// printVersionInfo prints the version information about this application
func printVersionInfo(f *os.File) {
const versionTempl = `
{{.AppName}} version {{.AppVersion}} ({{.Os}},{{.Arch}})
Built on:
{{.Sp3}}{{.BuildTime}}
Author:
{{.Sp3}}Fabio Hernandez
{{.Sp3}}IN2P3/CNRS computing center, Lyon (France)
Source code and documentation:
{{.Sp3}}https://github.com/airnandez/{{.AppName}}
`
fields := map[string]string{
"AppName": programName,
"AppVersion": version,
"BuildTime": buildTime,
"Os": runtime.GOOS,
"Arch": runtime.GOARCH,
"Sp3": " ",
}
minWidth, tabWidth, padding := 8, 4, 0
tabwriter := tabwriter.NewWriter(f, minWidth, tabWidth, padding, byte(' '), 0)
templ := template.Must(template.New("").Parse(versionTempl))
templ.Execute(tabwriter, fields)
tabwriter.Flush()
}
func (infos InfoSet) String() string {
//no error checking, none of this should fail
buffer := bytes.NewBuffer(make([]byte, 0, 1024))
tabwriter := tabwriter.NewWriter(buffer, 4, 4, 2, ' ', 0)
first := true
for _, info := range infos {
if first {
writeLine(tabwriter, true, info)
}
first = false
writeLine(tabwriter, false, info)
}
tabwriter.Flush()
return buffer.String()
}
// printUsage prints how to use this application
func printUsage(f *os.File, kind HelpType) {
const usageTempl = `
USAGE:
{{.Sp3}}{{.AppName}} --mount=<directory> --shadow=<directory> [--out=<file>]
{{.Sp3}}{{.AppNameFiller}} [(--csv | --json)] [--ro]
{{.Sp3}}{{.AppName}} --help
{{.Sp3}}{{.AppName}} --version
{{if eq .UsageVersion "short"}}
Use '{{.AppName}} --help' to get detailed information about options and
examples of usage.{{else}}
DESCRIPTION:
{{.Sp3}}{{.AppName}} mounts a synthesized file system which purpose is to generate
{{.Sp3}}trace events for each low level file I/O operation executed on any file
{{.Sp3}}or directory under its control. Examples of such operations are open(2),
{{.Sp3}}read(2), write(2), close(2), access(2), etc.
{{.Sp3}}{{.AppName}} exposes the contents of the directory specified by the
{{.Sp3}}option '--shadow' via the path specified by the option '--mount'. {{.AppName}}
{{.Sp3}}generates a trace event for each I/O operation and forwards the operation
{{.Sp3}}to the target file system, that is, the one which actually hosts the shadow
{{.Sp3}}directory. See the EXAMPLES section below.
{{.Sp3}}Individual trace events generated by {{.AppName}} are written to the specified
{{.Sp3}}output file (option --out) in the specified format.
OPTIONS:
{{.Sp3}}--mount=<directory>
{{.Tab1}}This is the top directory through which the files and directories residing
{{.Tab1}}under the shadow directory will be exposed. See the EXAMPLES section below.
{{.Tab1}}The specified directory must exist and must be empty.
{{.Sp3}}--shadow=<directory>
{{.Tab1}}This is a directory where the files and directories you want to trace
{{.Tab1}}actually reside.
{{.Tab1}}The specified directory must exist but may be empty.
{{.Sp3}}--out=<file>
{{.Tab1}}Path of the text file to write the trace events to. If this file
{{.Tab1}}does not exist it will be created, otherwise new events will be appended.
{{.Tab1}}Note that this file cannot be located under the shadow directory.
{{.Tab1}}Use '-' (dash) to write the trace events to the standard output.
{{.Tab1}}In addition, you can specify a file name with extension '.csv' or '.json'
{{.Tab1}}to instruct {{.AppName}} to emit records in the corresponding format,
{{.Tab1}}as if you had used the '--csv' or '--json' options (see below).
{{.Tab1}}Default: write trace records to standard output.
{{.Sp3}}--csv
{{.Tab1}}Format each individual trace event generated by {{.AppName}} as a set of
{{.Tab1}}comma-separated values in a single line.
