remote: T5650: Resize-aware progressbar implementation

(cherry picked from commit 799d24eba18d6710219b7380cbafb954b9eec5ce)

3 files changed, 93 insertions, 60 deletions

diff --git a/python/vyos/progressbar.py b/python/vyos/progressbar.py
new file mode 100644
index 000000000..1793c445b
--- /dev/null
+++ b/python/vyos/progressbar.py
@@ -0,0 +1,70 @@
+# Copyright 2023 VyOS maintainers and contributors <maintainers@vyos.io>
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library.  If not, see <http://www.gnu.org/licenses/>.
+
+import math
+import os
+import signal
+import subprocess
+import sys
+
+from vyos.utils.io import print_error
+
+class Progressbar:
+    def __init__(self, step=None):
+        self.total = 0.0
+        self.step = step
+    def __enter__(self):
+        # Recalculate terminal width with every window resize.
+        signal.signal(signal.SIGWINCH, lambda signum, frame: self._update_cols())
+        # Disable line wrapping to prevent the staircase effect.
+        subprocess.run(['tput', 'rmam'], check=False)
+        self._update_cols()
+        # Print an empty progressbar with entry.
+        self.progress(0, 1)
+        return self
+    def __exit__(self, exc_type, kexc_val, exc_tb):
+        # Revert to the default SIGWINCH handler (ie nothing).
+        signal.signal(signal.SIGWINCH, signal.SIG_DFL)
+        # Reenable line wrapping.
+        subprocess.run(['tput', 'smam'], check=False)
+    def _update_cols(self):
+        # `os.get_terminal_size()' is fast enough for our purposes.
+        self.col = max(os.get_terminal_size().columns - 15, 20)
+    def increment(self):
+        """
+        Stateful progressbar taking the step fraction at init and no input at
+        callback (for FTP)
+        """
+        if self.step:
+            if self.total < 1.0:
+                self.total += self.step
+            if self.total >= 1.0:
+                self.total = 1.0
+                # Ignore superfluous calls caused by fuzzy FTP size calculations.
+                self.step = None
+            self.progress(self.total, 1.0)
+    def progress(self, done, total):
+        """
+        Stateless progressbar taking no input at init and current progress with
+        final size at callback (for SSH)
+        """
+        if done <= total:
+            length = math.ceil(self.col * done / total)
+            percentage = str(math.ceil(100 * done / total)).rjust(3)
+            # Carriage return at the end will make sure the line will get overwritten.
+            print_error(f'[{length * "#"}{(self.col - length) * "_"}] {percentage}%', end='\r')
+        # Print a newline to make sure the full progressbar doesn't get overwritten by the next line.
+        if done == total:
+            print_error()
diff --git a/python/vyos/remote.py b/python/vyos/remote.py
index cf731c881..1ca8a9530 100644
--- a/python/vyos/remote.py
+++ b/python/vyos/remote.py
@@ -32,9 +32,8 @@ from requests import Session
 from requests.adapters import HTTPAdapter
 from requests.packages.urllib3 import PoolManager
 
+from vyos.progressbar import Progressbar
 from vyos.utils.io import ask_yes_no
-from vyos.utils.io import make_incremental_progressbar
-from vyos.utils.io import make_progressbar
 from vyos.utils.io import print_error
 from vyos.utils.misc import begin
 from vyos.utils.process import cmd
@@ -131,16 +130,16 @@ class FtpC:
             if self.secure:
                 conn.prot_p()
             # Almost all FTP servers support the `SIZE' command.
+            size = conn.size(self.path)
             if self.check_space:
-                check_storage(path, conn.size(self.path))
+                check_storage(path, size)
             # No progressbar if we can't determine the size or if the file is too small.
             if self.progressbar and size and size > CHUNK_SIZE:
-                progress = make_incremental_progressbar(CHUNK_SIZE / size)
-                next(progress)
-                callback = lambda block: begin(f.write(block), next(progress))
+                with Progressbar(CHUNK_SIZE / size) as p:
+                    callback = lambda block: begin(f.write(block), p.increment())
+                    conn.retrbinary('RETR ' + self.path, callback, CHUNK_SIZE)
             else:
-                callback = f.write
-            conn.retrbinary('RETR ' + self.path, callback, CHUNK_SIZE)
+                conn.retrbinary('RETR ' + self.path, f.write, CHUNK_SIZE)
 
