From patchwork Fri Nov 15 09:53:36 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Derrick Stolee via GitGitGadget X-Patchwork-Id: 11245773 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 73A6C159A for ; Fri, 15 Nov 2019 09:54:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 53E6B2073B for ; Fri, 15 Nov 2019 09:54:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="pvlm0GD0" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727519AbfKOJyE (ORCPT ); Fri, 15 Nov 2019 04:54:04 -0500 Received: from mail-wr1-f46.google.com ([209.85.221.46]:42517 "EHLO mail-wr1-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727386AbfKOJx6 (ORCPT ); Fri, 15 Nov 2019 04:53:58 -0500 Received: by mail-wr1-f46.google.com with SMTP id a15so10236960wrf.9 for ; Fri, 15 Nov 2019 01:53:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=message-id:in-reply-to:references:from:date:subject:fcc :content-transfer-encoding:mime-version:to:cc; bh=QvlSZrg2iZwXCDbIoVz7SYXz/1QPUitavJOghXfdqbg=; b=pvlm0GD0PH+IbK8CGZkC6R2izVOTe7Vt2LCsz/e4CDrfL09R+Ffbl8TFREKwPTbau5 5wwagsu3W+zmpfKy9+OIu7RTx1aD1OBV8wRlwyn4IhQqxLS+JxE7jlIJ2omwsNsqcvMO OKWImv0EGusEeU00L86PigI35HimMXpg5/1l6FIH23m+iZJqF+k6lFkqaYP9UeD6ftIa LrzA8TIdjdAoBTP+NBoVlhtqEJw1M5e80jgPCJgIpyh3z0m4A4Ka87PTSFYuMkCB0L8G 3u2bL3Q3HFT6u/Us1FNgzOoXgkr5DQbExRPV9TQm4m5oYb/SG5DCMs/5uNhXF4qUk3xg Wllg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:message-id:in-reply-to:references:from:date :subject:fcc:content-transfer-encoding:mime-version:to:cc; bh=QvlSZrg2iZwXCDbIoVz7SYXz/1QPUitavJOghXfdqbg=; b=VRCyeXo6lHXERAZGHVudA9DOnO0/mQ1tamlgYqyVFRNKzfTPoMJfVt/UlxOS9pbWTb zUSsRnIxum0uwFvyaAKRHb/gWFuvLW4+Q5cQf7lQu0WIl8zHu6blfoO315TsvBAAYFJa V7UKok3QKbnbQQqXU2B6LIS2Lrz4gsqpg2R2VEa/pf3h4tN1LiwhcovyxTm3YwT/dut1 /OhkltiDChWb9+PqWYbRgTic4FuTvZeyVgN76pfgjGe80zY2UrX+kHAwx+lIHArp9yom 8aZQImFtSn9h73+udkQShWHrW0+kd0eiz+mScTixxZX3iyITRiWPbqqs83SKQ8KuVkFB UNQw== X-Gm-Message-State: APjAAAWOpPKmA2GKmd0fvuOQs84IAm+GU3MhBmnJJJJpY7Vpqg3ahOXV pjqqCQiznp5ZTc8BZLYAFF+nf62e X-Google-Smtp-Source: APXvYqwBNNDMvkpelXGYX7+TH8J0zOTuAGG4fkfrdTGaFPVrOGdfzFiov9Nm/vcLJ660NLpf3WXInA== X-Received: by 2002:adf:e883:: with SMTP id d3mr13632410wrm.197.1573811636990; Fri, 15 Nov 2019 01:53:56 -0800 (PST) Received: from [127.0.0.1] ([13.74.141.28]) by smtp.gmail.com with ESMTPSA id w13sm10307033wrm.8.2019.11.15.01.53.56 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 15 Nov 2019 01:53:56 -0800 (PST) Message-Id: <240a4bcb3227224529945c9576b6e49891545841.1573811627.git.gitgitgadget@gmail.com> In-Reply-To: References: From: "Heba Waly via GitGitGadget" Date: Fri, 15 Nov 2019 09:53:36 +0000 Subject: [PATCH v4 11/21] sigchain: move doc to sigchain.h Fcc: Sent MIME-Version: 1.0 To: git@vger.kernel.org Cc: Heba Waly , Junio C Hamano , Heba Waly Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org From: Heba Waly Move the documentation from Documentation/technical/api-sigchain.txt to sigchain.h as it's easier for the developers to find the usage information beside the code instead of looking for it in another doc file. Also documentation/technical/api-sigchain.txt is removed because the information it has is now redundant and it'll be hard to keep it up to date and synchronized with the documentation in the header file. Signed-off-by: Heba Waly --- Documentation/technical/api-sigchain.txt | 41 --------------------- sigchain.h | 45 ++++++++++++++++++++++++ 2 files changed, 45 insertions(+), 41 deletions(-) delete mode 100644 