One long weekend.

.github/workflows/release.yml

@@ -0,0 +1,26 @@
+name: release
+
+on:
+  push:
+    tags:
+      - v*
+
+jobs:
+  build:
+    name: releasing
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          fetch-depth: 0
+
+      - uses: actions/setup-go@v3
+        with:
+          go-version: "1.19"
+      - uses: goreleaser/goreleaser-action@v3
+        with:
+          version: latest
+          args: release --rm-dist
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/test.yml

@@ -0,0 +1,22 @@
+name: tests
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+jobs:
+  test:
+    name: tests
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ ubuntu-latest ]
+
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-go@v3
+        with:
+          go-version: '1.19'
+          cache: true
+      - name: Run tests
+        run: sudo apt install -y musl-tools && make test

.gitignore

@@ -0,0 +1,3 @@
+.idea
+/grace
+/dist

.goreleaser.yml

@@ -0,0 +1,33 @@
+before:
+  hooks:
+    - sudo apt install -y musl-tools
+
+builds:
+  - id: grace
+    main: .
+    binary: grace
+    ldflags:
+      - "-linkmode external -s -w -extldflags '-fno-PIC -static'"
+    env:
+      - CGO_ENABLED=1
+      - CC=musl-gcc
+    goos:
+      - linux
+    goarch:
+      - "amd64"
+changelog:
+  sort: asc
+  filters:
+    exclude:
+      - "^docs:"
+      - "^test:"
+
+archives:
+  - format: binary
+    name_template: "{{ .Binary}}-{{ .Os }}-{{ .Arch }}"
+
+release:
+  prerelease: auto
+  github:
+    owner: liamg
+    name: grace

CONTRIBUTING.md

@@ -0,0 +1,7 @@
+# Contributing
+
+## Useful Links
+
+- [List of syscalls with descriptions](https://linuxhint.com/list_of_linux_syscalls/)
+- [Syscall table](https://chromium.googlesource.com/chromiumos/docs/+/master/constants/syscalls.md)
+- [Another Syscall table](https://blog.rchapman.org/posts/Linux_System_Call_Table_for_x86_64/)

LICENSE

@@ -0,0 +1,24 @@
+This is free and unencumbered software released into the public domain.
+
+Anyone is free to copy, modify, publish, use, compile, sell, or
+distribute this software, either in source code form or as a compiled
+binary, for any purpose, commercial or non-commercial, and by any
+means.
+
+In jurisdictions that recognize copyright laws, the author or authors
+of this software dedicate any and all copyright interest in the
+software to the public domain. We make this dedication for the benefit
+of the public at large and to the detriment of our heirs and
+successors. We intend this dedication to be an overt act of
+relinquishment in perpetuity of all present and future rights to this
+software under copyright law.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+OTHER DEALINGS IN THE SOFTWARE.
+
+For more information, please refer to <http://unlicense.org/>

Makefile

@@ -0,0 +1,13 @@
+default: build
+
+.PHONY: test
+test:
+	CC=musl-gcc CGO_ENABLED=1 go test ./...
+
+.PHONY: build
+build:
+	CGO_ENABLED=1 CC=musl-gcc go build --ldflags '-linkmode external -extldflags "-static"'
+
+.PHONY: demo
+demo: build
+	./grace -- cat /dev/null

