From: "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>
To: rostedt@goodmis.org
Cc: linux-trace-devel@vger.kernel.org
Subject: [PATCH v2 2/7] libtracefs: New APIs for opening and reading ftrace files
Date: Tue, 12 Jan 2021 11:20:19 +0200 [thread overview]
Message-ID: <20210112092024.605705-3-tz.stoyanov@gmail.com> (raw)
In-Reply-To: <20210112092024.605705-1-tz.stoyanov@gmail.com>
These new APIs can be used to read long long integer from frtace file
and to open ftrace file:
tracefs_instance_file_read_number();
tracefs_instance_file_open();
Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
include/tracefs.h | 4 +++
src/tracefs-instance.c | 60 +++++++++++++++++++++++++++++++++++++++++-
2 files changed, 63 insertions(+), 1 deletion(-)
diff --git a/include/tracefs.h b/include/tracefs.h
index 06e2130..bec8369 100644
--- a/include/tracefs.h
+++ b/include/tracefs.h
@@ -30,6 +30,10 @@ int tracefs_instance_file_write(struct tracefs_instance *instance,
const char *file, const char *str);
char *tracefs_instance_file_read(struct tracefs_instance *instance,
const char *file, int *psize);
+int tracefs_instance_file_read_number(struct tracefs_instance *instance,
+ const char *file, long long *res);
+int tracefs_instance_file_open(struct tracefs_instance *instance,
+ const char *file, int mode);
int tracefs_instances_walk(int (*callback)(const char *, void *), void *context);
bool tracefs_instance_exists(const char *name);
diff --git a/src/tracefs-instance.c b/src/tracefs-instance.c
index 6dc85ee..97bbb00 100644
--- a/src/tracefs-instance.c
+++ b/src/tracefs-instance.c
@@ -14,7 +14,7 @@
#include <sys/stat.h>
#include <fcntl.h>
#include <dirent.h>
-#include <linux/limits.h>
+#include <limits.h>
#include "tracefs.h"
#include "tracefs-local.h"
@@ -301,6 +301,64 @@ char *tracefs_instance_file_read(struct tracefs_instance *instance,
return buf;
}
+/**
+ * tracefs_instance_file_read_number - Read long long integer from a trace file.
+ * @instance: ftrace instance, can be NULL for the top instance
+ * @file: name of the file
+ * @res: The integer from the file.
+ *
+ * Returns 0 if the reading is successful and the result is stored in res, -1
+ * in case of an error.
+ */
+int tracefs_instance_file_read_number(struct tracefs_instance *instance,
+ const char *file, long long *res)
+{
+ long long num;
+ int ret = -1;
+ int size = 0;
+ char *str;
+
+ str = tracefs_instance_file_read(instance, file, &size);
+ if (size && str) {
+ errno = 0;
+ num = strtoll(str, NULL, 0);
+ if (errno == 0) {
+ *res = num;
+ ret = 0;
+ }
+ }
+ free(str);
+ return ret;
+}
+
+/**
+ * tracefs_instance_file_open - Open a trace file for reading and writing
+ * @instance: ftrace instance, can be NULL for the top instance
+ * @file: name of the file
+ * @mode: file open flags, -1 for default O_RDWR
+ *
+ * Returns -1 in case of an error, or a valid file descriptor otherwise.
+ * The returned FD must be closed with close()
+ */
+int tracefs_instance_file_open(struct tracefs_instance *instance,
+ const char *file, int mode)
+{
+ int flags = O_RDWR;
+ int fd = -1;
+ char *path;
+
+ path = tracefs_instance_get_file(instance, file);
+ if (!path)
+ return -1;
+
+ if (mode >= 0)
+ flags = mode;
+ fd = open(path, flags);
+ tracefs_put_tracing_file(path);
+
+ return fd;
+}
+
static bool check_file_exists(struct tracefs_instance *instance,
char *name, bool dir)
{
--
2.29.2
next prev parent reply other threads:[~2021-01-12 9:21 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-12 9:20 [PATCH v2 0/7] New libtracefs APIs Tzvetomir Stoyanov (VMware)
2021-01-12 9:20 ` [PATCH v2 1/7] libtracefs: tracefs_instance_file_read() get a const file name Tzvetomir Stoyanov (VMware)
2021-01-12 9:20 ` Tzvetomir Stoyanov (VMware) [this message]
2021-01-12 9:20 ` [PATCH v2 3/7] libtracefs: New APIs for enable / disable tracing Tzvetomir Stoyanov (VMware)
2021-02-19 3:07 ` Steven Rostedt
2021-01-12 9:20 ` [PATCH v2 4/7] libtracefs: Documentation for the new APIs for opening and reading ftrace files Tzvetomir Stoyanov (VMware)
2021-01-12 9:20 ` [PATCH v2 5/7] libtracefs: Documentation for enable / disable tracing APIs Tzvetomir Stoyanov (VMware)
2021-01-12 9:20 ` [PATCH v2 6/7] libtracefs: Unit tests for the new APIs for opening and reading ftrace files Tzvetomir Stoyanov (VMware)
2021-01-12 9:20 ` [PATCH v2 7/7] libtracefs: Unit tests for enable / disable tracing APIs Tzvetomir Stoyanov (VMware)
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