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Tue, 12 Jan 2021 01:20:28 -0800 (PST) From: "Tzvetomir Stoyanov (VMware)" 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 Message-Id: <20210112092024.605705-3-tz.stoyanov@gmail.com> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210112092024.605705-1-tz.stoyanov@gmail.com> References: <20210112092024.605705-1-tz.stoyanov@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org 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) --- 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 #include #include -#include +#include #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) {