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package fscommon
import (
"errors"
"fmt"
"math"
"path"
"strconv"
"strings"
"github.com/opencontainers/cgroups"
)
var (
// Deprecated: use cgroups.OpenFile instead.
OpenFile = cgroups.OpenFile
// Deprecated: use cgroups.ReadFile instead.
ReadFile = cgroups.ReadFile
// Deprecated: use cgroups.WriteFile instead.
WriteFile = cgroups.WriteFile
)
// ParseError records a parse error details, including the file path.
type ParseError struct {
Path string
File string
Err error
}
func (e *ParseError) Error() string {
return "unable to parse " + path.Join(e.Path, e.File) + ": " + e.Err.Error()
}
func (e *ParseError) Unwrap() error { return e.Err }
// ParseUint converts a string to an uint64 integer.
// Negative values are returned at zero as, due to kernel bugs,
// some of the memory cgroup stats can be negative.
func ParseUint(s string, base, bitSize int) (uint64, error) {
value, err := strconv.ParseUint(s, base, bitSize)
if err != nil {
intValue, intErr := strconv.ParseInt(s, base, bitSize)
// 1. Handle negative values greater than MinInt64 (and)
// 2. Handle negative values lesser than MinInt64
if intErr == nil && intValue < 0 {
return 0, nil
} else if errors.Is(intErr, strconv.ErrRange) && intValue < 0 {
return 0, nil
}
return value, err
}
return value, nil
}
// ParseKeyValue parses a space-separated "key value" kind of cgroup
// parameter and returns its key as a string, and its value as uint64
// (using [ParseUint] to convert the value). For example,
// "io_service_bytes 1234" will be returned as "io_service_bytes", 1234.
func ParseKeyValue(t string) (string, uint64, error) {
key, val, ok := strings.Cut(t, " ")
if !ok || key == "" || val == "" {
return "", 0, fmt.Errorf(`line %q is not in "key value" format`, t)
}
value, err := ParseUint(val, 10, 64)
if err != nil {
return "", 0, err
}
return key, value, nil
}
// GetValueByKey reads space-separated "key value" pairs from the specified
// cgroup file, looking for a specified key, and returns its value as uint64,
// using [ParseUint] for conversion. If the value is not found, 0 is returned.
func GetValueByKey(path, file, key string) (uint64, error) {
content, err := cgroups.ReadFile(path, file)
if err != nil {
return 0, err
}
key += " "
lines := strings.Split(content, "\n")
for _, line := range lines {
v, ok := strings.CutPrefix(line, key)
if ok {
val, err := ParseUint(v, 10, 64)
if err != nil {
err = &ParseError{Path: path, File: file, Err: err}
}
return val, err
}
}
return 0, nil
}
// GetCgroupParamUint reads a single uint64 value from the specified cgroup file.
// If the value read is "max", the math.MaxUint64 is returned.
func GetCgroupParamUint(path, file string) (uint64, error) {
contents, err := GetCgroupParamString(path, file)
if err != nil {
return 0, err
}
if contents == "max" {
return math.MaxUint64, nil
}
res, err := ParseUint(contents, 10, 64)
if err != nil {
return res, &ParseError{Path: path, File: file, Err: err}
}
return res, nil
}
// GetCgroupParamInt reads a single int64 value from specified cgroup file.
// If the value read is "max", the math.MaxInt64 is returned.
func GetCgroupParamInt(path, file string) (int64, error) {
contents, err := GetCgroupParamString(path, file)
if err != nil {
return 0, err
}
if contents == "max" {
return math.MaxInt64, nil
}
res, err := strconv.ParseInt(contents, 10, 64)
if err != nil {
return res, &ParseError{Path: path, File: file, Err: err}
}
return res, nil
}
// GetCgroupParamString reads a string from the specified cgroup file.
func GetCgroupParamString(path, file string) (string, error) {
contents, err := cgroups.ReadFile(path, file)
if err != nil {
return "", err
}
return strings.TrimSpace(contents), nil
}
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