Print the amount of free space that we have available in our temporary...

Print the amount of free space that we have available in our temporary directory as a debugging message. (Re: #100)

diffoscope/main.py

@@ -40,12 +40,13 @@ from .tools import (
     OS_NAMES,
     get_current_os,
 )
+from .utils import format_bytes
 from .config import Config
 from .environ import normalize_environment
 from .logging import line_eraser, setup_logging
 from .progress import ProgressManager, Progress
 from .profiling import ProfileManager, profile
-from .tempfiles import clean_all_temp_files
+from .tempfiles import clean_all_temp_files, get_tempdir_free_space
 from .difference import Difference
 from .comparators import ComparatorManager
 from .external_tools import EXTERNAL_TOOLS
@@ -650,6 +651,10 @@ def run_diffoscope(parsed_args):
     """
 
     logger.debug("Starting diffoscope %s", VERSION)
+    logger.debug(
+        "Free space in temporary directory: %s",
+        format_bytes(get_tempdir_free_space()),
+    )
 
     ProfileManager().setup(parsed_args)
     PresenterManager().configure(parsed_args)

diffoscope/tempfiles.py

@@ -2,7 +2,7 @@
 #
 # diffoscope: in-depth comparison of files, archives, and directories
 #
-# Copyright © 2016-2019 Chris Lamb <lamby@debian.org>
+# Copyright © 2016-2020 Chris Lamb <lamby@debian.org>
 # Copyright © 2018 Mattia Rizzolo <mattia@debian.org>
 #
 # diffoscope is free software: you can redistribute it and/or modify
@@ -90,3 +90,16 @@ def _get_base_temporary_directory():
         _DIRS.append(d)
 
     return _DIRS[0].name
+
+
+def get_tempdir_free_space():
+    """
+    unsigned long f_frsize   Fundamental file system block size.
+    fsblkcnt_t    f_blocks   Total number of blocks on file system in units of f_frsize.
+    fsblkcnt_t    f_bfree    Total number of free blocks.
+    fsblkcnt_t    f_bavail   Number of free blocks available to
+                             non-privileged process.
+    """
+    statvfs = os.statvfs(tempfile.gettempdir())
+
+    return statvfs.f_frsize * statvfs.f_bavail

diffoscope/utils.py

@@ -2,7 +2,7 @@
 #
 # diffoscope: in-depth comparison of files, archives, and directories
 #
-# Copyright © 2019 Chris Lamb <lamby@debian.org>
+# Copyright © 2019-2020 Chris Lamb <lamby@debian.org>
 #
 # diffoscope is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -33,3 +33,14 @@ def format_cmdline(cmd, replace=(), truncate=None):
         result = result[: truncate + 4] + " […]"
 
     return result
+
+
+def format_bytes(size, decimal_places=2):
+    # https://stackoverflow.com/a/43690506
+
+    for unit in ('B', 'KiB', 'MiB', 'GiB', 'TiB'):
+        if size < 1024.0:
+            break
+        size /= 1024.0
+
+    return f"{size:.{decimal_places}f} {unit}"