95 lines
2.9 KiB
C
95 lines
2.9 KiB
C
#ifndef __PERF_STRBUF_H
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#define __PERF_STRBUF_H
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/*
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* Strbuf's can be use in many ways: as a byte array, or to store arbitrary
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* long, overflow safe strings.
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*
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* Strbufs has some invariants that are very important to keep in mind:
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*
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* 1. the ->buf member is always malloc-ed, hence strbuf's can be used to
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* build complex strings/buffers whose final size isn't easily known.
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*
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* It is NOT legal to copy the ->buf pointer away.
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* `strbuf_detach' is the operation that detachs a buffer from its shell
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* while keeping the shell valid wrt its invariants.
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*
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* 2. the ->buf member is a byte array that has at least ->len + 1 bytes
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* allocated. The extra byte is used to store a '\0', allowing the ->buf
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* member to be a valid C-string. Every strbuf function ensure this
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* invariant is preserved.
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*
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* Note that it is OK to "play" with the buffer directly if you work it
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* that way:
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*
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* strbuf_grow(sb, SOME_SIZE);
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* ... Here, the memory array starting at sb->buf, and of length
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* ... strbuf_avail(sb) is all yours, and you are sure that
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* ... strbuf_avail(sb) is at least SOME_SIZE.
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* strbuf_setlen(sb, sb->len + SOME_OTHER_SIZE);
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*
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* Of course, SOME_OTHER_SIZE must be smaller or equal to strbuf_avail(sb).
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*
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* Doing so is safe, though if it has to be done in many places, adding the
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* missing API to the strbuf module is the way to go.
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*
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* XXX: do _not_ assume that the area that is yours is of size ->alloc - 1
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* even if it's true in the current implementation. Alloc is somehow a
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* "private" member that should not be messed with.
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*/
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#include <assert.h>
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#include <stdarg.h>
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#include <stddef.h>
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#include <string.h>
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#include <linux/compiler.h>
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#include <sys/types.h>
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extern char strbuf_slopbuf[];
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struct strbuf {
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size_t alloc;
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size_t len;
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char *buf;
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};
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#define STRBUF_INIT { 0, 0, strbuf_slopbuf }
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/*----- strbuf life cycle -----*/
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int strbuf_init(struct strbuf *buf, ssize_t hint);
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void strbuf_release(struct strbuf *buf);
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char *strbuf_detach(struct strbuf *buf, size_t *);
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/*----- strbuf size related -----*/
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static inline ssize_t strbuf_avail(const struct strbuf *sb) {
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return sb->alloc ? sb->alloc - sb->len - 1 : 0;
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}
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int strbuf_grow(struct strbuf *buf, size_t);
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static inline int strbuf_setlen(struct strbuf *sb, size_t len) {
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if (!sb->alloc) {
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int ret = strbuf_grow(sb, 0);
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if (ret)
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return ret;
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}
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assert(len < sb->alloc);
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sb->len = len;
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sb->buf[len] = '\0';
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return 0;
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}
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/*----- add data in your buffer -----*/
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int strbuf_addch(struct strbuf *sb, int c);
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int strbuf_add(struct strbuf *buf, const void *, size_t);
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static inline int strbuf_addstr(struct strbuf *sb, const char *s) {
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return strbuf_add(sb, s, strlen(s));
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}
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int strbuf_addf(struct strbuf *sb, const char *fmt, ...) __printf(2, 3);
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/* XXX: if read fails, any partial read is undone */
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ssize_t strbuf_read(struct strbuf *, int fd, ssize_t hint);
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#endif /* __PERF_STRBUF_H */
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