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vrb_write_min(3)					      VRB Programmer's Manual						  vrb_write_min(3)

NAME
vrb_write_min - write data from a VRB LIBRARY
-lvrb SYNOPSIS
#include <vrb.h> size_t vrb_write_min(vrb_p vrb, int fd, size_t maxsize, size_t minsize); DESCRIPTION
vrb_write_min writes a minimum amount of data to a specified open file descriptor using write(2) from the specified virtual ring buffer until the specified maximum length has been written, the buffer is full, or an error is returned (including EAGAIN or EWOULDBLOCK for a non-blocking descriptor). If there is insufficient data in the buffer to write the minimum amount, then write(2) will not be called. ARGUMENTS
vrb_p vrb specifies which virtual ring buffer. int fd specifies the open file descriptor to write to size_t maxsize specifies the maximum length to write, or ~0 for unlimited. size_t minsize specifies the minimum length to write. RETURN VALUE
size_t If successful, the actual length of data written from the buffer is returned. If the minimum amount of data was not available to be writ- ten, 0 is returned. If an error occurs from write(2), the return value is ~0 and errno is set by write(2). ERRORS
If an error is returned, then errno will have one of the following values: 0 An end-of-file has occurred. Note that this is a different way of returning an end-of-file condition than write(2) uses. EINVAL An invalid virtual ring buffer pointer was specified. SEE ALSO
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_init_opt(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), write(2) vrb 2002-09-30 vrb_write_min(3)

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vrb_new_opt(3)						      VRB Programmer's Manual						    vrb_new_opt(3)

NAME
vrb_new_opt - create a new virtual ring buffer LIBRARY
-lvrb SYNOPSIS
#include <vrb.h> vrb_p vrb_new_opt(size_t size, const char *name, int options); DESCRIPTION
vrb_new_opt creates a new instance of a virtual ring buffer. 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. ARGUMENTS
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. Other- wise 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: VRB_NOGUARD Do not include guard pages that would protect against buffer overflow errors. VRB_ENVGUARD Override VRB_NOGUARD if the environment variable VRBGUARD is defined with a value other than the string "0". RETURN VALUE
vrb_p On success, a handle (pointer) to the newly created virtual ring buffer is returned. On error, NULL is returned. ERRORS
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 arithmetic. ENOMEM Out of memory allocating the virtual ring buffer structure. - An errno value set by a failing system call. SEE ALSO
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_init_opt(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_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) vrb 2002-09-30 vrb_new_opt(3)
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