Provided by: libvrb0-dev_0.5.1-5.1_amd64 bug


       vrb_init_opt - initialize a virtual ring buffer




       #include <vrb.h>

       vrb_p vrb_init_opt(vrb_p vrb, size_t size, const char *name, int options);


       vrb_init_opt Initialize a static or pre-allocated virtual ring buffer structure.

       A  virtual  ring  buffer  is  a  character  FIFO  queue with the special property that any
       sequence of characters in the buffer may be accessed  as  a  single  contiguous  block  of
       memory, eliminating the need to split any sequence to handle a buffer wraparound.


       vrb_p vrb
       specifies  the  virtual  ring buffer structure to be initialized.  The caller must release
       buffer resources via vrb_uninit(3) when this virtual ring buffer is no longer needed.   If
       NULL  is  given,  a  new  virtual  ring  buffer structure is allocated and the caller must
       release buffer resources via vrb_destroy(3) when an allocated virtual ring  buffer  is  no
       longer needed.

       size_t size
       specifies  the  requested  minimum  buffer  size to be allocated.  The given value will be
       rounded up to the nearest or equal whole multiple of the system page  size.   The  virtual
       ring  buffer  is  implemented  by mapping two adjacent blocks of memory to the same memory
       object.  Thus, twice as much virtual address space will be used  and  the  specified  size
       must be less than half of the available virtual address space for this process.

       const char *name
       specifies  an  optional  temporary  name pattern or an actual name of a file to be used as
       backing store via mmap(2)  in  a  mounted  filesystem  in  which  the  process  has  write
       permission.   If the name string ends in "XXXXXX" then mkstemp(3) will be used to make the
       file unique.  Otherwise it will be used as is.   If  the  named  file  already  exists  or
       otherwise  cannot  be opened for write, an error will occur.  If NULL is given, swap space
       will be used as backing store via shmat(2).

       int options
       specifies option flags that may be given to  alter  the  behaviour  of  the  virtual  ring
       buffer.  The implemented options are:

              Do not include guard pages that would protect against buffer overflow errors.

              Override  VRB_NOGUARD  if the environment variable VRBGUARD is defined with a value
              other than the string "0".


       On success, a handle (pointer) to the newly created virtual ring buffer is  returned.   On
       error, NULL is returned.


       If an error is returned, then errno will have one of the following values:

       EINVAL A  buffer  size  was  requested  which  is  too  large for address space allocation

       ENOMEM Out of memory allocating the virtual ring buffer structure.

       -      An errno value set by a failing system call.


       vrb(3), vrb_capacity(3),  vrb_data_len(3),  vrb_data_ptr(3),  vrb_destroy(3),  vrb_get(3),
       vrb_get_min(3),     vrb_give(3),     vrb_init(3),     vrb_is_empty(3),     vrb_is_full(3),
       vrb_is_not_empty(3),   vrb_is_not_full(3),   vrb_move(3),   vrb_new(3),    vrb_new_opt(3),
       vrb_put(3), vrb_put_all(3), vrb_read(3), vrb_read_min(3), vrb_resize(3), vrb_space_len(3),
       vrb_space_ptr(3), vrb_take(3), vrb_uninit(3), vrb_write(3), vrb_write_min(3)