[Python] How can I check if `src` and `dst` are the same when writing with `rasterio.open()`

I want to read a geotiff, reproject, and write to a new geotiff based on the code from the rasterio docs (https://rasterio.readthedocs.io/en/stable/topics/reproject.html) (the actual transformation is of course more complex than shown below).

There are a few potential problems that I need to deal with:

1. The output file might already exist; in this case I want to overwrite it

try:
os.remove(fname)
except FileNotFoundError:
pass

1. The output file might be opened in another program. Ideally I would like to overwrite it regardless but I understand this is difficult/impossible to do, therefore I catch this as a PermissionError:

try:
write_reprojected(...)
except (PermissionError, OSError):
print("output_file is opened elsewhere, close and try again")


3. However, if the input and output files are accidently specified to be the same I would like a different behaviour of the program. I am trying to catch this with

if os.path.abspath(src.files[0]) == os.path.abspath(fname):
#raise MyCustomException()
print("Trying to write file to its old location")


but I'm not sure if the string comparison is the best way.

Question: Is there a better way to check if src and dst are the same when writing with rasterio.open()? And also, is there a way to remove/overwrite a file that is used by a different program?


import os
import numpy as np
import rasterio
from rasterio.warp import calculate_default_transform, reproject, Resampling

def write_reprojected(src, crs, transform, width, height, fname):

# raise Exception if file is open for reading
if os.path.abspath(src.files[0]) == os.path.abspath(fname):
#raise MyCustomException()
print("Trying to write file to its old location")

kwargs = src.meta.copy()
kwargs.update({
'crs': crs,
'transform': transform,
'width': width,
'height': height})

# overwrite file if it already exists
try:
os.remove(fname)
except FileNotFoundError:
pass

with rasterio.open(fname, 'w', **kwargs) as dst:
for i in range(1, src.count + 1):
reproject(
source=rasterio.band(src, i),
destination=rasterio.band(dst, i),
src_transform=src.transform,
src_crs=src.crs,
dst_transform=transform,
dst_crs=crs,
resampling=Resampling.bilinear)


input_file = 'old_folder\old_file.tif'

output_folder = 'new_folder'
output_file = 'new_file.tif'
try:
os.makedirs(new_folder)
except FileExistsError:
pass

with rasterio.open(input_file, 'r') as src:
transform, width, height = aligned_target(
src.transform, src.width, src.height, [round(r) for r in src.res])
try:
write_reprojected(src, src.crs, transform, width, height,
os.path.join(output_folder, output_file))
except (PermissionError, OSError):
print("output_file is opened elsewhere, close and try again")

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