cosmopolitan/libc/stdio/fwrite_unlocked.c
2024-08-04 12:52:25 -07:00

147 lines
4.9 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et ft=c ts=8 sts=2 sw=2 fenc=utf-8 :vi │
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/calls.h"
#include "libc/calls/struct/iovec.internal.h"
#include "libc/errno.h"
#include "libc/fmt/conv.h"
#include "libc/macros.h"
#include "libc/stdckdint.h"
#include "libc/stdio/internal.h"
#include "libc/stdio/stdio.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/o.h"
static ssize_t writevall(int fd, struct iovec *iov, int iovlen) {
int olde;
ssize_t rc;
size_t got, toto;
toto = 0;
olde = errno;
do {
if ((rc = writev(fd, iov, iovlen)) == -1) {
if (toto && errno == EINTR) {
errno = olde;
continue;
}
return -1;
}
got = rc;
toto += got;
for (;;) {
if (!iov->iov_len) {
--iovlen;
++iov;
} else if (got >= iov->iov_len) {
got -= iov->iov_len;
--iovlen;
++iov;
} else {
iov->iov_base += got;
iov->iov_len -= got;
break;
}
}
} while (got && iovlen);
return toto;
}
/**
* Writes data to stream.
*
* @param stride specifies the size of individual items
* @param count is the number of strides to write
* @return count on success, [0,count) on EOF, 0 on error or count==0
*/
size_t fwrite_unlocked(const void *data, size_t stride, size_t count, FILE *f) {
ldiv_t d;
ssize_t rc;
size_t n, m;
const char *p;
struct iovec iov[2];
if (!stride || !count) {
return 0;
}
if ((f->iomode & O_ACCMODE) == O_RDONLY) {
f->state = errno = EBADF;
return 0;
}
if (ckd_mul(&n, stride, count)) {
f->state = errno = EOVERFLOW;
return 0;
}
m = f->size - f->beg;
if (n <= m && f->bufmode != _IONBF) {
// this isn't an unbuffered stream, and
// there's enough room in the buffer for the request
memcpy(f->buf + f->beg, data, n);
f->beg += n;
if (f->fd != -1 && f->bufmode == _IOLBF &&
(p = memrchr(f->buf, '\n', f->beg))) {
// write out as many lines as possible
n = p + 1 - f->buf;
if ((rc = write(f->fd, f->buf, n)) == -1) {
// the write() system call failed
if (errno == EINTR || errno == EAGAIN) {
return count;
} else {
f->state = errno;
return 0;
}
}
// copy backwards last line fragment or uncompleted data
n = rc;
if (f->beg - n) {
memmove(f->buf, f->buf + n, f->beg - n);
}
f->beg -= n;
}
return count;
}
// what's happening is either
// (1) a fully buffered stream, or
// (2) no room in buffer to hold full request
if (f->fd == -1) {
// this is an in-memory stream
// store as much of request as we can hold
n = MIN(n, m);
d = ldiv(n, stride);
n -= d.rem;
if (n) {
memcpy(f->buf + f->beg, data, n);
f->beg += n;
}
// trigger eof condition
f->state = EOF;
return d.quot;
}
// perform a fragmented write
// (1) we avoid needless copies in fully buffered mode
// (2) we avoid need for malloc() when it's out of room
iov[0].iov_base = f->buf;
iov[0].iov_len = f->beg;
iov[1].iov_base = (void *)data;
iov[1].iov_len = n;
n += f->beg;
if ((rc = writevall(f->fd, iov, 2)) == -1) {
f->state = errno;
return 0;
}
f->beg = 0;
return count;
}