thodg/libgit2/src/hash/hash_generic.c
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Hash : 0c7f49dd
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Date : 2017-06-30T13:39:01
Make sure to always include "common.h" first Next to including several files, our "common.h" header also declares various macros which are then used throughout the project. As such, we have to make sure to always include this file first in all implementation files. Otherwise, we might encounter problems or even silent behavioural differences due to macros or defines not being defined as they should be. So in fact, our header and implementation files should make sure to always include "common.h" first. This commit does so by establishing a common include pattern. Header files inside of "src" will now always include "common.h" as its first other file, separated by a newline from all the other includes to make it stand out as special. There are two cases for the implementation files. If they do have a matching header file, they will always include this one first, leading to "common.h" being transitively included as first file. If they do not have a matching header file, they instead include "common.h" as first file themselves. This fixes the outlined problems and will become our standard practice for header and source files inside of the "src/" from now on.
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src/hash/hash_generic.c
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/* * Copyright (C) the libgit2 contributors. All rights reserved. * * This file is part of libgit2, distributed under the GNU GPL v2 with * a Linking Exception. For full terms see the included COPYING file. */ #include "hash_generic.h" #include "hash.h" #if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__)) /* * Force usage of rol or ror by selecting the one with the smaller constant. * It _can_ generate slightly smaller code (a constant of 1 is special), but * perhaps more importantly it's possibly faster on any uarch that does a * rotate with a loop. */ #define SHA_ASM(op, x, n) (__extension__ ({ unsigned int __res; __asm__(op " %1,%0":"=r" (__res):"i" (n), "0" (x)); __res; })) #define SHA_ROL(x,n) SHA_ASM("rol", x, n) #define SHA_ROR(x,n) SHA_ASM("ror", x, n) #else #define SHA_ROT(X,l,r) (((X) << (l)) | ((X) >> (r))) #define SHA_ROL(X,n) SHA_ROT(X,n,32-(n)) #define SHA_ROR(X,n) SHA_ROT(X,32-(n),n) #endif /* * If you have 32 registers or more, the compiler can (and should) * try to change the array[] accesses into registers. However, on * machines with less than ~25 registers, that won't really work, * and at least gcc will make an unholy mess of it. * * So to avoid that mess which just slows things down, we force * the stores to memory to actually happen (we might be better off * with a 'W(t)=(val);asm("":"+m" (W(t))' there instead, as * suggested by Artur Skawina - that will also make gcc unable to * try to do the silly "optimize away loads" part because it won't * see what the value will be). * * Ben Herrenschmidt reports that on PPC, the C version comes close * to the optimized asm with this (ie on PPC you don't want that * 'volatile', since there are lots of registers). * * On ARM we get the best code generation by forcing a full memory barrier * between each SHA_ROUND, otherwise gcc happily get wild with spilling and * the stack frame size simply explode and performance goes down the drain. */ #if defined(__i386__) || defined(__x86_64__) #define setW(x, val) (*(volatile unsigned int *)&W(x) = (val)) #elif defined(__GNUC__) && defined(__arm__) #define setW(x, val) do { W(x) = (val); __asm__("":::"memory"); } while (0) #else #define setW(x, val) (W(x) = (val)) #endif /* * Performance might be improved if the CPU architecture is OK with * unaligned 32-bit loads and a fast ntohl() is available. * Otherwise fall back to byte loads and shifts which is portable, * and is faster on architectures with memory alignment issues. */ #if defined(__i386__) || defined(__x86_64__) || \ defined(_M_IX86) || defined(_M_X64) || \ defined(__ppc__) || defined(__ppc64__) || \ defined(__powerpc__) || defined(__powerpc64__) || \ defined(__s390__) || defined(__s390x__) #define get_be32(p) ntohl(*(const unsigned int *)(p)) #define put_be32(p, v) do { *(unsigned int *)(p) = htonl(v); } while (0) #else #define get_be32(p) ( \ (*((const unsigned char *)(p) + 0) << 24) | \ (*((const unsigned char *)(p) + 1) << 16) | \ (*((const unsigned char *)(p) + 2) << 8) | \ (*((const unsigned char *)(p) + 3) << 0) ) #define put_be32(p, v) do { \ unsigned int __v = (v); \ *((unsigned char *)(p) + 0) = __v >> 24; \ *((unsigned char *)(p) + 1) = __v >> 16; \ *((unsigned char *)(p) + 2) = __v >> 8; \ *((unsigned char *)(p) + 3) = __v >> 0; } while (0) #endif /* This "rolls" over the 512-bit array */ #define W(x) (array[(x)&15]) /* * Where do we get the