coredump: fix handling of num_pages

[rst0git]

This patch fixes the following error:

$ sudo make -C test/others/criu-coredump run
...
Traceback (most recent call last):
  File "/home/circleci/criu/coredump/coredump", line 55, in <module>
    main()
  File "/home/circleci/criu/coredump/coredump", line 47, in main
    coredump(opts)
  File "/home/circleci/criu/coredump/coredump", line 14, in coredump
    cores = generator(os.path.realpath(opts['in']))
  File "/home/circleci/criu/coredump/criu_coredump/coredump.py", line 192, in __call__
    self.coredumps[pid] = self._gen_coredump(pid)
  File "/home/circleci/criu/coredump/criu_coredump/coredump.py", line 214, in _gen_coredump
    cd.vmas = self._gen_vmas(pid)
  File "/home/circleci/criu/coredump/criu_coredump/coredump.py", line 992, in _gen_vmas
    v.data = self._gen_mem_chunk(pid, vma, v.filesz)
  File "/home/circleci/criu/coredump/criu_coredump/coredump.py", line 879, in _gen_mem_chunk
    page_mem = self._get_page(pid, page_no)
  File "/home/circleci/criu/coredump/criu_coredump/coredump.py", line 797, in _get_page
    num_pages = m.get("nr_pages", m.compat_nr_pages)
AttributeError: 'dict' object has no attribute 'compat_nr_pages'
+ exit 1 make[1]: *** [Makefile:3: run] Error 1

[avagin]

how is it possible? cmpat_nr_pages is a required field:

criu/images/pagemap.proto

Line 13 in e879d69

required uint32 compat_nr_pages = 2;

[rst0git]

The error appears in the CentOS Stream 9 based test CI test for the master branch (https://cirrus-ci.com/task/4855368628568064) and I was able to replicate it locally:

$ sudo crit show test/others/criu-coredump/pagemap-44763.img
{
    "magic": "PAGEMAP",
    "entries": [
        {
            "pages_id": 1
        },
        {
            "vaddr": "0x400000",
            "compat_nr_pages": 0,
            "flags": "PE_PRESENT",
            "nr_pages": 1
        },
        {
            "vaddr": "0x402000",
            "compat_nr_pages": 0,
            "flags": "PE_PRESENT",
            "nr_pages": 2
        },
        {
            "vaddr": "0x7fe251884000",
            "compat_nr_pages": 0,
            "flags": "PE_PRESENT",
            "nr_pages": 2
        },
        {
            "vaddr": "0x7fe251a6b000",
            "compat_nr_pages": 0,
            "flags": "PE_PRESENT",
            "nr_pages": 7
        },
        {
            "vaddr": "0x7fe251a75000",
            "compat_nr_pages": 0,
            "flags": "PE_PRESENT",
            "nr_pages": 4
        },
        {
            "vaddr": "0x7fe251a96000",
            "compat_nr_pages": 0,
            "flags": "PE_PRESENT",
            "nr_pages": 2
        },
        {
            "vaddr": "0x7fe251a9e000",
            "compat_nr_pages": 0,
            "flags": "PE_PRESENT",
            "nr_pages": 2
        },
        {
            "vaddr": "0x7fe251ad4000",
            "compat_nr_pages": 0,
            "flags": "PE_PRESENT",
            "nr_pages": 4
        },
        {
            "vaddr": "0x7fffaf010000",
            "compat_nr_pages": 0,
            "flags": "PE_PRESENT",
            "nr_pages": 4
        }
    ]
}

[rst0git]

In this case m is a dictionary, so m['compat_nr_pages'] works but m.compat_nr_pages does not.

[avagin]

should we use m['compat_nr_pages']?

[avagin]

What does this test do? Why doesn't get this error?

[rst0git]

What does this test do? Why doesn't get this error?

The test seems to be correct. It is just running criu-coredump and fails due to a syntax error in the Python code. I somehow missed this in #2809.

[avagin]

Merged. Thanks.