[*/regression] Use uniform and cleaner SGX environment check

As suggested by @yamahata in PR #612.

LibOS/shim/test/regression/30_mmap.py

@@ -2,10 +2,7 @@ import os, sys, mmap
 from regression import Regression
 
 loader = sys.argv[1]
-try:
-    sgx = os.environ['SGX_RUN']
-except KeyError:
-    sgx = False
+sgx = os.environ.get('SGX_RUN') == '1'
 
 # Running Bootstrap
 regression = Regression(loader, "mmap-file", None, 60000)

Pal/regression/00_Atomics.py

@@ -2,10 +2,10 @@ import os, sys, mmap
 from regression import Regression
 
 loader = os.environ['PAL_LOADER']
-is_sgx = 'SGX_RUN' in os.environ and os.environ['SGX_RUN'] == '1'
+sgx = os.environ.get('SGX_RUN') == '1'
 
 def manifest_file(file):
-    if is_sgx:
+    if sgx:
         return file + '.manifest.sgx'
     else:
         return file + '.manifest'

Pal/regression/00_Bootstrap.py

@@ -2,13 +2,10 @@ import os, sys, mmap
 from regression import Regression
 
 loader = os.environ['PAL_LOADER']
-try:
-    sgx = os.environ['SGX_RUN']
-except KeyError:
-    sgx = False
+sgx = os.environ.get('SGX_RUN') == '1'
 
 def manifest_file(file):
-    if 'SGX_RUN' in os.environ and os.environ['SGX_RUN'] == '1':
+    if sgx:
         return file + '.manifest.sgx'
     else:
         return file + '.manifest'

Pal/regression/02_Memory.py

@@ -2,10 +2,7 @@ import os, sys, mmap
 from regression import Regression
 
 loader = os.environ['PAL_LOADER']
-try:
-    sgx = os.environ['SGX_RUN']
-except KeyError:
-    sgx = 0
+sgx = os.environ.get('SGX_RUN') == '1'
 
 regression = Regression(loader, "Memory")
 

Pal/regression/04_Ipc.py

@@ -2,10 +2,7 @@ import os, sys, mmap
 from regression import Regression
 
 loader = os.environ['PAL_LOADER']
-try:
-    sgx = os.environ['SGX_RUN']
-except KeyError:
-    sgx = 0
+sgx = os.environ.get('SGX_RUN') == '1'
 
 if sgx:
     print("Bulk IPC not supported on SGX")

Pal/regression/06_AvxDisable.py

@@ -3,7 +3,7 @@ from regression import Regression
 
 loader = os.environ['PAL_LOADER']
 
-sgx = os.environ.get('SGX_RUN', False)
+sgx = os.environ.get('SGX_RUN') == '1'
 
 def manifest_file(file):
     if sgx: