From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk1-x743.google.com (mail-qk1-x743.google.com [IPv6:2607:f8b0:4864:20::743]) by sourceware.org (Postfix) with ESMTPS id 85D523851C25 for ; Thu, 27 Aug 2020 13:40:12 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 85D523851C25 Received: by mail-qk1-x743.google.com with SMTP id u3so5833666qkd.9 for ; Thu, 27 Aug 2020 06:40:12 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:to:cc:references:from:autocrypt:subject :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=wLYh36+BVbIff2pTKtQNy5fhaA8K8GEj+SsABLd60a4=; b=Mf51vS2ExKa684XyQt0nfYdw/pFnlH2RrnD4orgGGU6gh2O6vM/u7WijBJqp8JZB9s o8OpiMvwaR8rJckI/2EbCG0xgzf4f06u8oZ/VpVITzktjzdIgCxOIDBfYaJUVzxZNQW6 1GoXsqsko9xM3o9LEjuYdg5PNt0z4EO60PqCvx6DaPzoAb1gfv1qvdENU3bAZnAhs3cr F63CnNtGNV7drTQXkp6qB5fV3oSqgpDauk9TNFCQjs1qQ3nC+mOtTkElmBMn/C7OUSF7 0l1oAckRWdIKrncq391W1yQljgqGhnTt0Qds8D85Up9K8Xs/a1QYMN7ToCFsl3+Afmyq FzDA== X-Gm-Message-State: AOAM532ec8rPZ1niWp5gOyrSvM0brJ7gNZ0Nahjvf3DwBJsTif7z3k76 6CejxYgFIXohTfkewxm/7f9ImGVumAreqAMF X-Google-Smtp-Source: ABdhPJxTbGRabuFli9AIiEsqCuBbXIqs1WqzBwR4gwg3mCpmB6/QzT0fgHFhD7slZBvmIXKcQgPPQA== X-Received: by 2002:a37:638e:: with SMTP id x136mr16570823qkb.38.1598535611766; Thu, 27 Aug 2020 06:40:11 -0700 (PDT) Received: from [192.168.1.4] ([177.194.48.209]) by smtp.googlemail.com with ESMTPSA id d8sm1732408qtn.70.2020.08.27.06.40.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 27 Aug 2020 06:40:11 -0700 (PDT) To: Florian Weimer Cc: libc-alpha@sourceware.org References: <20200826210246.2830973-1-adhemerval.zanella@linaro.org> <20200826210246.2830973-4-adhemerval.zanella@linaro.org> <87pn7cw7ge.fsf@oldenburg2.str.redhat.com> From: Adhemerval Zanella Autocrypt: addr=adhemerval.zanella@linaro.org; prefer-encrypt=mutual; keydata= mQINBFcVGkoBEADiQU2x/cBBmAVf5C2d1xgz6zCnlCefbqaflUBw4hB/bEME40QsrVzWZ5Nq 8kxkEczZzAOKkkvv4pRVLlLn/zDtFXhlcvQRJ3yFMGqzBjofucOrmdYkOGo0uCaoJKPT186L NWp53SACXguFJpnw4ODI64ziInzXQs/rUJqrFoVIlrPDmNv/LUv1OVPKz20ETjgfpg8MNwG6 iMizMefCl+RbtXbIEZ3TE/IaDT/jcOirjv96lBKrc/pAL0h/O71Kwbbp43fimW80GhjiaN2y WGByepnkAVP7FyNarhdDpJhoDmUk9yfwNuIuESaCQtfd3vgKKuo6grcKZ8bHy7IXX1XJj2X/ BgRVhVgMHAnDPFIkXtP+SiarkUaLjGzCz7XkUn4XAGDskBNfbizFqYUQCaL2FdbW3DeZqNIa nSzKAZK7Dm9+0VVSRZXP89w71Y7JUV56xL/PlOE+YKKFdEw+gQjQi0e+DZILAtFjJLoCrkEX w4LluMhYX/X8XP6/C3xW0yOZhvHYyn72sV4yJ1uyc/qz3OY32CRy+bwPzAMAkhdwcORA3JPb kPTlimhQqVgvca8m+MQ/JFZ6D+K7QPyvEv7bQ7M+IzFmTkOCwCJ3xqOD6GjX3aphk8Sr0dq3 4Awlf5xFDAG8dn8Uuutb7naGBd/fEv6t8dfkNyzj6yvc4jpVxwARAQABtElBZGhlbWVydmFs IFphbmVsbGEgTmV0dG8gKExpbmFybyBWUE4gS2V5KSA8YWRoZW1lcnZhbC56YW5lbGxhQGxp bmFyby5vcmc+iQI3BBMBCAAhBQJXFRpKAhsDBQsJCAcDBRUKCQgLBRYCAwEAAh4BAheAAAoJ EKqx7BSnlIjv0e8P/1YOYoNkvJ+AJcNUaM5a2SA9oAKjSJ/M/EN4Id5Ow41ZJS4lUA0apSXW