1 | /* SPDX-License-Identifier: GPL-2.0 */ |
2 | #ifndef __PERF_STRBUF_H |
3 | #define __PERF_STRBUF_H |
4 | |
5 | /* |
6 | * Strbuf's can be use in many ways: as a byte array, or to store arbitrary |
7 | * long, overflow safe strings. |
8 | * |
9 | * Strbufs has some invariants that are very important to keep in mind: |
10 | * |
11 | * 1. the ->buf member is always malloc-ed, hence strbuf's can be used to |
12 | * build complex strings/buffers whose final size isn't easily known. |
13 | * |
14 | * It is NOT legal to copy the ->buf pointer away. |
15 | * `strbuf_detach' is the operation that detaches a buffer from its shell |
16 | * while keeping the shell valid wrt its invariants. |
17 | * |
18 | * 2. the ->buf member is a byte array that has at least ->len + 1 bytes |
19 | * allocated. The extra byte is used to store a '\0', allowing the ->buf |
20 | * member to be a valid C-string. Every strbuf function ensure this |
21 | * invariant is preserved. |
22 | * |
23 | * Note that it is OK to "play" with the buffer directly if you work it |
24 | * that way: |
25 | * |
26 | * strbuf_grow(sb, SOME_SIZE); |
27 | * ... Here, the memory array starting at sb->buf, and of length |
28 | * ... strbuf_avail(sb) is all yours, and you are sure that |
29 | * ... strbuf_avail(sb) is at least SOME_SIZE. |
30 | * strbuf_setlen(sb, sb->len + SOME_OTHER_SIZE); |
31 | * |
32 | * Of course, SOME_OTHER_SIZE must be smaller or equal to strbuf_avail(sb). |
33 | * |
34 | * Doing so is safe, though if it has to be done in many places, adding the |
35 | * missing API to the strbuf module is the way to go. |
36 | * |
37 | * XXX: do _not_ assume that the area that is yours is of size ->alloc - 1 |
38 | * even if it's true in the current implementation. Alloc is somehow a |
39 | * "private" member that should not be messed with. |
40 | */ |
41 | |
42 | #include <assert.h> |
43 | #include <stdarg.h> |
44 | #include <stddef.h> |
45 | #include <string.h> |
46 | #include <linux/compiler.h> |
47 | #include <sys/types.h> |
48 | |
49 | extern char strbuf_slopbuf[]; |
50 | struct strbuf { |
51 | size_t alloc; |
52 | size_t len; |
53 | char *buf; |
54 | }; |
55 | |
56 | #define STRBUF_INIT { 0, 0, strbuf_slopbuf } |
57 | |
58 | /*----- strbuf life cycle -----*/ |
59 | int strbuf_init(struct strbuf *buf, ssize_t hint); |
60 | void strbuf_release(struct strbuf *buf); |
61 | char *strbuf_detach(struct strbuf *buf, size_t *); |
62 | |
63 | /*----- strbuf size related -----*/ |
64 | static inline ssize_t strbuf_avail(const struct strbuf *sb) { |
65 | return sb->alloc ? sb->alloc - sb->len - 1 : 0; |
66 | } |
67 | |
68 | int strbuf_grow(struct strbuf *buf, size_t); |
69 | |
70 | static inline int strbuf_setlen(struct strbuf *sb, size_t len) { |
71 | if (!sb->alloc) { |
72 | int ret = strbuf_grow(buf: sb, 0); |
73 | if (ret) |
74 | return ret; |
75 | } |
76 | assert(len < sb->alloc); |
77 | sb->len = len; |
78 | sb->buf[len] = '\0'; |
79 | return 0; |
80 | } |
81 | |
82 | /*----- add data in your buffer -----*/ |
83 | int strbuf_addch(struct strbuf *sb, int c); |
84 | |
85 | int strbuf_add(struct strbuf *buf, const void *, size_t); |
86 | static inline int strbuf_addstr(struct strbuf *sb, const char *s) { |
87 | return strbuf_add(buf: sb, s, strlen(s)); |
88 | } |
89 | |
90 | int strbuf_addf(struct strbuf *sb, const char *fmt, ...) __printf(2, 3); |
91 | |
92 | /* XXX: if read fails, any partial read is undone */ |
93 | ssize_t strbuf_read(struct strbuf *, int fd, ssize_t hint); |
94 | |
95 | #endif /* __PERF_STRBUF_H */ |
96 | |