branch master updated: syscalls: Gracefully handle failure to load libc's libutil.

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The following commit(s) were added to refs/heads/master by this push:
     new 0a42998  syscalls: Gracefully handle failure to load libc's libutil.
0a42998 is described below

commit 0a42998a50e8bbe9e49142b21a570db00efe7491
Author: Ludovic Courtès <ludo@gnu.org>
AuthorDate: Tue Oct 26 14:50:54 2021 +0200

    syscalls: Gracefully handle failure to load libc's libutil.
    
    In particular, libutil is not found when running code on a
    statically-linked Guile.
    
    Reported by mahmooz on #guix.
    
    * guix/build/syscalls.scm (syscall->procedure): Add #:library parameter
    and honor it.
    (openpty, login-tty): Use 'syscall->procedure' instead of calling
    'dynamic-link' directly.
---
 guix/build/syscalls.scm | 22 +++++++++++++---------
 1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/guix/build/syscalls.scm b/guix/build/syscalls.scm
index 7ea6b56..b305133 100644
--- a/guix/build/syscalls.scm
+++ b/guix/build/syscalls.scm
@@ -424,15 +424,21 @@ expansion-time error is raised if FIELD does not exist in 
TYPE."
   "Evaluate EXPR and restart upon EINTR.  Return the value of EXPR."
   (call-with-restart-on-EINTR (lambda () expr)))
 
-(define (syscall->procedure return-type name argument-types)
+(define* (syscall->procedure return-type name argument-types
+                             #:key library)
   "Return a procedure that wraps the C function NAME using the dynamic FFI,
-and that returns two values: NAME's return value, and errno.
+and that returns two values: NAME's return value, and errno.  When LIBRARY is
+specified, look up NAME in that library rather than in the global symbol name
+space.
 
 If an error occurs while creating the binding, defer the error report until
 the returned procedure is called."
   (catch #t
     (lambda ()
-      (let ((ptr (dynamic-func name (dynamic-link))))
+      (let ((ptr (dynamic-func name
+                               (if library
+                                   (dynamic-link library)
+                                   (dynamic-link)))))
         ;; The #:return-errno? facility was introduced in Guile 2.0.12.
         (pointer->procedure return-type ptr argument-types
                             #:return-errno? #t)))
@@ -2289,9 +2295,8 @@ always a positive integer."
   (terminal-dimension window-size-rows port (const 25)))
 
 (define openpty
-  (let* ((ptr  (dynamic-func "openpty" (dynamic-link "libutil")))
-         (proc (pointer->procedure int ptr '(* * * * *)
-                                   #:return-errno? #t)))
+  (let ((proc (syscall->procedure int "openpty" '(* * * * *)
+                                  #:library "libutil")))
     (lambda ()
       "Return two file descriptors: one for the pseudo-terminal control side,
 and one for the controlled side."
@@ -2312,9 +2317,8 @@ and one for the controlled side."
           (values (* head) (* inferior)))))))
 
 (define login-tty
-  (let* ((ptr  (dynamic-func "login_tty" (dynamic-link "libutil")))
-         (proc (pointer->procedure int ptr (list int)
-                                   #:return-errno? #t)))
+  (let* ((proc (syscall->procedure int "login_tty" (list int)
+                                   #:library "libutil")))
     (lambda (fd)
       "Make FD the controlling terminal of the current process (with the
 TIOCSCTTY ioctl), redirect standard input, standard output and standard error