trace-cmd record: Add --name option to name unnamed guests

Commit Message

Steven Rostedt March 14, 2022, 9:19 p.m. UTC

From: "Steven Rostedt (Google)" <[e-mail]>

When using the vsocket port number to connect to a guest agent (-A @3:823)
the file that is created is called "unknown". This is not very
informative, and if you have more than one guest, it can cause confusion.

Add a "--name" option that allows the user to name the guest that it
connects with. The --name option takes one parameter (the name to call the
guest), and must be after a -A option.

Signed-off-by: Steven Rostedt (Google) <[e-mail]>
---
 .../trace-cmd/trace-cmd-record.1.txt          |  5 +++++
 tracecmd/trace-record.c                       | 22 +++++++++++++++++--
 tracecmd/trace-usage.c                        |  1 +
 3 files changed, 26 insertions(+), 2 deletions(-)

Patch

diff --git a/Documentation/trace-cmd/trace-cmd-record.1.txt b/Documentation/trace-cmd/trace-cmd-record.1.txt
index b36204741578..426e856bf74a 100644
--- a/Documentation/trace-cmd/trace-cmd-record.1.txt
+++ b/Documentation/trace-cmd/trace-cmd-record.1.txt
@@ -367,6 +367,11 @@  OPTIONS
     Traces are extracted by busy waiting, which will hog the CPUs, so only use
     when really needed.
 
+*--name*::
+    Give a specific name for the current agent being processed. Used after *-A* to
+    give the guest being traced a name. Useful when using the vsocket ID instead of
+    a name of the guest.
+
 *--verbose*[='level']::
      Set the log level. Supported log levels are "none", "critical", "error", "warning",
      "info", "debug", "all" or their identifiers "0", "1", "2", "3", "4", "5", "6". Setting the log
diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index 8d9cbac23088..c3e52a48fa07 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -5805,6 +5805,7 @@  enum {
 	OPT_nofifos		= 257,
 	OPT_cmdlines_size	= 258,
 	OPT_poll		= 259,
+	OPT_name		= 260,
 };
 
 void trace_stop(int argc, char **argv)
@@ -6222,6 +6223,7 @@  static void parse_record_options(int argc,
 			{"fork", no_argument, NULL, OPT_fork},
 			{"tsc2nsec", no_argument, NULL, OPT_tsc2nsec},
 			{"poll", no_argument, NULL, OPT_poll},
+			{"name", required_argument, NULL, OPT_name},
 			{"verbose", optional_argument, NULL, OPT_verbose},
 			{"compression", required_argument, NULL, OPT_compression},
 			{"file-version", required_argument, NULL, OPT_file_ver},
@@ -6240,7 +6242,7 @@  static void parse_record_options(int argc,
 		 * If the current instance is to record a guest, then save
 		 * all the arguments for this instance.
 		 */
-		if (c != 'B' && c != 'A' && is_guest(ctx->instance)) {
+		if (c != 'B' && c != 'A' && c != OPT_name && is_guest(ctx->instance)) {
 			add_arg(ctx->instance, c, opts, long_options, optarg);
 			if (c == 'C')
 				ctx->instance->flags |= BUFFER_FL_HAS_CLOCK;
@@ -6301,6 +6303,17 @@  static void parse_record_options(int argc,
 			add_trigger(event, optarg);
 			break;
 
+		case OPT_name:
+			if (!ctx->instance)
+				die("No instance defined for name option\n");
+			if (!is_guest(ctx->instance))
+				die("  --name is only used for -A options\n");
+			free(ctx->instance->name);
+			ctx->instance->name = strdup(optarg);
+			if (!ctx->instance->name)
+				die("Failed to allocate name");
+			break;
+
 		case 'A': {
 			char *name = NULL;
 			int cid = -1, port = -1;
@@ -6316,8 +6329,13 @@  static void parse_record_options(int argc,
 			if (!name || !*name) {
 				ret = asprintf(&name, "unnamed-%d", name_counter++);
 				if (ret < 0)
-					die("Failed to allocate guest name");
+					name = NULL;
+			} else {
+				/* Needs to be allocate */
+				name = strdup(name);
 			}
+			if (!name)
+				die("Failed to allocate guest name");
 
 			ctx->instance = allocate_instance(name);
 			ctx->instance->flags |= BUFFER_FL_GUEST;
diff --git a/tracecmd/trace-usage.c b/tracecmd/trace-usage.c
index ea7d510d1060..3eb32eba6185 100644
--- a/tracecmd/trace-usage.c
+++ b/tracecmd/trace-usage.c
@@ -69,6 +69,7 @@  static struct usage_help usage_help[] = {
 		"               If 0 is specified, no loop is performed - timestamps offset is calculated only twice,"
 		"                                                         at the beginnig and at the end of the trace\n"
 		"          --poll don't block while reading from the trace buffer\n"
+		"          --name used with -A to give the agent a specific name\n"
 		"          --file-version set the desired trace file version\n"
 		"          --compression compress the trace output file, one of these strings can be passed:\n"
 		"                            any  - auto select the best available compression algorithm\n"