/* * resource.c * * Read uncompressed and compressed metadata and file resources from a WIM file. */ /* * Copyright (C) 2012 Eric Biggers * * This file is part of wimlib, a library for working with WIM files. * * wimlib 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 3 of the License, or (at your option) any later * version. * * wimlib 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 * wimlib; if not, see http://www.gnu.org/licenses/. */ #include "wimlib_internal.h" #include "dentry.h" #include "lookup_table.h" #include "buffer_io.h" #include "lzx.h" #include "xpress.h" #include "sha1.h" #include #include #include #include #ifdef WITH_NTFS_3G #include #include #include #include #endif /* * Reads all or part of a compressed resource into an in-memory buffer. * * @fp: The FILE* for the WIM file. * @resource_compressed_size: The compressed size of the resource. * @resource_uncompressed_size: The uncompressed size of the resource. * @resource_offset: The offset of the start of the resource from * the start of the stream @fp. * @resource_ctype: The compression type of the resource. * @len: The number of bytes of uncompressed data to read from * the resource. * @offset: The offset of the bytes to read within the uncompressed * resource. * @contents_len: An array into which the uncompressed data is written. * It must be at least @len bytes long. * * Returns zero on success, nonzero on failure. */ static int read_compressed_resource(FILE *fp, u64 resource_compressed_size, u64 resource_uncompressed_size, u64 resource_offset, int resource_ctype, u64 len, u64 offset, u8 contents_ret[]) { DEBUG2("comp size = %"PRIu64", uncomp size = %"PRIu64", " "res offset = %"PRIu64"", resource_compressed_size, resource_uncompressed_size, resource_offset); DEBUG2("resource_ctype = %s, len = %"PRIu64", offset = %"PRIu64"", wimlib_get_compression_type_string(resource_ctype), len, offset); /* Trivial case */ if (len == 0) return 0; int (*decompress)(const void *, unsigned, void *, unsigned); /* Set the appropriate decompress function. */ if (resource_ctype == WIMLIB_COMPRESSION_TYPE_LZX) decompress = lzx_decompress; else decompress = xpress_decompress; /* The structure of a compressed resource consists of a table of chunk * offsets followed by the chunks themselves. Each chunk consists of * compressed data, and there is one chunk for each WIM_CHUNK_SIZE = * 32768 bytes of the uncompressed file, with the last chunk having any * remaining bytes. * * The chunk offsets are measured relative to the end of the chunk * table. The first chunk is omitted from the table in the WIM file * because its offset is implicitly given by the fact that it directly * follows the chunk table and therefore must have an offset of 0. */ /* Calculate how many chunks the resource conists of in its entirety. */ u64 num_chunks = (resource_uncompressed_size + WIM_CHUNK_SIZE - 1) / WIM_CHUNK_SIZE; /* As mentioned, the first chunk has no entry in the chunk table. */ u64 num_chunk_entries = num_chunks - 1; /* The index of the chunk that the read starts at. */ u64 start_chunk = offset / WIM_CHUNK_SIZE; /* The byte offset at which the read starts, within the start chunk. */ u64 start_chunk_offset = offset % WIM_CHUNK_SIZE; /* The index of the chunk that contains the last byte of the read. */ u64 end_chunk = (offset + len - 1) / WIM_CHUNK_SIZE; /* The byte offset of the last byte of the read, within the end chunk */ u64 end_chunk_offset = (offset + len - 1) % WIM_CHUNK_SIZE; /* Number of chunks that are actually needed to read the requested part * of the file. */ u64 num_needed_chunks = end_chunk - start_chunk + 1; /* If the end chunk is not the last chunk, an extra chunk entry is * needed because we need to know the offset of the chunk after the last * chunk read to figure out the size of the last read chunk. */ if (end_chunk != num_chunks - 1) num_needed_chunks++; /* Declare the chunk table. It will only contain offsets for the chunks * that are actually needed for this read. */ u64 chunk_offsets[num_needed_chunks]; /* Set