Very first cut at a klibc-derived C library for com32

1 files changed, 92 insertions, 0 deletions

diff --git a/com32/lib/sys/read.c b/com32/lib/sys/read.c
new file mode 100644
index 00000000..1c16ce47
--- /dev/null
+++ b/com32/lib/sys/read.c
@@ -0,0 +1,92 @@
+#ident "$Id$"
+/* ----------------------------------------------------------------------- *
+ *   
+ *   Copyright 2004 H. Peter Anvin - All Rights Reserved
+ *
+ *   Permission is hereby granted, free of charge, to any person
+ *   obtaining a copy of this software and associated documentation
+ *   files (the "Software"), to deal in the Software without
+ *   restriction, including without limitation the rights to use,
+ *   copy, modify, merge, publish, distribute, sublicense, and/or
+ *   sell copies of the Software, and to permit persons to whom
+ *   the Software is furnished to do so, subject to the following
+ *   conditions:
+ *   
+ *   The above copyright notice and this permission notice shall
+ *   be included in all copies or substantial portions of the Software.
+ *   
+ *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ *   OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * read.c
+ *
+ * Reading from a file
+ */
+
+#include <errno.h>
+#include <string.h>
+#include <com32.h>
+#include <minmax.h>
+#include "file.h"
+
+ssize_t read(int fd, void *buf, size_t count)
+{
+  com32sys_t ireg, oreg;
+  struct file_info *fp = &__file_info[fd];
+  char *bufp = buf;
+  size_t n = 0;
+  size_t ncopy;
+
+  if ( fd >= NFILES || fp->blocklg2 == 0 ) {
+    errno = EBADF;
+    return -1;
+  }
+
+  memset(&ireg, 0, sizeof ireg);
+  ireg.eax.w[0] = 0x0007;	/* Read file */
+  ireg.esi.w[0] = OFFS(__com32.cs_bounce);
+  ireg.es = SEG(__com32.cs_bounce);
+
+  while ( count ) {
+    if ( fp->nbytes == 0 ) {
+      if ( fp->offset >= fp->length || !fp->filedes )
+	return n;		/* As good as it gets... */
+
+      ireg.esi.w[0] = fp->filedes;
+      ireg.ecx.w[0] = MAXBLOCK >> fp->blocklg2;
+      
+      __intcall(0x22, &ireg, &oreg);
+
+      if ( oreg.eflags.l & EFLAGS_CF ) {
+	errno = EIO;
+	return -1;
+      }
+
+      fp->filedes = ireg.esi.w[0];
+      fp->nbytes = min(fp->length-fp->offset, (unsigned)MAXBLOCK);
+      fp->datap = fp->buf;
+      memcpy(fp->buf, __com32.cs_bounce, fp->nbytes);
+    }
+
+    ncopy = min(count, fp->nbytes);
+    memcpy(bufp, fp->datap, ncopy);
+
+    n += ncopy;
+    bufp += ncopy;
+    count -= ncopy;
+    fp->datap += ncopy;
+    fp->offset += ncopy;
+    fp->nbytes -= ncopy;
+  }
+
+  return n;
+}