From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx>
Add a helper function that will read an instance error_log file, and
either return the entire content of the error log (tracefs_error_all()) or
just the last error (tracefs_error_last()).
Also add tracefs_error_clear() to clear the error log.
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
include/tracefs.h | 4 ++
src/tracefs-utils.c | 112 ++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 116 insertions(+)
diff --git a/include/tracefs.h b/include/tracefs.h
index 447821e..b478684 100644
--- a/include/tracefs.h
+++ b/include/tracefs.h
@@ -58,6 +58,10 @@ int tracefs_trace_off_fd(int fd);
int tracefs_event_enable(struct tracefs_instance *instance, const char *system, const char *event);
int tracefs_event_disable(struct tracefs_instance *instance, const char *system, const char *event);
+char *tracefs_error_last(struct tracefs_instance *instance);
+char *tracefs_error_all(struct tracefs_instance *instance);
+int tracefs_error_clear(struct tracefs_instance *instance);
+
/**
* tracefs_trace_on_get_fd - Get a file descriptor of "tracing_on" in given instance
* @instance: ftrace instance, can be NULL for the top instance
diff --git a/src/tracefs-utils.c b/src/tracefs-utils.c
index 9e37e75..2028bee 100644
--- a/src/tracefs-utils.c
+++ b/src/tracefs-utils.c
@@ -23,6 +23,8 @@
#define TRACEFS_PATH "/sys/kernel/tracing"
#define DEBUGFS_PATH "/sys/kernel/debug"
+#define ERROR_LOG "error_log"
+
#define _STR(x) #x
#define STR(x) _STR(x)
@@ -253,3 +255,113 @@ __hidden int str_read_file(const char *file, char **buffer, bool warn)
return size;
}
+
+/**
+ * tracefs_error_all - return the content of the error log
+ * @instance: The instance to read the error log from (NULL for top level)
+ *
+ * Return NULL if the log is empty, or on error (where errno will be
+ * set. Otherwise the content of the entire log is returned in a string
+ * that must be freed with free().
+ */
+char *tracefs_error_all(struct tracefs_instance *instance)
+{
+ char *content;
+ char *path;
+ int size;
+
+ errno = 0;
+
+ path = tracefs_instance_get_file(instance, ERROR_LOG);
+ if (!path)
+ return NULL;
+ size = str_read_file(path, &content, false);
+ tracefs_put_tracing_file(path);
+
+ if (size <= 0)
+ return NULL;
+
+ return content;
+}
+
+enum line_states {
+ START,
+ CARROT,
+};
+
+/**
+ * tracefs_error_last - return the last error logged
+ * @instance: The instance to read the error log from (NULL for top level)
+ *
+ * Return NULL if the log is empty, or on error (where errno will be
+ * set. Otherwise a string containing the content of the last error shown
+* in the log that must be freed with free().
+ */
+char *tracefs_error_last(struct tracefs_instance *instance)
+{
+ enum line_states state = START;
+ char *content;
+ char *ret;
+ bool done = false;
+ int size;
+ int i;
+
+ content = tracefs_error_all(instance);
+ if (!content)
+ return NULL;
+
+ size = strlen(content);
+ if (!size) /* Should never happen */
+ return content;
+
+ for (i = size - 1; i > 0; i--) {
+ switch (state) {
+ case START:
+ if (content[i] == '\n') {
+ /* Remove extra new lines */
+ content[i] = '\0';
+ break;
+ }
+ if (content[i] == '^')
+ state = CARROT;
+ break;
+ case CARROT:
+ if (content[i] == '\n') {
+ /* Remember last new line */
+ size = i;
+ break;
+ }
+ if (content[i] == '^') {
+ /* Go just passed the last newline */
+ i = size + 1;
+ done = true;
+ }
+ break;
+ }
+ if (done)
+ break;
+ }
+
+ if (i) {
+ ret = strdup(content + i);
+ free(content);
+ } else {
+ ret = content;
+ }
+
+ return ret;
+}
+
+/**
+ * tracefs_error_clear - clear the error log of an instance
+ * @instance: The instance to clear (NULL for top level)
+ *
+ * Clear the content of the error log.
+ *
+ * Returns 0 on success, -1 otherwise.
+ */
+int tracefs_error_clear(struct tracefs_instance *instance)
+{
+ return tracefs_instance_file_clear(instance, ERROR_LOG);
+}
+
--
2.29.2
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