[PATCH v3 2/5] trace-cmd extract: Add -a option for all instances

[Howard Cochran <hcochran@kernelspring.com>]

This option will extract all instances that currently exist in the
system, including the top instance. This differs from the meaning of -a
for record and stream (enable all events), which would have no purpose
for extract. Such difference in meaning already exists for -s, so this
seemed reasonable.

Had to fix a bug in create_instance(), in which it ignored its parameter.

Signed-off-by: Howard Cochran <hcochran@kernelspring.com>
---
 Documentation/trace-cmd-extract.1.txt | 16 +++++++
 trace-local.h                         |  2 +-
 trace-record.c                        | 81 +++++++++++++++++++++++++++++++++--
 trace-usage.c                         |  5 ++-
 4 files changed, 98 insertions(+), 6 deletions(-)

diff --git a/Documentation/trace-cmd-extract.1.txt b/Documentation/trace-cmd-extract.1.txt
index ea98c20..73eda4e 100644
--- a/Documentation/trace-cmd-extract.1.txt
+++ b/Documentation/trace-cmd-extract.1.txt
@@ -52,6 +52,22 @@ OPTIONS
     does cause the extract routine to disable all tracing. That is,
     the end of the extract will perform something similar to trace-cmd-reset(1).
 
+*-B* 'buffer-name'::
+    If the kernel supports multiple buffers, this will extract the trace for
+    only the given buffer. It does not affect any other buffer. This may be
+    used multiple times to specify different buffers. When this option is
+    used, the top level instance will not be extracted unless *-t* is given.
+
+*-a*::
+    Extract all existing buffer instances. When this option is used, the
+    top level instance will not be extracted unless *-t* is given.
+
+*-t*::
+    Extracts the top level instance buffer. Without the *-B* or *-a* option
+    this is the same as the default. But if *-B* or *-a* is used, this is
+    required if the top level instance buffer should also be extracted.
+
+
 SEE ALSO
 --------
 trace-cmd(1), trace-cmd-record(1), trace-cmd-report(1), trace-cmd-start(1),
diff --git a/trace-local.h b/trace-local.h
index ab2bd34..fb2ce71 100644
--- a/trace-local.h
+++ b/trace-local.h
@@ -176,7 +176,7 @@ extern struct buffer_instance *first_instance;
 #define for_all_instances(i) for (i = first_instance; i; \
 				  i = i == &top_instance ? buffer_instances : (i)->next)
 
-struct buffer_instance *create_instance(char *name);
+struct buffer_instance *create_instance(const char *name);
 void add_instance(struct buffer_instance *instance);
 char *get_instance_file(struct buffer_instance *instance, const char *file);
 
diff --git a/trace-record.c b/trace-record.c
index 8340416..4a78fff 100644
--- a/trace-record.c
+++ b/trace-record.c
@@ -294,18 +294,91 @@ void add_instance(struct buffer_instance *instance)
  * Returns a newly allocated instance. Note that @name will not be
  * copied, and the instance buffer will point to the string itself.
  */
-struct buffer_instance *create_instance(char *name)
+struct buffer_instance *create_instance(const char *name)
 {
 	struct buffer_instance *instance;
 
 	instance = malloc_or_die(sizeof(*instance));
 	memset(instance, 0, sizeof(*instance));
-	instance->name = optarg;
+	instance->name = name;
 
 	return instance;
 }
 
 /**
+ * add_all_instances - Add all pre-existing instances to the internal list
+ * @tracing_dir: The top-level tracing directory
+ *
+ * Returns whether the operation succeeded
+ */
+int add_all_instances(const char *tracing_dir)
+{
+	struct dirent *dent;
+	char *instances_dir;
+	struct stat st;
+	DIR *dir;
+	int ret;
+
+	if (!tracing_dir)
+		return -1;
+
+	instances_dir = append_file(tracing_dir, "instances");
+	if (!instances_dir)
+		return -1;
+
+	ret = stat(instances_dir, &st);
+	if (ret < 0 || !S_ISDIR(st.st_mode)) {
+		ret = -1;
+		goto out_free;
+	}
+
+	dir = opendir(instances_dir);
+	if (!dir) {
+		ret = -1;
+		goto out_free;
+	}
+
+	while ((dent = readdir(dir))) {
+		const char *name = strdup(dent->d_name);
+		char *instance_path;
+		struct buffer_instance *instance;
+
+		if (strcmp(name, ".") == 0 ||
+		    strcmp(name, "..") == 0)
+			continue;
+
+		instance_path = append_file(instances_dir, name);
+		ret = stat(instance_path, &st);
+		if (ret < 0 || !S_ISDIR(st.st_mode)) {
+			free(instance_path);
+			continue;
+		}
+		free(instance_path);
+
+		instance = create_instance(name);
+		add_instance(instance);
+	}
+
+	closedir(dir);
+	ret = 0;
+
+ out_free:
+	free(instances_dir);
+	return ret;
+}
+
+void add_all_instances(void)
+{
+	char *tracing_dir = tracecmd_find_tracing_dir();
+	if (!tracing_dir)
+		die("malloc");
+
+	__add_all_instances(tracing_dir);
+
+	tracecmd_put_tracing_file(tracing_dir);
+}
+
+/**
  * tracecmd_stat_cpu - show the buffer stats of a particular CPU
  * @s: the trace_seq to record the data in.
  * @cpu: the CPU to stat
@@ -3887,7 +3960,9 @@ void trace_record (int argc, char **argv)
 			usage(argv);
 			break;
 		case 'a':
-			if (!extract) {
+			if (extract) {
+				add_all_instances();
+			} else {
 				record_all = 1;
 				record_all_events();
 			}
diff --git a/trace-usage.c b/trace-usage.c
index a708a85..39de386 100644
--- a/trace-usage.c
+++ b/trace-usage.c
@@ -62,11 +62,12 @@ static struct usage_help usage_help[] = {
 	{
 		"extract",
 		"extract a trace from the kernel",
-		" %s extract [-p plugin][-O option][-o file][-B buf][-s][-t]\n"
+		" %s extract [-p plugin][-O option][-o file][-B buf][-s][-a][-t]\n"
 		"          Uses similar options as record, but only reads an existing trace.\n"
 		"          -s : extract the snapshot instead of the main buffer\n"
 		"          -B : extract a given buffer (more than one may be specified)\n"
-		"          -t : include the top level buffer (useful with -B)\n"
+		"          -a : extract all buffers (except top one)\n"
+		"          -t : extract the top level buffer (useful with -B and -a)\n"
 	},
 	{
 		"stop",
-- 
1.9.1