New patch to review for coreboot: 0053795 cbfs: add cbfs_read()

[Marc Jones]

Marc Jones ([e-mail]) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/8181

-gerrit

commit 0053795fb7cb35e0d97f2b9b6c6cebdb54aba1e7
Author: Aaron Durbin 
Date:   Fri Jun 27 15:28:39 2014 -0500

cbfs: add cbfs_read()

Allow for reading from cbfs media without having a handle
    to a non-CBFS_DEFAULT_MEDIA cbfs_media. In conjunction with
    cbfs_locate_file() one can locate and cbfs_read() a file
    without bringing the entire file through a potentially
    temporary buffer (non-memory-mappable cbfs media platforms).

BUG=chrome-os-partner:29922
    BRANCH=None
    TEST=Built.

Original-Change-Id: Ib5d965334bce1267650fc23c9e9f496675cf8450
    Original-Signed-off-by: Aaron Durbin 
    Original-Reviewed-on: https://chromium-review.googlesource.com/205991
    Original-Reviewed-by: Furquan Shaikh 
    (cherry picked from commit 85200f28863e5ea8888322f5787dc6de9a2999f0)
    Signed-off-by: Marc Jones

Change-Id: I25e3221beefd0155305ad63da6be9f47e756f7d0
---
 src/include/cbfs_core.h |  4 ++++
 src/lib/cbfs_core.c     | 16 ++++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/src/include/cbfs_core.h b/src/include/cbfs_core.h
index 3cef903..b01a307 100644
--- a/src/include/cbfs_core.h
+++ b/src/include/cbfs_core.h
@@ -224,6 +224,10 @@ struct cbfs_media {
 ssize_t cbfs_locate_file(struct cbfs_media *media, struct cbfs_file *file,
    			const char *name);

+/* Read count bytes at offset into dest. Return number of bytes read. */
+size_t cbfs_read(struct cbfs_media *media, void *dest, size_t offset,
+			size_t count);
+
 /* returns pointer to a file entry inside CBFS or NULL */
 struct cbfs_file *cbfs_get_file(struct cbfs_media *media, const char *name);

diff --git a/src/lib/cbfs_core.c b/src/lib/cbfs_core.c
index 24e5998..6455a07 100644
--- a/src/lib/cbfs_core.c
+++ b/src/lib/cbfs_core.c
@@ -194,6 +194,22 @@ ssize_t cbfs_locate_file(struct cbfs_media *media, struct cbfs_file *file,
    return -1;
 }

+size_t cbfs_read(struct cbfs_media *media, void *dest, size_t offset,
+			size_t count)
+{
+	struct cbfs_media default_media;
+	size_t nread;
+
+	if (init_media(&media, &default_media))
+		return 0;
+
+	media->open(media);
+	nread = media->read(media, dest, offset, count);
+	media->close(media);
+
+	return nread;
+}
+
 struct cbfs_file *cbfs_get_file(struct cbfs_media *media, const char *name)
 {
    struct cbfs_media default_media;