From: Francis Deslauriers <francis.deslauriers@efficios.com>
Date: Fri, 17 Jan 2020 17:45:51 +0000 (-0500)
Subject: Fix: lttng: placing probe on symbol starting with `_`
X-Git-Tag: v2.10.10~3
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=aeb5443d0a475ef70fdaf3ceaa8f764f734453cd;p=lttng-tools.git

Fix: lttng: placing probe on symbol starting with `_`

Issue
=====
The lttng CLI tool does not parse `--probe` symbol name properly if the
name has an underscore at the beginning.
For example, the following command fails
  lttng enable-event -k --probe _do_fork my_do_fork_event

This happens because the `parse_probe_opts()` function looks if the
first character of the symbol field is an alphabetic character to
determine if a symbol was provided. The problem is that some kernel
symbols such as `_do_fork` start with an underscore.

Solution
========
check if the first character is an alphabetic character OR an
underscore.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Change-Id: I3ee6c26641ceee508ee78e895d372c6b09fe90fb
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---

diff --git a/src/bin/lttng/commands/enable_events.c b/src/bin/lttng/commands/enable_events.c
index 05f20f72d..959b38bc2 100644
--- a/src/bin/lttng/commands/enable_events.c
+++ b/src/bin/lttng/commands/enable_events.c
@@ -137,7 +137,7 @@ static int parse_probe_opts(struct lttng_event *ev, char *opt)
 	}
 
 	/* Check for symbol */
-	if (isalpha(name[0])) {
+	if (isalpha(name[0]) || name[0] == '_') {
 		match = sscanf(opt, "%" LTTNG_SYMBOL_NAME_LEN_SCANF_IS_A_BROKEN_API "s",
 			name);
 		if (match == 1) {