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