1 files changed, 99 insertions, 0 deletions
diff --git a/stdio/fread.c b/stdio/fread.c
new file mode 100644
index 0000000..52fea4d
--- /dev/null
+++ b/stdio/fread.c
@@ -0,0 +1,99 @@
+/*-*- 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/internal.h"
+#include "libc/str/str.h"
+#include "libc/sysv/consts/o.h"
+#include "libc/sysv/errfuns.h"
+
+/**
+ * Reads data from stream.
+ *
+ * @param stride specifies the size of individual items
+ * @param count is the number of strides to fetch
+ * @return count on success, [0,count) on eof, or 0 on error or count==0
+ */
+size_t fread(void *buf, size_t stride, size_t count, FILE *f) {
+  char *p;
+  ssize_t rc;
+  size_t n, m;
+  struct iovec iov[2];
+  if ((f->iomode & O_ACCMODE) == O_WRONLY) {
+    f->state = errno = EBADF;
+    return 0;
+  }
+  if (f->beg > f->end) {
+    f->state = errno = EINVAL;
+    return 0;
+  }
+  p = buf;
+  n = stride * count;
+  m = f->end - f->beg;
+  memcpy(p, f->buf + f->beg, MIN(n, m));
+  if (n < m) {
+    f->beg += n;
+    return count;
+  }
+  if (n == m) {
+    f->beg = f->end = 0;
+    return count;
+  }
+  if (f->fd == -1) {
+    f->beg = 0;
+    f->end = 0;
+    f->state = -1;
+    return m / stride;
+  }
+  iov[0].iov_base = p + m;
+  iov[0].iov_len = n - m;
+  if (f->bufmode != _IONBF && n < f->size) {
+    iov[1].iov_base = f->buf;
+    if (f->size > PUSHBACK) {
+      iov[1].iov_len = f->size - PUSHBACK;
+    } else {
+      iov[1].iov_len = f->size;
+    }
+  } else {
+    iov[1].iov_base = NULL;
+    iov[1].iov_len = 0;
+  }
+  if ((rc = readv(f->fd, iov, 2)) == -1) {
+    f->state = errno;
+    return 0;
+  }
+  n = rc;
+  f->beg = 0;
+  f->end = 0;
+  if (n > iov[0].iov_len) {
+    f->end += n - iov[0].iov_len;
+    return count;
+  } else {
+    n = (m + n) / stride;
+    if (n < count) f->state = -1;
+    return n;
+  }
+}