source: lib/iow-stdio.c @ baef9df

4.0.1-hotfixescachetimestampsdevelopdpdk-ndagetsilivegetfragoffhelplibtrace4ndag_formatpfringrc-4.0.1rc-4.0.2rc-4.0.3rc-4.0.4ringdecrementfixringperformanceringtimestampfixes
Last change on this file since baef9df was baef9df, checked in by Perry Lorier <perry@…>, 11 years ago

Add back support for opening files for write with arbitary flags

  • Property mode set to 100644
File size: 5.1 KB
Line 
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 = towrite - (DATA(iow)->offset+towrite) % MIN_WRITE_SIZE;
131                int amount = total;
132                int count=0;
133                if (DATA(iow)->offset) {
134                        iov[count].iov_base = DATA(iow)->buffer;
135                        iov[count].iov_len = min(DATA(iow)->offset,amount);
136                        amount -= iov[count].iov_len;
137                        ++count;
138                }
139                if (towrite) {
140                        iov[count].iov_base = (void*)buffer;    /* cast away constness, which is safe
141                                                                 * here
142                                                                 */
143                        iov[count].iov_len = amount;
144                        amount -= iov[count].iov_len;
145                        ++count;
146                }
147                assert(amount == 0);
148                err=writev(DATA(iow)->fd, iov, count);
149                if (err==-1)
150                        return -1;
151                if (err != total)
152                        fprintf(stderr,"Wrote %d/%d\n",err,total);
153
154                /* Drop off "err" bytes from the beginning of the buffers */
155                amount = min(DATA(iow)->offset, err); /* How much we took out of the buffer */
156                memmove(DATA(iow)->buffer, 
157                        DATA(iow)->buffer+amount,
158                        DATA(iow)->offset-amount);
159                DATA(iow)->offset -= amount;
160
161                err -= amount; /* How much was written */
162
163                assert(err <= towrite);
164
165                buffer += err;
166                towrite -= err;
167
168                assert(DATA(iow)->offset == 0);
169        }
170
171        /* Make sure we're not going to overflow the buffer.  The above writev should assure
172         * that this is true
173         */
174        assert(DATA(iow)->offset + towrite <= MIN_WRITE_SIZE);
175        assert(towrite >= 0);
176
177        if (towrite > 0) {
178                /* Copy the remainder into the buffer to write next time. */
179                memcpy(DATA(iow)->buffer + DATA(iow)->offset, buffer, towrite);
180                DATA(iow)->offset += towrite;
181        }
182
183        return len;
184}
185
186static void stdio_wclose(iow_t *iow)
187{
188        long err;
189        /* Now, there might be some non multiple of the direct filesize left over, if so turn off
190         * O_DIRECT and write the final chunk.
191         */
192#ifdef O_DIRECT
193        err=fcntl(DATA(iow)->fd, F_GETFL);
194        if (err != -1 && (err & O_DIRECT) != 0) {
195                fcntl(DATA(iow)->fd,F_SETFL, err & ~O_DIRECT);
196        }
197#endif
198        err=write(DATA(iow)->fd, DATA(iow)->buffer, DATA(iow)->offset);
199        DATA(iow)->offset = 0;
200        close(DATA(iow)->fd);
201        free(iow->data);
202        free(iow);
203}
204
205iow_source_t stdio_wsource = {
206        "stdiow",
207        stdio_wwrite,
208        stdio_wclose
209};
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