static fpos_t memstream_seek(void *cookie, fpos_t offset, int whence) {
struct memstream *ms = (struct memstream *)cookie;
fpos_t pos = 0;
memstream_check(ms);
memstream_info(("memstream_seek %p %i %i\n", ms, (int)offset, whence));
switch (whence) {
case SEEK_SET:
pos = offset;
break;
case SEEK_CUR:
pos = ms->position + offset;
break;
case SEEK_END:
pos = ms->size + offset;
break;
default:
errno = EINVAL;
return -1;
}
if (pos >= ms->capacity)
memstream_grow(ms, pos);
ms->position = pos;
if (ms->size < ms->position)
*ms->sizeloc = ms->size = ms->position;
memstream_print(ms);
memstream_info(("=> %i\n", (int)pos));
assert(ms->size < ms->capacity && ms->contents[ms->size] == 0);
return pos;
}
static int memstream_read(void *cookie, char *buf, int count)
{
struct memstream *ms= (struct memstream *)cookie; memstream_check(ms);
int n= min(ms->size - ms->position, count); memstream_info(("memstream_read %p %i\n", ms, count));
if (n < 1) return 0;
memcpy(buf, ms->contents, n);
ms->position += n; memstream_print(ms);
return n;
}
static int memstream_grow(struct memstream *ms, int minsize)
{
int newcap= ms->capacity * 2; memstream_check(ms);
while (newcap <= minsize) newcap *= 2; memstream_info(("grow %p to %i\n", ms, newcap));
ms->contents= realloc(ms->contents, newcap);
if (!ms->contents) return -1; /* errno == ENOMEM */
memset(ms->contents + ms->capacity, 0, newcap - ms->capacity);
ms->capacity= newcap;
*ms->ptr= ms->contents; /* size has not changed */
return 0;
}
static int memstream_write(void *cookie, const char *buf, int count)
{
struct memstream *ms= (struct memstream *)cookie; memstream_check(ms);
if (ms->capacity <= ms->position + count)
if (memstream_grow(ms, ms->position + count) < 0) /* errno == ENOMEM */
return -1;
memcpy(ms->contents + ms->position, buf, count); memstream_info(("memstream_write %p %i\n", ms, count));
ms->position += count;
if (ms->size < ms->position) *ms->sizeloc= ms->size= ms->position; memstream_print(ms);
assert(ms->size < ms->capacity);
assert(ms->contents[ms->size] == 0);
return count;
}