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 
strbuf_init(struct strbuf * sb,ssize_t hint)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 
strbuf_release(struct strbuf * sb)29 void strbuf_release(struct strbuf *sb)
30 {
31 	if (sb->alloc) {
32 		zfree(&sb->buf);
33 		strbuf_init(sb, 0);
34 	}
35 }
36 
strbuf_detach(struct strbuf * sb,size_t * sz)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 
strbuf_grow(struct strbuf * sb,size_t extra)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 
strbuf_addch(struct strbuf * sb,int c)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 
strbuf_add(struct strbuf * sb,const void * data,size_t len)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 
strbuf_addv(struct strbuf * sb,const char * fmt,va_list ap)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 
strbuf_addf(struct strbuf * sb,const char * fmt,...)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 
strbuf_read(struct strbuf * sb,int fd,ssize_t hint)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