Move two functions in the tools.py file

trimage/tools.py

@@ -1,9 +1,46 @@
 #!/usr/bin/env python3
 
+import sys
+import errno
+from subprocess import call, PIPE
 
-def human_readable_size(num, suffix='B'):
-    for unit in ['','K','M','G','T','P','E','Z']:
+
+def check_dependencies():
+    """Check if the required command line apps exist."""
+    exe = ".exe" if (sys.platform == "win32") else ""
+    status = True
+    dependencies = {
+        "jpegoptim": "--version",
+        "optipng": "-v",
+        "advpng": "--version",
+        "pngcrush": "-version"
+    }
+
+    for elt in dependencies:
+        retcode = safe_call(elt + exe + " " + dependencies[elt])
+        if retcode != 0:
+            status = False
+            print("[error] please install {}".format(elt), file=sys.stderr)
+
+    return status
+
+
+def safe_call(command):
+    """Cross-platform command-line check."""
+    while True:
+        try:
+            return call(command, shell=True, stdout=PIPE)
+        except OSError as e:
+            if e.errno == errno.EINTR:
+                continue
+            else:
+                raise
+
+
+def human_readable_size(num, suffix="B"):
+    """Bytes to a readable size format"""
+    for unit in ["", "K", "M", "G", "T", "P", "E", "Z"]:
         if abs(num) < 1024.0:
             return "%3.1f%s%s" % (num, unit, suffix)
         num /= 1024.0
-    return "%.1f%s%s" % (num, 'Y', suffix)
+    return "%.1f%s%s" % (num, "Y", suffix)