auto import from //depot/cupcake/@135843

1 files changed, 158 insertions, 0 deletions

diff --git a/libc/stdio/fread.c b/libc/stdio/fread.c
new file mode 100644
index 0000000..9f9977f
--- /dev/null
+++ b/libc/stdio/fread.c
@@ -0,0 +1,158 @@
+/*	$OpenBSD: fread.c,v 1.6 2005/08/08 08:05:36 espie Exp $ */
+/*-
+ * Copyright (c) 1990, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Chris Torek.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include "local.h"
+
+static int
+lflush(FILE *fp)
+{
+
+    if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
+        return (__sflush(fp));
+    return (0);
+}
+
+size_t
+fread(void *buf, size_t size, size_t count, FILE *fp)
+{
+	size_t resid;
+	char *p;
+	int r;
+	size_t total;
+
+	/*
+	 * The ANSI standard requires a return value of 0 for a count
+	 * or a size of 0.  Peculiarily, it imposes no such requirements
+	 * on fwrite; it only requires fread to be broken.
+	 */
+	if ((resid = count * size) == 0)
+		return (0);
+	if (fp->_r < 0)
+		fp->_r = 0;
+	total = resid;
+	p = buf;
+
+#if 1  /* BIONIC: optimize unbuffered reads */
+    if (fp->_flags & __SNBF && fp->_ur == 0)
+    {
+       /* the following comes mainly from __srefill(), with slight
+        * modifications
+        */
+
+        /* make sure stdio is set up */
+        if (!__sdidinit)
+            __sinit();
+
+        fp->_r = 0;     /* largely a convenience for callers */
+
+        /* SysV does not make this test; take it out for compatibility */
+        if (fp->_flags & __SEOF)
+            return (EOF);
+
+        /* if not already reading, have to be reading and writing */
+        if ((fp->_flags & __SRD) == 0) {
+            if ((fp->_flags & __SRW) == 0) {
+                errno = EBADF;
+                fp->_flags |= __SERR;
+                return (EOF);
+            }
+            /* switch to reading */
+            if (fp->_flags & __SWR) {
+                if (__sflush(fp))
+                    return (EOF);
+                fp->_flags &= ~__SWR;
+                fp->_w = 0;
+                fp->_lbfsize = 0;
+            }
+            fp->_flags |= __SRD;
+        } else {
+           /*
+            * We were reading.  If there is an ungetc buffer,
+            * we must have been reading from that.  Drop it,
+            * restoring the previous buffer (if any).  If there
+            * is anything in that buffer, return.
+            */
+            if (HASUB(fp)) {
+                FREEUB(fp);
+            }
+        }
+
+       /*
+        * Before reading from a line buffered or unbuffered file,
+        * flush all line buffered output files, per the ANSI C
+        * standard.
+        */
+
+        if (fp->_flags & (__SLBF|__SNBF))
+            (void) _fwalk(lflush);
+
+        while (resid > 0) {
+            int   len = (*fp->_read)(fp->_cookie, p, resid );
+            fp->_flags &= ~__SMOD;
+            if (len <= 0) {
+                if (len == 0)
+                    fp->_flags |= __SEOF;
+                else {
+                    fp->_flags |= __SERR;
+                }
+                return ((total - resid) / size);
+            }
+            p     += len;
+            resid -= len;
+        }
+        return (count);
+    }
+    else
+#endif
+    {
+        while (resid > (size_t)(r = fp->_r)) {
+            (void)memcpy((void *)p, (void *)fp->_p, (size_t)r);
+            fp->_p += r;
+            /* fp->_r = 0 ... done in __srefill */
+            p += r;
+            resid -= r;
+            if (__srefill(fp)) {
+                /* no more input: return partial result */
+                return ((total - resid) / size);
+            }
+        }
+    }
+
+	(void)memcpy((void *)p, (void *)fp->_p, resid);
+	fp->_r -= resid;
+	fp->_p += resid;
+	return (count);
+}