Added generic line-buffering code (a la stdio)
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136
src/core/linebuf.c
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136
src/core/linebuf.c
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/*
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* Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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/**
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* @file
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*
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* Line buffering
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*
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*/
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#include <stdint.h>
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#include <string.h>
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#include <stdlib.h>
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#include <errno.h>
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#include <gpxe/linebuf.h>
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/**
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* Line terminators
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*
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* These values are used in the @c skip_terminators bitmask.
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*/
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enum line_terminators {
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TERM_CR = 1,
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TERM_NL = 2,
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TERM_NUL = 4,
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};
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/**
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* Get terminator ID corresponding to character
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*
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* @v character Character
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* @ret terminator_id Terminator ID, or -1
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*/
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static int terminator_id ( unsigned int character ) {
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switch ( character ) {
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case '\r':
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return TERM_CR;
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case '\n':
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return TERM_NL;
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case '\0':
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return TERM_NUL;
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default:
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return -1;
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}
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}
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/**
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* Discard line buffer contents
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*
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* @v linebuf Line buffer
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*/
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void empty_line_buffer ( struct line_buffer *linebuf ) {
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free ( linebuf->data );
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linebuf->data = NULL;
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linebuf->len = 0;
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}
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/**
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* Buffer up received data by lines
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*
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* @v linebuf Line buffer
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* @v data New data to add
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* @v len Length of new data to add
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* @ret buffered Amount of data consumed and added to the buffer
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* @ret <0 Out of memory
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*
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* If line_buffer() does not consume the entirety of the new data
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* (i.e. if @c buffered is not equal to @c len), then an end of line
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* has been reached and the buffered-up line can be obtained from
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* buffered_line(). Carriage returns and newlines will have been
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* stripped, and the line will be NUL-terminated. This buffered line
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* is valid only until the next call to line_buffer() (or to
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* empty_line_buffer()).
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*
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* Note that line buffers use dynamically allocated storage; you
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* should call empty_line_buffer() before freeing a @c struct @c
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* line_buffer.
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*/
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int line_buffer ( struct line_buffer *linebuf, const char *data, size_t len ) {
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size_t consume = 0;
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size_t copy = 0;
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size_t new_len;
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char *new_data;
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int terminator;
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/* First, handle the termination of the previous line */
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if ( linebuf->skip_terminators ) {
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/* Free buffered string */
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empty_line_buffer ( linebuf );
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/* Skip over any terminators from the end of a previous line */
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for ( ; consume < len ; consume++ ) {
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terminator = terminator_id ( data[consume] );
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if ( ( terminator < 0 ) ||
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! ( linebuf->skip_terminators & terminator ) ) {
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linebuf->skip_terminators = 0;
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break;
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}
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linebuf->skip_terminators &= ~terminator;
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}
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}
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/* Scan up to the next terminator, if any */
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for ( ; consume < len ; consume++, copy++ ) {
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if ( terminator_id ( data[consume] ) >= 0 ) {
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linebuf->skip_terminators = -1U;
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break;
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}
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}
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/* Reallocate data buffer and copy in new data */
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new_len = ( linebuf->len + copy );
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new_data = realloc ( linebuf->data, ( new_len + 1 ) );
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if ( ! new_data )
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return -ENOMEM;
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memcpy ( ( new_data + linebuf->len ), ( data + consume - copy ),
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copy );
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new_data[new_len] = '\0';
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linebuf->data = new_data;
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linebuf->len = new_len;
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return consume;
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}
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37
src/include/gpxe/linebuf.h
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37
src/include/gpxe/linebuf.h
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#ifndef _GPXE_LINEBUF_H
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#define _GPXE_LINEBUF_H
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/** @file
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*
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* Line buffering
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*
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*/
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#include <stdint.h>
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#include <stddef.h>
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/** A line buffer */
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struct line_buffer {
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/** Current data in the buffer */
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char *data;
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/** Length of current data */
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size_t len;
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/** Bitmask of terminating characters to skip over */
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unsigned int skip_terminators;
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};
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/**
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* Retrieve buffered-up line
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*
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* @v linebuf Line buffer
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* @ret line Buffered line, or NULL if no line present
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*/
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static inline char * buffered_line ( struct line_buffer *linebuf ) {
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return linebuf->data;
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}
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extern int line_buffer ( struct line_buffer *linebuf, const char *data,
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size_t len );
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extern void empty_line_buffer ( struct line_buffer *linebuf );
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#endif /* _GPXE_LINEBUF_H */
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27
src/tests/linebuf_test.c
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27
src/tests/linebuf_test.c
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#include <stdint.h>
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#include <string.h>
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#include <vsprintf.h>
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#include <gpxe/linebuf.h>
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static const char data1[] =
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"Hello world\r\n"
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"This is a particularly mean set of lines\n"
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"with a mixture of terminators\r\r\n"
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"There should be exactly one blank line above\n"
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"and this line should never appear at all since it has no terminator";
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void linebuf_test ( void ) {
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struct line_buffer linebuf;
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const char *data = data1;
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size_t len = ( sizeof ( data1 ) - 1 /* be mean; strip the NUL */ );
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size_t buffered;
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memset ( &linebuf, 0, sizeof ( linebuf ) );
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while ( ( buffered = line_buffer ( &linebuf, data, len ) ) != len ) {
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printf ( "\"%s\"\n", buffered_line ( &linebuf ) );
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data += buffered;
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len -= buffered;
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}
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empty_line_buffer ( &linebuf );
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}
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