source: lib/iow-stdio.c @ 28318a4

4.0.1-hotfixescachetimestampsdevelopdpdk-ndagetsilivegetfragoffhelplibtrace4ndag_formatpfringrc-4.0.1rc-4.0.2rc-4.0.3rc-4.0.4ringdecrementfixringperformanceringtimestampfixes
Last change on this file since 28318a4 was 28318a4, checked in by Perry Lorier <perry@…>, 11 years ago

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1/*
2 * This file is part of libtrace
3 *
4 * Copyright (c) 2007,2008,2009,2010 The University of Waikato, Hamilton,
5 * New Zealand.
6 *
7 * Authors: Daniel Lawson
8 *          Perry Lorier
9 *          Shane Alcock
10 *         
11 * All rights reserved.
12 *
13 * This code has been developed by the University of Waikato WAND
14 * research group. For further information please see http://www.wand.net.nz/
15 *
16 * libtrace is free software; you can redistribute it and/or modify
17 * it under the terms of the GNU General Public License as published by
18 * the Free Software Foundation; either version 2 of the License, or
19 * (at your option) any later version.
20 *
21 * libtrace is distributed in the hope that it will be useful,
22 * but WITHOUT ANY WARRANTY; without even the implied warranty of
23 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
24 * GNU General Public License for more details.
25 *
26 * You should have received a copy of the GNU General Public License
27 * along with libtrace; if not, write to the Free Software
28 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
29 *
30 * $Id$
31 *
32 */
33
34
35#define _GNU_SOURCE 1
36#include "wandio.h"
37#include <sys/types.h>
38#include <sys/stat.h>
39#include <sys/uio.h>
40#include <fcntl.h>
41#include <stdlib.h>
42#include <unistd.h>
43#include <string.h>
44#include <assert.h>
45
46/* Libtrace IO module implementing a standard IO writer, i.e. no decompression
47 */
48
49enum { MIN_WRITE_SIZE = 4096 };
50
51struct stdiow_t {
52        char buffer[MIN_WRITE_SIZE];
53        int offset;
54        int fd;
55};
56
57extern iow_source_t stdio_wsource;
58
59#define DATA(iow) ((struct stdiow_t *)((iow)->data))
60
61static int safe_open(const char *filename, int flags)
62{
63        int fd;
64/* Try opening with O_DIRECT */
65#ifdef O_DIRECT
66        fd = open(filename,
67                flags
68                |O_WRONLY
69                |O_CREAT
70                |O_TRUNC
71                |(force_directio_write?O_DIRECT:0),
72                0666);
73        if (fd != -1)
74                return fd;
75#endif
76/* If that failed (or we don't support O_DIRECT) try opening without */
77        fd = open(filename,
78                flags
79                |O_WRONLY
80                |O_CREAT
81                |O_TRUNC,
82                0666);
83        if (fd != -1)
84                return fd;
85        return fd;
86}
87
88iow_t *stdio_wopen(const char *filename,int flags)
89{
90        iow_t *iow = malloc(sizeof(iow_t));
91        iow->source = &stdio_wsource;
92        iow->data = malloc(sizeof(struct stdiow_t));
93
94        if (strcmp(filename,"-") == 0) 
95                DATA(iow)->fd = 1; /* STDOUT */
96        else {
97                DATA(iow)->fd = safe_open(filename, flags);
98        }
99
100        if (DATA(iow)->fd == -1) {
101                free(iow);
102                return NULL;
103        }
104
105        DATA(iow)->offset = 0;
106
107        return iow;
108}
109
110#define min(a,b) ((a)<(b) ? (a) : (b))
111#define max(a,b) ((a)>(b) ? (a) : (b))
112/* Round A Down to the nearest multiple of B */
113#define rounddown(a,b) ((a)-((a)%b)
114
115/* When doing directio (O_DIRECT) we need to make sure that we write multiples of MIN_WRITE_SIZE.
116 * So we accumulate data into DATA(iow)->buffer, and write it out when we get at least MIN_WRITE_SIZE.
117 *
118 * Since most writes are likely to be larger than MIN_WRITE_SIZE optimise for that case.
119 */
120static off_t stdio_wwrite(iow_t *iow, const char *buffer, off_t len)
121{
122        int towrite = len;
123        /* Round down size to the nearest multiple of MIN_WRITE_SIZE */
124
125        assert(towrite >= 0);
126
127        while (DATA(iow)->offset + towrite >= MIN_WRITE_SIZE) {
128                int err;
129                struct iovec iov[2];
130                int total = (DATA(iow)->offset+towrite);
131                int amount;
132                int count=0;
133                /* Round down to the nearest multiple */
134                total = total - (total % MIN_WRITE_SIZE);
135                amount = total;
136                if (DATA(iow)->offset) {
137                        iov[count].iov_base = DATA(iow)->buffer;
138                        iov[count].iov_len = min(DATA(iow)->offset,amount);
139                        amount -= iov[count].iov_len;
140                        ++count;
141                }
142                /* How much to write from this buffer? */
143                if (towrite) {
144                        iov[count].iov_base = (void*)buffer;    /* cast away constness, which is safe
145                                                                 * here
146                                                                 */
147                        iov[count].iov_len = amount;
148                        amount -= iov[count].iov_len;
149                        ++count;
150                }
151                assert(amount == 0);
152                err=writev(DATA(iow)->fd, iov, count);
153                if (err==-1)
154                        return -1;
155
156                /* Drop off "err" bytes from the beginning of the buffers */
157                amount = min(DATA(iow)->offset, err); /* How much we took out of the buffer */
158                memmove(DATA(iow)->buffer, 
159                        DATA(iow)->buffer+amount,
160                        DATA(iow)->offset-amount);
161                DATA(iow)->offset -= amount;
162
163                err -= amount; /* How much was written */
164
165                assert(err <= towrite);
166
167                buffer += err;
168                towrite -= err;
169
170                assert(DATA(iow)->offset == 0);
171        }
172
173        /* Make sure we're not going to overflow the buffer.  The above writev should assure
174         * that this is true
175         */
176        assert(DATA(iow)->offset + towrite <= MIN_WRITE_SIZE);
177        assert(towrite >= 0);
178
179        if (towrite > 0) {
180                /* Copy the remainder into the buffer to write next time. */
181                memcpy(DATA(iow)->buffer + DATA(iow)->offset, buffer, towrite);
182                DATA(iow)->offset += towrite;
183        }
184
185        return len;
186}
187
188static void stdio_wclose(iow_t *iow)
189{
190        long err;
191        /* Now, there might be some non multiple of the direct filesize left over, if so turn off
192         * O_DIRECT and write the final chunk.
193         */
194#ifdef O_DIRECT
195        err=fcntl(DATA(iow)->fd, F_GETFL);
196        if (err != -1 && (err & O_DIRECT) != 0) {
197                fcntl(DATA(iow)->fd,F_SETFL, err & ~O_DIRECT);
198        }
199#endif
200        err=write(DATA(iow)->fd, DATA(iow)->buffer, DATA(iow)->offset);
201        DATA(iow)->offset = 0;
202        close(DATA(iow)->fd);
203        free(iow->data);
204        free(iow);
205}
206
207iow_source_t stdio_wsource = {
208        "stdiow",
209        stdio_wwrite,
210        stdio_wclose
211};
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