tests: Disallow use of util.subp except for where needed.

In many cases, cloud-init uses 'util.subp' to run a subprocess.
This is not really desirable in our unit tests as it makes the tests
dependent upon existance of those utilities.

The change here is to modify the base test case class (CiTestCase) to
raise exception any time subp is called.  Then, fix all callers.
For cases where subp is necessary or actually desired, we can use it
via
  a.) context hander CiTestCase.allow_subp(value)
  b.) class level self.allowed_subp = value

Both cases the value is a list of acceptable executable names that
will be called (essentially argv[0]).

Some cleanups in AltCloud were done as the code was being updated.

2 files changed, 27 insertions, 26 deletions

diff --git a/cloudinit/sources/DataSourceAltCloud.py b/cloudinit/sources/DataSourceAltCloud.py
index 24fd65ff..8cd312d0 100644
--- a/cloudinit/sources/DataSourceAltCloud.py
+++ b/cloudinit/sources/DataSourceAltCloud.py
@@ -181,27 +181,18 @@ class DataSourceAltCloud(sources.DataSource):
 
         # modprobe floppy
         try:
-            cmd = CMD_PROBE_FLOPPY
-            (cmd_out, _err) = util.subp(cmd)
-            LOG.debug('Command: %s\nOutput%s', ' '.join(cmd), cmd_out)
+            modprobe_floppy()
         except ProcessExecutionError as e:
-            util.logexc(LOG, 'Failed command: %s\n%s', ' '.join(cmd), e)
-            return False
-        except OSError as e:
-            util.logexc(LOG, 'Failed command: %s\n%s', ' '.join(cmd), e)
+            util.logexc(LOG, 'Failed modprobe: %s', e)
             return False
 
         floppy_dev = '/dev/fd0'
 
         # udevadm settle for floppy device
         try:
-            (cmd_out, _err) = util.udevadm_settle(exists=floppy_dev, timeout=5)
-            LOG.debug('Command: %s\nOutput%s', ' '.join(cmd), cmd_out)
-        except ProcessExecutionError as e:
-            util.logexc(LOG, 'Failed command: %s\n%s', ' '.join(cmd), e)
-            return False
-        except OSError as e:
-            util.logexc(LOG, 'Failed command: %s\n%s', ' '.join(cmd), e)
+            util.udevadm_settle(exists=floppy_dev, timeout=5)
+        except (ProcessExecutionError, OSError) as e:
+            util.logexc(LOG, 'Failed udevadm_settle: %s\n', e)
             return False
 
         try:
@@ -258,6 +249,11 @@ class DataSourceAltCloud(sources.DataSource):
             return False
 
 
+def modprobe_floppy():
+    out, _err = util.subp(CMD_PROBE_FLOPPY)
+    LOG.debug('Command: %s\nOutput%s', ' '.join(CMD_PROBE_FLOPPY), out)
+
+
 # Used to match classes to dependencies
 # Source DataSourceAltCloud does not really depend on networking.
 # In the future 'dsmode' like behavior can be added to offer user
diff --git a/cloudinit/sources/DataSourceSmartOS.py b/cloudinit/sources/DataSourceSmartOS.py
index ad8cfb9c..593ac91a 100644
--- a/cloudinit/sources/DataSourceSmartOS.py
+++ b/cloudinit/sources/DataSourceSmartOS.py
@@ -683,6 +683,18 @@ def jmc_client_factory(
     raise ValueError("Unknown value for smartos_type: %s" % smartos_type)
 
 
+def identify_file(content_f):
+    cmd = ["file", "--brief", "--mime-type", content_f]
+    f_type = None
+    try:
+        (f_type, _err) = util.subp(cmd)
+        LOG.debug("script %s mime type is %s", content_f, f_type)
+    except util.ProcessExecutionError as e:
+        util.logexc(
+            LOG, ("Failed to identify script type for %s" % content_f, e))
+    return None if f_type is None else f_type.strip()
+
+
 def write_boot_content(content, content_f, link=None, shebang=False,
                        mode=0o400):
     """
@@ -715,18 +727,11 @@ def write_boot_content(content, content_f, link=None, shebang=False,
     util.write_file(content_f, content, mode=mode)
 
     if shebang and not content.startswith("#!"):
-        try:
-            cmd = ["file", "--brief", "--mime-type", content_f]
-            (f_type, _err) = util.subp(cmd)
-            LOG.debug("script %s mime type is %s", content_f, f_type)
-            if f_type.strip() == "text/plain":
-                new_content = "\n".join(["#!/bin/bash", content])
-                util.write_file(content_f, new_content, mode=mode)
-                LOG.debug("added shebang to file %s", content_f)
-
-        except Exception as e:
-            util.logexc(LOG, ("Failed to identify script type for %s" %
-                              content_f, e))
+        f_type = identify_file(content_f)
+        if f_type == "text/plain":
+            util.write_file(
+                content_f, "\n".join(["#!/bin/bash", content]), mode=mode)
+            LOG.debug("added shebang to file %s", content_f)
 
     if link:
         try: