90 lines
3.6 KiB
C
90 lines
3.6 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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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/alg/arraylist2.h"
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#include "libc/bits/safemacros.h"
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#include "libc/calls/calls.h"
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#include "libc/calls/struct/stat.h"
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#include "libc/errno.h"
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#include "libc/mem/mem.h"
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#include "libc/str/str.h"
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#include "libc/sysv/consts/madv.h"
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#include "libc/sysv/consts/o.h"
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static size_t getfilesize(int fd) {
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struct stat st;
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st.st_size = 0;
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fstat(fd, &st);
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return st.st_size;
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}
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static size_t smudgefilesize(size_t size) {
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return roundup(size, PAGESIZE) + PAGESIZE;
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}
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/**
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* Reads entire file into memory.
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*
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* This function is fantastic for being lazy. It may waste space if the
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* file is large, but it's implemented in a conscientious way that won't
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* bomb the systemwide page cache. It means performance too, naturally.
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*
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* @return contents which must be free()'d or NULL w/ errno
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*/
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char *slurp(const char *path, size_t *opt_out_readlength) {
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int fd;
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ssize_t rc;
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char *res, *p;
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size_t i, n, got, want;
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res = NULL;
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if ((fd = open(path, O_RDONLY)) == -1) goto Failure;
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n = getfilesize(fd);
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/* TODO(jart): Fix this, it's totally broken */
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if (!(res = valloc(smudgefilesize(n)))) goto Failure;
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if (n > FRAMESIZE) fadvise(fd, 0, n, MADV_SEQUENTIAL);
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i = 0;
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for (;;) {
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want = smudgefilesize(n - i);
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TryAgain:
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if ((rc = read(fd, &res[i], want)) == -1) {
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if (errno == EINTR) goto TryAgain;
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goto Failure;
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}
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got = (size_t)rc;
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if (i + 1 >= n) {
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if ((p = realloc(res, smudgefilesize((n += n >> 1))))) {
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res = p;
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} else {
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goto Failure;
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}
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}
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i += got;
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if (got == 0) break;
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if (got > want) abort();
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}
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if (opt_out_readlength) *opt_out_readlength = i;
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res[i] = '\0';
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close(fd);
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return res;
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Failure:
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free(res);
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close(fd);
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return NULL;
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}
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