From patchwork Thu Apr 15 12:13:11 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yordan Karadzhov X-Patchwork-Id: 12205301 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-20.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B9B13C43461 for ; Thu, 15 Apr 2021 12:13:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 941F7613C0 for ; Thu, 15 Apr 2021 12:13:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231919AbhDOMNv (ORCPT ); Thu, 15 Apr 2021 08:13:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36902 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232769AbhDOMNu (ORCPT ); Thu, 15 Apr 2021 08:13:50 -0400 Received: from mail-ej1-x632.google.com (mail-ej1-x632.google.com [IPv6:2a00:1450:4864:20::632]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 73172C061574 for ; Thu, 15 Apr 2021 05:13:26 -0700 (PDT) Received: by mail-ej1-x632.google.com with SMTP id n2so36487836ejy.7 for ; Thu, 15 Apr 2021 05:13:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=hd4tyOOmUPYpQksWbSiqZqMIJjD/1lFPBVjhmFW/SmQ=; b=A0g35bUKF4fQJ39lFAAY4+dXkdjmmOcBrguHTi3krUQDBddo0qNdPAxHBV6L8fVXt5 QFZoL5IMn/xBVwj6MZmlbmuUl/n19fU9rTdW5lUcssOZM30qQHC05fKnkkDfoOGDNGSu 9f6GDq2PJianxryrUQvMahFjhgjSU7fhAlcEYcubbb1EjIPON6ARQdb5Ie1RPRicLhN8 3IR7ZMEQ7c4beMyMwKZDtu0lI3O45t8gieQxJN21WB8f6BzfjQJGsjw2q6sMh1ULbCJc 1HkIJpMncpOlKsP6PFsxOIH1s0vmFPhuoa9LiOqYjs4oU3kmaJmR7IHrAs84+UmFGwkz EKDw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=hd4tyOOmUPYpQksWbSiqZqMIJjD/1lFPBVjhmFW/SmQ=; b=SDue1pQQ8matW+cdb8sJavDhhYxB21jTJxRvumGfzWNpRxNiW58AQ+WheFC8dK1Pgy l1jsHiBaxLovzdOvFWebJdTYxwhgZ0oZhZrmsFWtGnrtlL1Sk5qkVluosfyWGQ5hKLzh vhhAxdYNs0m6cqIdr7KqhiqAYblQbcoLsjbiGMmRBiVwdoSuVGMv1zVuHVd18g1SvgCZ SgbwX5oeVHRDCW/beYcAl+xU/90Z3FMNvywDgfvpAYAMjbjHWKG1PL7oNfvdqgwTc9Ea lbu67s8sssoDO0Xo351/nAa+g8aUuCO7k5PU/AgKZQa0E/UPd2ZDgPNfVfVvr7i2x/Wp W1sg== X-Gm-Message-State: AOAM53230kXCTIIMuljFPZRSoV4peo2TEaFIpmHpL/iX3mnH2PZK5rZP Kl/N9qBBHDCAIBf4QnyCNZ5454TpyIw= X-Google-Smtp-Source: ABdhPJwocpTY1PILt5WAS6As+tl0yo92ayrW8mMbNCelj6/Xf0hzFi8DPU3XjM9tZZqXX6S+EAGy0g== X-Received: by 2002:a17:906:c9d8:: with SMTP id hk24mr3146124ejb.480.1618488805136; Thu, 15 Apr 2021 05:13:25 -0700 (PDT) Received: from localhost.localdomain ([84.40.93.55]) by smtp.gmail.com with ESMTPSA id o20sm2364863eds.65.2021.04.15.05.13.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 15 Apr 2021 05:13:24 -0700 (PDT) From: "Yordan Karadzhov (VMware)" To: rostedt@goodmis.org Cc: tz.stoyanov@gmail.com, linux-trace-devel@vger.kernel.org, "Yordan Karadzhov (VMware)" Subject: [PATCH 3/3] libtracefs: Document the new methods for writing to file. Date: Thu, 15 Apr 2021 15:13:11 +0300 Message-Id: <20210415121311.59787-4-y.karadz@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210415121311.59787-1-y.karadz@gmail.com> References: <20210415121311.59787-1-y.karadz@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org Documentation for "int tracefs_instance_file_append()" and "int tracefs_instance_file_clear()" is being added. The file "Documentation/libtracefs-instances-files.txt" gets split, because when adding two more APIs we exceed the limit of APIs per file. Signed-off-by: Yordan Karadzhov (VMware) --- .../libtracefs-instances-file-manip.txt | 199 ++++++++++++++++++ Documentation/libtracefs-instances-files.txt | 35 +-- 2 files changed, 201 insertions(+), 33 deletions(-) create mode 100644 Documentation/libtracefs-instances-file-manip.txt diff --git a/Documentation/libtracefs-instances-file-manip.txt b/Documentation/libtracefs-instances-file-manip.txt new file mode 100644 index 0000000..942e7ad --- /dev/null +++ b/Documentation/libtracefs-instances-file-manip.txt @@ -0,0 +1,199 @@ +libtracefs(3) +============= + +NAME +---- + +tracefs_instance_file_open, +tracefs_instance_file_write, tracefs_instance_file_append, tracefs_instance_file_clear, +tracefs_instance_file_read, tracefs_instance_file_read_number - Work with files in tracing instances. + +SYNOPSIS +-------- +[verse] +-- +*#include * + +int *tracefs_instance_file_open*(struct tracefs_instance pass:[*]_instance_, const char pass:[*]_file_, int _mode_); +int *tracefs_instance_file_write*(struct tracefs_instance pass:[*]_instance_, const char pass:[*]_file_, const char pass:[*]_str_); +int *tracefs_instance_file_append*(struct tracefs_instance pass:[*]_instance_, const char pass:[*]_file_, const char pass:[*]_str_); +int *tracefs_instance_file_clear*(struct tracefs_instance pass:[*]_instance_, const char