cosmopolitan/libc/zipos/read.c

45 lines
2.7 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program is distributed in the hope that it will be useful, but │
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/bits/safemacros.h"
#include "libc/calls/internal.h"
#include "libc/calls/struct/iovec.h"
#include "libc/str/str.h"
#include "libc/zipos/zipos.internal.h"
/**
* Reads data from zip store object.
*
* @return [1..size] bytes on success, 0 on EOF, or -1 w/ errno; with
* exception of size==0, in which case return zero means no error
* @asyncsignalsafe
*/
ssize_t __zipos_read(struct ZiposHandle *h, const struct iovec *iov,
size_t iovlen, ssize_t opt_offset) {
size_t i, b, x, y;
x = y = opt_offset != -1 ? opt_offset : h->pos;
for (i = 0; i < iovlen && y < h->size; ++i, y += b) {
b = min(iov[i].iov_len, h->size - y);
memcpy(iov[i].iov_base, h->mem + y, b);
}
if (opt_offset == -1) h->pos = y;
return y - x;
}