     def upload(self, location: str):
         size = os.path.getsize(location)
@@ -150,12 +149,10 @@ class FtpC:
             if self.secure:
                 conn.prot_p()
             if self.progressbar and size and size > CHUNK_SIZE:
-                progress = make_incremental_progressbar(CHUNK_SIZE / size)
-                next(progress)
-                callback = lambda block: next(progress)
+                with Progressbar(CHUNK_SIZE / size) as p:
+                    conn.storbinary('STOR ' + self.path, f, CHUNK_SIZE, lambda block: p.increment())
             else:
-                callback = None
-            conn.storbinary('STOR ' + self.path, f, CHUNK_SIZE, callback)
+                conn.storbinary('STOR ' + self.path, f, CHUNK_SIZE)
 
 class SshC:
     known_hosts = os.path.expanduser('~/.ssh/known_hosts')
@@ -190,14 +187,16 @@ class SshC:
         return ssh
 
     def download(self, location: str):
-        callback = make_progressbar() if self.progressbar else None
         with self._establish() as ssh, ssh.open_sftp() as sftp:
             if self.check_space:
                 check_storage(location, sftp.stat(self.path).st_size)
-            sftp.get(self.path, location, callback=callback)
+            if self.progressbar:
+                with Progressbar() as p:
+                    sftp.get(self.path, location, callback=p.progress)
+            else:
+                sftp.get(self.path, location)
 
     def upload(self, location: str):
-        callback = make_progressbar() if self.progressbar else None
         with self._establish() as ssh, ssh.open_sftp() as sftp:
             try:
                 # If the remote path is a directory, use the original filename.
@@ -210,7 +209,11 @@ class SshC:
             except IOError:
                 path = self.path
             finally:
-                sftp.put(location, path, callback=callback)
+                if self.progressbar:
+                    with Progressbar() as p:
+                        sftp.put(location, path, callback=p.progress)
+                else:
+                    sftp.put(location, path)
 
 
 class HttpC:
@@ -264,10 +267,9 @@ class HttpC:
             with s.get(final_urlstring, stream=True,
                        timeout=self.timeout) as r, open(location, 'wb') as f:
                 if self.progressbar and size:
-                    progress = make_incremental_progressbar(CHUNK_SIZE / size)
-                    next(progress)
-                    for chunk in iter(lambda: begin(next(progress), r.raw.read(CHUNK_SIZE)), b''):
-                        f.write(chunk)
+                    with Progressbar(CHUNK_SIZE / size) as p:
+                        for chunk in iter(lambda: begin(p.increment(), r.raw.read(CHUNK_SIZE)), b''):
+                            f.write(chunk)
                 else:
                     # We'll try to stream the download directly with `copyfileobj()` so that large
                     #  files (like entire VyOS images) don't occupy much memory.
diff --git a/python/vyos/utils/io.py b/python/vyos/utils/io.py
index 843494855..5fffa62f8 100644
--- a/python/vyos/utils/io.py
+++ b/python/vyos/utils/io.py
@@ -24,45 +24,6 @@ def print_error(str='', end='\n'):
     sys.stderr.write(end)
     sys.stderr.flush()
 
-def make_progressbar():
-    """
-    Make a procedure that takes two arguments `done` and `total` and prints a
-     progressbar based on the ratio thereof, whose length is determined by the
-     width of the terminal.
-    """
-    import shutil, math
-    col, _ = shutil.get_terminal_size()
-    col = max(col - 15, 20)
-    def print_progressbar(done, total):
-        if done <= total:
-            increment = total / col
-            length = math.ceil(done / increment)
-            percentage = str(math.ceil(100 * done / total)).rjust(3)
-            print_error(f'[{length * "#"}{(col - length) * "_"}] {percentage}%', '\r')
-            # Print a newline so that the subsequent prints don't overwrite the full bar.
-        if done == total:
-            print_error()
-    return print_progressbar
-
-def make_incremental_progressbar(increment: float):
-    """
-    Make a generator that displays a progressbar that grows monotonically with
-     every iteration.
-    First call displays it at 0% and every subsequent iteration displays it
-     at `increment` increments where 0.0 < `increment` < 1.0.
-    Intended for FTP and HTTP transfers with stateless callbacks.
-    """
-    print_progressbar = make_progressbar()
-    total = 0.0
-    while total < 1.0:
-        print_progressbar(total, 1.0)
-        yield
-        total += increment
-    print_progressbar(1, 1)
-    # Ignore further calls.
-    while True:
-        yield
-
 def ask_input(question, default='', numeric_only=False, valid_responses=[]):
     question_out = question
     if default: