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-rw-r--r--guix/serialization.scm27
1 files changed, 19 insertions, 8 deletions
diff --git a/guix/serialization.scm b/guix/serialization.scm
index 677ca60b66..9e2dce8bb0 100644
--- a/guix/serialization.scm
+++ b/guix/serialization.scm
@@ -457,9 +457,22 @@ depends on TYPE."
(&message (message "unsupported nar entry type"))
(&nar-read-error (port port) (file file) (token x)))))))))
-(define (restore-file port file)
+(define (dump-file file input size type)
+ "Dump SIZE bytes from INPUT to FILE."
+ (call-with-output-file file
+ (lambda (output)
+ (dump input output size))))
+
+(define* (restore-file port file
+ #:key (dump-file dump-file))
"Read a file (possibly a directory structure) in Nar format from PORT.
-Restore it as FILE with canonical permissions and timestamps."
+Restore it as FILE with canonical permissions and timestamps. To write a
+regular or executable file, call:
+
+ (DUMP-FILE FILE INPUT SIZE TYPE)
+
+The default is to dump SIZE bytes from INPUT to FILE, but callers can provide
+a custom procedure, for instance to deduplicate FILE on the fly."
(fold-archive (lambda (file type content result)
(match type
('directory
@@ -473,12 +486,10 @@ Restore it as FILE with canonical permissions and timestamps."
((or 'regular 'executable)
(match content
((input . size)
- (call-with-output-file file
- (lambda (output)
- (dump input output size)
- (chmod output (if (eq? type 'executable)
- #o555
- #o444))))
+ (dump-file file input size type)
+ (chmod file (if (eq? type 'executable)
+ #o555
+ #o444))
(utime file 1 1 0 0))))))
#t
port