[Emacs-diffs] emacs-26 b3df372: * lisp/emacs-lisp/package.el: Obey buffer-file-coding-system (bug#35739)

[Stefan Monnier]

branch: emacs-26
commit b3df3729596332a39404c364798a61bfef2adcc2
Author: Stefan Monnier <address@hidden>
Commit: Stefan Monnier <address@hidden>

    * lisp/emacs-lisp/package.el: Obey buffer-file-coding-system (bug#35739)
    
    `url-insert-file-contents` saves in buffer-file-coding-system
    the coding-system used to decode the contents.  Preserve this
    as the contents is moved from buffer to string to buffer, and use
    it when saving the contents to file, so as to try and better preserve
    the original byte sequence.
    
    (package--buffer-string, package--cs): New functions.
    (package--check-signature): Encode `string` if a coding-system
    was specified in buffer-file-coding-system.
    (package--download-one-archive, package-install-from-archive):
    Obey and preserve the buffer-file-coding-system if specified.
    
    Do not merge.
---
 lisp/emacs-lisp/package.el | 36 +++++++++++++++++++++++++++---------
 1 file changed, 27 insertions(+), 9 deletions(-)

diff --git a/lisp/emacs-lisp/package.el b/lisp/emacs-lisp/package.el
index 1a185de..46f7c91 100644
--- a/lisp/emacs-lisp/package.el
+++ b/lisp/emacs-lisp/package.el
@@ -1241,6 +1241,17 @@ errors."
         (signal 'bad-signature (list sig-file)))
       good-signatures)))
 
+(defun package--buffer-string ()
+  (let ((string (buffer-string)))
+    (when (and buffer-file-coding-system
+               (> (length string) 0))
+      (put-text-property 0 1 'package--cs buffer-file-coding-system string))
+    string))
+
+(defun package--cs (string)
+  (and (> (length string) 0)
+       (get-text-property 0 'package--cs string)))
+
 (defun package--check-signature (location file &optional string async callback 
unwind)
   "Check signature of the current buffer.
 Download the signature file from LOCATION by appending \".sig\"
@@ -1260,8 +1271,12 @@ Otherwise, an error is signaled.
 
 UNWIND, if provided, is a function to be called after everything
 else, even if an error is signaled."
-  (let ((sig-file (concat file ".sig"))
-        (string (or string (buffer-string))))
+  (let* ((sig-file (concat file ".sig"))
+         (string (or string (package--buffer-string)))
+         (cs (package--cs string)))
+    ;; Re-encode the downloaded file with the coding-system with which
+    ;; it was decoded, so we (hopefully) get the exact same bytes back.
+    (when cs (setq string (encode-coding-string string cs)))
     (package--with-response-buffer location :file sig-file
       :async async :noerror t
       ;; Connection error is assumed to mean "no sig-file".
@@ -1529,7 +1544,7 @@ similar to an entry in `package-alist'.  Save the cached 
copy to
     :error-form (package--update-downloads-in-progress archive)
     (let* ((location (cdr archive))
            (name (car archive))
-           (content (buffer-string))
+           (content (package--buffer-string))
            (dir (expand-file-name (format "archives/%s" name) 
package-user-dir))
            (local-file (expand-file-name file dir)))
       (when (listp (read content))
@@ -1538,7 +1553,8 @@ similar to an entry in `package-alist'.  Save the cached 
copy to
                 (member name package-unsigned-archives))
             ;; If we don't care about the signature, save the file and
             ;; we're done.
-            (progn (let ((coding-system-for-write 'utf-8))
+            (progn (let ((coding-system-for-write
+                          (or (package--cs content) 'utf-8)))
                      (write-region content nil local-file nil 'silent))
                    (package--update-downloads-in-progress archive))
           ;; If we care, check it (perhaps async) and *then* write the file.
@@ -1546,7 +1562,7 @@ similar to an entry in `package-alist'.  Save the cached 
copy to
            location file content async
            ;; This function will be called after signature checking.
            (lambda (&optional good-sigs)
-             (let ((coding-system-for-write 'utf-8))
+             (let ((coding-system-for-write (or (package--cs content) 'utf-8)))
                (write-region content nil local-file nil 'silent))
              ;; Write out good signatures into archive-contents.signed file.
              (when good-sigs
@@ -1838,15 +1854,17 @@ if all the in-between dependencies are also in 
PACKAGE-LIST."
           (let ((save-silently t))
             (package-unpack pkg-desc))
         ;; If we care, check it and *then* write the file.
-        (let ((content (buffer-string)))
+        (let ((content (package--buffer-string)))
           (package--check-signature
            location file content nil
            ;; This function will be called after signature checking.
            (lambda (&optional good-sigs)
              ;; Signature checked, unpack now.
-             (with-temp-buffer (insert content)
-                               (let ((save-silently t))
-                                 (package-unpack pkg-desc)))
+             (with-temp-buffer
+               (insert content)
+               (setq buffer-file-coding-system (package--cs content))
+               (let ((save-silently t))
+                 (package-unpack pkg-desc)))
              ;; Here the package has been installed successfully, mark it as
              ;; signed if appropriate.
              (when good-sigs