[lttng-dev] [lttng-tools] Fix: channel name with '.' and '/' brings problems

[Philippe Proulx]

This patch ensures:

  1. A channel name does not contain any '/' character, since
     relative paths may be injected in the channel name
     otherwise (knowing that the channel name is eventually
     part of a file name)
  2. A channel name does not start with a '.' character, since
     trace readers (Babeltrace is one of them) could interpret
     files starting with a dot as hidden files and ignore
     them when opening the CTF trace

Fixes: #751

Signed-off-by: Philippe Proulx <eeppeliteloop at gmail.com>
---
 src/bin/lttng/commands/enable_channels.c | 38 +++++++++++++++++++++++++++-----
 1 file changed, 33 insertions(+), 5 deletions(-)

diff --git a/src/bin/lttng/commands/enable_channels.c b/src/bin/lttng/commands/enable_channels.c
index f8272e9..e6cce49 100644
--- a/src/bin/lttng/commands/enable_channels.c
+++ b/src/bin/lttng/commands/enable_channels.c
@@ -275,11 +275,39 @@ static int enable_channel(char *session_name)
 	/* Strip channel list (format: chan1,chan2,...) */
 	channel_name = strtok(opt_channels, ",");
 	while (channel_name != NULL) {
-		/* Copy channel name and normalize it */
+		/* Copy channel name, sanitize and normalize it */
 		strncpy(chan.name, channel_name, NAME_MAX);
 		chan.name[NAME_MAX - 1] = '\0';
 
-		DBG("Enabling channel %s", channel_name);
+		char *src, *dst;
+		int got_first = 0;
+
+		for (src = dst = chan.name; *src != '\0'; ++src) {
+			*dst = *src;
+
+			/*
+			 * Channel name could be used in file names, so remove
+			 * invalid '/'
+			 */
+			if (*dst != '/') {
+				/*
+				 * Remove starting dots since this could create
+				 * file names starting with dots, and trace
+				 * readers could interpret them as hidden files
+				 * and ignore them.
+				 */
+				if (*dst != '.') {
+					got_first = 1;
+					dst++;
+				} else if (got_first) {
+					dst++;
+				}
+			}
+		}
+
+		*dst = '\0';
+
+		DBG("Enabling channel %s", chan.name);
 
 		ret = lttng_enable_channel(handle, &chan);
 		if (ret < 0) {
@@ -288,19 +316,19 @@ static int enable_channel(char *session_name)
 			case LTTNG_ERR_KERN_CHAN_EXIST:
 			case LTTNG_ERR_UST_CHAN_EXIST:
 			case LTTNG_ERR_CHAN_EXIST:
-				WARN("Channel %s: %s (session %s)", channel_name,
+				WARN("Channel %s: %s (session %s)", chan.name,
 						lttng_strerror(ret), session_name);
 				warn = 1;
 				break;
 			default:
-				ERR("Channel %s: %s (session %s)", channel_name,
+				ERR("Channel %s: %s (session %s)", chan.name,
 						lttng_strerror(ret), session_name);
 				error = 1;
 				break;
 			}
 		} else {
 			MSG("%s channel %s enabled for session %s",
-					get_domain_str(dom.type), channel_name, session_name);
+					get_domain_str(dom.type), chan.name, session_name);
 			success = 1;
 		}
 
-- 
2.1.3