trace-cmd: Add tracecmd_local_events()

Add tracecmd_local_events() that returns an pevent that will
consist of the events local to the machine. It reads the
/debugfs/tracing/events directory to create them.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

2 files changed, 183 insertions, 0 deletions

diff --git a/trace-cmd.h b/trace-cmd.h
index ea6c356..b732484 100644
--- a/trace-cmd.h
+++ b/trace-cmd.h
@@ -37,6 +37,7 @@ void tracecmd_unload_plugins(struct plugin_list *list);
 
 char **tracecmd_event_systems(const char *tracing_dir);
 char **tracecmd_system_events(const char *tracing_dir, const char *system);
+struct pevent *tracecmd_local_events(const char *tracing_dir);
 
 enum {
         RINGBUF_TYPE_PADDING            = 29,
diff --git a/trace-util.c b/trace-util.c
index 456687c..6d813c5 100644
--- a/trace-util.c
+++ b/trace-util.c
@@ -26,6 +26,8 @@
 #include <ctype.h>
 #include <errno.h>
 #include <dlfcn.h>
+#include <fcntl.h>
+#include <unistd.h>
 #include <sys/mount.h>
 #include <sys/types.h>
 #include <sys/stat.h>
@@ -412,6 +414,186 @@ char **tracecmd_system_events(const char *tracing_dir, const char *system)
         return events;
 }
 
+static int read_file(const char *file, char **buffer)
+{
+        char *buf;
+        int len = 0;
+        int fd;
+        int r;
+
+        fd = open(file, O_RDONLY);
+        if (fd < 0)
+                return -1;
+
+        buf = malloc_or_die(BUFSIZ);
+
+        while ((r = read(fd, buf + len, BUFSIZ)) > 0) {
+                len += r;
+                buf = realloc(buf, len + BUFSIZ);
+                if (!buf) {
+                        len = -1;
+                        goto out;
+                }
+        }
+
+        *buffer = buf;
+
+ out:
+        close(fd);
+
+        return len;
+}
+
+static void load_events(struct pevent *pevent, const char *system,
+                        const char *sys_dir)
+{
+        struct dirent *dent;
+        struct stat st;
+        DIR *dir;
+        int len = 0;
+        int ret;
+
+        ret = stat(sys_dir, &st);
+        if (ret < 0 || !S_ISDIR(st.st_mode))
+                return;
+
+        dir = opendir(sys_dir);
+        if (!dir)
+                return;
+
+        while ((dent = readdir(dir))) {
+                const char *name = dent->d_name;
+                char *event;
+                char *format;
+                char *buf;
+
+                if (strcmp(name, ".") == 0 ||
+                    strcmp(name, "..") == 0)
+                        continue;
+
+                event = append_file(sys_dir, name);
+                ret = stat(event, &st);
+                if (ret < 0 || !S_ISDIR(st.st_mode))
+                        goto free_event;
+
+                format = append_file(event, "format");
+                ret = stat(format, &st);
+                if (ret < 0)
+                        goto free_format;
+
+                len = read_file(format, &buf);
+                if (len < 0)
+                        goto free_format;
+
+                pevent_parse_event(pevent, buf, len, system);
+                free(buf);
+ free_format:
+                free(format);
+ free_event:
+                free(event);
+        }
+
+        closedir(dir);
+}
+
+static int read_header(struct pevent *pevent, const char *events_dir)
+{
+        struct stat st;
+        char *header;
+        char *buf;
+        int len;
+        int ret = -1;
+
+        header = append_file(events_dir, "header_page");
+
+        ret = stat(header, &st);
+        if (ret < 0)
+                goto out;
+
+        len = read_file(header, &buf);
+        if (len < 0)
+                goto out;
+
+        pevent_parse_header_page(pevent, buf, len, sizeof(long));
+
+        free(buf);
+
+        ret = 0;
+ out:
+        free(header);
+        return ret;
+}
+
+/**
+ * tracecmd_local_events - create a pevent from the events on system
+ * @tracing_dir: The directory that contains the events.
+ *
+ * Returns a pevent structure that contains the pevents local to
+ * the system.
+ */
+struct pevent *tracecmd_local_events(const char *tracing_dir)
+{
+        struct pevent *pevent = NULL;
+        struct dirent *dent;
+        char *events_dir;
+        struct stat st;
+        DIR *dir;
+        int ret;
+
+        if (!tracing_dir)
+                return NULL;
+
+        events_dir = append_file(tracing_dir, "events");
+        if (!events_dir)
+                return NULL;
+
+        ret = stat(events_dir, &st);
+        if (ret < 0 || !S_ISDIR(st.st_mode))
+                goto out_free;
+
+        dir = opendir(events_dir);
+        if (!dir)
+                goto out_free;
+
+        pevent = pevent_alloc();
+        if (!pevent)
+                goto out_free;
+
+        ret = read_header(pevent, events_dir);
+        if (ret < 0) {
+                pevent_free(pevent);
+                pevent = NULL;
+                goto out_free;
+        }
+
+        while ((dent = readdir(dir))) {
+                const char *name = dent->d_name;
+                char *sys;
+
+                if (strcmp(name, ".") == 0 ||
+                    strcmp(name, "..") == 0)
+                        continue;
+
+                sys = append_file(events_dir, name);
+                ret = stat(sys, &st);
+                if (ret < 0 || !S_ISDIR(st.st_mode)) {
+                        free(sys);
+                        continue;
+                }
+
+                load_events(pevent, name, sys);
+
+                free(sys);
+        }
+
+        closedir(dir);
+
+ out_free:
+        free(events_dir);
+
+        return pevent;
+}
+
 static void
 trace_util_load_plugins_dir(struct pevent *pevent, const char *suffix,
                             const char *path,