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 */
18 char strbuf_slopbuf[1];
19
20 int 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
29 void strbuf_release(struct strbuf *sb)
30 {
31 if (sb->alloc) {
32 zfree(&sb->buf);
33 strbuf_init(sb, 0);
34 }
35 }
36
37 char *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
46 int 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
73 int 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
84 int 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
94 static 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
128 int 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
139 ssize_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
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