the implicit offset of the first chunk if it is included in the * needed chunks. * * Note: M$'s documentation includes a picture that shows the first * chunk starting right after the chunk entry table, labeled as offset * 0x10. However, in the actual file format, the offset is measured * from the end of the chunk entry table, so the first chunk has an * offset of 0. */ if (start_chunk == 0) chunk_offsets[0] = 0; /* According to M$'s documentation, if the uncompressed size of * the file is greater than 4 GB, the chunk entries are 8-byte * integers. Otherwise, they are 4-byte integers. */ u64 chunk_entry_size = (resource_uncompressed_size >= (u64)1 << 32) ? 8 : 4; /* Size of the full chunk table in the WIM file. */ u64 chunk_table_size = chunk_entry_size * num_chunk_entries; /* Read the needed chunk offsets from the table in the WIM file. */ /* Index, in the WIM file, of the first needed entry in the * chunk table. */ u64 start_table_idx = (start_chunk == 0) ? 0 : start_chunk - 1; /* Number of entries we need to actually read from the chunk * table (excludes the implicit first chunk). */ u64 num_needed_chunk_entries = (start_chunk == 0) ? num_needed_chunks - 1 : num_needed_chunks; /* Skip over unneeded chunk table entries. */ u64 file_offset_of_needed_chunk_entries = resource_offset + start_table_idx * chunk_entry_size; if (fseeko(fp, file_offset_of_needed_chunk_entries, SEEK_SET) != 0) { ERROR_WITH_ERRNO("Failed to seek to byte %"PRIu64" to read " "chunk table of compressed resource", file_offset_of_needed_chunk_entries); return WIMLIB_ERR_READ; } /* Number of bytes we need to read from the chunk table. */ size_t size = num_needed_chunk_entries * chunk_entry_size; u8 chunk_tab_buf[size]; if (fread(chunk_tab_buf, 1, size, fp) != size) goto err; /* Now fill in chunk_offsets from the entries we have read in * chunk_tab_buf. */ u64 *chunk_tab_p = chunk_offsets; if (start_chunk == 0) chunk_tab_p++; if (chunk_entry_size == 4) { u32 *entries = (u32*)chunk_tab_buf; while (num_needed_chunk_entries--) *chunk_tab_p++ = le32_to_cpu(*entries++); } else { u64 *entries = (u64*)chunk_tab_buf; while (num_needed_chunk_entries--) *chunk_tab_p++ = le64_to_cpu(*entries++); } /* Done with the chunk table now. We must now seek to the first chunk * that is needed for the read. */ u64 file_offset_of_first_needed_chunk = resource_offset + chunk_table_size + chunk_offsets[0]; if (fseeko(fp, file_offset_of_first_needed_chunk, SEEK_SET) != 0) { ERROR_WITH_ERRNO("Failed to seek to byte %"PRIu64" to read " "first chunk of compressed resource", file_offset_of_first_needed_chunk); return WIMLIB_ERR_READ; } /* Pointer to current position in the output buffer for uncompressed * data. */ u8 *out_p = (u8*)contents_ret; /* Buffer for compressed data. While most compressed chunks will have a * size much less than WIM_CHUNK_SIZE, WIM_CHUNK_SIZE - 1 is the maximum * size in the worst-case. This assumption is valid only if chunks that * happen to compress to more than the uncompressed size (i.e. a * sequence of random bytes) are always stored uncompressed. But this seems * to be the case in M$'s WIM files, even though it is undocumented. */ u8 compressed_buf[WIM_CHUNK_SIZE - 1]; /* Decompress all the chunks. */ for (u64 i = start_chunk; i <= end_chunk; i++) { DEBUG2("Chunk %"PRIu64" (start %"PRIu64", end %"PRIu64").", i, start_chunk, end_chunk); /* Calculate the sizes of the compressed chunk and of the * uncompressed chunk. */ unsigned compressed_chunk_size; unsigned uncompressed_chunk_size; if (i != num_chunks - 1) { /* All the chunks except the last one in the resource * expand to WIM_CHUNK_SIZE uncompressed, and the amount * of compressed data for the chunk is given by the * difference of offsets in the chunk offset table. */ compressed_chunk_size = chunk_offsets[i + 1 - start_chunk] - chunk_offsets[i - start_chunk]; uncompressed_chunk_size = WIM_CHUNK_SIZE; } else { /* The last compressed chunk consists of the remaining * bytes in the file resource, and the last uncompressed * chunk has size equal to however many