From patchwork Tue Jan 26 16:01:21 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Derrick Stolee X-Patchwork-Id: 12047311 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=-12.8 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,SPF_HELO_NONE,SPF_PASS 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 E4B8EC433E0 for ; Tue, 26 Jan 2021 16:09:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A85C12082D for ; Tue, 26 Jan 2021 16:09:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404380AbhAZQGI (ORCPT ); Tue, 26 Jan 2021 11:06:08 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37728 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404633AbhAZQC7 (ORCPT ); Tue, 26 Jan 2021 11:02:59 -0500 Received: from mail-wr1-x42c.google.com (mail-wr1-x42c.google.com [IPv6:2a00:1450:4864:20::42c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D624CC0698C6 for ; Tue, 26 Jan 2021 08:01:40 -0800 (PST) Received: by mail-wr1-x42c.google.com with SMTP id 7so17030706wrz.0 for ; Tue, 26 Jan 2021 08:01:40 -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=IVzb1Uw8OscK/sUGg6fnMfB7FooZ5hvv1wQJ6LJPxtc=; b=E/bnB1tABI+6hzYIT3mOfJbaiqWTVa6bSJE4vg3MxIEEh0c3yMDOtAjP+lqprmfy3K mkOnHC9P7X22DkKlQLQz/358o+SFwj6oOKoJeOPcCTmVIVRZ/sEm9jjkOsO26nsfXPDz zPXkL4zT5ann1AqYKXT0jDZBt1SI6Ppqk32hT5zC+mwgsg4phLh+B3qmZPgN/S6t5YL6 zoaY5Q56wTyJHkR5tIh8qce/QHwHw7zkLqRN2WbjkTRHrU96pNqoW9ivup7iYSIGuwHe 5hhcXWOZi5ssd7VDXI+I+YLlebHajiq4iPWOoMZe5BVB4yfmASI3cBVBgmfy6W+78As+ 7mmA== 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=IVzb1Uw8OscK/sUGg6fnMfB7FooZ5hvv1wQJ6LJPxtc=; b=OpdrjBAaDa4dTX5RargIZQ9YcpuA6tdBwWa38mun0q0667MJ/9TvA+sZWVwH7/cszr bQ7YmK7xIWG/rZd+YbRKAfi4mZtBA75ZVzSSbO1j3/cVLtp/aHw/kunbVimUPXhPs0Hk FojQFg0RGNgOoPJRzlj+IDnY3ogPkjQWfSh30icMRT4/Sl26u/KQEM9Gw2/TQ0RCH2Xg qPV9qXR2ClUS2bTL26XnnGkOvdSh8t6I7YSOKBqFR4SLSxwZN7X3boQq8IXg+TEUqSVi 2GpywKILofHX//IOZ2kVaXYb+e/kmPC3yPXmxjKr9mFZ8HDTCHrn7gw93kyq7buWDnJB Y39Q== X-Gm-Message-State: AOAM530c2xAxnAwUAL8TaZKhC+jmpbFMU6epXaozL0phnFS3igDaMHXY Q5Otul9vxzpl3I4lurzZZsXOfnHi9PM= X-Google-Smtp-Source: ABdhPJwtWWc57xHBhOlce1m/GovXvyMHlLMWqlOAC+HRsQjbkX16hZd/pRe7pYVOdyY83vOja4B8Xw== X-Received: by 2002:adf:d1cb:: with SMTP id b11mr6984727wrd.118.1611676899395; Tue, 26 Jan 2021 08:01:39 -0800 (PST) Received: from [127.0.0.1] ([13.74.141.28]) by smtp.gmail.com with ESMTPSA id w25sm3136289wmc.42.2021.01.26.08.01.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 26 Jan 2021 08:01:38 -0800 (PST) Message-Id: In-Reply-To: References: Date: Tue, 26 Jan 2021 16:01:21 +0000 Subject: [PATCH 12/17] chunk-format: create read chunk API Fcc: Sent MIME-Version: 1.0 To: git@vger.kernel.org Cc: me@ttaylorr.com, gitster@pobox.com, l.s.r@web.de, szeder.dev@gmail.com, Derrick Stolee , Derrick Stolee Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org From: Derrick Stolee From: Derrick Stolee Add the capability to read the table of contents, then pair the chunks with necessary logic using read_chunk_fn pointers. Callers will be added in future changes, but the typical outline will be: 1. initialize a 'struct chunkfile' with init_chunkfile(NULL). 2. call read_table_of_contents(). 