Adding access(2) interface.

lib/chibi/filesystem.scm

@@ -157,6 +157,15 @@
 ;;> is satisfied, and \scheme{#f} otherwise.
 ;;/
 
+(define (file-is-readable? path) (zero? (file-access path access/read)))
+(define (file-is-writable? path) (zero? (file-access path access/write)))
+(define (file-is-executable? path) (zero? (file-access path access/execute)))
+
+;;> File access tests.  Returns true iff the current real UID and GID
+;;> have the corresponding permissions on path.  Equivalent to the
+;;> test -r, -w, -x operators in sh.
+;;/
+
 ;;> Equivalent to duplicating the file descriptor \var{old} to
 ;;> \var{new} and closing \var{old}.
 

lib/chibi/filesystem.sld

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

lib/chibi/filesystem.stub

@@ -193,6 +193,12 @@
 (define-c int (file-truncate "ftruncate")
   (port-or-fileno off_t))
 
+;; Used for file-is-readable?, file-is-writable?, file-is-executable?.
+(define-c-const int (access/read "R_OK"))
+(define-c-const int (access/write "W_OK"))
+(define-c-const int (access/execute "X_OK"))
+(define-c int (file-access "access") (string int))
+
 ;;> Applies the specified locking operation using flock(2) to the port
 ;;> or file-descriptor.