source from? The first 16 iterations get it from * the input data, the next mix it from the 512-bit array. */ #define SHA_SRC(t) get_be32(data + t) #define SHA_MIX(t) SHA_ROL(W(t+13) ^ W(t+8) ^ W(t+2) ^ W(t), 1) #define SHA_ROUND(t, input, fn, constant, A, B, C, D, E) do { \ unsigned int TEMP = input(t); setW(t, TEMP); \ E += TEMP + SHA_ROL(A,5) + (fn) + (constant); \ B = SHA_ROR(B, 2); } while (0) #define T_0_15(t, A, B, C, D, E) SHA_ROUND(t, SHA_SRC, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E ) #define T_16_19(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E ) #define T_20_39(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0x6ed9eba1, A, B, C, D, E ) #define T_40_59(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, ((B&C)+(D&(B^C))) , 0x8f1bbcdc, A, B, C, D, E ) #define T_60_79(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0xca62c1d6, A, B, C, D, E ) static void hash__block(git_hash_ctx *ctx, const unsigned int *data) { unsigned int A,B,C,D,E; unsigned int array[16]; A = ctx->H[0]; B = ctx->H[1]; C = ctx->H[2]; D = ctx->H[3]; E = ctx->H[4]; /* Round 1 - iterations 0-16 take their input from 'data' */ T_0_15( 0, A, B, C, D, E); T_0_15( 1, E, A, B, C, D); T_0_15( 2, D, E, A, B, C); T_0_15( 3, C, D, E, A, B); T_0_15( 4, B, C, D, E, A); T_0_15( 5, A, B, C, D, E); T_0_15( 6, E, A, B, C, D); T_0_15( 7, D, E, A, B, C); T_0_15( 8, C, D, E, A, B); T_0_15( 9, B, C, D, E, A); T_0_15(10, A, B, C, D, E); T_0_15(11, E, A, B, C, D); T_0_15(12, D, E, A, B, C); T_0_15(13, C, D, E, A, B); T_0_15(14, B, C, D, E, A); T_0_15(15, A, B, C, D, E); /* Round 1 - tail. Input from 512-bit mixing array */ T_16_19(16, E, A, B, C, D); T_16_19(17, D, E, A, B, C); T_16_19(18, C, D, E, A, B); T_16_19(19, B, C, D, E, A); /* Round 2 */ T_20_39(20, A, B, C, D, E); T_20_39(21, E, A, B, C, D); T_20_39(22, D, E, A, B, C); T_20_39(23, C, D, E, A, B); T_20_39(24, B, C, D, E, A); T_20_39(25, A, B, C, D, E); T_20_39(26, E, A, B, C, D); T_20_39(27, D, E, A, B, C); T_20_39(28, C, D, E, A, B); T_20_39(29, B, C, D, E, A); T_20_39(30, A, B, C, D, E); T_20_39(31, E, A, B, C, D); T_20_39(32, D, E, A, B, C); T_20_39(33, C, D, E, A, B); T_20_39(34, B, C, D, E, A); T_20_39(35, A, B, C, D, E); T_20_39(36, E, A, B, C, D); T_20_39(37, D, E, A, B, C); T_20_39(38, C, D, E, A, B); T_20_39(39, B, C, D, E, A); /* Round 3 */ T_40_59(40, A, B, C, D, E); T_40_59(41, E, A, B, C, D); T_40_59(42, D, E, A, B, C); T_40_59(43, C, D, E, A, B); T_40_59(44, B, C, D, E, A); T_40_59(45, A, B, C, D, E); T_40_59(46, E, A, B, C, D); T_40_59(47, D, E, A, B, C); T_40_59(48, C, D, E, A, B); T_40_59(49, B, C, D, E, A); T_40_59(50, A, B, C, D, E); T_40_59(51, E, A, B, C, D); T_40_59(52, D, E, A, B, C); T_40_59(53, C, D, E, A, B); T_40_59(54, B, C, D, E, A); T_40_59(55, A, B, C, D, E); T_40_59(56, E, A, B, C, D); T_40_59(57, D, E, A, B, C); T_40_59(58, C, D, E, A, B); T_40_59(59, B, C, D, E, A); /* Round 4 */ T_60_79(60, A, B, C, D, E); T_60_79(61, E, A, B, C, D); T_60_79(62, D, E, A, B, C); T_60_79(63, C, D, E, A, B); T_60_79(64, B, C, D, E, A); T_60_79(65, A, B, C, D, E); T_60_79(66, E, A, B, C, D); T_60_79(67, D, E, A, B, C); T_60_79(68, C, D, E, A, B); T_60_79(69, B, C, D, E, A); T_60_79(70, A, B, C, D, E); T_60_79(71, E, A, B, C, D); T_60_79(72, D, E, A, B, C); T_60_79(73, C, D, E, A, B); T_60_79(74, B, C, D, E, A); T_60_79(75, A, B, C, D, E); T_60_79(76, E, A, B, C, D); T_60_79(77, D, E, A, B, C); T_60_79(78, C, D, E, A, B); T_60_79(79, B, C, D, E, A); ctx->H[0] += A; ctx->H[1] += B; ctx->H[2] += C; ctx->H[3] += D; ctx->H[4] += E; } int git_hash_init(git_hash_ctx *ctx) { ctx->size = 0; /* Initialize H with the magic constants (see FIPS180 for constants) */ ctx->H[0] = 0x67452301; ctx->H[1] = 0xefcdab89; ctx->H[2] = 0x98badcfe; ctx->H[3] = 0x10325476; ctx->H[4] = 0xc3d2e1f0; return 0; } int git_hash_update(git_hash_ctx *ctx, const void *data, size_t len) { unsigned int lenW = ctx->size & 63; ctx->size += len; /* Read the data into W and process blocks as they get full */ if (lenW) { unsigned int left = 64 - lenW; if (len < left) left = (unsigned int)len; memcpy(lenW + (char *)ctx->W, data, left); lenW = (lenW + left) & 63; len -= left; data = ((const char *)data + left); if (lenW) return 0; hash__block(ctx, ctx->W); } while (len >= 64) { hash__block(ctx, data); data = ((const char *)data + 64); len -= 64; } if (len) memcpy(ctx->W, data, len); return 0; } int git_hash_final(git_oid *out, git_hash_ctx *ctx) { static const unsigned char pad[64] = { 0x80 }; unsigned int padlen[2]; int i; /* Pad with a binary 1 (ie 0x80), then zeroes, then length */ padlen[0] = htonl((uint32_t)(ctx->size >> 29)); padlen[1] = htonl((uint32_t)(ctx->size << 3)); i = ctx->size & 63; git_hash_update(ctx, pad, 1+ (63 & (55 - i))); git_hash_update(ctx, padlen, 8); /* Output hash */ for (i = 0; i < 5; i++) put_be32(out->id + i*4, ctx->H[i]); return 0; }