From 610d4d8c9bb5f04a86afc8a63b671bd035d24e36 Mon Sep 17 00:00:00 2001
From: Andrew Hyatt <ahyatt@gmail.com>
Date: Fri, 18 Oct 2019 21:56:52 -0400
Subject: [PATCH] Enable password-less connections for sql where possible.

* lisp/progmodes/sql.el (sql-comint-mysql):
  When a blank password is provided (not entered by the user), send an
  argument to signal to the SQL process to read the password inside
  the process.  This removes the slight chance that someone can spy
  on the password from ps or via other methods.

  We also watch for the password inside the SQL process and
  automatically fill it with `sql-password' (if it exists).
---
 lisp/progmodes/sql.el | 42 +++++++++++++++++++++++++++++++-----------
 1 file changed, 31 insertions(+), 11 deletions(-)

diff --git a/lisp/progmodes/sql.el b/lisp/progmodes/sql.el
index b17364b08f..c453de382d 100644
--- a/lisp/progmodes/sql.el
+++ b/lisp/progmodes/sql.el
@@ -160,13 +160,16 @@
 ;;       "Connect ti XyzDB in a comint buffer."
 ;;
 ;;         ;; Do something with `sql-user', `sql-password',
-;;         ;; `sql-database', and `sql-server'.
+;;         ;; `sql-database', and `sql-server'.  `sql-password' will
+;;         ;; be sent automatically if not sent in the command-line.
+;;         ;; It is recommended to avoid sending in the command-line
+;;         ;; if possible, since this can briefly expose passwords.
 ;;         (let ((params
 ;;                (append
 ;;           (if (not (string= "" sql-user))
 ;;                     (list "-U" sql-user))
 ;;                 (if (not (string= "" sql-password))
-;;                     (list "-P" sql-password))
+;;                     (list "-P"))
 ;;                 (if (not (string= "" sql-database))
 ;;                     (list "-D" sql-database))
 ;;                 (if (not (string= "" sql-server))
@@ -4664,8 +4667,8 @@ the call to \\[sql-product-interactive] with
                     (sql-database   (default-value 'sql-database))
                     (sql-port       (default-value 'sql-port))
                     (default-directory
-                                    (or sql-default-directory
-                                        default-directory)))
+                      (or sql-default-directory
+                          default-directory)))
 
                 ;; The password wallet returns a function which supplies the password.
                 (when (functionp sql-password)
@@ -4681,9 +4684,9 @@ the call to \\[sql-product-interactive] with
                            (sql-generate-unique-sqli-buffer-name product nil))
                           ((consp new-name)
                            (sql-generate-unique-sqli-buffer-name product
-                            (read-string
-                             "Buffer name (\"*SQL: XXX*\"; enter `XXX'): "
-                             (sql-make-alternate-buffer-name product))))
+                                                                 (read-string
+                                                                  "Buffer name (\"*SQL: XXX*\"; enter `XXX'): "
+                                                                  (sql-make-alternate-buffer-name product))))
                           ((stringp new-name)
                            (if (or (string-prefix-p " " new-name)
                                    (string-match-p "\\`[*].*[*]\\'" new-name))
@@ -4733,12 +4736,27 @@ the call to \\[sql-product-interactive] with
               (get-buffer new-sqli-buffer)))))
     (user-error "No default SQL product defined: set `sql-product'")))
 
+(define-advice comint-watch-for-password-prompt
+    (:around (inner-func string) sql-password-autopopulate)
+  "Intercept password prompts when we know the password. This
+must also do the job of detecting password prompts.  STRING is
+the potential password prompt.  INNER-FUNC is the previous
+definition of comint-watch-for-password-prompt, which is called
+only when there is no prefilled password."
+  (if (and
+       (eq major-mode 'sql-interactive-mode)
+       (not (string= "" sql-password))
+       (let ((case-fold-search t))
+         (string-match comint-password-prompt-regexp string)))
+      (funcall comint-input-sender (get-buffer-process (current-buffer)) sql-password)
+    (funcall inner-func string)))
+
 (defun sql-comint (product params &optional buf-name)
   "Set up a comint buffer to run the SQL processor.
 
-PRODUCT is the SQL product.  PARAMS is a list of strings which are
-passed as command line arguments.  BUF-NAME is the name of the new
-buffer.  If nil, a name is chosen for it."
+PRODUCT is the SQL product.  PARAMS is a list of strings which
+are passed as command line arguments.  BUF-NAME is the name of
+the new buffer.  If nil, a name is chosen for it."
 
   (let ((program (sql-get-product-feature product :sqli-program)))
     ;; Make sure we can find the program.  `executable-find' does not
@@ -5188,7 +5206,9 @@ The default comes from `process-coding-system-alist' and
           (if (not (string= "" sql-user))
               (list (concat "--user=" sql-user)))
           (if (not (string= "" sql-password))
-              (list (concat "--password=" sql-password)))
+              ;; Sending --password will make MySQL prompt for the
+              ;; password.
+              (list "--password"))
           (if (not (= 0 sql-port))
               (list (concat "--port=" (number-to-string sql-port))))
           (if (not (string= "" sql-server))
-- 
2.19.0.605.g01d371f741-goog