PR: Remove linux distribution detection, search first on local paths for libraries (#2457)

* Remove linux distribution detection, search first on local paths for libraries

* Use not in

* Remove unused variables

setup.py

@@ -88,6 +88,15 @@ def find_library(name, vision_include):
     include_folder = None
     library_header = '{0}.h'.format(name)
 
+    # Lookup in TORCHVISION_INCLUDE or in the package file
+    package_path = [os.path.join(this_dir, 'torchvision')]
+    for folder in vision_include + package_path:
+        candidate_path = os.path.join(folder, library_header)
+        library_found = os.path.exists(candidate_path)
+        if library_found:
+            break
+
+    if not library_found:
         print('Running build on conda-build: {0}'.format(is_conda_build))
         if is_conda_build:
             # Add conda headers/libraries
@@ -124,38 +133,10 @@ def find_library(name, vision_include):
                     library_header))
                 library_found = library_found or os.path.exists(
                     '/usr/local/include/{0}'.format(library_header))
-        else:
-            # Lookup in TORCHVISION_INCLUDE or in the package file
-            package_path = [os.path.join(this_dir, 'torchvision')]
-            for folder in vision_include + package_path:
-                candidate_path = os.path.join(folder, library_header)
-                library_found = os.path.exists(candidate_path)
-                if library_found:
-                    break
 
     return library_found, conda_installed, include_folder, lib_folder
 
 
-def get_linux_distribution():
-    release_data = {}
-    with open("/etc/os-release") as f:
-        reader = csv.reader(f, delimiter="=")
-        for row in reader:
-            if row:
-                release_data[row[0]] = row[1]
-    if release_data["ID"] in ["debian", "raspbian"]:
-        with open("/etc/debian_version") as f:
-            debian_version = f.readline().strip()
-        major_version = debian_version.split(".")[0]
-        version_split = release_data["VERSION"].split(" ", maxsplit=1)
-        if version_split[0] == major_version:
-            # Just major version shown, replace it with the full version
-            release_data["VERSION"] = " ".join(
-                [debian_version] + version_split[1:])
-    print("{} {}".format(release_data["NAME"], release_data["VERSION"]))
-    return release_data
-
-
 def get_extensions():
     this_dir = os.path.dirname(os.path.abspath(__file__))
     extensions_dir = os.path.join(this_dir, 'torchvision', 'csrc')
@@ -267,14 +248,6 @@ def get_extensions():
     image_library = []
     image_link_flags = []
 
-    # Detect if build is running under conda/conda-build
-    conda = distutils.spawn.find_executable('conda')
-    is_conda = conda is not None
-
-    build_prefix = os.environ.get('BUILD_PREFIX', None)
-    is_conda_build = build_prefix is not None
-    running_under_conda = is_conda or is_conda_build
-
     # Locating libPNG
     libpng = distutils.spawn.find_executable('libpng-config')
     pngfix = distutils.spawn.find_executable('pngfix')
@@ -291,20 +264,10 @@ def get_extensions():
             png_version = parse_version(png_version)
             if png_version >= parse_version("1.6.0"):
                 print('Building torchvision with PNG image support')
-                linux = sys.platform == 'linux'
-                not_debian = False
-                libpng_on_conda = False
-                if linux:
-                    bin_folder = os.path.dirname(sys.executable)
-                    png_bin_folder = os.path.dirname(libpng)
-                    libpng_on_conda = (
-                        running_under_conda and bin_folder == png_bin_folder)
-                    release_info = get_linux_distribution()
-                    not_debian = release_info["NAME"] not in {'Ubuntu', 'Debian'}
-                if not linux or libpng_on_conda or not_debian:
                 png_lib = subprocess.run([libpng, '--libdir'],
                                          stdout=subprocess.PIPE)
                 png_lib = png_lib.stdout.strip().decode('utf-8')
+                if 'disabled' not in png_lib:
                     image_library += [png_lib]
                 png_include = subprocess.run([libpng, '--I_opts'],
                                              stdout=subprocess.PIPE)