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/* 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;
}
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