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This commit is contained in:
Hugo Mårdbrink 2025-08-01 23:16:51 +02:00
commit 3e2b956786
6 changed files with 559 additions and 0 deletions

1
.gitignore vendored Normal file
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skal

2
Makefile Normal file
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run:
odin run .

48
main.odin Normal file
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package main
import "core:os"
import "core:fmt"
import "core:log"
import "core:mem"
import "parser"
import "shell"
INPUT_MAX :: 4096
main :: proc() {
track: mem.Tracking_Allocator
mem.tracking_allocator_init(&track, context.temp_allocator)
context.temp_allocator = mem.tracking_allocator(&track)
defer {
if len(track.allocation_map) > 0 {
fmt.eprintf("=== %v allocations not freed: ===\n", len(track.allocation_map))
for _, entry in track.allocation_map {
fmt.eprintf("- %v bytes @ %v\n", entry.size, entry.location)
}
}
mem.tracking_allocator_destroy(&track)
}
buf: [INPUT_MAX]byte
for true {
prompt := shell.get_prompt()
fmt.print(prompt)
buf_len, err := os.read(os.stdin, buf[:])
log.assertf(err == nil, "Error reading input")
input := string(buf[:buf_len])
cmd_seq, parser_err := parser.parse(input)
log.assertf(parser_err == nil, "Could not parse input")
stop := shell.execute(&cmd_seq)
free_all(context.temp_allocator)
if stop == .Stop do break
}
}

