06/15: build: syscalls: Add mkdtemp!

[David Thompson]

davexunit pushed a commit to branch wip-container
in repository guix.

commit 138bbc90cbde4dce1b2b61372ebb705f0a8663fd
Author: David Thompson <address@hidden>
Date:   Wed Jun 24 20:50:34 2015 -0400

    build: syscalls: Add mkdtemp!
    
    * guix/build/syscalls.scm (mkdtemp!): New procedure.
---
 guix/build/syscalls.scm |   15 +++++++++++++++
 1 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/guix/build/syscalls.scm b/guix/build/syscalls.scm
index 7fb353e..2ac1263 100644
--- a/guix/build/syscalls.scm
+++ b/guix/build/syscalls.scm
@@ -46,6 +46,7 @@
             swapoff
             processes
             pivot-root
+            mkdtemp!
 
             CLONE_NEWNS
             CLONE_NEWUTS
@@ -289,6 +290,20 @@ system to PUT-OLD."
                  (list new-root put-old (strerror err))
                  (list err)))))))
 
+(define mkdtemp!
+  (let* ((ptr  (dynamic-func "mkdtemp" (dynamic-link)))
+         (proc (pointer->procedure '* ptr '(*))))
+    (lambda (tmpl)
+      "Create a new unique directory in the file system using the template
+string TMPL and return its file name.  TMPL must end with 'XXXXXX'."
+      (let ((result (proc (string->pointer tmpl)))
+            (err    (errno)))
+        (when (null-pointer? result)
+          (throw 'system-error "mkdtemp!" "mkdtemp ~S: ~A"
+                 (list tmpl (strerror err))
+                 (list err)))
+        (pointer->string result)))))
+
 ;; Linux clone flags, from linux/sched.h
 (define CLONE_NEWNS   #x00020000)
 (define CLONE_NEWUTS  #x04000000)