summaryrefslogtreecommitdiffstats
path: root/tools/perf/util/strbuf.h
diff options
context:
space:
mode:
Diffstat (limited to 'tools/perf/util/strbuf.h')
-rw-r--r--tools/perf/util/strbuf.h95
1 files changed, 95 insertions, 0 deletions
diff --git a/tools/perf/util/strbuf.h b/tools/perf/util/strbuf.h
new file mode 100644
index 000000000..ea94d8628
--- /dev/null
+++ b/tools/perf/util/strbuf.h
@@ -0,0 +1,95 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __PERF_STRBUF_H
+#define __PERF_STRBUF_H
+
+/*
+ * Strbuf's can be use in many ways: as a byte array, or to store arbitrary
+ * long, overflow safe strings.
+ *
+ * Strbufs has some invariants that are very important to keep in mind:
+ *
+ * 1. the ->buf member is always malloc-ed, hence strbuf's can be used to
+ * build complex strings/buffers whose final size isn't easily known.
+ *
+ * It is NOT legal to copy the ->buf pointer away.
+ * `strbuf_detach' is the operation that detachs a buffer from its shell
+ * while keeping the shell valid wrt its invariants.
+ *
+ * 2. the ->buf member is a byte array that has at least ->len + 1 bytes
+ * allocated. The extra byte is used to store a '\0', allowing the ->buf
+ * member to be a valid C-string. Every strbuf function ensure this
+ * invariant is preserved.
+ *
+ * Note that it is OK to "play" with the buffer directly if you work it
+ * that way:
+ *
+ * strbuf_grow(sb, SOME_SIZE);
+ * ... Here, the memory array starting at sb->buf, and of length
+ * ... strbuf_avail(sb) is all yours, and you are sure that
+ * ... strbuf_avail(sb) is at least SOME_SIZE.
+ * strbuf_setlen(sb, sb->len + SOME_OTHER_SIZE);
+ *
+ * Of course, SOME_OTHER_SIZE must be smaller or equal to strbuf_avail(sb).
+ *
+ * Doing so is safe, though if it has to be done in many places, adding the
+ * missing API to the strbuf module is the way to go.
+ *
+ * XXX: do _not_ assume that the area that is yours is of size ->alloc - 1
+ * even if it's true in the current implementation. Alloc is somehow a
+ * "private" member that should not be messed with.
+ */
+
+#include <assert.h>
+#include <stdarg.h>
+#include <stddef.h>
+#include <string.h>
+#include <linux/compiler.h>
+#include <sys/types.h>
+
+extern char strbuf_slopbuf[];
+struct strbuf {
+ size_t alloc;
+ size_t len;
+ char *buf;
+};
+
+#define STRBUF_INIT { 0, 0, strbuf_slopbuf }
+
+/*----- strbuf life cycle -----*/
+int strbuf_init(struct strbuf *buf, ssize_t hint);
+void strbuf_release(struct strbuf *buf);
+char *strbuf_detach(struct strbuf *buf, size_t *);
+
+/*----- strbuf size related -----*/
+static inline ssize_t strbuf_avail(const struct strbuf *sb) {
+ return sb->alloc ? sb->alloc - sb->len - 1 : 0;
+}
+
+int strbuf_grow(struct strbuf *buf, size_t);
+
+static inline int strbuf_setlen(struct strbuf *sb, size_t len) {
+ if (!sb->alloc) {
+ int ret = strbuf_grow(sb, 0);
+ if (ret)
+ return ret;
+ }
+ assert(len < sb->alloc);
+ sb->len = len;
+ sb->buf[len] = '\0';
+ return 0;
+}
+
+/*----- add data in your buffer -----*/
+int strbuf_addch(struct strbuf *sb, int c);
+
+int strbuf_add(struct strbuf *buf, const void *, size_t);
+static inline int strbuf_addstr(struct strbuf *sb, const char *s) {
+ return strbuf_add(sb, s, strlen(s));
+}
+
+int strbuf_addf(struct strbuf *sb, const char *fmt, ...) __printf(2, 3);
+
+/* XXX: if read fails, any partial read is undone */
+ssize_t strbuf_read(struct strbuf *, int fd, ssize_t hint);
+
+#endif /* __PERF_STRBUF_H */