lcn < LCN_HOLE) { free(cb); free(dest); if (total) return total; /* FIXME: Do we want EIO or the error code? (AIA) */ errno = EIO; return -1; } if (rl->lcn == LCN_HOLE) { /* Sparse cb, zero out destination range overlapping the cb. */ ntfs_log_debug("Found sparse compression block.\n"); to_read = min(count, cb_size - ofs); memset(b, 0, to_read); ofs = 0; total += to_read; count -= to_read; b = (u8*)b + to_read; } else if (!ntfs_is_cb_compressed(na, rl, vcn, cb_clusters)) { s64 tdata_size, tinitialized_size; /* * Uncompressed cb, read it straight into the destination range * overlapping the cb. */ ntfs_log_debug("Found uncompressed compression block.\n"); /* * Read the uncompressed data into the destination buffer. * NOTE: We cheat a little bit here by marking the attribute as * not compressed in the ntfs_attr structure so that we can * read the data by simply using ntfs_attr_pread(). (-8 * NOTE: we have to modify data_size and initialized_size * temporarily as well... */ to_read = min(count, cb_size - ofs); ofs += vcn << vol->cluster_size_bits; NAttrClearCompressed(na); na->data_flags &= ~ATTR_COMPRESSION_MASK; tdata_size = na->data_size; tinitialized_size = na->initialized_size; na->data_size = na->initialized_size = na->allocated_size; do { br = ntfs_attr_pread(na, ofs, to_read, b); if (br <= 0) { if (!br) { ntfs_log_error("Failed to read an" " uncompressed cluster," " inode %lld offs 0x%llx\n", (long long)na->ni->mft_no, (long long)ofs); errno = EIO; } err = errno; na->data_size = tdata_size; na->initialized_size = tinitialized_size; na->ni->flags |= compression; na->data_flags = data_flags; free(cb); free(dest); if (total) return total; errno = err; return br; } total += br; count -= br; b = (u8*)b + br; to_read -= br; ofs += br; } while (to_read > 0); na->data_size = tdata_size; na->initialized_size = tinitialized_size; na->ni->flags |= compression; na->data_flags = data_flags; ofs = 0; } else { s64 tdata_size, tinitialized_size; /* * Compressed cb, decompress it into the temporary buffer, then * copy the data to the destination range overlapping the cb. */ ntfs_log_debug("Found compressed compression block.\n"); /* * Read the compressed data into the temporary buffer. * NOTE: We cheat a little bit here by marking the attribute as * not compressed in the ntfs_attr structure so that we can * read the raw, compressed data by simply using * ntfs_attr_pread(). (-8 * NOTE: We have to modify data_size and initialized_size * temporarily as well... */ to_read = cb_size; NAttrClearCompressed(na); na->data_flags &= ~ATTR_COMPRESSION_MASK; tdata_size = na->data_size; tinitialized_size = na->initialized_size; na->data_size = na->initialized_size = na->allocated_size; do { br = ntfs_attr_pread(na, (vcn << vol->cluster_size_bits) + (cb_pos - cb), to_read, cb_pos); if (br <= 0) { if (!br) { ntfs_log_error("Failed to read a" " compressed cluster, " " inode %lld offs 0x%llx\n", (long long)na->ni->mft_no, (long long)(vcn << vol->cluster_size_bits)); errno = EIO; } err = errno; na->data_size = tdata_size; na->initialized_size = tinitialized_size; na->ni->flags |= compression; na->data_flags = data_flags; free(cb); free(dest); if (total) return total; errno = err; return br; } cb_pos += br; to_read -= br; } while (to_read > 0); na->data_size = tdata_size; na->initialized_size = tinitialized_size; na->ni->flags |= compression; na->data_flags = data_flags; /* Just a precaution. */ if (cb_pos + 2 <= cb_end) *(u16*)cb_pos = 0; ntfs_log_debug("Successfully read the compression block.