3. for each chunk to parse, call pair_chunk() with appropriate pointers. 4. call free_chunkfile() to clear the 'struct chunkfile' data. We are re-using the anonymous 'struct chunkfile' data, as it is internal to the chunk-format API. This gives it essentially two modes: write and read. If the same struct instance was used for both reads and writes, then there would be failures. Signed-off-by: Derrick Stolee --- chunk-format.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++ chunk-format.h | 21 +++++++++++++++++ 2 files changed, 85 insertions(+) diff --git a/chunk-format.c b/chunk-format.c index 2ce37ecc6bb..674d31d5e58 100644 --- a/chunk-format.c +++ b/chunk-format.c @@ -12,6 +12,8 @@ struct chunk_info { uint32_t id; uint64_t size; chunk_write_fn write_fn; + + const void *start; }; struct chunkfile { @@ -89,3 +91,65 @@ int write_chunkfile(struct chunkfile *cf, void *data) return 0; } + +int read_table_of_contents(struct chunkfile *cf, + const unsigned char *mfile, + size_t mfile_size, + uint64_t toc_offset, + int toc_length) +{ + uint32_t chunk_id; + const unsigned char *table_of_contents = mfile + toc_offset; + + ALLOC_GROW(cf->chunks, toc_length, cf->chunks_alloc); + + while (toc_length--) { + uint64_t chunk_offset, next_chunk_offset; + + chunk_id = get_be32(table_of_contents); + chunk_offset = get_be64(table_of_contents + 4); + + if (!chunk_id) { + error(_("terminating chunk id appears earlier than expected")); + return 1; + } + + table_of_contents += CHUNK_LOOKUP_WIDTH; + next_chunk_offset = get_be64(table_of_contents + 4); + + if (next_chunk_offset < chunk_offset || + next_chunk_offset > mfile_size - the_hash_algo->rawsz) { + error(_("improper chunk offset(s) %"PRIx64" and %"PRIx64""), + chunk_offset, next_chunk_offset); + return -1; + } + + cf->chunks[cf->chunks_nr].id = chunk_id; + cf->chunks[cf->chunks_nr].start = mfile + chunk_offset; + cf->chunks[cf->chunks_nr].size = next_chunk_offset - chunk_offset; + cf->chunks_nr++; + } + + chunk_id = get_be32(table_of_contents); + if (chunk_id) { + error(_("final chunk has non-zero id %"PRIx32""), chunk_id); + return -1; + } + + return 0; +} + +int pair_chunk(struct chunkfile *cf, + uint32_t chunk_id, + chunk_read_fn fn, + void *data) +{ + int i; + + for (i = 0; i < cf->chunks_nr; i++) { + if (cf->chunks[i].id == chunk_id) + return fn(cf->chunks[i].start, cf->chunks[i].size, data); + } + + return CHUNK_NOT_FOUND; +} diff --git a/chunk-format.h b/chunk-format.h index bfaed672813..250e08b8e6a 100644 --- a/chunk-format.h +++ b/chunk-format.h @@ -17,4 +17,25 @@ void add_chunk(struct chunkfile *cf, size_t size); int write_chunkfile(struct chunkfile *cf, void *data); +int read_table_of_contents(struct chunkfile *cf, + const unsigned char *mfile, + size_t mfile_size, + uint64_t toc_offset, + int toc_length); + +/* + * When reading a table of contents, we find the chunk with matching 'id' + * then call its read_fn to populate the necessary 'data' based on the + * chunk start and size. + */ +typedef int (*chunk_read_fn)(const unsigned char *chunk_start, + size_t chunk_size, void *data); + + +#define CHUNK_NOT_FOUND (-2) +int pair_chunk(struct chunkfile *cf, + uint32_t chunk_id, + chunk_read_fn fn, + void *data); + #endif