diff options
Diffstat (limited to 'lib/tar/src/istream.c')
| -rw-r--r-- | lib/tar/src/istream.c | 222 |
1 files changed, 222 insertions, 0 deletions
diff --git a/lib/tar/src/istream.c b/lib/tar/src/istream.c new file mode 100644 index 0000000..30b8a34 --- /dev/null +++ b/lib/tar/src/istream.c @@ -0,0 +1,222 @@ +/* SPDX-License-Identifier: GPL-3.0-or-later */ +/* + * istream.c + * + * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at> + */ +#include "internal.h" + +#include <string.h> +#include <stdlib.h> + +typedef struct { + sqfs_u64 offset; + sqfs_u64 count; +} sparse_ent_t; + +typedef struct { + istream_t base; + + istream_t *parent; + + char *filename; + + sparse_ent_t *sparse; + size_t num_sparse; + + sqfs_u64 record_size; + sqfs_u64 file_size; + sqfs_u64 offset; + + size_t last_chunk; + bool last_sparse; + + sqfs_u8 buffer[4096]; +} tar_istream_t; + +static bool is_sparse_region(tar_istream_t *tar, sqfs_u64 *count) +{ + size_t i; + + *count = tar->file_size - tar->offset; + if (tar->num_sparse == 0) + return false; + + for (i = 0; i < tar->num_sparse; ++i) { + if (tar->offset >= tar->sparse[i].offset) { + sqfs_u64 diff = tar->offset - tar->sparse[i].offset; + + if (diff < tar->sparse[i].count) { + *count = tar->sparse[i].count - diff; + return false; + } + } + } + + for (i = 0; i < tar->num_sparse; ++i) { + if (tar->offset < tar->sparse[i].offset) { + sqfs_u64 diff = tar->sparse[i].offset - tar->offset; + + if (diff < *count) + *count = diff; + } + } + + return true; +} + +static int precache(istream_t *strm) +{ + tar_istream_t *tar = (tar_istream_t *)strm; + sqfs_u64 diff, avail; + + tar->offset += tar->last_chunk; + + if (!tar->last_sparse) { + tar->parent->buffer_offset += tar->last_chunk; + tar->record_size -= tar->last_chunk; + } + + if (tar->offset >= tar->file_size) { + strm->eof = true; + strm->buffer_used = 0; + strm->buffer = tar->buffer; + if (tar->record_size > 0) + goto fail_rec_sz; + return 0; + } + + if (is_sparse_region(tar, &diff)) { + if (diff > sizeof(tar->buffer)) + diff = sizeof(tar->buffer); + + strm->buffer = tar->buffer; + strm->buffer_used = diff; + tar->last_chunk = diff; + tar->last_sparse = true; + + memset(tar->buffer, 0, diff); + } else { + if (diff > tar->record_size) + goto fail_rec_sz; + + avail = tar->parent->buffer_used - tar->parent->buffer_offset; + + if ((diff > avail) && + ((tar->parent->buffer_offset > 0) || avail == 0)) { + if (istream_precache(tar->parent)) + return -1; + + if (tar->parent->buffer_used == 0 && tar->parent->eof) + goto fail_eof; + + avail = tar->parent->buffer_used; + } + + if (diff > avail) + diff = avail; + + strm->buffer = tar->parent->buffer + tar->parent->buffer_offset; + strm->buffer_used = diff; + tar->last_chunk = diff; + tar->last_sparse = false; + } + + return 0; +fail_rec_sz: + fprintf(stderr, + "%s: missmatch in tar record size vs file size for `%s`.\n", + istream_get_filename(tar->parent), istream_get_filename(strm)); + return -1; +fail_eof: + fprintf(stderr, "%s: unexpected end-of-file while reading `%s`\n", + istream_get_filename(tar->parent), istream_get_filename(strm)); + return -1; +} + +static const char *get_filename(istream_t *strm) +{ + return ((tar_istream_t *)strm)->filename; +} + +static void tar_istream_destroy(sqfs_object_t *obj) +{ + tar_istream_t *strm = (tar_istream_t *)obj; + + sqfs_drop(strm->parent); + free(strm->sparse); + free(strm->filename); + free(strm); +} + +istream_t *tar_record_istream_create(istream_t *parent, + const tar_header_decoded_t *hdr) +{ + tar_istream_t *strm; + sparse_map_t *it; + sqfs_u64 diff; + size_t idx; + + strm = calloc(1, sizeof(*strm)); + if (strm == NULL) + goto fail_oom; + + sqfs_object_init(strm, tar_istream_destroy, NULL); + + strm->filename = strdup(hdr->name); + if (strm->filename == NULL) + goto fail_oom; + + strm->num_sparse = 0; + for (it = hdr->sparse; it != NULL; it = it->next) + strm->num_sparse += 1; + + if (strm->num_sparse > 0) { + strm->sparse = alloc_array(sizeof(strm->sparse[0]), + strm->num_sparse); + if (strm->sparse == NULL) + goto fail_oom; + + idx = 0; + it = hdr->sparse; + while (it != NULL && idx < strm->num_sparse) { + strm->sparse[idx].offset = it->offset; + strm->sparse[idx].count = it->count; + ++idx; + it = it->next; + } + } + + for (idx = 1; idx < strm->num_sparse; ++idx) { + if (strm->sparse[idx].offset <= strm->sparse[idx - 1].offset) + goto fail_sparse; + + diff = strm->sparse[idx].offset - strm->sparse[idx - 1].offset; + + if (diff < strm->sparse[idx - 1].count) + goto fail_sparse; + } + + strm->record_size = hdr->record_size; + strm->file_size = hdr->actual_size; + strm->parent = sqfs_grab(parent); + + ((istream_t *)strm)->precache = precache; + ((istream_t *)strm)->get_filename = get_filename; + ((istream_t *)strm)->buffer = strm->buffer; + ((istream_t *)strm)->eof = false; + return (istream_t *)strm; +fail_sparse: + fprintf(stderr, "%s: sparse map is not ordered or overlapping!\n", + hdr->name); + goto fail; +fail_oom: + fputs("tar istream create: out-of-memory\n", stderr); + goto fail; +fail: + if (strm != NULL) { + free(strm->filename); + free(strm); + } + return NULL; +} |