\n"); if (ntfs_decompress(dest, cb_size, cb, cb_size) < 0) { err = errno; free(cb); free(dest); if (total) return total; errno = err; return -1; } to_read = min(count, cb_size - ofs); memcpy(b, dest + ofs, to_read); total += to_read; count -= to_read; b = (u8*)b + to_read; ofs = 0; } /* Do we have more work to do? */ if (nr_cbs) goto do_next_cb; /* We no longer need the buffers. */ free(cb); free(dest); /* Return number of bytes read. */ return total + total2; } /* * Read data from a set of clusters * * Returns the amount of data read */ static u32 read_clusters(ntfs_volume *vol, const runlist_element *rl, s64 offs, u32 to_read, char *inbuf) { u32 count; int xgot; u32 got; s64 xpos; BOOL first; char *xinbuf; const runlist_element *xrl; got = 0; xrl = rl; xinbuf = inbuf; first = TRUE; do { count = xrl->length << vol->cluster_size_bits; xpos = xrl->lcn << vol->cluster_size_bits; if (first) { count -= offs; xpos += offs; } if ((to_read - got) < count) count = to_read - got; xgot = ntfs_pread(vol->dev, xpos, count, xinbuf); if (xgot == (int)count) { got += count; xpos += count; xinbuf += count; xrl++; } first = FALSE; } while ((xgot == (int)count) && (got < to_read)); return (got); } /* * Write data to a set of clusters * * Returns the amount of data written */ static s32 write_clusters(ntfs_volume *vol, const runlist_element *rl, s64 offs, s32 to_write, const char *outbuf) { s32 count; s32 put, xput; s64 xpos; BOOL first; const char *xoutbuf; const runlist_element *xrl; put = 0; xrl = rl; xoutbuf = outbuf; first = TRUE; do { count = xrl->length << vol->cluster_size_bits; xpos = xrl->lcn << vol->cluster_size_bits; if (first) { count -= offs; xpos += offs; } if ((to_write - put) < count) count = to_write - put; xput = ntfs_pwrite(vol->dev, xpos, count, xoutbuf); if (xput == count) { put += count; xpos += count; xoutbuf += count; xrl++; } first = FALSE; } while ((xput == count) && (put < to_write)); return (put); } /* * Compress and write a set of blocks * * returns the size actually written (rounded to a full cluster) * or 0 if all zeroes (nothing is written) * or -1 if could not compress (nothing is written) * or -2 if there were an irrecoverable error (errno set) */ static s32 ntfs_comp_set(ntfs_attr *na, runlist_element *rl, s64 offs, u32 insz, const char *inbuf) { ntfs_volume *vol; char *outbuf; char *pbuf; u32 compsz; s32 written; s32 rounded; unsigned int clsz; u32 p; unsigned int sz; unsigned int bsz; BOOL fail; BOOL allzeroes; /* a single compressed zero */ static char onezero[] = { 0x01, 0xb0, 0x00, 0x00 } ; /* a couple of compressed zeroes */ static char twozeroes[] = { 0x02, 0xb0, 0x00, 0x00, 0x00 } ; /* more compressed zeroes, to be followed by some count */ static char morezeroes[] = { 0x03, 0xb0, 0x02, 0x00 } ; vol = na->ni->vol; written = -1; /* default return */ clsz = 1 << vol->cluster_size_bits; /* may need 2 extra bytes per block and 2 more bytes */ outbuf = (char*)ntfs_malloc(na->compression_block_size + 2*(na->compression_block_size/NTFS_SB_SIZE) + 2); if (outbuf) { fail = FALSE; compsz = 0; allzeroes = TRUE; for (p=0; (p na->compression_block_size)) fail = TRUE; else { if (allzeroes) { /* check whether this is all zeroes */ switch (sz) { case 4 : allzeroes = !memcmp( pbuf,onezero,4); break; case 5 : allzeroes = !memcmp( pbuf,twozeroes,5); break; case 6 : allzeroes = !memcmp( pbuf,morezeroes,4); break; default : allzeroes = FALSE; break; } } compsz += sz; } } if (!fail && !allzeroes) { /* add a couple of null bytes, space has been checked */ outbuf[compsz++] = 0; outbuf[compsz++] = 0; /* write a full cluster, to avoid partial reading */ rounded = ((compsz - 1) | (clsz - 1)) + 1; written = write_clusters(vol, rl, offs, rounded, outbuf); if (written != rounded) { /* * TODO : previously written text has been * spoilt, should return a specific error */ ntfs_log_error("error writing compressed data\n"); errno = EIO; written = -2; } } else if (!fail) written = 0; free(outbuf); } return (written); } /* * Check the validity of a compressed runlist * The check starts at the beginning of current run and ends * at the end of runlist * errno is set if the runlist is not valid */ static BOOL valid_compressed_run(ntfs_attr *na, runlist_element *rl, BOOL fullcheck, const char *text) { runlist_element *xrl; const char *err; BOOL ok = TRUE; xrl = rl; while (xrl->vcn & (na->compression_block_clusters - 1)) xrl--; err = (const char*)NULL; while (xrl->length) { if ((xrl->vcn + xrl->length) != xrl[1].vcn) err = "Runs not adjacent"; if (xrl->lcn == LCN_HOLE) { if ((xrl->vcn + xrl->length) & (na->compression_block_clusters - 1)) { err = "Invalid hole"; } if (fullcheck && (xrl[1].lcn == LCN_HOLE)) { err = "Adjacent holes"; } } if (err) { ntfs_log_error("%s at %s index %ld inode %lld\n", err, text, (long)(xrl - na->rl), (long long)na->ni->mft_no); errno = EIO; ok = FALSE; err = (const char*)NULL; } xrl++; } return (ok); } /* * Free unneeded clusters after overwriting compressed data * * This generally requires one or two empty slots at the end of runlist, * but we do not want to reallocate the runlist here because * there are many pointers to it. * So the empty slots have to be reserved beforehand * * Returns zero unless some error occurred (described by errno) * * +======= start of block =====+ * 0 |A chunk may overflow | <-- rl usedcnt : A + B * |A on previous block | then B * |A | * +-- end of allocated chunk --+ freelength : C * |B | (incl overflow) * +== end of compressed data ==+ * |C | <-- freerl freecnt : C + D * |C chunk may overflow | * |C on next block | * +-- end of allocated chunk --+ * |D | * |D chunk may overflow | * 15 |D on next block | * +======== end of block ======+ * */ static int ntfs_compress_overwr_free(ntfs_attr *na, runlist_element *rl, s32 usedcnt, s32 freecnt, VCN *update_from) { BOOL beginhole; BOOL mergeholes; s32 oldlength; s32 freelength; s64 freelcn; s64 freevcn; runlist_element *freerl; ntfs_volume *vol; s32 carry; int res; vol = na->ni->vol; res = 0; freelcn = rl->lcn + usedcnt; freevcn = rl->vcn + usedcnt; freelength = rl->length - usedcnt; beginhole = !usedcnt && !rl->vcn; /* can merge with hole before ? */ mergeholes = !usedcnt && rl[0].vcn && (rl[-1].lcn == LCN_HOLE); /* truncate current run, carry to subsequent hole */ carry = freelength; oldlength = rl->length; if (mergeholes) { /* merging with a hole before */ freerl = rl; } else { rl->length -= freelength; /* warning : can be zero */ freerl = ++rl; } if (!mergeholes && (usedcnt || beginhole)) { s32 freed; runlist_element *frl; runlist_element *erl; int holes = 0; BOOL threeparts; /* free the unneeded clusters from initial run, then freerl */ threeparts = (freelength > freecnt); freed = 0; frl = freerl; if (freelength) { res = ntfs_cluster_free_basic(vol,freelcn, (threeparts ? freecnt : freelength)); if (!res) freed += (threeparts ? freecnt : freelength); if (!usedcnt) { holes++; freerl--; freerl->length += (threeparts ? freecnt : freelength); if (freerl->vcn < *update_from) *update_from = freerl->vcn; } } while (!res && frl->length && (freed < freecnt)) { if (frl->length <= (freecnt - freed)) { res = ntfs_cluster_free_basic(vol, frl->lcn, frl->length); if (!res) { freed += frl->length; frl->lcn = LCN_HOLE; frl->length += carry; carry = 0; holes++; } } else { res = ntfs_cluster_free_basic(vol, frl->lcn, freecnt - freed); if (!res) { frl->lcn += freecnt - freed; frl->vcn += freecnt - freed; frl->length -= freecnt - freed; freed = freecnt; } } frl++; } na->compressed_size -= freed << vol->cluster_size_bits; switch (holes) { case 0 : /* there are no hole, must insert one */ /* space for hole has been prereserved */ if (freerl->lcn == LCN_HOLE) { if (threeparts) { erl = freerl; while (erl->length) erl++; do { erl[2] = *erl; } while (erl-- != freerl); freerl[1].length = freelength - freecnt; freerl->length = freecnt; freerl[1].lcn = freelcn + freecnt; freerl[1].vcn = freevcn + freecnt; freerl[2].lcn = LCN_HOLE; freerl[2].vcn = freerl[1].vcn + freerl[1].length; freerl->vcn = freevcn; } else { freerl->vcn = freevcn; freerl->length += freelength; } } else { erl = freerl; while (erl->length) erl++; if (threeparts) { do { erl[2] = *erl; } while (erl-- != freerl); freerl[1].lcn = freelcn + freecnt; freerl[1].vcn = freevcn + freecnt; freerl[1].length = oldlength - usedcnt - freecnt; } else { do { erl[1] = *erl; } while (erl-- != freerl); } freerl->lcn = LCN_HOLE; freerl->vcn = freevcn; freerl->length = freecnt; } break; case 1 : /* there is a single hole, may have to merge */ freerl->vcn = freevcn; freerl->length = freecnt; if (freerl[1].lcn == LCN_HOLE) { freerl->length += freerl[1].length; erl = freerl; do { erl++; *erl = erl[1]; } while (erl->length); } break; default : /* there were several holes, must merge them */ freerl->lcn = LCN_HOLE; freerl->vcn = freevcn; freerl->length = freecnt; if (freerl[holes].lcn == LCN_HOLE) { freerl->length += freerl[holes].length; holes++; } erl = freerl; do { erl++; *erl = erl[holes - 1]; } while (erl->length); break; } } else { s32 freed; runlist_element *frl; runlist_element *xrl; freed = 0; frl = freerl--; if (freerl->vcn < *update_from) *update_from = freerl->vcn; while (!res && frl->length && (freed < freecnt)) { if (frl->length <= (freecnt - freed)) { freerl->length += frl->length; freed += frl->length; res = ntfs_cluster_free_basic(vol, frl->lcn, frl->length); frl++; } else { freerl->length += freecnt - freed; res = ntfs_cluster_free_basic(vol, frl->lcn, freecnt - freed); frl->lcn += freecnt - freed; frl->vcn += freecnt - freed; frl->length -= freecnt - freed; freed = freecnt; } } /* remove unneded runlist entries */ xrl = freerl; /* group with next run if also a hole */ if (frl->length && (frl->lcn == LCN_HOLE)) { xrl->length += frl->length; frl++; } while (frl->length) { *++xrl = *frl++; } *++xrl = *frl; /* terminator */ na->compressed_size -= freed << vol->cluster_size_bits; } return (res); } /* * Free unneeded clusters after compression * * This generally requires one or two empty slots at the end of runlist, * but we do not want to reallocate the runlist here because * there are many pointers to it. * So the empty slots have to be reserved beforehand * * Returns zero unless some error occurred (described by errno) */ static int ntfs_compress_free(ntfs_attr *na, runlist_element *rl, s64 used, s64 reserved, BOOL appending, VCN *update_from) { s32 freecnt; s32 usedcnt; int res; s64 freelcn; s64 freevcn; s32 freelength; BOOL mergeholes; BOOL beginhole; ntfs_volume *vol; runlist_element *freerl; res = -1; /* default return */ vol = na->ni->vol; freecnt = (reserved - used) >> vol->cluster_size_bits; usedcnt = (reserved >> vol->cluster_size_bits) - freecnt; if (rl->vcn < *update_from) *update_from = rl->vcn; /* skip entries fully used, if any */ while (rl->length && (rl->length < usedcnt)) { usedcnt -= rl->length; /* must be > 0 */ rl++; } if (rl->length) { /* * Splitting the current allocation block requires * an extra runlist element to create the hole. * The required entry has been prereserved when * mapping the runlist. */ /* get the free part in initial run */ freelcn = rl->lcn + usedcnt; freevcn = rl->vcn + usedcnt; /* new count of allocated clusters */ if (!