loader: Add load_image_size() to replace load_image()

A subsequent patch to ppc/spapr needs to load the RTAS blob into
qemu memory rather than target memory (so it can later be copied
into the right spot at machine reset time).

I would use load_image() but it is marked deprecated because it
doesn't take a buffer size as argument, so let's add load_image_size()
that does.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
[aik: fixed errors from checkpatch.pl]
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Alexander Graf <agraf@suse.de>

hw/core/loader.c

@@ -89,6 +89,27 @@ int load_image(const char *filename, uint8_t *addr)
     return size;
 }
 
+/* return the size or -1 if error */
+ssize_t load_image_size(const char *filename, void *addr, size_t size)
+{
+    int fd;
+    ssize_t actsize;
+
+    fd = open(filename, O_RDONLY | O_BINARY);
+    if (fd < 0) {
+        return -1;
+    }
+
+    actsize = read(fd, addr, size);
+    if (actsize < 0) {
+        close(fd);
+        return -1;
+    }
+    close(fd);
+
+    return actsize;
+}
+
 /* read()-like version */
 ssize_t read_targphys(const char *name,
                       int fd, hwaddr dst_addr, size_t nbytes)

include/hw/loader.h

@@ -13,6 +13,7 @@
  */
 int get_image_size(const char *filename);
 int load_image(const char *filename, uint8_t *addr); /* deprecated */
+ssize_t load_image_size(const char *filename, void *addr, size_t size);
 int load_image_targphys(const char *filename, hwaddr,
                         uint64_t max_sz);
 int load_image_gzipped(const char *filename, hwaddr addr, uint64_t max_sz);