1// SPDX-License-Identifier: GPL-2.0
2#include "cache.h"
3#include "debug.h"
4#include "strbuf.h"
5#include <linux/kernel.h>
6#include <linux/string.h>
7#include <linux/zalloc.h>
8#include <errno.h>
9#include <stdio.h>
10#include <stdlib.h>
11#include <unistd.h>
12
13/*
14 * Used as the default ->buf value, so that people can always assume
15 * buf is non NULL and ->buf is NUL terminated even for a freshly
16 * initialized strbuf.
17 */
18char strbuf_slopbuf[1];
19
20int strbuf_init(struct strbuf *sb, ssize_t hint)
21{
22	sb->alloc = sb->len = 0;
23	sb->buf = strbuf_slopbuf;
24	if (hint)
25		return strbuf_grow(sb, hint);
26	return 0;
27}
28
29void strbuf_release(struct strbuf *sb)
30{
31	if (sb->alloc) {
32		zfree(&sb->buf);
33		strbuf_init(sb, 0);
34	}
35}
36
37char *strbuf_detach(struct strbuf *sb, size_t *sz)
38{
39	char *res = sb->alloc ? sb->buf : NULL;
40	if (sz)
41		*sz = sb->len;
42	strbuf_init(sb, 0);
43	return res;
44}
45
46int strbuf_grow(struct strbuf *sb, size_t extra)
47{
48	char *buf;
49	size_t nr = sb->len + extra + 1;
50
51	if (nr < sb->alloc)
52		return 0;
53
54	if (nr <= sb->len)
55		return -E2BIG;
56
57	if (alloc_nr(sb->alloc) > nr)
58		nr = alloc_nr(sb->alloc);
59
60	/*
61	 * Note that sb->buf == strbuf_slopbuf if sb->alloc == 0, and it is
62	 * a static variable. Thus we have to avoid passing it to realloc.
63	 */
64	buf = realloc(sb->alloc ? sb->buf : NULL, nr * sizeof(*buf));
65	if (!buf)
66		return -ENOMEM;
67
68	sb->buf = buf;
69	sb->alloc = nr;
70	return 0;
71}
72
73int strbuf_addch(struct strbuf *sb, int c)
74{
75	int ret = strbuf_grow(sb, 1);
76	if (ret)
77		return ret;
78
79	sb->buf[sb->len++] = c;
80	sb->buf[sb->len] = '\0';
81	return 0;
82}
83
84int strbuf_add(struct strbuf *sb, const void *data, size_t len)
85{
86	int ret = strbuf_grow(sb, len);
87	if (ret)
88		return ret;
89
90	memcpy(sb->buf + sb->len, data, len);
91	return strbuf_setlen(sb, sb->len + len);
92}
93
94static int strbuf_addv(struct strbuf *sb, const char *fmt, va_list ap)
95{
96	int len, ret;
97	va_list ap_saved;
98
99	if (!strbuf_avail(sb)) {
100		ret = strbuf_grow(sb, 64);
101		if (ret)
102			return ret;
103	}
104
105	va_copy(ap_saved, ap);
106	len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap);
107	if (len < 0) {
108		va_end(ap_saved);
109		return len;
110	}
111	if (len > strbuf_avail(sb)) {
112		ret = strbuf_grow(sb, len);
113		if (ret) {
114			va_end(ap_saved);
115			return ret;
116		}
117		len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap_saved);
118		if (len > strbuf_avail(sb)) {
119			pr_debug("this should not happen, your vsnprintf is broken");
120			va_end(ap_saved);
121			return -EINVAL;
122		}
123	}
124	va_end(ap_saved);
125	return strbuf_setlen(sb, sb->len + len);
126}
127
128int strbuf_addf(struct strbuf *sb, const char *fmt, ...)
129{
130	va_list ap;
131	int ret;
132
133	va_start(ap, fmt);
134	ret = strbuf_addv(sb, fmt, ap);
135	va_end(ap);
136	return ret;
137}
138
139ssize_t strbuf_read(struct strbuf *sb, int fd, ssize_t hint)
140{
141	size_t oldlen = sb->len;
142	size_t oldalloc = sb->alloc;
143	int ret;
144
145	ret = strbuf_grow(sb, hint ? hint : 8192);
146	if (ret)
147		return ret;
148
149	for (;;) {
150		ssize_t cnt;
151
152		cnt = read(fd, sb->buf + sb->len, sb->alloc - sb->len - 1);
153		if (cnt < 0) {
154			if (oldalloc == 0)
155				strbuf_release(sb);
156			else
157				strbuf_setlen(sb, oldlen);
158			return cnt;
159		}
160		if (!cnt)
161			break;
162		sb->len += cnt;
163		ret = strbuf_grow(sb, 8192);
164		if (ret)
165			return ret;
166	}
167
168	sb->buf[sb->len] = '\0';
169	return sb->len - oldlen;
170}
171