1 #ifndef __PERF_STRBUF_H
2 #define __PERF_STRBUF_H
3
4 /*
5 * Strbuf's can be use in many ways: as a byte array, or to store arbitrary
6 * long, overflow safe strings.
7 *
8 * Strbufs has some invariants that are very important to keep in mind:
9 *
10 * 1. the ->buf member is always malloc-ed, hence strbuf's can be used to
11 * build complex strings/buffers whose final size isn't easily known.
12 *
13 * It is NOT legal to copy the ->buf pointer away.
14 * `strbuf_detach' is the operation that detachs a buffer from its shell
15 * while keeping the shell valid wrt its invariants.
16 *
17 * 2. the ->buf member is a byte array that has at least ->len + 1 bytes
18 * allocated. The extra byte is used to store a '\0', allowing the ->buf
19 * member to be a valid C-string. Every strbuf function ensure this
20 * invariant is preserved.
21 *
22 * Note that it is OK to "play" with the buffer directly if you work it
23 * that way:
24 *
25 * strbuf_grow(sb, SOME_SIZE);
26 * ... Here, the memory array starting at sb->buf, and of length
27 * ... strbuf_avail(sb) is all yours, and you are sure that
28 * ... strbuf_avail(sb) is at least SOME_SIZE.
29 * strbuf_setlen(sb, sb->len + SOME_OTHER_SIZE);
30 *
31 * Of course, SOME_OTHER_SIZE must be smaller or equal to strbuf_avail(sb).
32 *
33 * Doing so is safe, though if it has to be done in many places, adding the
34 * missing API to the strbuf module is the way to go.
35 *
36 * XXX: do _not_ assume that the area that is yours is of size ->alloc - 1
37 * even if it's true in the current implementation. Alloc is somehow a
38 * "private" member that should not be messed with.
39 */
40
41 #include <assert.h>
42
43 extern char strbuf_slopbuf[];
44 struct strbuf {
45 size_t alloc;
46 size_t len;
47 char *buf;
48 };
49
50 #define STRBUF_INIT { 0, 0, strbuf_slopbuf }
51
52 /*----- strbuf life cycle -----*/
53 extern void strbuf_init(struct strbuf *buf, ssize_t hint);
54 extern void strbuf_release(struct strbuf *);
55 extern char *strbuf_detach(struct strbuf *, size_t *);
56
57 /*----- strbuf size related -----*/
strbuf_avail(const struct strbuf * sb)58 static inline ssize_t strbuf_avail(const struct strbuf *sb) {
59 return sb->alloc ? sb->alloc - sb->len - 1 : 0;
60 }
61
62 extern void strbuf_grow(struct strbuf *, size_t);
63
strbuf_setlen(struct strbuf * sb,size_t len)64 static inline void strbuf_setlen(struct strbuf *sb, size_t len) {
65 if (!sb->alloc)
66 strbuf_grow(sb, 0);
67 assert(len < sb->alloc);
68 sb->len = len;
69 sb->buf[len] = '\0';
70 }
71
72 /*----- add data in your buffer -----*/
strbuf_addch(struct strbuf * sb,int c)73 static inline void strbuf_addch(struct strbuf *sb, int c) {
74 strbuf_grow(sb, 1);
75 sb->buf[sb->len++] = c;
76 sb->buf[sb->len] = '\0';
77 }
78
79 extern void strbuf_remove(struct strbuf *, size_t pos, size_t len);
80
81 extern void strbuf_add(struct strbuf *, const void *, size_t);
strbuf_addstr(struct strbuf * sb,const char * s)82 static inline void strbuf_addstr(struct strbuf *sb, const char *s) {
83 strbuf_add(sb, s, strlen(s));
84 }
85
86 __attribute__((format(printf,2,3)))
87 extern void strbuf_addf(struct strbuf *sb, const char *fmt, ...);
88
89 /* XXX: if read fails, any partial read is undone */
90 extern ssize_t strbuf_read(struct strbuf *, int fd, ssize_t hint);
91
92 #endif /* __PERF_STRBUF_H */
93