((freevcn + freecnt) & (na->compression_block_clusters - 1))) { if (!appending) res = ntfs_compress_overwr_free(na,rl, usedcnt,freecnt,update_from); else { freelength = rl->length - usedcnt; beginhole = !usedcnt && !rl->vcn; mergeholes = !usedcnt && rl[0].vcn && (rl[-1].lcn == LCN_HOLE); if (mergeholes) { s32 carry; /* shorten the runs which have free space */ carry = freecnt; freerl = rl; while (freerl->length < carry) { carry -= freerl->length; freerl++; } freerl->length = carry; freerl = rl; } else { rl->length = usedcnt; /* can be zero ? */ freerl = ++rl; } if ((freelength > 0) && !mergeholes && (usedcnt || beginhole)) { /* * move the unused part to the end. Doing so, * the vcn will be out of order. This does * not harm, the vcn are meaningless now, and * only the lcn are meaningful for freeing. */ /* locate current end */ while (rl->length) rl++; /* new terminator relocated */ rl[1].vcn = rl->vcn; rl[1].lcn = LCN_ENOENT; rl[1].length = 0; /* hole, currently allocated */ rl->vcn = freevcn; rl->lcn = freelcn; rl->length = freelength; } else { /* why is this different from the begin hole case ? */ if ((freelength > 0) && !mergeholes && !usedcnt) { freerl--; freerl->length = freelength; if (freerl->vcn < *update_from) *update_from = freerl->vcn; } } /* free the hole */ res = ntfs_cluster_free_from_rl(vol,freerl); if (!res) { na->compressed_size -= freecnt << vol->cluster_size_bits; if (mergeholes) { /* merge with adjacent hole */ freerl--; freerl->length += freecnt; } else { if (beginhole) freerl--; /* mark hole as free */ freerl->lcn = LCN_HOLE; freerl->vcn = freevcn; freerl->length = freecnt; } if (freerl->vcn < *update_from) *update_from = freerl->vcn; /* and set up the new end */ freerl[1].lcn = LCN_ENOENT; freerl[1].vcn = freevcn + freecnt; freerl[1].length = 0; } } } else { ntfs_log_error("Bad end of a compression block set\n"); errno = EIO; } } else { ntfs_log_error("No cluster to free after compression\n"); errno = EIO; } return (res); } /* * Read existing data, decompress and append buffer * Do nothing if something fails */ static int ntfs_read_append(ntfs_attr *na, const runlist_element *rl, s64 offs, u32 compsz, s32 pos, BOOL appending, char *outbuf, s64 to_write, const void *b) { int fail = 1; char *compbuf; u32 decompsz; u32 got; if (compsz == na->compression_block_size) { /* if the full block was requested, it was a hole */ memset(outbuf,0,compsz); memcpy(&outbuf[pos],b,to_write); fail = 0; } else { compbuf = (char*)ntfs_malloc(compsz); if (compbuf) { /* must align to full block for decompression */ if (appending) decompsz = ((pos - 1) | (NTFS_SB_SIZE - 1)) + 1; else decompsz = na->compression_block_size; got = read_clusters(na->ni->vol, rl, offs, compsz, compbuf); if ((got == compsz) && !ntfs_decompress((u8*)outbuf,decompsz, (u8*)compbuf,compsz)) { memcpy(&outbuf[pos],b,to_write); fail = 0; } free(compbuf); } } return (fail); } /* * Flush a full compression block * * returns the size actually written (rounded to a full cluster) * or 0 if could not compress (and written uncompressed) * or -1 if there were an irrecoverable error (errno set) */ static s32 ntfs_flush(ntfs_attr *na, runlist_element *rl, s64 offs, const char *outbuf, s32 count, BOOL compress, BOOL appending, VCN *update_from) { s32 rounded; s32 written; int clsz; if (compress) { written = ntfs_comp_set(na, rl, offs, count, outbuf); if (written == -1) compress = FALSE; if ((written >= 0) && ntfs_compress_free(na,rl,offs + written, offs + na->compression_block_size, appending, update_from)) written = -1; } else written = 0; if (!compress) { clsz = 1 << na->ni->vol->cluster_size_bits; rounded = ((count - 1) | (clsz - 1)) + 1; written = write_clusters(na->ni->vol, rl, offs, rounded, outbuf); if (written != rounded) written = -1; } return (written); } /* * Write some data to be compressed. * Compression only occurs when a few clusters (usually 16) are * full. When this occurs an extra runlist slot may be needed, so * it has to be reserved beforehand. * * Returns the size of uncompressed data written, * or negative if an error occurred. * When the returned size is less than requested, new clusters have * to be allocated before the function is called again. */ s64 ntfs_compressed_pwrite(ntfs_attr *na, runlist_element *wrl, s64 wpos, s64 offs, s64 to_write, s64 rounded, const void *b, int compressed_part, VCN *update_from) { ntfs_volume *vol; runlist_element *brl; /* entry containing the beginning of block */ int compression_length; s64 written; s64 to_read; s64 to_flush; s64 roffs; s64 got; s64 start_vcn; s64 nextblock; s64 endwrite; u32 compsz; char *inbuf; char *outbuf; BOOL fail; BOOL done; BOOL compress; BOOL appending; if (!valid_compressed_run(na,wrl,FALSE,"begin compressed write")) { return (-1); } if ((*update_from < 0) || (compressed_part < 0) || (compressed_part > (int)na->compression_block_clusters)) { ntfs_log_error("Bad update vcn or compressed_part %d for compressed write\n", compressed_part); errno = EIO; return (-1); } /* make sure there are two unused entries in runlist */ if (na->unused_runs < 2) { ntfs_log_error("No unused runs for compressed write\n"); errno = EIO; return (-1); } if (wrl->vcn < *update_from) *update_from = wrl->vcn; written = -1; /* default return */ vol = na->ni->vol; compression_length = na->compression_block_clusters; compress = FALSE; done = FALSE; /* * Cannot accept writing beyond the current compression set * because when compression occurs, clusters are freed * and have to be reallocated. * (cannot happen with standard fuse 4K buffers) * Caller has to avoid this situation, or face consequences. */ nextblock = ((offs + (wrl->vcn << vol->cluster_size_bits)) | (na->compression_block_size - 1)) + 1; /* determine whether we are appending to file */ endwrite = offs + to_write + (wrl->vcn << vol->cluster_size_bits); appending = endwrite >= na->initialized_size; if (endwrite >= nextblock) { /* it is time to compress */ compress = TRUE; /* only process what we can */ to_write = rounded = nextblock - (offs + (wrl->vcn << vol->cluster_size_bits)); } start_vcn = 0; fail = FALSE; brl = wrl; roffs = 0; /* * If we are about to compress or we need to decompress * existing data, we have to process a full set of blocks. * So relocate the parameters to the beginning of allocation * containing the first byte of the set of blocks. */ if (compress || compressed_part) { /* find the beginning of block */ start_vcn = (wrl->vcn + (offs >> vol->cluster_size_bits)) & -compression_length; if (start_vcn < *update_from) *update_from = start_vcn; while (brl->vcn && (brl->vcn > start_vcn)) { /* jumping back a hole means big trouble */ if (brl->lcn == (LCN)LCN_HOLE) { ntfs_log_error("jump back over a hole when appending\n"); fail = TRUE; errno = EIO; } brl--; offs += brl->length << vol->cluster_size_bits; } roffs = (start_vcn - brl->vcn) << vol->cluster_size_bits; } if (compressed_part && !fail) { /* * The set of compression blocks contains compressed data * (we are reopening an existing file to append to it) * Decompress the data and append */ compsz = (s32)compressed_part << vol->cluster_size_bits; outbuf = (char*)ntfs_malloc(na->compression_block_size); if (outbuf) { if (appending) { to_read = offs - roffs; to_flush = to_read + to_write; } else { to_read = na->data_size - (brl->vcn << vol->cluster_size_bits); if (to_read > na->compression_block_size) to_read = na->compression_block_size; to_flush = to_read; } if (!ntfs_read_append(na, brl, roffs, compsz, (s32)(offs - roffs), appending, outbuf, to_write, b)) { written = ntfs_flush(na, brl, roffs, outbuf, to_flush, compress, appending, update_from); if (written >= 0) { written = to_write; done = TRUE; } } free(outbuf); } } else { if (compress && !fail) { /* * we are filling up a block, read the full set * of blocks and compress it */ inbuf = (char*)ntfs_malloc(na->compression_block_size); if (inbuf) { to_read = offs - roffs; if (to_read) got = read_clusters(vol, brl, roffs, to_read, inbuf); else got = 0; if (got == to_read) { memcpy(&inbuf[to_read],b,to_write); written = ntfs_comp_set(na, brl, roffs, to_read + to_write, inbuf); /* * if compression was not successful, * only write the part which was requested */ if ((written >= 0) /* free the unused clusters */ && !ntfs_compress_free(na,brl, written + roffs, na->compression_block_size + roffs, appending, update_from)) { done = TRUE; written = to_write; } } free(inbuf); } } if (!done) { /* * if the compression block is not full, or * if compression failed for whatever reason, * write uncompressed */ /* check we are not overflowing current allocation */ if ((wpos + rounded) > ((wrl->lcn + wrl->length) << vol->cluster_size_bits)) { ntfs_log_error("writing on unallocated clusters\n"); errno = EIO; } else { written = ntfs_pwrite(vol->dev, wpos, rounded, b); if (written == rounded) written = to_write; } } } if ((written >= 0) && !valid_compressed_run(na,wrl,TRUE,"end compressed write")) written = -1; return (written); } /* * Close a file written compressed. * This compresses the last partial compression block of the file. * Two empty runlist slots have to be reserved beforehand. * * Returns zero if closing is successful. */ int ntfs_compressed_close(ntfs_attr *na, runlist_element *wrl, s64 offs, VCN *update_from) { ntfs_volume *vol; runlist_element *brl; /* entry containing the beginning of block */ int compression_length; s64 written; s64 to_read; s64 roffs; s64 got; s64 start_vcn; char *inbuf; BOOL fail; BOOL done; if (na->unused_runs < 2) { ntfs_log_error("No unused runs for compressed close\n"); errno = EIO; return (-1); } if (*update_from < 0) { ntfs_log_error("Bad update vcn for compressed close\n"); errno = EIO; return (-1); } if (wrl->vcn < *update_from) *update_from = wrl->vcn; vol = na->ni->vol; compression_length = na->compression_block_clusters; done = FALSE; /* * There generally is an uncompressed block at end of file, * read the full block and compress it */ inbuf = (char*)ntfs_malloc(na->compression_block_size); if (inbuf) { start_vcn = (wrl->vcn + (offs >> vol->cluster_size_bits)) & -compression_length; if (start_vcn < *update_from) *update_from = start_vcn; to_read = offs + ((wrl->vcn - start_vcn) << vol->cluster_size_bits); brl = wrl; fail = FALSE; while (brl->vcn && (brl->vcn > start_vcn)) { if (brl->lcn == (LCN)LCN_HOLE) { ntfs_log_error("jump back over a hole when closing\n"); fail = TRUE; errno = EIO; } brl--; } if (!fail) { /* roffs can be an offset from another uncomp block */ roffs = (start_vcn - brl->vcn) << vol->cluster_size_bits; if (to_read) { got = read_clusters(vol, brl, roffs, to_read, inbuf); if (got == to_read) { written = ntfs_comp_set(na, brl, roffs, to_read, inbuf); if ((written >= 0) /* free the unused clusters */ && !ntfs_compress_free(na,brl, written + roffs, na->compression_block_size + roffs, TRUE, update_from)) { done = TRUE; } else /* if compression failed, leave uncompressed */ if (written == -1) done = TRUE; } } else done = TRUE; free(inbuf); } } if (done && !valid_compressed_run(na,wrl,TRUE,"end compressed close")) done = FALSE; return (!done); }