cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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strbuf.h (3021B)

      1/* SPDX-License-Identifier: GPL-2.0 */
      2#ifndef __PERF_STRBUF_H
      3#define __PERF_STRBUF_H
      4
      5/*
      6 * Strbuf's can be use in many ways: as a byte array, or to store arbitrary
      7 * 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 to
     12 *    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 shell
     16 *    while keeping the shell valid wrt its invariants.
     17 *
     18 * 2. the ->buf member is a byte array that has at least ->len + 1 bytes
     19 *    allocated. The extra byte is used to store a '\0', allowing the ->buf
     20 *    member to be a valid C-string. Every strbuf function ensure this
     21 *    invariant is preserved.
     22 *
     23 *    Note that it is OK to "play" with the buffer directly if you work it
     24 *    that way:
     25 *
     26 *    strbuf_grow(sb, SOME_SIZE);
     27 *       ... Here, the memory array starting at sb->buf, and of length
     28 *       ... strbuf_avail(sb) is all yours, and you are sure that
     29 *       ... 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 the
     35 *    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 - 1
     38 *         even if it's true in the current implementation. Alloc is somehow a
     39 *         "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 */