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
  43extern char strbuf_slopbuf[];
  44struct strbuf {
  45        size_t alloc;
  46        size_t len;
  47        char *buf;
  48};
  49
  50#define STRBUF_INIT  { 0, 0, strbuf_slopbuf }
  51
  52/*----- strbuf life cycle -----*/
  53extern void strbuf_init(struct strbuf *buf, ssize_t hint);
  54extern void strbuf_release(struct strbuf *);
  55extern char *strbuf_detach(struct strbuf *, size_t *);
  56
  57/*----- strbuf size related -----*/
  58static inline ssize_t strbuf_avail(const struct strbuf *sb) {
  59        return sb->alloc ? sb->alloc - sb->len - 1 : 0;
  60}
  61
  62extern void strbuf_grow(struct strbuf *, size_t);
  63
  64static inline void strbuf_setlen(struct strbuf *sb, size_t len) {
  65        if (!sb->alloc)
  66                strbuf_grow(sb, 0);
  67        assert(len < sb->alloc);
  68        sb->len = len;
  69        sb->buf[len] = '\0';
  70}
  71
  72/*----- add data in your buffer -----*/
  73static inline void strbuf_addch(struct strbuf *sb, int c) {
  74        strbuf_grow(sb, 1);
  75        sb->buf[sb->len++] = c;
  76        sb->buf[sb->len] = '\0';
  77}
  78
  79extern void strbuf_remove(struct strbuf *, size_t pos, size_t len);
  80
  81extern void strbuf_add(struct strbuf *, const void *, size_t);
  82static inline void strbuf_addstr(struct strbuf *sb, const char *s) {
  83        strbuf_add(sb, s, strlen(s));
  84}
  85
  86__attribute__((format(printf,2,3)))
  87extern void strbuf_addf(struct strbuf *sb, const char *fmt, ...);
  88
  89/* XXX: if read fails, any partial read is undone */
  90extern ssize_t strbuf_read(struct strbuf *, int fd, ssize_t hint);
  91
  92#endif /* __PERF_STRBUF_H */
  93