[Xen-changelog] [xen master] libxl: add libxl__random_bytes() which fills a buffer with random bytes

[patchbot@xxxxxxx]

commit 6a2ba5cb7ec7a87a4c2b023f4f0ea61d19fc360a
Author:     David Vrabel <david.vrabel@xxxxxxxxxx>
AuthorDate: Wed Jun 18 17:12:51 2014 +0100
Commit:     Ian Campbell <ian.campbell@xxxxxxxxxx>
CommitDate: Fri Jun 27 14:13:21 2014 +0100

    libxl: add libxl__random_bytes() which fills a buffer with random bytes
    
    The random bytes are obtained from /dev/urandom and are suitable for
    almost all uses (except for generating long-lived secure keys).
    
    Documentation suggests that /dev/urandom is widely available on Unix-like
    systems (such FreeBSD and NetBSD).
    
    A public libxl_random_bytes() (or similar) could be trivially added,
    if this required in the future.
    
    Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
    Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
 tools/libxl/libxl_internal.h |    2 ++
 tools/libxl/libxl_utils.c    |   22 ++++++++++++++++++++++
 2 files changed, 24 insertions(+), 0 deletions(-)

diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index a0d4f24..a9343e8 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -3180,6 +3180,8 @@ int libxl__uint64_parse_json(libxl__gc *gc, const 
libxl__json_object *o,
 int libxl__string_parse_json(libxl__gc *gc, const libxl__json_object *o,
                              char **p);
 
+int libxl__random_bytes(libxl__gc *gc, uint8_t *buf, size_t len);
+
 #endif
 
 /*
diff --git a/tools/libxl/libxl_utils.c b/tools/libxl/libxl_utils.c
index 16b734e..0001ab8 100644
--- a/tools/libxl/libxl_utils.c
+++ b/tools/libxl/libxl_utils.c
@@ -1014,6 +1014,28 @@ int libxl_domid_valid_guest(uint32_t domid)
 }
 
 /*
+ * Fill @buf with @len random bytes.
+ */
+int libxl__random_bytes(libxl__gc *gc, uint8_t *buf, size_t len)
+{
+    static const char *dev = "/dev/urandom";
+    int fd;
+    int ret;
+
+    fd = open(dev, O_RDONLY | O_CLOEXEC);
+    if (fd < 0) {
+        LOGE(ERROR, "failed to open \"%s\"", dev);
+        return ERROR_FAIL;
+    }
+
+    ret = libxl_read_exactly(CTX, fd, buf, len, dev, NULL);
+
+    close(fd);
+
+    return ret;
+}
+
+/*
  * Local variables:
  * mode: C
  * c-basic-offset: 4
--
generated by git-patchbot for /home/xen/git/xen.git#master

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