bytes are left- * that is, the remainder of the uncompressed size when * divided by WIM_CHUNK_SIZE. * * Note that the resource_compressed_size includes the * chunk table, so the size of it must be subtracted. */ compressed_chunk_size = resource_compressed_size - chunk_table_size - chunk_offsets[i - start_chunk]; uncompressed_chunk_size = resource_uncompressed_size % WIM_CHUNK_SIZE; /* If the remainder is 0, the last chunk actually * uncompresses to a full WIM_CHUNK_SIZE bytes. */ if (uncompressed_chunk_size == 0) uncompressed_chunk_size = WIM_CHUNK_SIZE; } DEBUG2("compressed_chunk_size = %u, " "uncompressed_chunk_size = %u", compressed_chunk_size, uncompressed_chunk_size); /* Figure out how much of this chunk we actually need to read */ u64 start_offset; if (i == start_chunk) start_offset = start_chunk_offset; else start_offset = 0; u64 end_offset; if (i == end_chunk) end_offset = end_chunk_offset; else end_offset = WIM_CHUNK_SIZE - 1; u64 partial_chunk_size = end_offset + 1 - start_offset; bool is_partial_chunk = (partial_chunk_size != uncompressed_chunk_size); DEBUG2("start_offset = %u, end_offset = %u", start_offset, end_offset); DEBUG2("partial_chunk_size = %u", partial_chunk_size); /* This is undocumented, but chunks can be uncompressed. This * appears to always be the case when the compressed chunk size * is equal to the uncompressed chunk size. */ if (compressed_chunk_size == uncompressed_chunk_size) { /* Probably an uncompressed chunk */ if (start_offset != 0) { if (fseeko(fp, start_offset, SEEK_CUR) != 0) { ERROR_WITH_ERRNO("Uncompressed partial " "chunk fseek() error"); return WIMLIB_ERR_READ; } } if (fread(out_p, 1, partial_chunk_size, fp) != partial_chunk_size) goto err; } else { /* Compressed chunk */ int ret; /* Read the compressed data into compressed_buf. */ if (fread(compressed_buf, 1, compressed_chunk_size, fp) != compressed_chunk_size) goto err; /* For partial chunks we must buffer the uncompressed * data because we don't need all of it. */ if (is_partial_chunk) { u8 uncompressed_buf[uncompressed_chunk_size]; ret = decompress(compressed_buf, compressed_chunk_size, uncompressed_buf, uncompressed_chunk_size); if (ret != 0) return WIMLIB_ERR_DECOMPRESSION; memcpy(out_p, uncompressed_buf + start_offset, partial_chunk_size); } else { ret = decompress(compressed_buf, compressed_chunk_size, out_p, uncompressed_chunk_size); if (ret != 0) return WIMLIB_ERR_DECOMPRESSION; } } /* Advance the pointer into the uncompressed output data by the * number of uncompressed bytes that were written. */ out_p += partial_chunk_size; } return 0; err: if (feof(fp)) ERROR("Unexpected EOF in compressed file resource"); else ERROR_WITH_ERRNO("Error reading compressed file resource"); return WIMLIB_ERR_READ; } /* * Reads uncompressed data from an open file stream. */ int read_uncompressed_resource(FILE *fp, u64 offset, u64 len, u8 contents_ret[]) { if (fseeko(fp, offset, SEEK_SET) != 0) { ERROR("Failed to seek to byte %"PRIu64" of input file " "to read uncompressed resource (len = %"PRIu64")", offset, len); return WIMLIB_ERR_READ; } if (fread(contents_ret, 1, len, fp) != len) { if (feof(fp)) { ERROR("Unexpected EOF in uncompressed file resource"); } else { ERROR("Failed to read %"PRIu64" bytes from " "uncompressed resource at offset %"PRIu64, len, offset); } return WIMLIB_ERR_READ; } return 0; } /* Reads the contents of a struct resource_entry, as represented in the on-disk * format, from the memory pointed to by @p, and fills in the fields of @entry. * A pointer to the byte after the memory read at @p is returned. */ const u8 *get_resource_entry(const u8 *p, struct resource_entry *entry) { u64 size; u8 flags; p = get_u56(p, &size); p = get_u8(p, &flags); entry->size = size; entry->flags = flags; /* offset and original_size are truncated to 62 bits to avoid possible * overflows, when converting to a signed 64-bit integer (off_t) or when * adding size or original_size. This is okay since no one would ever * actually have a WIM bigger than 4611686018427387903 bytes... */ p = get_u64(p, &entry->offset); if (entry->offset & 0xc000000000000000ULL) { WARNING("Truncating offset in resource entry"); entry->offset &= 0x3fffffffffffffffULL; } p = get_u64(p, &entry->original_size); if (entry->original_size & 0xc000000000000000ULL) { WARNING("Truncating original_size in resource entry"); entry->original_size &= 0x3fffffffffffffffULL; } return p; } /* Copies the struct resource_entry @entry to the memory pointed to by @p in the * on-disk format. A pointer to the byte after the memory written at @p is * returned. */ u8 *put_resource_entry(u8 *p, const struct resource_entry *entry) { p = put_u56(p, entry->size); p = put_u8(p, entry->flags); p = put_u64(p, entry->offset); p = put_u64(p, entry->original_size); return p; } #ifdef WITH_FUSE static FILE *wim_get_fp(WIMStruct *w) { pthread_mutex_lock(&w->fp_tab_mutex); FILE *fp; wimlib_assert(w->filename != NULL); for (size_t i = 0; i < w->num_allocated_fps; i++) { if (w->fp_tab[i]) { fp = w->fp_tab[i]; w->fp_tab[i] = NULL; goto out; } } DEBUG("Opening extra file descriptor to `%s'", w->filename); fp = fopen(w->filename, "rb"); if (!fp) ERROR_WITH_ERRNO("Failed to open `%s'", w->filename); out: pthread_mutex_unlock(&w->fp_tab_mutex); return fp; } static int wim_release_fp(WIMStruct *w, FILE *fp) { int ret = 0; FILE **fp_tab; pthread_mutex_lock(&w->fp_tab_mutex); for (size_t i = 0; i < w->num_allocated_fps; i++) { if (w->fp_tab[i] == NULL) { w->fp_tab[i] = fp; goto out; } } fp_tab = REALLOC(w->fp_tab, sizeof(FILE*) * (w->num_allocated_fps + 4)); if (!fp_tab) { ret = WIMLIB_ERR_NOMEM; goto out; } w->fp_tab = fp_tab; memset(&w->fp_tab[w->num_allocated_fps], 0, 4 * sizeof(FILE*)); w->fp_tab[w->num_allocated_fps] = fp; w->num_allocated_fps += 4; out: pthread_mutex_unlock(&w->fp_tab_mutex); return ret; } #endif /* * Reads some data from the resource corresponding to a WIM lookup table entry. * * @lte: The WIM lookup table entry for the resource. * @buf: Buffer into which to write the data. * @size: Number of bytes to read. * @offset: Offset at which to start reading the resource. * * Returns zero on success, nonzero on failure. */ int read_wim_resource(const struct wim_lookup_table_entry *lte, u8 buf[], size_t size, u64 offset, int flags) { int ctype; int ret = 0; FILE *fp; /* We shouldn't be allowing read over-runs in any part of the library. * */ if (flags & WIMLIB_RESOURCE_FLAG_RAW) wimlib_assert(offset + size <= lte->resource_entry.size); else wimlib_assert(offset + size <= lte->resource_entry.original_size); switch (lte->resource_location) { case RESOURCE_IN_WIM: /* The resource is in a WIM file, and its WIMStruct is given by * the lte->wim member. The resource may be either compressed * or uncompressed. */ wimlib_assert(lte->wim != NULL); #ifdef WITH_FUSE if (flags & WIMLIB_RESOURCE_FLAG_MULTITHREADED) { fp = wim_get_fp(lte->wim); if (!fp) return WIMLIB_ERR_OPEN; } else #endif { wimlib_assert(!(flags & WIMLIB_RESOURCE_FLAG_MULTITHREADED)); wimlib_assert(lte->wim->fp != NULL); fp = lte->wim->fp; } ctype = wim_resource_compression_type(lte); wimlib_assert(ctype != WIMLIB_COMPRESSION_TYPE_NONE || (lte->resource_entry.original_size == lte->resource_entry.size)); if ((flags & WIMLIB_RESOURCE_FLAG_RAW) || ctype == WIMLIB_COMPRESSION_TYPE_NONE) ret = read_uncompressed_resource(fp, lte->resource_entry.offset + offset, size, buf); else ret = read_compressed_resource(fp, lte->resource_entry.size, lte->resource_entry.original_size, lte->resource_entry.offset, ctype, size, offset, buf); #ifdef WITH_FUSE if (flags & WIMLIB_RESOURCE_FLAG_MULTITHREADED) { int ret2 = wim_release_fp(lte->wim, fp); if (ret == 0) ret = ret2; } #endif break; case RESOURCE_IN_STAGING_FILE: case RESOURCE_IN_FILE_ON_DISK: /* The resource is in some file on the external filesystem and * needs to be read uncompressed */ wimlib_assert(lte->file_on_disk); wimlib_assert(<e->file_on_disk == <e->staging_file_name); /* Use existing file pointer if available; otherwise open one * temporarily */ if (lte->file_on_disk_fp) { fp = lte->file_on_disk_fp; } else { fp = fopen(lte->file_on_disk, "rb"); if (!fp) { ERROR_WITH_ERRNO("Failed to open the file " "`%s'", lte->file_on_disk); ret = WIMLIB_ERR_OPEN; break; } } ret = read_uncompressed_resource(fp, offset, size, buf); if (fp != lte->file_on_disk_fp) fclose(fp); break; case RESOURCE_IN_ATTACHED_BUFFER: /* The resource is directly attached uncompressed in an * in-memory buffer. */ wimlib_assert(lte->attached_buffer != NULL); memcpy(buf, lte->attached_buffer + offset, size); break; #ifdef WITH_NTFS_3G case RESOURCE_IN_NTFS_VOLUME: wimlib_assert(lte->ntfs_loc != NULL); wimlib_assert(lte->attr != NULL); if (lte->ntfs_loc->is_reparse_point) offset += 8; if (ntfs_attr_pread(lte->attr, offset, size, buf) != size) { ERROR_WITH_ERRNO("Error reading NTFS attribute " "at `%s'", lte->ntfs_loc->path_utf8); ret = WIMLIB_ERR_NTFS_3G; } break; #endif default: wimlib_assert(0); ret = -1; break; } return ret; } /* * Reads all the data from the resource corresponding to a WIM lookup table * entry. * * @lte: The WIM lookup table entry for the resource. * @buf: Buffer into which to write the data. It must be at least * wim_resource_size(lte) bytes long. * * Returns 0 on success; nonzero on failure. */ int read_full_wim_resource(const struct wim_lookup_table_entry *lte, u8 buf[], int flags) { return read_wim_resource(lte, buf, wim_resource_size(lte), 0, flags); } /* Extracts the first @size bytes of a WIM resource to somewhere. In the * process, the SHA1 message digest of the resource is checked if the full * resource is being extracted. * * @extract_chunk is a function that is called to extract each chunk of the * resource. */ int extract_wim_resource(const struct wim_lookup_table_entry *lte, u64 size, extract_chunk_func_t extract_chunk, void *extract_chunk_arg) { u64 bytes_remaining = size; u8 buf[min(WIM_CHUNK_SIZE, bytes_remaining)]; u64 offset = 0; int ret = 0; u8 hash[SHA1_HASH_SIZE]; bool check_hash = (size == wim_resource_size(lte)); SHA_CTX ctx; if (check_hash) sha1_init(&ctx); while (bytes_remaining) { u64 to_read = min(bytes_remaining, sizeof(buf)); ret = read_wim_resource(lte, buf, to_read, offset, 0); if (ret != 0) return ret; if (check_hash) sha1_update(&ctx, buf, to_read); ret = extract_chunk(buf, to_read, offset, extract_chunk_arg); if (ret != 0) { ERROR_WITH_ERRNO("Error extracting WIM resource"); return ret; } bytes_remaining -= to_read; offset += to_read; } if (check_hash) { sha1_final(hash, &ctx); if (!hashes_equal(hash, lte->hash)) { #ifdef ENABLE_ERROR_MESSAGES ERROR("Invalid checksum on the following WIM resource:"); print_lookup_table_entry(lte); #endif return WIMLIB_ERR_INVALID_RESOURCE_HASH; } } return 0; } /* Write @n bytes from @buf to the file descriptor @fd, retrying on internupt * and on short writes. * * Returns short count and set errno on failure. */ static ssize_t full_write(int fd, const void *buf, size_t n) { const char *p = buf; ssize_t ret; ssize_t total = 0; while (total != n) { ret = write(fd, p, n); if (ret < 0) { if (errno == EINTR) continue; else break; } total += ret; p += ret; } return total; } int extract_wim_chunk_to_fd(const u8 *buf, size_t len, u64 offset, void *arg) { int fd = *(int*)arg; ssize_t ret = full_write(fd, buf, len); if (ret < len) { ERROR_WITH_ERRNO("Error writing to file descriptor"); return WIMLIB_ERR_WRITE; } else { return 0; } } /* * Copies the file resource specified by the lookup table entry @lte from the * input WIM to the output WIM that has its FILE * given by * ((WIMStruct*)wim)->out_fp. * * The output_resource_entry, out_refcnt, and part_number fields of @lte are * updated. * * (This function is confusing and should be refactored somehow.) */ int copy_resource(struct wim_lookup_table_entry *lte, void *wim) { WIMStruct *w = wim; int ret; if ((lte->resource_entry.flags & WIM_RESHDR_FLAG_METADATA) && !w->write_metadata) return 0; ret = write_wim_resource(lte, w->out_fp, wim_resource_compression_type(lte), <e->output_resource_entry, 0); if (ret != 0) return ret; lte->out_refcnt = lte->refcnt; lte->part_number = w->hdr.part_number; return 0; }