int databuf_reset(DataBuf *db)
{
if (debug) databuf_print(db, 1, "databuf_reset() entry");
if (!(db->flags & DATABUF_FLAG_PRESERVE_HEAD)) return -1;
db->offset = 0;
db->len = MIN(db->alloc_size, db->max_len);
if (debug) databuf_print(db, 1, "databuf_reset() exit");
return 1;
}
int main(int argc, char **argv)
{
size_t size = 0;
DataBuf buf;
char *data;
assert(databuf_init(&buf, size, DATABUF_FLAG_STRING));
databuf_print(&buf, 1, "after init size=%d", size);
#if 1
data = "a";
assert(databuf_strcat(&buf, data));
databuf_print(&buf, 1, "after strcat(%s)", data);
data = "bb";
assert(databuf_strcat(&buf, data));
databuf_print(&buf, 1, "after strcat(%s)", data);
data = "ccc";
assert(databuf_strcat(&buf, data));
databuf_print(&buf, 1, "after strcat(%s)", data);
#endif
databuf_free(&buf);
#if 0
assert(databuf_init(&buf, size, 0));
databuf_print(&buf, 1, "after init size=%d", size);
size = 8;
data = make_data(size, "a");
assert(databuf_append(&buf, data, size));
databuf_print(&buf, 1, "after append size=%d", size);
assert(databuf_append(&buf, data, size));
free(data);
databuf_print(&buf, 1, "after append size=%d", size);
assert(databuf_advance(&buf, 4));
databuf_print(&buf, 1, "after databuf_advance(%d", 4);
size = 5;
data = make_data(size, "b");
assert(databuf_append(&buf, data, size));
free(data);
databuf_print(&buf, 1, "after append size=%d", size);
size = 7;
data = make_data(size, "c");
assert(databuf_append(&buf, data, size));
free(data);
databuf_print(&buf, 1, "after append size=%d", size);
databuf_free(&buf);
#endif
exit(0);
}
int databuf_append(DataBuf *db, const char *src, size_t src_size)
{
size_t new_size;
DATABUF_VALIDATE(db);
if (src == NULL || src_size == 0) return 0;
new_size = db->len+src_size;
#ifdef DEBUG
if (debug) databuf_print(db, 1, "databuf_append() size=%zd", src_size);
#endif
if ((new_size > db->alloc_size) ||
((db->flags & DATABUF_FLAG_PRESERVE_HEAD) && !databuf_tail_available(db, src_size))) {
/* not enough room, we must realloc */
void *new_alloc;
databuf_shift_data_to_beginning(db);
if ((new_alloc = realloc(db->alloc_ptr, new_size))) {
db->alloc_ptr = new_alloc;
db->alloc_size = new_size;
} else {
return -1; /* realloc failed */
}
} else {
/* we can fit within current allocation, but can we append? */
if (!databuf_tail_available(db, src_size)) {
/* we can't append in place, must create room at tail by shifting
data forward to the beginning of the allocation block */
databuf_shift_data_to_beginning(db);
}
}
#ifdef DEBUG
if (debug) databuf_print(db, 1, "databuf_append() about to memmove()");
#endif
/* pointers all set up and room availble, move the data and update */
memmove(databuf_end(db), src, src_size);
db->len = new_size;
db->max_len = MAX(db->max_len, new_size);
#ifdef DEBUG
if (debug) databuf_print(db, 1, "databuf_append() conclusion");
#endif
DATABUF_VALIDATE(db);
return 1;
}
int databuf_advance(DataBuf *db, size_t advance)
{
size_t actual_advance;
DATABUF_VALIDATE(db);
if (debug) databuf_print(db, 1, "databuf_advance() enter, advance=%d", advance);
actual_advance = MIN(advance, db->len);
db->offset += actual_advance;
db->len -= actual_advance;
if (debug) databuf_print(db, 1, "databuf_advance() leave, actual_advance=%d", actual_advance);
DATABUF_VALIDATE(db);
if (advance == actual_advance) {
return 1;
} else {
errno = ESPIPE; // Illegal seek
return -1;
}
}