This page describes the CRiu Image Tool. CRIT is a feature-rich replacement for existing "criu show". It is written completely in Python, so it is quite easy to read the code and extend its features.
Usage
usage: crit [-h] [-i IN] [-o OUT] [--pretty] {decode,encode}
CRiu Image Tool
positional arguments:
{decode,encode} decode/encode - convert criu image from/to binary type
to/from json
optional arguments:
-h, --help show this help message and exit
-i IN, --in IN input file (stdin by default)
-o OUT, --out OUT output file (stdout by default)
--pretty multi-line with indentation and some fields printed in more human-readable format
Pretty output
By default CRIT prints JSON text in one line. This can be read by any further JSON-aware tool for parsing. For human eyes it's more convenient to read JSON multi-line with indentation. However, CRIT does a little bit more and prints some fields in even more pretty manner.
- Addresses and registers
- VM addresses and core.img register values are all printed in hex. Since JSON doesn't support this form of numbers, such fields are encoded as strings.
- Bit-fields
- Such things as flags and masks (e.g. sig-block mask) are also better understood when written in hex, so CRIT does this.
- IP addresses
- By default those a printed in decimal, but the "1.2.3.4" for v4 or "::1" for v6 can be seen in the --pretty mode.
TODO
- Symbolic names for flags
- Some known bits (e.g. MAP_PRIVATE, MAP_ANONYMOUS, etc. for vma->flags) can be shown with names.
Functionality
Convert images to JSON and back
Status: ready
This is the replacement for (rather nasty) criu show code. Also this is the way to edit the images before restoring from them.
It uses text_format as a human-readable format for protobuf messages.
The output file is structured in the following way.
Without "--pretty":
{ "magic" : "FOO", "entries" : [{"foo": "bar", "bar": "foo", "extra": "abc"}, {"foo": "bar", "bar" : "foo", "extra" : "abc"} ]}
With "--pretty":
{
"magic" : "FOO",
"entries" : [
{
"foo" : "bar",
"bar" : "foo",
"extra" : "abc"
},
{
"foo" : "bar",
"bar" : "foo",
"extra" : "abc"
}
]
}
Example("crit decode -i core-5679.img --pretty")
{
"magic": "CORE",
"entries": [
{
"mtype": "X86_64",
"thread_core": {
"futex_rla_len": 24,
"sched_policy": 0,
"sched_nice": 0,
"futex_rla": 0,
"signals_p": {},
"sas": {
"ss_size": 0,
"ss_sp": 0,
"ss_flags": 2
}
},
"thread_info": {
"fpregs": {
"st_space": [
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0
],
"fop": 0,
"rdp": 0,
"twd": 0,
"mxcsr": 8064,
"swd": 0,
"rip": 0,
"xsave": {
"ymmh_space": [
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0
],
"xstate_bv": 2
},
"xmm_space": [
0,
4278190080,
4294967295,
4294967295,
1701145715,
3219568,
0,
0,
0,
0,
33,
0,
792358505,
1953460082,
1852400175,
0,
942882145,
876295483,
774519349,
1031303283,
893073459,
976565307,
1937255978,
859661936,
993344312,
3814708,
65,
0,
37049520,
0,
37049632,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
4294901760,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0
],
"cwd": 0,
"mxcsr_mask": 65535
},
"clear_tid_addr": 0,
"gpregs": {
"gs": "0x0",
"ip": "0x7f172cf1ea04",
"cx": "0xffffffffffffffff",
"cs": "0x33",
"ax": "0x38",
"orig_ax": "0x38",
"di": "0x1200011",
"es": "0x0",
"gs_base": "0x0",
"r14": "0x0",
"r15": "0x2355e00",
"r12": "0x7ffffdbf74f0",
"r13": "0x0",
"r10": "0x7f172d83d9d0",
"r11": "0x246",
"fs_base": "0x7f172d83d700",
"bp": "0x7ffffdbf7530",
"dx": "0x0",
"bx": "0x0",
"ds": "0x0",
"ss": "0x2b",
"sp": "0x7ffffdbf74f0",
"r8": "0x0",
"r9": "0x0",
"fs": "0x0",
"si": "0x0",
"flags": "0x246"
}
},
"tc": {
"timers": {
"real": {
"isec": 0,
"vusec": 0,
"iusec": 0,
"vsec": 0
},
"virt": {
"isec": 0,
"vusec": 0,
"iusec": 0,
"vsec": 0
},
"prof": {
"isec": 0,
"vusec": 0,
"iusec": 0,
"vsec": 0
}
},
"cg_set": 1,
"signals_s": {},
"blk_sigset": "0x10002",
"exit_code": 0,
"rlimits": {
"rlimits": [
{
"max": 18446744073709551615,
"cur": 18446744073709551615
},
{
"max": 18446744073709551615,
"cur": 18446744073709551615
},
{
"max": 18446744073709551615,
"cur": 18446744073709551615
},
{
"max": 18446744073709551615,
"cur": 8388608
},
{
"max": 18446744073709551615,
"cur": 0
},
{
"max": 18446744073709551615,
"cur": 18446744073709551615
},
{
"max": 62844,
"cur": 62844
},
{
"max": 4096,
"cur": 1024
},
{
"max": 65536,
"cur": 65536
},
{
"max": 18446744073709551615,
"cur": 18446744073709551615
},
{
"max": 18446744073709551615,
"cur": 18446744073709551615
},
{
"max": 62844,
"cur": 62844
},
{
"max": 819200,
"cur": 819200
},
{
"max": 0,
"cur": 0
},
{
"max": 0,
"cur": 0
},
{
"max": 18446744073709551615,
"cur": 18446744073709551615
}
]
},
"comm": "loop.sh",
"flags": 1077960704,
"task_state": 1,
"personality": 0
}
}
]
}
Generate core files out of task images
Status: ready
Moved into separate project called criu-coredump.
On-the-fly conversion
Status: not ready
There's an idea to make CRIU spawn CRIT and read images "through" it, to allow for at-the-restore-time modifications
Convert between different image versions
Status: not ready
Right now we store the images version in inventory.img and collect info about what's bad with V1 images. If some day we have v2, CRIT will convert from v1. And for backward compatibility we'll use on-the-fly conversion when restoring from old images.
Show images statistics
Status: not ready
E.g. -- total number of processes, files, memory, sockets, etc.
Check/validate images
Status: not ready
Check that
- all images are present
- the inter-images IDs are in consistent state