get root from environment variable

conda_subprocess/process.py

@@ -2,7 +2,9 @@
 from subprocess import Popen as subprocess_Popen
 
 from conda.auxlib.compat import shlex_split_unicode
-from conda.base.context import context, validate_prefix_name
+from conda.auxlib.ish import dals
+from conda.base.context import context, _first_writable_envs_dir, ROOT_ENV_NAME, PREFIX_NAME_DISALLOWED_CHARS
+from conda.exceptions import EnvironmentNameNotFound, CondaValueError
 from conda.cli.common import validate_prefix
 from conda.common.compat import encode_arguments, encode_environment, isiterable
 from conda.common.path import expand
@@ -37,7 +39,7 @@ def Popen(
 ):
     # create run script
     script, command = wrap_subprocess_call(
-        root_prefix=os.path.abspath(os.path.join(os.environ["CONDA_EXE"], "..", "..")),
+        root_prefix=context.root_prefix,
         prefix=validate_prefix(
             prefix=_check_prefix(
                 prefix_name=prefix_name,
@@ -92,11 +94,60 @@ def _check_prefix(prefix_name=None, prefix_path=None):
     elif prefix_path is not None:
         return expand(prefix_path)
     else:
-        return validate_prefix_name(prefix_name, ctx=context)
+        return _validate_prefix_name(prefix_name, ctx=context)
 
 
 def _check_args(args):
     if isinstance(args, str):
         return args.split()
     else:
         return args
+
+
+def _locate_prefix_by_name(name, envs_dirs=None):
+    """Find the location of a prefix given a conda env name.  If the location does not exist, an
+    error is raised.
+    """
+    assert name
+    if name in (ROOT_ENV_NAME, "root"):
+        return context.root_prefix
+    if envs_dirs is None:
+        envs_dirs = context.envs_dirs
+    for envs_dir in envs_dirs:
+        if not os.path.isdir(envs_dir):
+            continue
+        prefix = os.path.join(envs_dir, name)
+        if os.path.isdir(prefix):
+            return os.path.abspath(prefix)
+    raise EnvironmentNameNotFound(name)
+
+
+def _validate_prefix_name(prefix_name: str, ctx: context.Context, allow_base=True) -> str:
+    """Run various validations to make sure prefix_name is valid"""
+    if PREFIX_NAME_DISALLOWED_CHARS.intersection(prefix_name):
+        raise CondaValueError(
+            dals(
+                f"""
+                Invalid environment name: {prefix_name!r}
+                Characters not allowed: {PREFIX_NAME_DISALLOWED_CHARS}
+                If you are specifying a path to an environment, the `-p`
+                flag should be used instead.
+                """
+            )
+        )
+
+    if prefix_name in (ROOT_ENV_NAME, "root"):
+        if allow_base:
+            return ctx.root_prefix
+        else:
+            raise CondaValueError(
+                "Use of 'base' as environment name is not allowed here."
+            )
+
+    else:
+        envs_dirs = context.envs_dirs
+        envs_dirs += [os.path.abspath(os.path.join(os.environ["CONDA_EXE"], "..", ".."))]
+        try:
+            return _locate_prefix_by_name(name=prefix_name, envs_dirs=envs_dirs)
+        except EnvironmentNameNotFound:
+            return os.path.join(_first_writable_envs_dir(), prefix_name)