1/*	$OpenBSD: dba_write.c,v 1.1 2016/08/01 10:32:39 schwarze Exp $ */
2/*
3 * Copyright (c) 2016 Ingo Schwarze <schwarze@openbsd.org>
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 *
17 * Low-level functions for serializing allocation-based data to disk.
18 * The interface is defined in "dba_write.h".
19 */
20#include <assert.h>
21#include <endian.h>
22#include <err.h>
23#include <errno.h>
24#include <fcntl.h>
25#include <stdint.h>
26#include <stdio.h>
27
28#include "dba_write.h"
29
30static FILE	*ofp;
31
32
33int
34dba_open(const char *fname)
35{
36	ofp = fopen(fname, "w");
37	return ofp == NULL ? -1 : 0;
38}
39
40int
41dba_close(void)
42{
43	return fclose(ofp) == EOF ? -1 : 0;
44}
45
46int32_t
47dba_tell(void)
48{
49	long		 pos;
50
51	if ((pos = ftell(ofp)) == -1)
52		err(1, "ftell");
53	if (pos >= INT32_MAX) {
54		errno = EOVERFLOW;
55		err(1, "ftell = %ld", pos);
56	}
57	return pos;
58}
59
60void
61dba_seek(int32_t pos)
62{
63	if (fseek(ofp, pos, SEEK_SET) == -1)
64		err(1, "fseek(%d)", pos);
65}
66
67int32_t
68dba_align(void)
69{
70	int32_t		 pos;
71
72	pos = dba_tell();
73	while (pos & 3) {
74		dba_char_write('\0');
75		pos++;
76	}
77	return pos;
78}
79
80int32_t
81dba_skip(int32_t nmemb, int32_t sz)
82{
83	const int32_t	 out[5] = {0, 0, 0, 0, 0};
84	int32_t		 i, pos;
85
86	assert(sz >= 0);
87	assert(nmemb > 0);
88	assert(nmemb <= 5);
89	pos = dba_tell();
90	for (i = 0; i < sz; i++)
91		if (nmemb - fwrite(&out, sizeof(out[0]), nmemb, ofp))
92			err(1, "fwrite");
93	return pos;
94}
95
96void
97dba_char_write(int c)
98{
99	if (putc(c, ofp) == EOF)
100		err(1, "fputc");
101}
102
103void
104dba_str_write(const char *str)
105{
106	if (fputs(str, ofp) == EOF)
107		err(1, "fputs");
108	dba_char_write('\0');
109}
110
111void
112dba_int_write(int32_t i)
113{
114	i = htobe32(i);
115	if (fwrite(&i, sizeof(i), 1, ofp) != 1)
116		err(1, "fwrite");
117}
118