.\" $OpenBSD: evbuffer_new.3,v 1.14 2018/07/26 12:50:04 rob Exp $ .\" .\" Copyright (c) 2014 David Gwynne .\" .\" Permission to use, copy, modify, and distribute this software for any .\" purpose with or without fee is hereby granted, provided that the above .\" copyright notice and this permission notice appear in all copies. .\" .\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES .\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF .\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR .\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES .\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. .\" .Dd $Mdocdate: July 26 2018 $ .Dt EVBUFFER_NEW 3 .Os .Sh NAME .Nm evbuffer_new , .Nm evbuffer_free , .Nm evbuffer_setcb , .Nm evbuffer_expand , .Nm evbuffer_add , .Nm evbuffer_add_buffer , .Nm evbuffer_add_printf , .Nm evbuffer_add_vprintf , .Nm evbuffer_drain , .Nm evbuffer_remove , .Nm evbuffer_write , .Nm evbuffer_read , .Nm evbuffer_find , .Nm evbuffer_readline , .Nm evbuffer_readln , .Nm EVBUFFER_LENGTH , .Nm EVBUFFER_DATA .Nd libevent utility API for buffered input/output .Sh SYNOPSIS .In event.h .Ft "struct evbuffer *" .Fn "evbuffer_new" "void" .Ft void .Fn "evbuffer_free" "struct evbuffer *buf" .Ft void .Fo evbuffer_setcb .Fa "struct evbuffer *buf" .Fa "void (*cb)(struct evbuffer *, size_t, size_t, void *)" .Fa "void *cbarg" .Fc .Ft int .Fn "evbuffer_expand" "struct evbuffer *buf" "size_t datlen" .Ft int .Fn "evbuffer_add" "struct evbuffer *buf" "const void *data" "size_t size" .Ft int .Fn "evbuffer_add_buffer" "struct evbuffer *dst" "struct evbuffer *src" .Ft int .Fn "evbuffer_add_printf" "struct evbuffer *buf" "const char *fmt" "..." .Ft int .Fn "evbuffer_add_vprintf" "struct evbuffer *buf" "const char *fmt" "va_list ap" .Ft void .Fn "evbuffer_drain" "struct evbuffer *buf" "size_t size" .Ft int .Fn "evbuffer_remove" "struct evbuffer *buf" "void *data" "size_t datlen" .Ft int .Fn "evbuffer_write" "struct evbuffer *buf" "int fd" .Ft int .Fn "evbuffer_read" "struct evbuffer *buf" "int fd" "int size" .Ft "u_char *" .Fn "evbuffer_find" "struct evbuffer *buf" "const u_char *data" "size_t size" .Ft "char *" .Fn "evbuffer_readline" "struct evbuffer *buf" .Ft "char *" .Fo evbuffer_readln .Fa "struct evbuffer *buf" .Fa "size_t *read_out" .Fa "enum evbuffer_eol_style eol_style" .Fc .Ft size_t .Fn "EVBUFFER_LENGTH" "const struct evbuffer *buf" .Ft "u_char *" .Fn "EVBUFFER_DATA" "const struct evbuffer *buf" .Sh DESCRIPTION The evbuffer API provides an implementation of buffering for use with libevent. .Pp .Fn evbuffer_new allocates and initialises a new evbuffer structure. .Pp .Fn evbuffer_free deallocates the evbuffer structure .Fa buf and any referenced storage. .Pp .Fn evbuffer_setcb sets the callback .Fa cb to be invoked with argument .Fa cbarg when the data in evbuffer .Fa buf is modified. .Pp .Fn evbuffer_expand expands the available space in .Fa buf to at least .Fa datlen bytes. .Pp .Fn evbuffer_add appends a copy of .Fa size bytes from buffer .Fa data to the end of the evbuffer .Fa buf . .Pp .Fn evbuffer_add_buffer moves the data off the .Fa src evbuffer and appends it to .Fa dst . .Pp .Fn evbuffer_add_printf appends a .Xr printf 3 style formatted string specified by .Fa fmt to the end of .Fa buf . .Pp .Fn evbuffer_add_vprintf appends a .Xr vprintf 3 style formatted string specified by .Fa fmt with a va_list .Fa ap to the end of .Fa buf . .Pp .Fn evbuffer_drain deletes .Fa size bytes from the beginning of the evbuffer .Fa buf . .Pp .Fn evbuffer_remove reads and drains up to .Fa datlen bytes from the beginning of the evbuffer .Fa buf into .Fa data . .Pp .Fn evbuffer_write writes and drains the contents of evbuffer .Fa buf to the file descriptor .Fa fd . .Pp .Fn evbuffer_read appends up to .Fa size bytes on to the end of the evbuffer .Fa buf by reading from the file descriptor .Fa fd . .Pp .Fn evbuffer_find finds the .Fa size length string .Fa data in the evbuffer .Fa buf . .Pp .Fn evbuffer_readline reads and drains a single line from the evbuffer .Fa buf . A line is delimited by "\en", "\er", "\er\en", or "\en\er". It is the responsibility of the caller to free the returned line with .Xr free 3 . .Pp .Fn evbuffer_readln reads and drains a single line from the evbuffer .Fa buf . The length of the line will be stored in .Fa read_out on success. It is the responsibility of the caller to free the returned line with .Xr free 3 . The line delimiter is specified as one of the following: .Bl -tag -width xxx -offset indent .It Dv EVBUFFER_EOL_ANY Any sequence of newline or carriage return characters. .It Dv EVBUFFER_EOL_CRLF A new line optionally preceded by a carriage return. .It Dv EVBUFFER_EOL_CRLF_STRICT A carriage return followed by a new line character. .It Dv EVBUFFER_EOL_LF A new line character. .El .Pp .Fn EVBUFFER_LENGTH reports how many bytes are stored in the evbuffer .Fa buf . .Sh RETURN VALUES .Fn evbuffer_new returns a pointer to a newly allocated buffer on success, or .Dv NULL on failure and sets .Va errno to indicate the failure. .Pp .Fn evbuffer_expand , .Fn evbuffer_add , and .Fn evbuffer_add_buffer return 0 on success, or -1 on failure and set .Va errno to indicate the failure. .Pp .Fn evbuffer_add_printf and .Fn evbuffer_add_vprintf return the number of bytes added on success, or -1 on failure. .Pp .Fn evbuffer_remove returns the number of bytes read. .Pp .Fn evbuffer_write returns the number of bytes written and drained on success, or -1 on failure and sets .Va errno to indicate the failure. .Pp .Fn evbuffer_read returns the number of bytes appended to the evbuffer on success, 0 on an end of file condition, or -1 on failure and sets .Va errno to indicate the failure. .Pp .Fn evbuffer_find returns a pointer to the start of the string within the evbuffer on success, or .Dv NULL on failure. .Pp .Fn evbuffer_readline and .Fn evbuffer_readln return a pointer to the line on success, or .Dv NULL on failure. .Pp .Fn EVBUFFER_LENGTH returns the number of bytes available in the evbuffer. .Pp .Fn EVBUFFER_DATA returns a pointer to the evbuffer .Fa buf on success. .Sh SEE ALSO .Xr errno 2 , .Xr event 3 , .Xr free 3 , .Xr printf 3 .Sh AUTHORS The .Nm event library was written by .An Niels Provos .