Documentation/technical/api-sigchain.txt diff --git a/Documentation/technical/api-sigchain.txt b/Documentation/technical/api-sigchain.txt deleted file mode 100644 index 9e1189ef01..0000000000 --- a/Documentation/technical/api-sigchain.txt +++ /dev/null @@ -1,41 +0,0 @@ -sigchain API -============ - -Code often wants to set a signal handler to clean up temporary files or -other work-in-progress when we die unexpectedly. For multiple pieces of -code to do this without conflicting, each piece of code must remember -the old value of the handler and restore it either when: - - 1. The work-in-progress is finished, and the handler is no longer - necessary. The handler should revert to the original behavior - (either another handler, SIG_DFL, or SIG_IGN). - - 2. The signal is received. We should then do our cleanup, then chain - to the next handler (or die if it is SIG_DFL). - -Sigchain is a tiny library for keeping a stack of handlers. Your handler -and installation code should look something like: - ------------------------------------------- - void clean_foo_on_signal(int sig) - { - clean_foo(); - sigchain_pop(sig); - raise(sig); - } - - void other_func() - { - sigchain_push_common(clean_foo_on_signal); - mess_up_foo(); - clean_foo(); - } ------------------------------------------- - -Handlers are given the typedef of sigchain_fun. This is the same type -that is given to signal() or sigaction(). It is perfectly reasonable to -push SIG_DFL or SIG_IGN onto the stack. - -You can sigchain_push and sigchain_pop individual signals. For -convenience, sigchain_push_common will push the handler onto the stack -for many common signals. diff --git a/sigchain.h b/sigchain.h index 138b20f54b..8e6bada892 100644 --- a/sigchain.h +++ b/sigchain.h @@ -1,12 +1,57 @@ #ifndef SIGCHAIN_H #define SIGCHAIN_H +/** + * Code often wants to set a signal handler to clean up temporary files or + * other work-in-progress when we die unexpectedly. For multiple pieces of + * code to do this without conflicting, each piece of code must remember + * the old value of the handler and restore it either when: + * + * 1. The work-in-progress is finished, and the handler is no longer + * necessary. The handler should revert to the original behavior + * (either another handler, SIG_DFL, or SIG_IGN). + * + * 2. The signal is received. We should then do our cleanup, then chain + * to the next handler (or die if it is SIG_DFL). + * + * Sigchain is a tiny library for keeping a stack of handlers. Your handler + * and installation code should look something like: + * + * ------------------------------------------ + * void clean_foo_on_signal(int sig) + * { + * clean_foo(); + * sigchain_pop(sig); + * raise(sig); + * } + * + * void other_func() + * { + * sigchain_push_common(clean_foo_on_signal); + * mess_up_foo(); + * clean_foo(); + * } + * ------------------------------------------ + * + */ + +/** + * Handlers are given the typedef of sigchain_fun. This is the same type + * that is given to signal() or sigaction(). It is perfectly reasonable to + * push SIG_DFL or SIG_IGN onto the stack. + */ typedef void (*sigchain_fun)(int); +/* You can sigchain_push and sigchain_pop individual signals. */ int sigchain_push(int sig, sigchain_fun f); int sigchain_pop(int sig); +/** + * push the handler onto the stack for the common signals: + * SIGINT, SIGHUP, SIGTERM, SIGQUIT and SIGPIPE. + */ void sigchain_push_common(sigchain_fun f); + void sigchain_pop_common(void); #endif /* SIGCHAIN_H */