Linux Kernel  3.7.1
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
strbuf.h
Go to the documentation of this file.
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 -----*/
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 
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 -----*/
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);
82 static inline void strbuf_addstr(struct strbuf *sb, const char *s) {
83  strbuf_add(sb, s, strlen(s));
84 }
85 
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 */