NjQg3VeVc2RiHab2LIB4MxdJhaWTuzfLkYnBeoy4u6njYcaoSwf3g9dSsvsl3mhtuzm6aXFH /Qsauav77enJh99tI4T+58rp0EuLhDsQbnBic/ukYNv7sQV8dy9KxA54yLnYUFqH6pfH8Lly sTVAMyi5Fg5O5/hVV+Z0Kpr+ZocC1YFJkTsNLAW5EIYSP9ftniqaVsim7MNmodv/zqK0IyDB GLLH1kjhvb5+6ySGlWbMTomt/or/uvMgulz0bRS+LUyOmlfXDdT+t38VPKBBVwFMarNuREU2 69M3a3jdTfScboDd2ck1u7l+QbaGoHZQ8ZNUrzgObltjohiIsazqkgYDQzXIMrD9H19E+8fw kCNUlXxjEgH/Kg8DlpoYJXSJCX0fjMWfXywL6ZXc2xyG/hbl5hvsLNmqDpLpc1CfKcA0BkK+ k8R57fr91mTCppSwwKJYO9T+8J+o4ho/CJnK/jBy1pWKMYJPvvrpdBCWq3MfzVpXYdahRKHI ypk8m4QlRlbOXWJ3TDd/SKNfSSrWgwRSg7XCjSlR7PNzNFXTULLB34sZhjrN6Q8NQZsZnMNs TX8nlGOVrKolnQPjKCLwCyu8PhllU8OwbSMKskcD1PSkG6h3r0AquQINBFcVGkoBEACgAdbR Ck+fsfOVwT8zowMiL3l9a2DP3Eeak23ifdZG+8Avb/SImpv0UMSbRfnw/N81IWwlbjkjbGTu oT37iZHLRwYUFmA8fZX0wNDNKQUUTjN6XalJmvhdz9l71H3WnE0wneEM5ahu5V1L1utUWTyh VUwzX1lwJeV3vyrNgI1kYOaeuNVvq7npNR6t6XxEpqPsNc6O77I12XELic2+36YibyqlTJIQ V1SZEbIy26AbC2zH9WqaKyGyQnr/IPbTJ2Lv0dM3RaXoVf+CeK7gB2B+w1hZummD21c1Laua +VIMPCUQ+EM8W9EtX+0iJXxI+wsztLT6vltQcm+5Q7tY+HFUucizJkAOAz98YFucwKefbkTp eKvCfCwiM1bGatZEFFKIlvJ2QNMQNiUrqJBlW9nZp/k7pbG3oStOjvawD9ZbP9e0fnlWJIsj 6c7pX354Yi7kxIk/6gREidHLLqEb/otuwt1aoMPg97iUgDV5mlNef77lWE8vxmlY0FBWIXuZ yv0XYxf1WF6dRizwFFbxvUZzIJp3spAao7jLsQj1DbD2s5+S1BW09A0mI/1DjB6EhNN+4bDB SJCOv/ReK3tFJXuj/HbyDrOdoMt8aIFbe7YFLEExHpSk+HgN05Lg5TyTro8oW7TSMTk+8a5M kzaH4UGXTTBDP/g5cfL3RFPl79ubXwARAQABiQIfBBgBCAAJBQJXFRpKAhsMAAoJEKqx7BSn lIjvI/8P/jg0jl4Tbvg3B5kT6PxJOXHYu9OoyaHLcay6Cd+ZrOd1VQQCbOcgLFbf4Yr+rE9l mYsY67AUgq2QKmVVbn9pjvGsEaz8UmfDnz5epUhDxC6yRRvY4hreMXZhPZ1pbMa6A0a/WOSt AgFj5V6Z4dXGTM/lNManr0HjXxbUYv2WfbNt3/07Db9T+GZkpUotC6iknsTA4rJi6u2ls0W9 1UIvW4o01vb4nZRCj4rni0g6eWoQCGoVDk/xFfy7ZliR5B+3Z3EWRJcQskip/QAHjbLa3pml xAZ484fVxgeESOoaeC9TiBIp0NfH8akWOI0HpBCiBD5xaCTvR7ujUWMvhsX2n881r/hNlR9g fcE6q00qHSPAEgGr1bnFv74/1vbKtjeXLCcRKk3Ulw0bY1OoDxWQr86T2fZGJ/HIZuVVBf3+ gaYJF92GXFynHnea14nFFuFgOni0Mi1zDxYH/8yGGBXvo14KWd8JOW0NJPaCDFJkdS5hu0VY 7vJwKcyHJGxsCLU+Et0mryX8qZwqibJIzu7kUJQdQDljbRPDFd/xmGUFCQiQAncSilYOcxNU EMVCXPAQTteqkvA+gNqSaK1NM9tY0eQ4iJpo+aoX8HAcn4sZzt2pfUB9vQMTBJ2d4+m/qO6+ cFTAceXmIoFsN8+gFN3i8Is3u12u8xGudcBPvpoy4OoG Subject: Re: [PATCH 4/4] io: Reorganize the getcwd implementation Message-ID: <716a2504-03bc-79c5-8708-1a7a7fc8d3f1@linaro.org> Date: Thu, 27 Aug 2020 10:40:08 -0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <87pn7cw7ge.fsf@oldenburg2.str.redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-14.7 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, NICE_REPLY_A, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 27 Aug 2020 13:40:14 -0000 On 27/08/2020 10:21, Florian Weimer wrote: > * Adhemerval Zanella: > >> With this patch above applied over this set I remove the generic >> implementation from rtld. It allowed some code simplification and the >> resulting ld.so