add bcat() utility

Signed-off-by: Giampaolo Rodola <g.rodola@gmail.com>

1 files changed, 53 insertions, 42 deletions

diff --git a/psutil/_pslinux.py b/psutil/_pslinux.py
index ab1b6f1b..60959871 100644
--- a/psutil/_pslinux.py
+++ b/psutil/_pslinux.py
@@ -283,20 +283,33 @@ def set_scputimes_ntuple(procfs_path):
     scputimes = namedtuple('scputimes', fields)
 
 
-def cat(fname, fallback=_DEFAULT, binary=True):
-    """Return file content.
-    fallback: the value returned in case the file does not exist or
-              cannot be read
-    binary: whether to open the file in binary or text mode.
+def cat(fname, fallback=_DEFAULT):
+    """Return file content. File is opened in text mode.
+    If specified, `fallback` is the value returned in case of error,
+    either if the file does not exist or cannot be read().
     """
-    try:
-        with open_binary(fname) if binary else open_text(fname) as f:
-            return f.read().strip()
-    except (IOError, OSError):
-        if fallback is not _DEFAULT:
+    if fallback is _DEFAULT:
+        with open_text(fname) as f:
+            return f.read()
+    else:
+        try:
+            with open_text(fname) as f:
+                return f.read()
+        except (IOError, OSError):
+            return fallback
+
+
+def bcat(fname, fallback=_DEFAULT):
+    """Same as above but in binary mode."""
+    if fallback is _DEFAULT:
+        with open_binary(fname) as f:
+            return f.read()
+    else:
+        try:
+            with open_binary(fname) as f:
+                return f.read()
+        except (IOError, OSError):
             return fallback
-        else:
-            raise
 
 
 try:
@@ -751,17 +764,17 @@ if os.path.exists("/sys/devices/system/cpu/cpufreq/policy0") or \
                 # https://github.com/giampaolo/psutil/issues/1851
                 curr = cpuinfo_freqs[i] * 1000
             else:
-                curr = cat(pjoin(path, "scaling_cur_freq"), fallback=None)
+                curr = bcat(pjoin(path, "scaling_cur_freq"), fallback=None)
             if curr is None:
                 # Likely an old RedHat, see:
                 # https://github.com/giampaolo/psutil/issues/1071
-                curr = cat(pjoin(path, "cpuinfo_cur_freq"), fallback=None)
+                curr = bcat(pjoin(path, "cpuinfo_cur_freq"), fallback=None)
                 if curr is None:
                     raise NotImplementedError(
                         "can't find current frequency file")
             curr = int(curr) / 1000
-            max_ = int(cat(pjoin(path, "scaling_max_freq"))) / 1000
-            min_ = int(cat(pjoin(path, "scaling_min_freq"))) / 1000
+            max_ = int(bcat(pjoin(path, "scaling_max_freq"))) / 1000
+            min_ = int(bcat(pjoin(path, "scaling_min_freq"))) / 1000
             ret.append(_common.scpufreq(curr, min_, max_))
         return ret
 
@@ -1349,9 +1362,9 @@ def sensors_temperatures():
     for base in basenames:
         try:
             path = base + '_input'
-            current = float(cat(path)) / 1000.0
+            current = float(bcat(path)) / 1000.0
             path = os.path.join(os.path.dirname(base), 'name')
-            unit_name = cat(path, binary=False)
+            unit_name = cat(path).strip()
         except (IOError, OSError, ValueError):
             # A lot of things can go wrong here, so let's just skip the
             # whole entry. Sure thing is Linux's /sys/class/hwmon really
@@ -1363,9 +1376,9 @@ def sensors_temperatures():
             # https://github.com/giampaolo/psutil/issues/1323
             continue
 
