Remove preemptive allocations.
[git/git.git] / strbuf.h
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1#ifndef STRBUF_H
2#define STRBUF_H
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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 legal to copy the ->buf pointer away. Though if you want to reuse
14 * the strbuf after that, setting ->buf to NULL isn't legal.
15 * `strbuf_detach' is the operation that detachs 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 areay starting at sb->buf, and of length
28 * // sb_avail(sb) is all yours, and you are sure that sb_avail(sb) is at
29 * // 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 sb_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
d1df5743 44struct strbuf {
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45 size_t alloc;
46 size_t len;
d1df5743 47 int eof;
bf0f910d 48 char *buf;
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49};
50
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51#define STRBUF_INIT { 0, 0, 0, NULL }
52
53/*----- strbuf life cycle -----*/
f1696ee3 54extern void strbuf_init(struct strbuf *, size_t);
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55extern void strbuf_release(struct strbuf *);
56extern void strbuf_reset(struct strbuf *);
57extern char *strbuf_detach(struct strbuf *);
917c9a71 58extern void strbuf_attach(struct strbuf *, void *, size_t, size_t);
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59
60/*----- strbuf size related -----*/
61static inline size_t strbuf_avail(struct strbuf *sb) {
62 return sb->alloc ? sb->alloc - sb->len - 1 : 0;
63}
64static inline void strbuf_setlen(struct strbuf *sb, size_t len) {
65 assert (len < sb->alloc);
66 sb->len = len;
67 sb->buf[len] = '\0';
68}
69
70extern void strbuf_grow(struct strbuf *, size_t);
71
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72/*----- content related -----*/
73extern void strbuf_rtrim(struct strbuf *);
74
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75/*----- add data in your buffer -----*/
76static inline void strbuf_addch(struct strbuf *sb, int c) {
77 strbuf_grow(sb, 1);
78 sb->buf[sb->len++] = c;
79 sb->buf[sb->len] = '\0';
80}
81
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82/* inserts after pos, or appends if pos >= sb->len */
83extern void strbuf_insert(struct strbuf *, size_t pos, const void *, size_t);
84
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85/* splice pos..pos+len with given data */
86extern void strbuf_splice(struct strbuf *, size_t pos, size_t len,
87 const void *, size_t);
88
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89extern void strbuf_add(struct strbuf *, const void *, size_t);
90static inline void strbuf_addstr(struct strbuf *sb, const char *s) {
91 strbuf_add(sb, s, strlen(s));
92}
93static inline void strbuf_addbuf(struct strbuf *sb, struct strbuf *sb2) {
94 strbuf_add(sb, sb2->buf, sb2->len);
95}
96
97__attribute__((format(printf,2,3)))
98extern void strbuf_addf(struct strbuf *sb, const char *fmt, ...);
99
100extern size_t strbuf_fread(struct strbuf *, size_t, FILE *);
101/* XXX: if read fails, any partial read is undone */
f1696ee3 102extern ssize_t strbuf_read(struct strbuf *, int fd, size_t hint);
b449f4cf 103
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104extern void read_line(struct strbuf *, FILE *, int);
105
106#endif /* STRBUF_H */