size change from: >> >> $ size elf/ld.so >> text data bss dec hex filename >> 164592 7304 392 172288 2a100 elf/ld.so >> >> To >> >> $ size elf/ld.so >> text data bss dec hex filename >> 162222 7304 392 169918 297be elf/ld.so >> >> It also has de advantage of not pulling the generic implementation on >> hurd build (which does not use it anyway). > > Thanks for doing the experiment. > >> diff --git a/io/getcwd.c b/io/getcwd.c >> index cf7a8e1a30..574f51085b 100644 >> --- a/io/getcwd.c >> +++ b/io/getcwd.c >> @@ -19,6 +19,10 @@ >> #include >> #include >> >> +#if !IS_IN(rtld) >> +#include >> +#endif >> + >> /* Get the pathname of the current working directory, >> and put it in SIZE bytes of BUF. Returns NULL if the >> directory couldn't be determined or SIZE was too small. >> @@ -30,8 +34,10 @@ char * >> __getcwd (char *buf, size_t size) >> { >> char *r = __getcwd_system (buf, size); >> +#if !IS_IN(rtld) >> if (r == NULL) >> r = __getcwd_generic (buf, size); >> +#endif >> return r; >> } >> libc_hidden_def (__getcwd) > > Right, that's what I had in mind. > >> diff --git a/sysdeps/unix/sysv/linux/getcwd-system.c b/sysdeps/unix/sysv/linux/getcwd-system.c >> index a7e8535b72..8526b1465b 100644 >> --- a/sysdeps/unix/sysv/linux/getcwd-system.c >> +++ b/sysdeps/unix/sysv/linux/getcwd-system.c >> @@ -20,18 +20,11 @@ >> #include >> #include >> >> -/* If we compile the file for use in ld.so we don't need the feature >> - that getcwd() allocates the buffers itself. */ >> -#if IS_IN (rtld) >> -# define NO_ALLOCATION 1 >> -#endif >> - >> char * >> __getcwd_system (char *buf, size_t size) >> { >> char *path; >> >> -#ifndef NO_ALLOCATION >> size_t alloc_size = size; >> if (size == 0) >> { >> @@ -51,9 +44,6 @@ __getcwd_system (char *buf, size_t size) >> return NULL; >> } >> else >> -#else >> -# define alloc_size size >> -#endif >> path = buf; >> >> int retval; > > That part I'm less sure about. I think this could allocate a 64K page > that's never freed? Maybe that's a bit excessive. The original patch limits the maximum allocation to PATH_MAX and for a successful __NR_getcwd syscall the memory will be realloced to fit the returned size from kernel. So the worst case of returning the maximum allocation size would just happen if realloc fails. Another possibility would be to use the the scratch_buffer strategy I used on my realpath Linux optimization [1]: call __NR_getcwd in a loop and either return the strdup if scratch_buffer did not allocated memory or the resulting buffer otherwise. I think once the realpath is up I can send a patch with this strategy, but it trades some performance (to avoid calling realloc) with some extra syscalls in case or large paths. [1] https://sourceware.org/pipermail/libc-alpha/2020-August/116935.html