Libguestfs - Nov 2017 - [PATCH 0/3] Small improvements and fixes to urandom.

Small improvements and fixes to urandom.

---
 customize/urandom.ml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/customize/urandom.ml b/customize/urandom.ml
index 3686f77d2..fd8cc8e8f 100644
--- a/customize/urandom.ml
+++ b/customize/urandom.ml
@@ -26,7 +26,7 @@
 
 open Unix
 
-let open_urandom_fd () = openfile "/dev/urandom" [O_RDONLY] 0
+let open_urandom_fd () = openfile "/dev/urandom" [O_RDONLY;
O_CLOEXEC] 0
 
 let read_byte fd    let b = Bytes.make 1 ' ' in
-- 
2.13.2

---
 customize/urandom.ml | 26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/customize/urandom.ml b/customize/urandom.ml
index fd8cc8e8f..ff5d028d4 100644
--- a/customize/urandom.ml
+++ b/customize/urandom.ml
@@ -26,13 +26,12 @@
 
 open Unix
 
-let open_urandom_fd () = openfile "/dev/urandom" [O_RDONLY;
O_CLOEXEC] 0
+open Std_utils
 
 let read_byte fd    let b = Bytes.make 1 ' ' in
   fun () ->
     if read fd b 0 1 = 0 then (
-      close fd;
       raise End_of_file
     );
     Char.code (Bytes.unsafe_get b 0)
@@ -40,11 +39,12 @@ let read_byte fd  let urandom_bytes n    assert (n > 0);
   let ret = Bytes.make n ' ' in
-  let fd = open_urandom_fd () in
-  for i = 0 to n-1 do
-    Bytes.unsafe_set ret i (Char.chr (read_byte fd ()))
-  done;
-  close fd;
+  with_openfile "/dev/urandom" [O_RDONLY; O_CLOEXEC] 0 (
+    fun fd ->
+      for i = 0 to n-1 do
+        Bytes.unsafe_set ret i (Char.chr (read_byte fd ()))
+      done
+  );
   Bytes.to_string ret
 
 (* Return a random number uniformly distributed in [0, upper_bound)
@@ -61,9 +61,11 @@ let urandom_uniform n chars    assert (nr_chars > 0);
 
   let ret = Bytes.make n ' ' in
-  let fd = open_urandom_fd () in
-  for i = 0 to n-1 do
-    Bytes.unsafe_set ret i (chars.[uniform_random (read_byte fd) nr_chars])
-  done;
-  close fd;
+  with_openfile "/dev/urandom" [O_RDONLY; O_CLOEXEC] 0 (
+    fun fd ->
+      for i = 0 to n-1 do
+        Bytes.unsafe_set ret i
+                         (chars.[uniform_random (read_byte fd) nr_chars])
+      done
+  );
   Bytes.to_string ret
-- 
2.13.2

This is an unexpected error, so fail hard instead of leaking
End_of_file exception.

Nothing that calls into the Urandom module expects or handles
End_of_file.
---
 customize/urandom.ml | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/customize/urandom.ml b/customize/urandom.ml
index ff5d028d4..ce0e2cf65 100644
--- a/customize/urandom.ml
+++ b/customize/urandom.ml
@@ -27,13 +27,14 @@
 open Unix
 
 open Std_utils
+open Tools_utils
+open Common_gettext.Gettext
 
 let read_byte fd    let b = Bytes.make 1 ' ' in
   fun () ->
-    if read fd b 0 1 = 0 then (
-      raise End_of_file
-    );
+    if read fd b 0 1 = 0 then
+      error (f_"unexpected end of file while reading /dev/urandom");
     Char.code (Bytes.unsafe_get b 0)
 
 let urandom_bytes n -- 
2.13.2