pass:[*]_file_); +char pass:[*]*tracefs_instance_file_read*(struct tracefs_instance pass:[*]_instance_, const char pass:[*]_file_, int pass:[*]_psize_); +int *tracefs_instance_file_read_number*(struct tracefs_instance pass:[*]_instance_, const char pass:[*]_file_, long long int pass:[*]_res_); + +-- + +DESCRIPTION +----------- +This set of APIs can be used to work with trace files in all trace instances. +Each of these APIs take an _instance_ argument, that can be NULL to act +on the top level instance. Otherwise, it acts on an instance created with +*tracefs_insance_create*(3) + +The _tracefs_instance_file_open()_ function opens trace _file_ from given _instance_ and returns +a file descriptor to it. The file access _mode_ can be specified, see *open*(3) for more details. +If -1 is passed as _mode_, default O_RDWR is used. + +The _tracefs_instance_file_write()_ function writes a string _str_ in a _file_ from +the given _instance_, without the terminating NULL character. When opening the file, this function +tries to truncates the size of the file to zero, which clears all previously existing settings. + +The _tracefs_instance_file_append()_ function writes a string _str_ in a _file_ from +the given _instance_, without the terminating NULL character. This function is similar to +_tracefs_instance_file_write()_, but the existing content of the is not cleared. Thus the +new settings are appended to the existing ones (if any). + +The _tracefs_instance_file_clear()_ function tries to truncates the size of the file to zero, +which clears all previously existing settings. If the file has content that does not get +cleared in this way, this will not have any effect. + +The _tracefs_instance_file_read()_ function reads the content of a _file_ from +the given _instance_. + +The _tracefs_instance_file_read_number()_ function reads the content of a _file_ from +the given _instance_ and converts it to a long long integer, which is stored in _res_. + +RETURN VALUE +------------ +The _tracefs_instance_file_open()_ function returns a file descriptor to the opened file. It must be +closed with *close*(3). In case of an error, -1 is returned. + +The _tracefs_instance_file_write()_ function returns the number of written bytes, +or -1 in case of an error. + +The _tracefs_instance_file_append()_ function returns the number of written bytes, +or -1 in case of an error. + +The _tracefs_instance_file_clear()_ function returns 0 on success, or -1 in case of an error. + +The _tracefs_instance_file_read()_ function returns a pointer to a NULL terminated +string, read from the file, or NULL in case of an error. The returned string must +be freed with free(). + +The _tracefs_instance_file_read_number()_ function returns 0 if a valid integer is read from +the file and stored in _res_ or -1 in case of an error. + +EXAMPLE +------- +[source,c] +-- +#include + +struct tracefs_instance *inst = tracefs_instance_create("foo"); + if (!inst) { + /* Error creating a new trace instance */ + ... + } + + if (tracefs_file_exists(inst,"trace_clock")) { + /* The instance foo supports trace clock */ + char *path, *clock; + int size; + + path = = tracefs_instance_get_file(inst, "trace_clock") + if (!path) { + /* Error getting the path to trace_clock file in instance foo */ + ... + } + ... + tracefs_put_tracing_file(path); + + clock = tracefs_instance_file_read(inst, "trace_clock", &size); + if (!clock) { + /* Failed to read trace_clock file in instance foo */ + ... + } + ... + free(clock); + + if (tracefs_instance_file_write(inst, "trace_clock", "global") != strlen("global")) { + /* Failed to set gloabl trace clock in instance foo */ + ... + } + } else { + /* The instance foo does not support trace clock */ + } + + if (tracefs_dir_exists(inst,"options")) { + /* The instance foo supports trace options */ + char *path = tracefs_instance_get_file(inst, "options"); + if (!path) { + /* Error getting the path to options directory in instance foo */ + ... + } + + tracefs_put_tracing_file(path); + } else { + /* The instance foo does not support trace options */ + } + + ... + + if (tracefs_instance_is_new(inst)) + tracefs_instance_destroy(inst); + else + tracefs_instance_free(inst); + ... + + long long int res; + if (tracefs_instance_file_read_number(NULL, "tracing_on", &res) == 0) { + if (res == 0) { + /* tracing is disabled in the top instance */ + } else if (res == 1) { + /* tracing is enabled in the top instance */ + } else { + /* Unknown tracing state of the top instance */ + } + } else { + /* Failed to read integer from tracing_on file */ + } + + ... + + int fd; + fd = tracefs_instance_file_open(NULL, "tracing_on", O_WRONLY); + if (fd >= 0) { + /* Got file descriptor to the tracing_on file from the top instance for writing */ + ... + close(fd); + } +-- +FILES +----- +[verse] +-- +*tracefs.h* + Header file to include in order to have access to the library APIs. +*-ltracefs* + Linker switch to add when building a program that uses the library. +-- + +SEE ALSO +-------- +_libtracefs(3)_, +_libtraceevent(3)_, +_trace-cmd(1)_ + +AUTHOR +------ +[verse] +-- +*Steven Rostedt* +*Tzvetomir Stoyanov* +-- +REPORTING BUGS +-------------- +Report bugs to + +LICENSE +------- +libtracefs is Free Software licensed under the GNU LGPL 2.1 + +RESOURCES +--------- +https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/ + +COPYING +------- +Copyright \(C) 2020 VMware, Inc. Free use of this software is granted under +the terms of the GNU Public License (GPL). diff --git a/Documentation/libtracefs-instances-files.txt b/Documentation/libtracefs-instances-files.txt index 124ef52..4ac87d1 100644 --- a/Documentation/libtracefs-instances-files.txt +++ b/Documentation/libtracefs-instances-files.txt @@ -3,9 +3,8 @@ libtracefs(3) NAME ---- -tracefs_file_exists, tracefs_dir_exists, tracefs_instance_get_file, -tracefs_instance_get_dir, tracefs_instance_file_open, tracefs_instance_file_write, -tracefs_instance_file_read, tracefs_instance_file_read_number - Work with files in tracing instances. +tracefs_file_exists, tracefs_dir_exists, +tracefs_instance_get_file, tracefs_instance_get_dir - Work with files directories in tracing instances. SYNOPSIS -------- @@ -17,10 +16,6 @@ bool *tracefs_file_exists*(struct tracefs_instance pass:[*]_instance_, char pass bool *tracefs_dir_exists*(struct tracefs_instance pass:[*]_instance_, char pass:[*]_name_); char pass:[*]*tracefs_instance_get_file*(struct tracefs_instance pass:[*]_instance_, const char pass:[*]_file_); char pass:[*]*tracefs_instance_get_dir*(struct tracefs_instance pass:[*]_instance_); -int *tracefs_instance_file_open*(struct tracefs_instance pass:[*]_instance_, const char pass:[*]_file_, int _mode_); -int *tracefs_instance_file_write*(struct tracefs_instance pass:[*]_instance_, const char pass:[*]_file_, const char pass:[*]_str_); -char pass:[*]*tracefs_instance_file_read*(struct tracefs_instance pass:[*]_instance_, const char pass:[*]_file_, int pass:[*]_psize_); -int *tracefs_instance_file_read_number*(struct tracefs_instance pass:[*]_instance_, const char pass:[*]_file_, long long int pass:[*]_res_); -- @@ -43,19 +38,6 @@ The _tracefs_instance_get_dir()_ function returns the full path of the director with given _name_ in _instance_. Note, it does not check if the directory exists in the instance. -The _tracefs_instance_file_open()_ function opens trace _file_ from given _instance_ and returns -a file descriptor to it. The file access _mode_ can be specified, see *open*(3) for more details. -If -1 is passed as _mode_, default O_RDWR is used. - -The _tracefs_instance_file_write()_ function writes a string _str_ in a _file_ from -the given _instance_, without the terminating NULL character. - -The _tracefs_instance_file_read()_ function reads the content of a _file_ from -the given _instance_. - -The _tracefs_instance_file_read_number()_ function reads the content of a _file_ from -the given _instance_ and converts it to a long long integer, which is stored in _res_. - RETURN VALUE ------------ The _tracefs_file_exists()_ and _tracefs_dir_exists()_ functions return true if the @@ -65,19 +47,6 @@ The _tracefs_instance_get_file()_ and _tracefs_instance_get_dir()_ functions ret a string or NULL in case of an error. The returned string must be freed with _tracefs_put_tracing_file()_. -The _tracefs_instance_file_open()_ function returns a file descriptor to the opened file. It must be -closed with *close*(3). In case of an error, -1 is returned. - -The _tracefs_instance_file_write()_ function returns the number of written bytes, -or -1 in case of an error. - -The _tracefs_instance_file_read()_ function returns a pointer to a NULL terminated -string, read from the file, or NULL in case of an error. The returned string must -be freed with free(). - -The _tracefs_instance_file_read_number()_ function returns 0 if a valid integer is read from -the file and stored in _res_ or -1 in case of an error. - EXAMPLE ------- [source,c]