The files in the '/proc' directory are empty about graphene HOT 8 CLOSED

Do you mean mounting the host proc file system to /proc in the library OS? I will strongly suggest not to do so. The proc file system is a pseudo file system which should reflect the OS states. The library OS has its own OS states so should only run its own proc file system.

from graphene.

But how to read the proc files of the library OS? There are no proc files in libOS if I don't mount th proc files of host system.

from graphene.

There is a simple proc file system in Graphene.

Graphene/LibOS/shim/test/native$ ./pal ls.manifest /proc
1
cpuinfo
meminfo
self

If you need a specific file in proc but Graphene hasn't implement it yet, you can try to mount only that file into graphene. Like this:

fs.mount.bin.type = chroot
fs.mount.bin.path = /proc/stat
fs.mount.bin.uri = file:/proc/stat

from graphene.

I tried this:

fs.mount.stat.type = chroot
fs.mount.stat.path = /proc/stat
fs.mount.stat.uri = file:/proc/stat

and my python code like this:

import sys
import os
#print sys.modules['psutil']

for filename in os.listdir(r'/proc'):
   	print filename

and the output:

meminfo
self
1
cpuinfo

It still cannot find the 'stat'
And I tried to read the /proc/stat directly , like this:

f=open('/proc/stat', 'rb')
values = f.readline()
print values

It should read the info of CPU time but the output is a blank line

So I think the /proc/stat in LibOS is empty. It's confusing.

from graphene.

Graphene currently does not implement /proc/stat within the libOS. I am curious why you need it? If there is an application that requires this information, it would not be hard to add (although some fields would either need to be bogus, or would need a host ABI to expose correctly). In general, we have added /proc files "on demand", or when we hit an application that we want to support that requires a given interface.

What you are doing with this manifest entry is creating a passthrough to the host /proc/stat, which might be ok, but it doesn't sound like what you want.

from graphene.

Hi, sorry to intrude on this but I have a question. You said that

fs.mount.stat.type = chroot
fs.mount.stat.path = /proc/stat
fs.mount.stat.uri = file:/proc/stat

creates a pass-through to the host's /proc/stat file. But that does not seem to be the case when I
try the same. It gives me an empty file. Is that expected behavior?

For clarification, I am trying to do something of the sort:

int fd = open("/proc/stat", O_RDONLY);
  if (fd < 0) {
    printf("File could not be opened\n");
    return -1; 
  }

  printf("File opened successfully\n");

  char buf[1024];
  int ret = read(fd, buf, 10);
  if (ret == 0) {
    printf("Buffer size is zero (0)\n");
    return -1; 
  }

from graphene.

I suspect the issue is that /proc/stat reports its size as zero bytes, and graphene is checking this size before trying to read more bytes.

On my system:

$ ls -l /proc/stat -r--r--r-- 1 root root 0 Jun 19 22:17 /proc/stat

If there is a good reason to add /proc/stat, we can put this on the feature list, either for graphene-internal emulation or as a host pass-through.

from graphene.

Already fixed on master. Host passthrough of procfs is wrong and unsupported, but we now have a proper emulation for procfs inside Graphene.

from graphene.