buffer_get man page
buffer_get — read binary data from buffer
ssize_t buffer_get(buffer* b,char* x,size_t len);
Normally buffer_get copies data to x, x, ..., x[len-1] from the beginning of a string stored in preallocated space; removes these len bytes from the string; and returns len.
If, however, the string has fewer than len (but more than 0) bytes, buffer_get copies only that many bytes, and returns that number.
If the string is empty, buffer_get first uses a read operation to feed data into the string. The read operation may indicate end of input, in which case buffer_get returns 0; or a read error, in which case buffer_get returns -1, setting errno appropriately.
The preallocated space and the read operation are specified by b. You must initialize b using buffer_init before calling buffer_get (or use the pre-initialized buffer_0).
buffer_init(3), buffer_feed(3), buffer_peek(3), buffer_seek(3), buffer(3)
buffer(3), buffer_feed(3), buffer_getc(3), buffer_getn(3), buffer_peek(3), buffer_seek(3).