README.md

@@ -1,2 +1,51 @@
 # grace
-It's strace, with colours.
+
+_grace_ is a tool for monitoring and modifying syscalls for a given process.
+
+It's essentially a lightweight [strace](https://en.wikipedia.org/wiki/Strace), in Go, with colours and pretty output.
+
+![](screenshot.png)
+
+// TODO: new screenshot
+
+## Features/Usage Examples
+
+### grace vs. strace
+
+_grace_ isn't meant to compete with _strace_, it's purely meant to be a user-friendly, lightweight alternative. However, the following should provide a rough idea of what is supported in _grace_ so far.
+
+| Feature                                                                               | grace | strace |
+|---------------------------------------------------------------------------------------|-------|--------|
+| Start a program and print all syscalls it makes                                       | ✅     | ✅      |
+| Attach to an existing process by `pid` and print all syscalls it makes                | ✅     | ✅      |
+| Filter syscalls by name, e.g. only show occurrences of the `open` syscall             | ❌     | ✅      |
+| Filter syscalls using a given path, e.g. only show syscalls that access `/etc/passwd` | ❌     | ✅      |
+| Dump I/O for certain file descriptors                                                 | ❌     | ✅      |
+| Count occurrences and duration of all syscalls and present in a useful format         | ❌     | ✅      |
+| Print relative/absolute timestamps                                                    | ❌     | ✅      |
+| Tamper with syscalls                                                                  | ❌     | ✅      |
+| Print extra information about file descriptors, such as path, socket addresses etc.   | some  | ✅      |
+| Print stack traces                                                                    | ❌     | ✅      |
+| Filter by return value                                                                | ❌     | ✅      |
+| Decode SELinux context info                                                           | ❌     | ✅      |
+| Pretty colours to make output easier to read                                          | ✅     | ❌      |
+
+### Usage Examples
+
+```
+// TODO
+```
+
+## Installation
+
+Grab a statically compiled binary from the [latest release](https://github.com/liamg/grace/releases/latest).
+
+## Build Dependencies
+
+If you want to build _grace_ yourself instead of using the precompiled binaries, you'll need a recent version of Go (1.19+), `musl-gcc` installed (you can install `musl-tools` on Ubuntu or `musl` on Arch), and kernel headers (install `linux-headers-$(uname -r)` on Ubuntu or `linux-headers` on Arch). _grace_ mainly just pulls constants from the kernel headers, so it's not a huge dependency. You should then have some success running `make build`. Note that many architectures are not yet supported (see below.)
+
+## Supported Platforms/Architecture
+
+Currently only Linux/amd64 is supported. Other architectures coming soon.
+
+If you'd like to implement a new architecture, you can duplicate `tracer/sys_amd64.go` and convert it to contain the syscall definitions for your arch.

go.mod

@@ -0,0 +1,17 @@
+module github.com/liamg/grace
+
+go 1.19
+
+require (
+	github.com/spf13/cobra v1.6.1
+	github.com/stretchr/testify v1.8.1
+	golang.org/x/sys v0.1.0
+)
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/inconshreveable/mousetrap v1.0.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/spf13/pflag v1.0.5 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)

go.sum

@@ -0,0 +1,27 @@
+github.com/cpuguy83/go-md2man/v2 v2.0.2/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/inconshreveable/mousetrap v1.0.1 h1:U3uMjPSQEBMNp1lFxmllqCPM6P5u/Xq7Pgzkat/bFNc=
+github.com/inconshreveable/mousetrap v1.0.1/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
+github.com/spf13/cobra v1.6.1 h1:o94oiPyS4KD1mPy2fmcYYHHfCxLqYjJOhGsCHFZtEzA=
+github.com/spf13/cobra v1.6.1/go.mod h1:IOw/AERYS7UzyrGinqmz6HLUo219MORXGxhbaJUqzrY=
+github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
+github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
+github.com/stretchr/objx v0.5.0/go.mod h1:Yh+to48EsGEfYuaHDzXPcE3xhTkx73EhmCGUpEOglKo=
+github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
+github.com/stretchr/testify v1.8.1 h1:w7B6lhMri9wdJUVmEZPGGhZzrYTPvgJArz7wNPgYKsk=
+github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
+golang.org/x/sys v0.1.0 h1:kunALQeHf1/185U1i0GOB/fy1IPRDDpuoOOqRReG57U=
+golang.org/x/sys v0.1.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

