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1/* SPDX-License-Identifier: GPL-2.0 */2#ifndef __PERF_STRBUF_H3#define __PERF_STRBUF_H4 5/*6 * Strbuf's can be use in many ways: as a byte array, or to store arbitrary7 * 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 to12 * 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 shell16 * while keeping the shell valid wrt its invariants.17 *18 * 2. the ->buf member is a byte array that has at least ->len + 1 bytes19 * allocated. The extra byte is used to store a '\0', allowing the ->buf20 * member to be a valid C-string. Every strbuf function ensure this21 * invariant is preserved.22 *23 * Note that it is OK to "play" with the buffer directly if you work it24 * that way:25 *26 * strbuf_grow(sb, SOME_SIZE);27 * ... Here, the memory array starting at sb->buf, and of length28 * ... strbuf_avail(sb) is all yours, and you are sure that29 * ... 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 the35 * 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 - 138 * even if it's true in the current implementation. Alloc is somehow a39 * "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 49extern char strbuf_slopbuf[];50struct 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 -----*/59int strbuf_init(struct strbuf *buf, ssize_t hint);60void strbuf_release(struct strbuf *buf);61char *strbuf_detach(struct strbuf *buf, size_t *);62 63/*----- strbuf size related -----*/64static inline ssize_t strbuf_avail(const struct strbuf *sb) {65 return sb->alloc ? sb->alloc - sb->len - 1 : 0;66}67 68int strbuf_grow(struct strbuf *buf, size_t);69 70static inline int strbuf_setlen(struct strbuf *sb, size_t len) {71 if (!sb->alloc) {72 int ret = strbuf_grow(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 -----*/83int strbuf_addch(struct strbuf *sb, int c);84 85int strbuf_add(struct strbuf *buf, const void *, size_t);86static inline int strbuf_addstr(struct strbuf *sb, const char *s) {87 return strbuf_add(sb, s, strlen(s));88}89 90int strbuf_addf(struct strbuf *sb, const char *fmt, ...) __printf(2, 3);91 92/* XXX: if read fails, any partial read is undone */93ssize_t strbuf_read(struct strbuf *, int fd, ssize_t hint);94 95#endif /* __PERF_STRBUF_H */96