diff options
| -rw-r--r-- | include/frag_reader.h | 31 | ||||
| -rw-r--r-- | lib/Makemodule.am | 3 | ||||
| -rw-r--r-- | lib/sqfs/frag_reader.c | 179 |
3 files changed, 212 insertions, 1 deletions
diff --git a/include/frag_reader.h b/include/frag_reader.h new file mode 100644 index 0000000..6495f5b --- /dev/null +++ b/include/frag_reader.h @@ -0,0 +1,31 @@ +/* SPDX-License-Identifier: GPL-3.0-or-later */ +#ifndef FRAG_READER_H +#define FRAG_READER_H + +#include "squashfs.h" +#include "compress.h" + +#include <stdint.h> +#include <stddef.h> + +typedef struct { + sqfs_fragment_t *tbl; + size_t num_fragments; + + int fd; + compressor_t *cmp; + size_t block_size; + size_t used; + size_t current_index; + uint8_t buffer[]; +} frag_reader_t; + +frag_reader_t *frag_reader_create(sqfs_super_t *super, int fd, + compressor_t *cmp); + +void frag_reader_destroy(frag_reader_t *f); + +int frag_reader_read(frag_reader_t *f, size_t index, size_t offset, + void *buffer, size_t size); + +#endif /* FRAG_READER_H */ diff --git a/lib/Makemodule.am b/lib/Makemodule.am index 3b171c6..f23d9b7 100644 --- a/lib/Makemodule.am +++ b/lib/Makemodule.am @@ -14,7 +14,8 @@ libsquashfs_a_SOURCES += lib/sqfs/table.c include/table.h libsquashfs_a_SOURCES += lib/sqfs/read_super.c lib/sqfs/meta_reader.c libsquashfs_a_SOURCES += include/meta_reader.h lib/sqfs/id_table_write.c libsquashfs_a_SOURCES += lib/sqfs/id_table_read.c lib/sqfs/read_inode.c -libsquashfs_a_SOURCES += lib/sqfs/readdir.c +libsquashfs_a_SOURCES += lib/sqfs/readdir.c lib/sqfs/frag_reader.c +libsquashfs_a_SOURCES += include/frag_reader.h libutil_a_SOURCES = lib/util/canonicalize_name.c lib/util/write_retry.c libutil_a_SOURCES += lib/util/read_retry.c include/util.h diff --git a/lib/sqfs/frag_reader.c b/lib/sqfs/frag_reader.c new file mode 100644 index 0000000..1906376 --- /dev/null +++ b/lib/sqfs/frag_reader.c @@ -0,0 +1,179 @@ +/* SPDX-License-Identifier: GPL-3.0-or-later */ +#include "meta_reader.h" +#include "frag_reader.h" +#include "util.h" + +#include <unistd.h> +#include <string.h> +#include <stdlib.h> +#include <stdio.h> + +static int precache_block(frag_reader_t *f, size_t i) +{ + bool compressed; + size_t size; + ssize_t ret; + + if (i == f->current_index) + return 0; + + if (lseek(f->fd, f->tbl[i].start_offset, SEEK_SET) == (off_t)-1) { + perror("seeking to fragment location"); + return -1; + } + + compressed = (f->tbl[i].size & (1 << 24)) == 0; + size = f->tbl[i].size & ((1 << 24) - 1); + + if (size > f->block_size) { + fputs("found fragment block larger than block size\n", stderr); + return -1; + } + + ret = read_retry(f->fd, f->buffer, size); + if (ret < 0) { + perror("reading fragment"); + return -1; + } + + if ((size_t)ret < size) { + fputs("reading fragment: unexpected end of file\n", stderr); + return -1; + } + + if (compressed) { + ret = f->cmp->do_block(f->cmp, f->buffer, size); + + if (ret <= 0) { + fputs("extracting fragment failed\n", stderr); + return -1; + } + } + + f->current_index = i; + f->used = ret; + return 0; +} + + +frag_reader_t *frag_reader_create(sqfs_super_t *super, int fd, + compressor_t *cmp) +{ + size_t i, blockcount, j, diff, count; + sqfs_fragment_t *tbl = NULL; + uint64_t *locations = NULL; + meta_reader_t *m = NULL; + frag_reader_t *f = NULL; + ssize_t ret; + + count = super->fragment_entry_count; + blockcount = count / (SQFS_META_BLOCK_SIZE / sizeof(tbl[0])); + + if (count % (SQFS_META_BLOCK_SIZE / sizeof(tbl[0]))) + ++blockcount; + + /* pre allocate all the stuff */ + f = calloc(1, sizeof(*f) + super->block_size); + if (f == NULL) + goto fail_rd; + + tbl = malloc(count * sizeof(tbl[0])); + if (tbl == NULL) + goto fail_rd; + + locations = malloc(blockcount * sizeof(locations[0])); + if (locations == NULL) + goto fail_rd; + + /* read the meta block offset table */ + if (lseek(fd, super->fragment_table_start, SEEK_SET) == (off_t)-1) + goto fail_seek; + + ret = read_retry(fd, locations, blockcount * sizeof(locations[0])); + if (ret < 0) + goto fail_rd; + + if ((size_t)ret < (blockcount * sizeof(locations[0]))) + goto fail_trunc; + + for (i = 0; i < blockcount; ++i) + locations[i] = le64toh(locations[i]); + + /* read the meta blocks */ + m = meta_reader_create(fd, cmp); + if (m == NULL) + goto fail; + + for (i = 0, j = 0; i < blockcount && j < count; ++i, j += diff) { + if (meta_reader_seek(m, locations[i], 0)) + goto fail; + + diff = SQFS_META_BLOCK_SIZE / sizeof(tbl[0]); + if (diff > count) + diff = count; + + if (meta_reader_read(m, tbl + j, diff * sizeof(tbl[0]))) + goto fail; + } + + for (i = 0; i < count; ++i) { + tbl[i].start_offset = le64toh(tbl[i].start_offset); + tbl[i].size = le32toh(tbl[i].size); + } + + /* cleanup and ship it */ + meta_reader_destroy(m); + free(locations); + + f->tbl = tbl; + f->num_fragments = count; + f->cmp = cmp; + f->fd = fd; + f->block_size = super->block_size; + f->current_index = count; + return f; +fail_seek: + perror("seek to fragment table"); + goto fail; +fail_trunc: + fputs("reading fragment table: unexpected end of file\n", stderr); + goto fail; +fail_rd: + perror("reading fragment table"); + goto fail; +fail: + if (m != NULL) + meta_reader_destroy(m); + free(tbl); + free(locations); + free(f); + return NULL; +} + +void frag_reader_destroy(frag_reader_t *f) +{ + free(f->tbl); + free(f); +} + +int frag_reader_read(frag_reader_t *f, size_t index, size_t offset, + void *buffer, size_t size) +{ + if (precache_block(f, index)) + return -1; + + if (offset >= f->used) + goto fail_range; + + if (size == 0) + return 0; + + if ((offset + size - 1) >= f->used) + goto fail_range; + + memcpy(buffer, f->buffer + offset, size); + return 0; +fail_range: + fputs("attempted to read past fragment block limits\n", stderr); + return -1; +} |