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https://github.com/jart/cosmopolitan.git
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5b42c810a5
This change brings the /zip/... read-only filesystem into performance parity with the native Linux filesystem which doesn't use compression therefore, imagine how much faster this could be with bloom filtering rather than simple binary search, and if we used zstd instead of zlib
105 lines
4.2 KiB
C
105 lines
4.2 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 2023 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/macros.internal.h"
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#include "libc/runtime/zipos.internal.h"
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#include "libc/str/str.h"
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#include "libc/sysv/consts/s.h"
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#include "libc/sysv/errfuns.h"
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#include "libc/zip.internal.h"
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ssize_t __zipos_scan(struct Zipos *zipos, struct ZiposUri *name) {
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// strip trailing slash from search name
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int len = name->len;
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if (len && name->path[len - 1] == '/') {
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--len;
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}
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// empty string means the /zip root directory
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if (!len) {
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return ZIPOS_SYNTHETIC_DIRECTORY;
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}
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// binary search for leftmost name in central directory
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int l = 0;
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int r = zipos->records;
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while (l < r) {
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int m = (l & r) + ((l ^ r) >> 1); // floor((a+b)/2)
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const char *xp = ZIP_CFILE_NAME(zipos->map + zipos->index[m]);
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const char *yp = name->path;
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int xn = ZIP_CFILE_NAMESIZE(zipos->map + zipos->index[m]);
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int yn = len;
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int n = MIN(xn, yn);
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int c;
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if (n) {
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if (!(c = memcmp(xp, yp, n))) {
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c = xn - yn; // xn and yn are 16-bit
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}
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} else {
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c = xn - yn;
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}
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if (c < 0) {
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l = m + 1;
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} else {
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r = m;
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}
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}
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// return pointer to leftmost record if it matches
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if (l < zipos->records) {
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size_t cfile = zipos->index[l];
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const char *zname = ZIP_CFILE_NAME(zipos->map + cfile);
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int zsize = ZIP_CFILE_NAMESIZE(zipos->map + cfile);
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if ((len == zsize || (len + 1 == zsize && zname[len] == '/')) &&
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!memcmp(name->path, zname, len)) {
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return cfile;
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} else if (len + 1 < zsize && zname[len] == '/' &&
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!memcmp(name->path, zname, len)) {
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return ZIPOS_SYNTHETIC_DIRECTORY;
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}
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}
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// otherwise return not found
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return -1;
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}
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// support code for open(), stat(), and access()
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ssize_t __zipos_find(struct Zipos *zipos, struct ZiposUri *name) {
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ssize_t cf;
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if ((cf = __zipos_scan(zipos, name)) == -1) {
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// test if parent component exists that isn't a directory
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char *p;
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while ((p = memrchr(name->path, '/', name->len))) {
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name->path[name->len = p - name->path] = 0;
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if ((cf = __zipos_scan(zipos, name)) != -1 &&
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cf != ZIPOS_SYNTHETIC_DIRECTORY &&
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!S_ISDIR(GetZipCfileMode(zipos->map + cf))) {
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return enotdir();
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}
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}
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return enoent();
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}
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// test if we're opening "foo/" and "foo" isn't a directory
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if (cf != ZIPOS_SYNTHETIC_DIRECTORY && //
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name->len && name->path[name->len - 1] == '/' &&
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!S_ISDIR(GetZipCfileMode(zipos->map + cf))) {
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return enotdir();
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}
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return cf;
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}
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