Adding call-with-locked-file utility.

lib/chibi/filesystem.scm

@@ -106,6 +106,15 @@
       thunk
       (lambda () (change-directory pwd)))))
 
+;;> Calls \var{proc} on a read/write opened file descriptor for
+;;> \var{path}, locked with \scheme{file-lock}, and automatically
+;;> removes the lock when \var{proc} returns the first time.
+
+(define (call-with-locked-file path proc)
+  (let ((fd (open path open/read-write)))
+    (file-lock fd lock/exclusive)
+    (exception-protect (proc fd) (file-lock fd lock/unlock))))
+
 ;;> Returns the \scheme{status} object for the given \var{file},
 ;;> which should be a string indicating the path or a file
 ;;> descriptor.

lib/chibi/filesystem.sld

@@ -31,6 +31,7 @@
           open/create      open/exclusive         open/truncate
           open/append      open/non-block
           file-lock        file-truncate
+          call-with-locked-file
           lock/shared lock/exclusive lock/non-blocking lock/unlock
           is-a-tty?)
   (import (chibi) (chibi string))