bin: Allow pulling only one host in each invocation.

* bin/tissue (tissue-pull): Allow pulling only one host in each
invocation.

1 files changed, 19 insertions, 10 deletions

diff --git a/bin/tissue b/bin/tissue
index 0d0d162..5357c66 100755
--- a/bin/tissue
+++ b/bin/tissue
@@ -472,16 +472,25 @@ Pull latest from upstream repositories.
                    "State directory ~a does not exist.~%"
                    state-directory)
            (exit #f))
-         ;; Pull state for specific host, or for all hosts when none
-         ;; are specified on the command-line.
-         (for-each (match-lambda
-                     ((hostname . parameters)
-                      (when (or (not (assq-ref args 'host))
-                                (string=? hostname (assq-ref args 'host)))
-                        (pull state-directory
-                              hostname
-                              (assq-ref parameters 'upstream-repository)))))
-                   (assq-ref args 'hosts)))))))
+         ;; Pull state for specificied host.
+         ;; It is not a good idea to pull for all configured hosts
+         ;; when no host is specified on the command line. Since
+         ;; pulling requires executing code in each repository,
+         ;; pulling for multiple hosts in a single process can cause
+         ;; interaction of code across hosts.
+         (let ((hostname (assq-ref args 'host)))
+           (cond
+            ((assoc-ref (assq-ref args 'hosts)
+                        hostname)
+             => (lambda (parameters)
+                  (pull state-directory
+                        hostname
+                        (assq-ref parameters 'upstream-repository))))
+            (else
+             (format (current-error-port)
+                     "Host ~a not found in configuration file."
+                     hostname)
+             (exit #f)))))))))
 
 (define (main . args)
   (guard (c ((condition-git-error c)