-        high = cat(base + '_max', fallback=None)
-        critical = cat(base + '_crit', fallback=None)
-        label = cat(base + '_label', fallback='', binary=False)
+        high = bcat(base + '_max', fallback=None)
+        critical = bcat(base + '_crit', fallback=None)
+        label = cat(base + '_label', fallback='').strip()
 
         if high is not None:
             try:
@@ -1388,9 +1401,9 @@ def sensors_temperatures():
         for base in basenames:
             try:
                 path = os.path.join(base, 'temp')
-                current = float(cat(path)) / 1000.0
+                current = float(bcat(path)) / 1000.0
                 path = os.path.join(base, 'type')
-                unit_name = cat(path, binary=False)
+                unit_name = cat(path).strip()
             except (IOError, OSError, ValueError) as err:
                 debug(err)
                 continue
@@ -1402,13 +1415,13 @@ def sensors_temperatures():
             high = None
             for trip_point in trip_points:
                 path = os.path.join(base, trip_point + "_type")
-                trip_type = cat(path, fallback='', binary=False)
+                trip_type = cat(path, fallback='').strip()
                 if trip_type == 'critical':
-                    critical = cat(os.path.join(base, trip_point + "_temp"),
-                                   fallback=None)
+                    critical = bcat(os.path.join(base, trip_point + "_temp"),
+                                    fallback=None)
                 elif trip_type == 'high':
-                    high = cat(os.path.join(base, trip_point + "_temp"),
-                               fallback=None)
+                    high = bcat(os.path.join(base, trip_point + "_temp"),
+                                fallback=None)
 
                 if high is not None:
                     try:
@@ -1446,13 +1459,12 @@ def sensors_fans():
     basenames = sorted(set([x.split('_')[0] for x in basenames]))
     for base in basenames:
         try:
-            current = int(cat(base + '_input'))
+            current = int(bcat(base + '_input'))
         except (IOError, OSError) as err:
             debug(err)
             continue
-        unit_name = cat(os.path.join(os.path.dirname(base), 'name'),
-                        binary=False)
-        label = cat(base + '_label', fallback='', binary=False)
+        unit_name = cat(os.path.join(os.path.dirname(base), 'name'))
+        label = cat(base + '_label', fallback='')
         ret[unit_name].append(_common.sfan(label, current))
 
     return dict(ret)
@@ -1467,12 +1479,12 @@ def sensors_battery():
     """
     null = object()
 
-    def multi_cat(*paths):
+    def multi_bcat(*paths):
         """Attempt to read the content of multiple files which may
         not exist. If none of them exist return None.
         """
         for path in paths:
-            ret = cat(path, fallback=null)
+            ret = bcat(path, fallback=null)
             if ret != null:
                 try:
                     return int(ret)
@@ -1490,16 +1502,16 @@ def sensors_battery():
     root = os.path.join(POWER_SUPPLY_PATH, sorted(bats)[0])
 
     # Base metrics.
-    energy_now = multi_cat(
+    energy_now = multi_bcat(
         root + "/energy_now",
         root + "/charge_now")
-    power_now = multi_cat(
+    power_now = multi_bcat(
         root + "/power_now",
         root + "/current_now")
-    energy_full = multi_cat(
+    energy_full = multi_bcat(
         root + "/energy_full",
         root + "/charge_full")
-    time_to_empty = multi_cat(root + "/time_to_empty_now")
+    time_to_empty = multi_bcat(root + "/time_to_empty_now")
 
     # Percent. If we have energy_full the percentage will be more
     # accurate compared to reading /capacity file (float vs. int).
@@ -1517,13 +1529,13 @@ def sensors_battery():
     # Note: AC0 is not always available and sometimes (e.g. CentOS7)
     # it's called "AC".
     power_plugged = None
-    online = multi_cat(
+    online = multi_bcat(
         os.path.join(POWER_SUPPLY_PATH, "AC0/online"),
         os.path.join(POWER_SUPPLY_PATH, "AC/online"))
     if online is not None:
         power_plugged = online == 1
     else:
-        status = cat(root + "/status", fallback="", binary=False).lower()
+        status = cat(root + "/status", fallback="").strip().lower()
         if status == "discharging":
             power_plugged = False
         elif status in ("charging", "full"):
@@ -1700,8 +1712,7 @@ class Process(object):
         The return value is cached in case oneshot() ctx manager is
         in use.
         """
-        with open_binary("%s/%s/stat" % (self._procfs_path, self.pid)) as f:
-            data = f.read()
+        data = bcat("%s/%s/stat" % (self._procfs_path, self.pid))
         # Process name is between parentheses. It can contain spaces and
         # other parentheses. This is taken into account by looking for
         # the first occurrence of "(" and the last occurence of ")".