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