[PATCH 1/3] python-linux-procfs: Progate error to user if a pid is completed

[John Kacur]

If a pid is completed and disappears a FileNotFoundError will occur
because /proc/pid/stat will disappear too.

It is not possible to check for the file first because it could still
disappear between the time of the check and the time of use.

Progate this error to the user.
The user should handle this with a try, except clause and ignore it if
an exception occurs.

Signed-off-by: John Kacur <jkacur(a)redhat.com&gt;
---
 procfs/procfs.py | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/procfs/procfs.py b/procfs/procfs.py
index 408b2bcd0a31..a0e9977214fe 100755
--- a/procfs/procfs.py
+++ b/procfs/procfs.py
@@ -130,7 +130,12 @@ class pidstat:
 
     def __init__(self, pid, basedir="/proc"):
         self.pid = pid
-        self.load(basedir)
+        try:
+            self.load(basedir)
+        except FileNotFoundError:
+            # The file representing the pid has disappeared
+            #  propagate the error to the user to handle
+            raise
 
     def __getitem__(self, fieldname):
         return self.fields[fieldname]
@@ -151,7 +156,11 @@ class pidstat:
         return fieldname in self.fields
 
     def load(self, basedir="/proc"):
-        f = open("%s/%d/stat" % (basedir, self.pid))
+        try:
+            f = open("%s/%d/stat" % (basedir, self.pid))
+        except FileNotFoundError:
+            # The pid has disappeared, propagate the error
+            raise
         fields = f.readline().strip().split(') ')
         f.close()
         fields = fields[0].split(' (') + fields[1].split()
@@ -338,7 +347,11 @@ class process:
                 else:
                     sclass = pidstatus
 
-                setattr(self, attr, sclass(self.pid, self.basedir))
+                try:
+                    setattr(self, attr, sclass(self.pid, self.basedir))
+                except FileNotFoundError:
+                    # The pid has disappeared, progate the error
+                    raise
             elif attr == "cmdline":
                 self.load_cmdline()
             elif attr == "threads":
-- 
2.31.1

[PATCH 2/3] python-linux-procfs: pflags: Handle pids that completed

[John Kacur]

Sometimes pids disappear when they are completed.

Programs such as pflags that use procfs must account for that.
The solution is to simply recognize this situation, and to continue.

Signed-off-by: John Kacur <jkacur(a)redhat.com&gt;
---
 pflags | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/pflags b/pflags
index 3407b6f51c96..46d396c87c2b 100755
--- a/pflags
+++ b/pflags
@@ -50,14 +50,25 @@ def main(argv):
         pids = list(ps.processes.keys())
 
     pids.sort()
-    len_comms = [len(ps[pid]["stat"]["comm"]) for pid in pids if pid
in ps]
+    len_comms = []
+    for pid in pids:
+        if pid in ps:
+            try:
+                len(ps[pid]["stat"]["comm"])
+            except (TypeError, FileNotFoundError):
+                continue
+            len_comms.append(len(ps[pid]["stat"]["comm"]))
+
     max_comm_len = max(len_comms, default=0)
     del len_comms
 
     for pid in pids:
         if pid not in ps:
             continue
-        flags = ps[pid].stat.process_flags()
+        try:
+            flags = ps[pid].stat.process_flags()
+        except AttributeError:
+            continue
         # Remove flags that were superseeded
         if "PF_THREAD_BOUND" in flags and "PF_NO_SETAFFINITY" in
flags:
             flags.remove("PF_THREAD_BOUND")
-- 
2.31.1

[PATCH 2/3] python-linux-procfs: pflags: Handle pids that completed

[Leah Leshchinsky]

