1 files changed, 89 insertions, 0 deletions
diff --git a/stdio/fwrite.c b/stdio/fwrite.c
new file mode 100644
index 0000000..30f1000
--- /dev/null
+++ b/stdio/fwrite.c
@@ -0,0 +1,89 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net 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.h"
+#include "libc/errno.h"
+#include "libc/fmt/conv.h"
+#include "libc/macros.internal.h"
+#include "libc/runtime/runtime.h"
+#include "libc/sock/sock.h"
+#include "libc/stdio/internal.h"
+#include "libc/stdio/stdio.h"
+#include "libc/str/str.h"
+#include "libc/sysv/consts/o.h"
+
+/**
+ * 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(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 ((f->iomode & O_ACCMODE) == O_RDONLY) {
+    f->state = errno = EBADF;
+    return 0;
+  }
+  n = stride * count;
+  m = f->size - f->beg;
+  if (n <= m && f->bufmode != _IONBF) {
+    memcpy(f->buf + f->beg, data, n);
+    f->beg += n;
+    if (f->fd != -1 && f->bufmode == _IOLBF &&
+        (p = memrchr(f->buf, '\n', f->beg))) {
+      n = p + 1 - f->buf;
+      if ((rc = write(f->fd, f->buf, n)) == -1) {
+        if (errno == EINTR || errno == EAGAIN) return count;
+        f->state = errno;
+        return 0;
+      }
+      n = rc;
+      memmove(f->buf, f->buf + n, f->beg - n);
+      f->beg -= n;
+    }
+    return count;
+  }
+  if (f->fd == -1) {
+    n = MIN(n, m);
+    d = ldiv(n, stride);
+    n -= d.rem;
+    memcpy(f->buf + f->beg, data, n);
+    f->beg += n;
+    f->state = -1;
+    return d.quot;
+  }
+  iov[0].iov_base = f->buf;
+  iov[0].iov_len = f->beg;
+  iov[1].iov_base = data;
+  iov[1].iov_len = n;
+  n += f->beg;
+  if ((rc = writev(f->fd, iov, 2)) == -1) {
+    f->state = errno;
+    return 0;
+  }
+  m = rc;
+  if (n != m) abort();
+  f->beg = 0;
+  return count;
+}