LXR linux/tools/perf/util/strbuf.h

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