main.go

@@ -0,0 +1,102 @@
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/liamg/grace/printer"
+
+	"github.com/liamg/grace/tracer"
+	"github.com/spf13/cobra"
+)
+
+var (
+	flagDisableColours      = false
+	flagMaxStringLen        = 32
+	flagHexDumpLongStrings  = true
+	flagMaxHexDumpLen       = 4096
+	flagPID                 = 0
+	flagSuppressOutput      = false
+	flagMaxObjectProperties = 2
+	flagVerbose             = false
+	flagExtraNewLine        = false
+	flagMultiline           = false
+)
+
+var rootCmd = &cobra.Command{
+	Use:     "grace [flags] [command [args]]",
+	Example: `grace -- cat /etc/passwd`,
+	Short: `grace is a CLI tool for monitoring and modifying syscalls for a given process.
+
+It's essentially strace, in Go, with colours and pretty output.`,
+	RunE: func(cmd *cobra.Command, args []string) error {
+		cmd.SilenceErrors = true
+		cmd.SilenceUsage = true
+
+		if len(args) == 0 && flagPID == 0 {
+			return cmd.Help()
+		}
+
+		var t *tracer.Tracer
+		var err error
+		if flagPID > 0 {
+			t = tracer.New(flagPID)
+		} else {
+			t, err = tracer.FromCommand(flagSuppressOutput, args[0], args[1:]...)
+			if err != nil {
+				return err
+			}
+		}
+
+		p := printer.New(cmd.OutOrStdout())
+
+		p.SetUseColours(!flagDisableColours)
+		p.SetMaxStringLen(flagMaxStringLen)
+		p.SetMaxHexDumpLen(flagMaxHexDumpLen)
+		p.SetExtraNewLine(flagExtraNewLine)
+		p.SetMultiLine(flagMultiline)
+
+		if flagVerbose {
+			p.SetHexDumpLongStrings(true)
+			p.SetMaxObjectProperties(0)
+		} else {
+			p.SetHexDumpLongStrings(flagHexDumpLongStrings)
+			p.SetMaxObjectProperties(flagMaxObjectProperties)
+		}
+
+		t.SetSyscallEnterHandler(p.PrintSyscallEnter)
+		t.SetSyscallExitHandler(p.PrintSyscallExit)
+		t.SetSignalHandler(p.PrintSignal)
+		t.SetProcessExitHandler(p.PrintProcessExit)
+
+		// TODO: set signal handler!
+
+		defer func() { _, _ = fmt.Fprintln(cmd.ErrOrStderr(), "") }()
+
+		return t.Start()
+	},
+}
+
+func init() {
+	rootCmd.Flags().BoolVarP(&flagDisableColours, "no-colours", "C", flagDisableColours, "disable colours in output")
+	rootCmd.Flags().IntVarP(&flagMaxStringLen, "max-string-len", "s", flagMaxStringLen, "maximum length of strings to print")
+	rootCmd.Flags().BoolVarP(&flagHexDumpLongStrings, "hex-dump-long-strings", "x", flagHexDumpLongStrings, "hex dump strings longer than --max-string-len")
+	rootCmd.Flags().IntVarP(&flagMaxHexDumpLen, "max-hex-dump-len", "l", flagMaxHexDumpLen, "maximum length of hex dumps")
+	rootCmd.Flags().IntVarP(&flagPID, "pid", "p", flagPID, "trace an existing process by PID")
+	rootCmd.Flags().BoolVarP(&flagSuppressOutput, "suppress-output", "S", flagSuppressOutput, "suppress output of command")
+	rootCmd.Flags().IntVarP(&flagMaxObjectProperties, "max-object-properties", "o", flagMaxObjectProperties, "maximum number of properties to print for objects (recursive) - this also applies to array elements")
+	rootCmd.Flags().BoolVarP(&flagVerbose, "verbose", "v", flagVerbose, "enable verbose output (overrides other verbosity settings)")
+	rootCmd.Flags().BoolVarP(&flagExtraNewLine, "extra-newline", "n", flagExtraNewLine, "print an extra newline after each syscall to aid readability")
+	rootCmd.Flags().BoolVarP(&flagMultiline, "multiline", "m", flagMultiline, "print each syscall argument on a separate line to aid readability")
+}
+
+func main() {
+
+	if err := rootCmd.Execute(); err != nil {
+		if err.Error() == "no such process" {
+			os.Exit(0)
+		}
+		_, _ = fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}