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/* SPDX-License-Identifier: GPL-3.0-or-later */
/*
* mem.c
*
* Copyright (C) 2023 David Oberhollenzer <goliath@infraroot.at>
*/
#include "config.h"
#include "io/mem.h"
#include "compat.h"
#include "sqfs/io.h"
#include <stdlib.h>
#include <string.h>
#include <assert.h>
typedef struct {
sqfs_istream_t base;
sqfs_u8 *buffer;
size_t bufsz;
const void *data;
size_t size;
size_t offset;
size_t visible;
char *name;
} mem_istream_t;
static int mem_get_buffered_data(sqfs_istream_t *strm, const sqfs_u8 **out,
size_t *size, size_t want)
{
mem_istream_t *mem = (mem_istream_t *)strm;
size_t have = mem->size - mem->offset;
if (have > mem->bufsz)
have = mem->bufsz;
if (want > have)
want = have;
if (mem->visible == 0 || mem->visible < want) {
memcpy(mem->buffer + mem->visible,
(const char *)mem->data + mem->offset + mem->visible,
have - mem->visible);
mem->visible = have;
}
*out = mem->buffer;
*size = mem->visible;
return (mem->visible == 0) ? 1 : 0;
}
static void mem_advance_buffer(sqfs_istream_t *strm, size_t count)
{
mem_istream_t *mem = (mem_istream_t *)strm;
assert(count <= mem->visible);
if (count > 0 && count < mem->visible)
memmove(mem->buffer, mem->buffer + count, mem->visible - count);
mem->offset += count;
mem->visible -= count;
if (mem->visible < mem->bufsz) {
memset(mem->buffer + mem->visible, 0,
mem->bufsz - mem->visible);
}
}
static const char *mem_in_get_filename(sqfs_istream_t *strm)
{
return ((mem_istream_t *)strm)->name;
}
static void mem_in_destroy(sqfs_object_t *obj)
{
free(((mem_istream_t *)obj)->buffer);
free(((mem_istream_t *)obj)->name);
free(obj);
}
sqfs_istream_t *istream_memory_create(const char *name, size_t bufsz,
const void *data, size_t size)
{
mem_istream_t *mem = calloc(1, sizeof(*mem));
sqfs_istream_t *strm = (sqfs_istream_t *)mem;
if (mem == NULL)
return NULL;
sqfs_object_init(mem, mem_in_destroy, NULL);
mem->name = strdup(name);
if (mem->name == NULL)
return sqfs_drop(mem);
mem->buffer = malloc(bufsz);
if (mem->buffer == NULL)
return sqfs_drop(mem);
mem->data = data;
mem->size = size;
mem->bufsz = bufsz;
strm->get_buffered_data = mem_get_buffered_data;
strm->advance_buffer = mem_advance_buffer;
strm->get_filename = mem_in_get_filename;
return strm;
}
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