{{.Tab1}}Note that not all events contain the same information since each
{{.Tab1}}low level I/O operation requires specific arguments. Please refer to
{{.Tab1}}the documentation at 'https://github.com/airnandez/{{.AppName}}' for
{{.Tab1}}details on the format of each event.
{{.Tab1}}CSV is the default output format unless the output file name (see option
{{.Tab1}}'--out' above) has a '.json' extension.
{{.Sp3}}--json
{{.Tab1}}Format each individual trace event generated by {{.AppName}} as
{{.Tab1}}a JSON object. Events in this format are self-described but not all
{{.Tab1}}events contain the same information since each low level I/O operation
{{.Tab1}}requires specific arguments. Please refer to the documentation
{{.Tab1}}at 'https://github.com/airnandez/{{.AppName}}' for details on the format
{{.Tab1}}of each event.
{{.Sp3}}--ro
{{.Tab1}}Expose the shadow file system as a read-only file system.
{{.Tab1}}Default: if this option is not specified, the file system is mounted in
{{.Tab1}}read-write mode.
{{.Sp3}}--help
{{.Tab1}}Show this help
{{.Sp3}}--version
{{.Tab1}}Show version information and source repository location
EXAMPLES:
{{.Sp3}}To trace file I/O operations on files under $HOME/data use:
{{.Tab1}}{{.AppName}} --mount=/tmp/trace --shadow=$HOME/data
{{.Sp3}}After a successfull mount, the contents under $HOME/data are also
{{.Sp3}}accessible by using the path /tmp/trace. For instance, if the
{{.Sp3}}file $HOME/data/hello.txt exists, {{.AppName}} traces all the file I/O
{{.Sp3}}operations induced by the command:
{{.Tab1}}cat /tmp/trace/hello.txt
{{.Sp3}}Trace events for each one of the low level operations induced by the
{{.Sp3}}'cat' command above will be written to the output file, the standard
{{.Sp3}}output in this particular example.
{{.Sp3}}You can also create new files under /tmp/trace. For instance, the file
{{.Sp3}}I/O operations induced by the shell command:
{{.Tab1}}echo "This is a new file" > /tmp/trace/newfile.txt
{{.Sp3}}will be traced and the file will actually be created in
{{.Sp3}}$HOME/data/newfile.txt. This file will persist even after unmounting
{{.Sp3}}{{.AppName}} (see below on how to unmount the synthetized file system).
{{.Sp3}}Please note that any destructive action, such as removing or modifying
{{.Sp3}}the contents of a file or directory using the path /tmp/trace will
{{.Sp3}}affect the corresponding file or directory under $HOME/data.
{{.Sp3}}For example, the command:
{{.Tab1}}rm /tmp/trace/notes.txt
{{.Sp3}}will have the same destructive effect as if you had executed
{{.Tab1}}rm $HOME/data/notes.txt
{{.Sp3}}To unmount the file system exposed by {{.AppName}} use:
{{.Tab1}}umount /tmp/trace
{{.Sp3}}Alternatively, on MacOS X you can also use the diskutil(8) command:
{{.Tab1}}/usr/sbin/diskutil unmount /tmp/trace
{{end}}
`
fields := map[string]string{
"AppName": programName,
"AppNameFiller": strings.Repeat(" ", len(programName)),
"Sp2": " ",
"Sp3": " ",
"Sp4": " ",
"Sp5": " ",
"Sp6": " ",
"Tab1": "\t",
"Tab2": "\t\t",
"Tab3": "\t\t\t",
"Tab4": "\t\t\t\t",
"Tab5": "\t\t\t\t\t",
"Tab6": "\t\t\t\t\t\t",
"UsageVersion": "short",
}
if kind == HelpLong {
fields["UsageVersion"] = "long"
}
minWidth, tabWidth, padding := 8, 4, 0
tabwriter := tabwriter.NewWriter(f, minWidth, tabWidth, padding, byte(' '), 0)
templ := template.Must(template.New("").Parse(usageTempl))
templ.Execute(tabwriter, fields)
tabwriter.Flush()
}