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
43extern char strbuf_slopbuf[];
44struct 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 -----*/
53extern void strbuf_init(struct strbuf *buf, ssize_t hint);
54extern void strbuf_release(struct strbuf *);
55extern char *strbuf_detach(struct strbuf *, size_t *);
56
57/*----- strbuf size related -----*/
58static inline ssize_t strbuf_avail(const struct strbuf *sb) {
59	return sb->alloc ? sb->alloc - sb->len - 1 : 0;
60}
61
62extern void strbuf_grow(struct strbuf *, size_t);
63
64static 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 -----*/
73static 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
79extern void strbuf_remove(struct strbuf *, size_t pos, size_t len);
80
81extern void strbuf_add(struct strbuf *, const void *, size_t);
82static 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)))
87extern void strbuf_addf(struct strbuf *sb, const char *fmt, ...);
88
89/* XXX: if read fails, any partial read is undone */
90extern ssize_t strbuf_read(struct strbuf *, int fd, ssize_t hint);
91
92#endif /* __PERF_STRBUF_H */
93