v4.19.13 snapshot.
diff --git a/tools/perf/util/strbuf.c b/tools/perf/util/strbuf.c
new file mode 100644
index 0000000..9005fbe
--- /dev/null
+++ b/tools/perf/util/strbuf.c
@@ -0,0 +1,165 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "debug.h"
+#include "util.h"
+#include <linux/kernel.h>
+#include <errno.h>
+
+/*
+ * Used as the default ->buf value, so that people can always assume
+ * buf is non NULL and ->buf is NUL terminated even for a freshly
+ * initialized strbuf.
+ */
+char strbuf_slopbuf[1];
+
+int strbuf_init(struct strbuf *sb, ssize_t hint)
+{
+ sb->alloc = sb->len = 0;
+ sb->buf = strbuf_slopbuf;
+ if (hint)
+ return strbuf_grow(sb, hint);
+ return 0;
+}
+
+void strbuf_release(struct strbuf *sb)
+{
+ if (sb->alloc) {
+ zfree(&sb->buf);
+ strbuf_init(sb, 0);
+ }
+}
+
+char *strbuf_detach(struct strbuf *sb, size_t *sz)
+{
+ char *res = sb->alloc ? sb->buf : NULL;
+ if (sz)
+ *sz = sb->len;
+ strbuf_init(sb, 0);
+ return res;
+}
+
+int strbuf_grow(struct strbuf *sb, size_t extra)
+{
+ char *buf;
+ size_t nr = sb->len + extra + 1;
+
+ if (nr < sb->alloc)
+ return 0;
+
+ if (nr <= sb->len)
+ return -E2BIG;
+
+ if (alloc_nr(sb->alloc) > nr)
+ nr = alloc_nr(sb->alloc);
+
+ /*
+ * Note that sb->buf == strbuf_slopbuf if sb->alloc == 0, and it is
+ * a static variable. Thus we have to avoid passing it to realloc.
+ */
+ buf = realloc(sb->alloc ? sb->buf : NULL, nr * sizeof(*buf));
+ if (!buf)
+ return -ENOMEM;
+
+ sb->buf = buf;
+ sb->alloc = nr;
+ return 0;
+}
+
+int strbuf_addch(struct strbuf *sb, int c)
+{
+ int ret = strbuf_grow(sb, 1);
+ if (ret)
+ return ret;
+
+ sb->buf[sb->len++] = c;
+ sb->buf[sb->len] = '\0';
+ return 0;
+}
+
+int strbuf_add(struct strbuf *sb, const void *data, size_t len)
+{
+ int ret = strbuf_grow(sb, len);
+ if (ret)
+ return ret;
+
+ memcpy(sb->buf + sb->len, data, len);
+ return strbuf_setlen(sb, sb->len + len);
+}
+
+static int strbuf_addv(struct strbuf *sb, const char *fmt, va_list ap)
+{
+ int len, ret;
+ va_list ap_saved;
+
+ if (!strbuf_avail(sb)) {
+ ret = strbuf_grow(sb, 64);
+ if (ret)
+ return ret;
+ }
+
+ va_copy(ap_saved, ap);
+ len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap);
+ if (len < 0) {
+ va_end(ap_saved);
+ return len;
+ }
+ if (len > strbuf_avail(sb)) {
+ ret = strbuf_grow(sb, len);
+ if (ret) {
+ va_end(ap_saved);
+ return ret;
+ }
+ len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap_saved);
+ va_end(ap_saved);
+ if (len > strbuf_avail(sb)) {
+ pr_debug("this should not happen, your vsnprintf is broken");
+ va_end(ap_saved);
+ return -EINVAL;
+ }
+ }
+ va_end(ap_saved);
+ return strbuf_setlen(sb, sb->len + len);
+}
+
+int strbuf_addf(struct strbuf *sb, const char *fmt, ...)
+{
+ va_list ap;
+ int ret;
+
+ va_start(ap, fmt);
+ ret = strbuf_addv(sb, fmt, ap);
+ va_end(ap);
+ return ret;
+}
+
+ssize_t strbuf_read(struct strbuf *sb, int fd, ssize_t hint)
+{
+ size_t oldlen = sb->len;
+ size_t oldalloc = sb->alloc;
+ int ret;
+
+ ret = strbuf_grow(sb, hint ? hint : 8192);
+ if (ret)
+ return ret;
+
+ for (;;) {
+ ssize_t cnt;
+
+ cnt = read(fd, sb->buf + sb->len, sb->alloc - sb->len - 1);
+ if (cnt < 0) {
+ if (oldalloc == 0)
+ strbuf_release(sb);
+ else
+ strbuf_setlen(sb, oldlen);
+ return cnt;
+ }
+ if (!cnt)
+ break;
+ sb->len += cnt;
+ ret = strbuf_grow(sb, 8192);
+ if (ret)
+ return ret;
+ }
+
+ sb->buf[sb->len] = '\0';
+ return sb->len - oldlen;
+}