On Tue, Nov 23, 2021 at 01:07:51PM -0500, John Kacur wrote:
>  Sometimes pids disappear when they are completed.
>  
>  Programs such as pflags that use procfs must account for that.
>  The solution is to simply recognize this situation, and to continue.
>  
>  Signed-off-by: John Kacur <jkacur(a)redhat.com&gt;
>  ---
>   pflags | 15 +++++++++++++--
>   1 file changed, 13 insertions(+), 2 deletions(-)
>  
>  diff --git a/pflags b/pflags
>  index 3407b6f51c96..46d396c87c2b 100755
>  --- a/pflags
>  +++ b/pflags
>  @@ -50,14 +50,25 @@ def main(argv):
>           pids = list(ps.processes.keys())
>   
>       pids.sort()
>  -    len_comms = [len(ps[pid]["stat"]["comm"]) for pid in pids if pid
> in ps]
>  +    len_comms = []
>  +    for pid in pids:
>  +        if pid in ps:
>  +            try:
>  +                len(ps[pid]["stat"]["comm"])
>  +            except (TypeError, FileNotFoundError):
>  +                continue
>  +            len_comms.append(len(ps[pid]["stat"]["comm"]))
>  +
>       max_comm_len = max(len_comms, default=0)
>       del len_comms
>   
>       for pid in pids:
>           if pid not in ps:
>               continue
>  -        flags = ps[pid].stat.process_flags()
>  +        try:
>  +            flags = ps[pid].stat.process_flags()
>  +        except AttributeError:
>  +            continue
>           # Remove flags that were superseeded
>           if "PF_THREAD_BOUND" in flags and "PF_NO_SETAFFINITY" in
> flags:
>               flags.remove("PF_THREAD_BOUND")
>  -- 
>  2.31.1
>   
Reviewed-by: Leah Leshchinsky <lleshchi(a)redhat.com&gt;

[PATCH 2/3] python-linux-procfs: pflags: Handle pids that completed

[John Kacur]

On Wed, 24 Nov 2021, Leah Leshchinsky wrote:

>  On Tue, Nov 23, 2021 at 01:07:51PM -0500, John Kacur wrote:
>  > Sometimes pids disappear when they are completed.
>  > 
>  > Programs such as pflags that use procfs must account for that.
>  > The solution is to simply recognize this situation, and to continue.
>  > 
>  > Signed-off-by: John Kacur <jkacur(a)redhat.com&gt;
>  > ---
>  >  pflags | 15 +++++++++++++--
>  >  1 file changed, 13 insertions(+), 2 deletions(-)
>  > 
>  > diff --git a/pflags b/pflags
>  > index 3407b6f51c96..46d396c87c2b 100755
>  > --- a/pflags
>  > +++ b/pflags
>  > @@ -50,14 +50,25 @@ def main(argv):
>  >          pids = list(ps.processes.keys())
>  >  
>  >      pids.sort()
>  > -    len_comms = [len(ps[pid]["stat"]["comm"]) for pid in pids
> if pid in ps]
>  > +    len_comms = []
>  > +    for pid in pids:
>  > +        if pid in ps:
>  > +            try:
>  > +                len(ps[pid]["stat"]["comm"])
>  > +            except (TypeError, FileNotFoundError):
>  > +                continue
>  > +            len_comms.append(len(ps[pid]["stat"]["comm"]))
>  > +
>  >      max_comm_len = max(len_comms, default=0)
>  >      del len_comms
>  >  
>  >      for pid in pids:
>  >          if pid not in ps:
>  >              continue
>  > -        flags = ps[pid].stat.process_flags()
>  > +        try:
>  > +            flags = ps[pid].stat.process_flags()
>  > +        except AttributeError:
>  > +            continue
>  >          # Remove flags that were superseeded
>  >          if "PF_THREAD_BOUND" in flags and "PF_NO_SETAFFINITY"
> in flags:
>  >              flags.remove("PF_THREAD_BOUND")
>  > -- 
>  > 2.31.1
>  > 
>  Reviewed-by: Leah Leshchinsky <lleshchi(a)redhat.com&gt; 
Added your Reviewed-by:

Thanks

John

[PATCH 3/3] python-linux-procfs: Makefile: Add ctags

[John Kacur]

Add the ability to use ctags to the Makefile. This adds the commands

make tags
make cleantags

and modifies
make clean

to call cleantags

Signed-off-by: John Kacur <jkacur(a)redhat.com&gt;
---
 Makefile | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index ebca02d47f95..b29f968b726f 100644
--- a/Makefile
+++ b/Makefile
@@ -31,4 +31,12 @@ rpmclean:
 pyclean:
 	@find . -type f \( -name \*~ -o -name \*.pyc \) -delete
 
-clean: pyclean rpmclean
+.PHONY: tags
+tags:
+	ctags -R --extra=+fq --python-kinds=+cfmvi
+
+.PHONY: cleantags
+cleantags:
+	rm -f tags
+
+clean: pyclean rpmclean cleantags
-- 
2.31.1