From 8892e1485d2157e0e9be8f337d1d2ff7b1a6c338 Mon Sep 17 00:00:00 2001
From: Arun Isaac
Date: Mon, 4 Feb 2019 01:28:34 +0530
Subject: Signal a file-missing error when file is not found.

* exiftool.el (exiftool--assert-file-exists): New function.
(exiftool-read, exiftool-copy, exiftool-write): Assert that file
arguments exist before operating on them.
* tests/exiftool-tests.el (read-file-not-found-test,
copy-file-not-found-test, write-file-not-found-test): New tests.
---
 exiftool.el             | 10 +++++++++-
 tests/exiftool-tests.el | 15 ++++++++++++++-
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/exiftool.el b/exiftool.el
index a9495c5..3e5327b 100644
--- a/exiftool.el
+++ b/exiftool.el
@@ -1,7 +1,7 @@
 ;;; exiftool.el --- Elisp wrapper around ExifTool -*- lexical-binding: t -*-
 
 ;; Elisp wrapper around ExifTool
-;; Copyright (C) 2017 by Arun I
+;; Copyright (C) 2017, 2019 by Arun I
 ;;
 ;; Author: Arun I <arunisaac@systemreboot.net>
 ;; Version: 0.3
@@ -77,6 +77,10 @@ exiftool command line application."
 			   "\n-execute\n")
 		suffix))))))
 
+(defun exiftool--assert-file-exists (file)
+  (unless (file-exists-p file)
+    (signal 'file-missing file)))
+
 (defun exiftool-read (file &rest tags)
   "Read TAGS from FILE, return an alist mapping TAGS to values.
 
@@ -84,6 +88,7 @@ If a tag is not found, return an empty string \"\" as the
 value. If no TAGS are specified, read all tags from FILE.
 
 \(fn FILE TAG...)"
+  (exiftool--assert-file-exists file)
   (mapcar
    (lambda (line)
      (string-match "\\([^:]*\\): \\(.*\\)" line)
@@ -105,6 +110,8 @@ value. If no TAGS are specified, read all tags from FILE.
   "Copy TAGS from SOURCE file to DESTINATION file.
 
 If no TAGS are specified, copy all tags from SOURCE."
+  (exiftool--assert-file-exists source)
+  (exiftool--assert-file-exists destination)
   (apply 'exiftool-command
 	 "-m" "-overwrite_original"
 	 "-tagsFromFile" source
@@ -123,6 +130,7 @@ pairs.  Specifying the empty string \"\" for VALUE deletes that
 TAG.
 
 \(fn FILE (TAG . VALUE)...)"
+  (exiftool--assert-file-exists file)
   (apply 'exiftool-command
 	 "-m" "-overwrite_original"
 	 (append
diff --git a/tests/exiftool-tests.el b/tests/exiftool-tests.el
index 8d040c4..0ef5fa2 100644
--- a/tests/exiftool-tests.el
+++ b/tests/exiftool-tests.el
@@ -1,7 +1,7 @@
 ;;; exiftool.el --- Elisp wrapper around exiftool ;; -*- lexical-binding: t -*-
 
 ;; Elisp wrapper around exiftool
-;; Copyright (C) 2017 by Arun I
+;; Copyright (C) 2017, 2019 by Arun I
 ;;
 ;; Author: Arun I <arunisaac@systemreboot.net>
 ;; Keywords: data
@@ -90,6 +90,19 @@
 		     (equal (apply 'exiftool-read temp-1 some-tags)
 			    (apply 'exiftool-read temp-2 some-tags))))))))
 
+(ert-deftest read-file-not-found-test ()
+  (should-error (exiftool-read "non-existent-file.png")
+                :type 'file-missing))
+
+(ert-deftest copy-file-not-found-test ()
+  (should-error (exiftool-copy "non-existent-file-1.png"
+                               "non-existent-file-2.png")
+                :type 'file-missing))
+
+(ert-deftest write-file-not-found-test ()
+  (should-error (exiftool-write "non-existent-file.png")
+                :type 'file-missing))
+
 (provide 'exiftool-tests)
 
 ;;; exiftool-tests.el ends here
-- 
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