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https://github.com/jart/cosmopolitan.git
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0c630d95b5
The build/bootstrap/ar.com program is now tinier. This change reduces its size from 140kb to 53kb. Nothing was traded away. Cosmopolitan Ar performance is now 2x better than llvm-ar largely thanks to using the copy_file_range() system call. This change homebrews a new allocation API that addresses the shortcomings of the C standard library design. Using these new balloc() and reballoc() functions I managed to reduce memory consumption so much that Cosmpolitan Ar should now use roughly 100x fewer bytes of peak resident memory compared to llvm-ar. Correct behavior with better compatibility has been assured. Binary output is now pretty much bit-identical to llvm-ar, as of this change. This can and should be the living proof we need to show that a better world is possible for software.
41 lines
2.7 KiB
C
41 lines
2.7 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/elf/elf.h"
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#include "libc/elf/scalar.h"
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#include "libc/elf/struct/phdr.h"
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/**
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* Returns program header at `elf.phdr[i]`.
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*
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* @param elf points to the start of the executable image
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* @param mapsize is the number of bytes past `elf` we can access
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* @param i is the program header index, starting at zero
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* @return program header pointer, or null on error
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*/
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Elf64_Phdr *GetElfProgramHeaderAddress(const Elf64_Ehdr *elf, //
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size_t mapsize, //
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Elf64_Half i) { //
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Elf64_Off off;
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if (i >= elf->e_phnum) return 0;
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if (elf->e_phoff <= 0) return 0;
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if (elf->e_phoff >= mapsize) return 0;
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if (elf->e_phentsize < sizeof(Elf64_Phdr)) return 0;
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if ((off = elf->e_phoff + (unsigned)i * elf->e_phentsize) > mapsize) return 0;
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return (Elf64_Phdr *)((char *)elf + off);
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}
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