253
parser/parser.odin Normal file
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package parser
import "core:strings"
import "core:fmt"
import "core:mem"
import "core:slice"
import "core:log"
FORBIDDEN_TOKENS :: []string {
"&&",
"||",
"|",
">",
"&>",
"<",
"2>",
}
@private
ParseError :: enum {
None = 0,
MissingCommand,
MissingRedirect,
ForbiddenToken,
}
SequenceType :: enum {
Head,
Or,
And
}
Command :: struct {
name: cstring,
args: [dynamic]cstring,
}
PipeSequence :: struct {
rstdin: cstring,
rstdout: cstring,
rstderr: cstring,
is_background: bool,
commands: [dynamic]Command,
sequence_type: SequenceType,
}
CommandSequence :: struct {
pipe_sequences: [dynamic]PipeSequence,
}
ParserState :: struct {
cmd_seq: CommandSequence,
cur_pipe_seq: PipeSequence,
cur_cmd: Command,
tokens: []cstring,
token_idx: int,
}
@private
new_command :: proc() -> Command {
cmd := Command{ name = "" }
err: mem.Allocator_Error
cmd.args, err = make([dynamic]cstring, 0, 1, context.temp_allocator)
log.assertf(err == nil, "Memory allocation failed")
return cmd
}
@private
new_pipe_sequence :: proc(seq_type: SequenceType) -> PipeSequence {
pipe_seq := PipeSequence{ sequence_type = seq_type }
err: mem.Allocator_Error
pipe_seq.commands, err = make([dynamic]Command, 0, 1, context.temp_allocator)
log.assertf(err == nil, "Memory allocation failed")
return pipe_seq
}
@private
parse_token :: proc(parser_state: ^ParserState) -> ParseError {
token := parser_state.tokens[parser_state.token_idx]
switch(token) {
case "&":
if parser_state^.cur_cmd.name == "" do return ParseError.MissingCommand
parser_state^.cur_pipe_seq.is_background = true
parser_state^.token_idx += 1
case "&&":
if parser_state^.cur_cmd.name == "" do return ParseError.MissingCommand
_, mem_err := append(&parser_state^.cur_pipe_seq.commands, parser_state^.cur_cmd)
log.assertf(mem_err == nil, "Memory allocation failed")
_, mem_err = append(&parser_state^.cmd_seq.pipe_sequences, parser_state^.cur_pipe_seq)
log.assertf(mem_err == nil, "Memory allocation failed")
parser_state^.cur_pipe_seq = new_pipe_sequence(SequenceType.And)
parser_state^.cur_cmd = new_command()
parser_state^.token_idx += 1
case "||":
if parser_state^.cur_cmd.name == "" do return ParseError.MissingCommand
_, mem_err := append(&parser_state^.cur_pipe_seq.commands, parser_state^.cur_cmd)
log.assertf(mem_err == nil, "Memory allocation failed")
_, mem_err = append(&parser_state^.cmd_seq.pipe_sequences, parser_state^.cur_pipe_seq)
log.assertf(mem_err == nil, "Memory allocation failed")
parser_state^.cur_pipe_seq = new_pipe_sequence(SequenceType.Or)
parser_state^.cur_cmd = new_command()
parser_state^.token_idx += 1
case "|":
if parser_state^.cur_cmd.name == "" do return ParseError.MissingCommand
_, mem_err := append(&parser_state^.cur_pipe_seq.commands, parser_state^.cur_cmd)
log.assertf(mem_err == nil, "Memory allocation failed")
parser_state^.cur_cmd = new_command()
parser_state^.token_idx += 1
case ">":
if parser_state^.cur_cmd.name == "" do return ParseError.MissingCommand
if len(parser_state^.cur_pipe_seq.commands) >= parser_state^.token_idx + 1 do return ParseError.MissingRedirect
next_token := parser_state.tokens[parser_state.token_idx + 1]
if slice.contains(FORBIDDEN_TOKENS, string(next_token)) do return ParseError.ForbiddenToken
parser_state^.cur_pipe_seq.rstdout = next_token
parser_state^.token_idx += 2
case "&>":
if parser_state^.cur_cmd.name == "" do return ParseError.MissingCommand
if len(parser_state^.cur_pipe_seq.commands) >= parser_state^.token_idx + 1 do return ParseError.MissingRedirect
next_token := parser_state.tokens[parser_state.token_idx + 1]
if slice.contains(FORBIDDEN_TOKENS, string(next_token)) do return ParseError.ForbiddenToken
parser_state^.cur_pipe_seq.rstdout = next_token
parser_state^.cur_pipe_seq.rstderr = next_token
parser_state^.token_idx += 2
case "<":
if parser_state^.cur_cmd.name == "" do return ParseError.MissingCommand
if len(parser_state^.cur_pipe_seq.commands) >= parser_state^.token_idx + 1 do return ParseError.MissingRedirect
next_token := parser_state.tokens[parser_state.token_idx + 1]
if slice.contains(FORBIDDEN_TOKENS, string(next_token)) do return ParseError.ForbiddenToken
parser_state^.cur_pipe_seq.rstdin = next_token
parser_state^.token_idx += 2
case "2>":
if parser_state^.cur_cmd.name == "" do return ParseError.MissingCommand
if len(parser_state^.cur_pipe_seq.commands) >= parser_state^.token_idx + 1 do return ParseError.MissingRedirect
next_token := parser_state.tokens[parser_state.token_idx + 1]
if slice.contains(FORBIDDEN_TOKENS, string(next_token)) do return ParseError.ForbiddenToken
parser_state^.cur_pipe_seq.rstderr = next_token
parser_state^.token_idx += 2
case:
if parser_state^.cur_cmd.name != "" {
_, mem_err := append(&parser_state^.cur_cmd.args, token)
log.assertf(mem_err == nil, "Memory allocation failed")
} else {
parser_state^.cur_cmd.name = token
}
parser_state^.token_idx += 1
}
return nil
}
get_cstring_tokens ::proc(input: string) -> []cstring {
tokens, mem_err := strings.fields(input, context.temp_allocator)
log.assertf(mem_err == nil, "Memory allocation failed")
c_tokens: []cstring
c_tokens, mem_err = make([]cstring, len(tokens), context.temp_allocator)
log.assertf(mem_err == nil, "Memory allocation failed")
for token, i in tokens {
c_tokens[i], mem_err = strings.clone_to_cstring(token, context.temp_allocator)
log.assertf(mem_err == nil, "Memory allocation failed")
}
return c_tokens
}
parse :: proc(input: string) -> (cmd_seq: CommandSequence, err: ParseError) {
mem_err: mem.Allocator_Error
cur_cmd_seq := CommandSequence{}
cur_cmd_seq.pipe_sequences, mem_err = make([dynamic]PipeSequence, 0, 1, context.temp_allocator)
log.assertf(mem_err == nil, "Memory allocation failed")
c_tokens := get_cstring_tokens(input)
cur_pipe_seq := new_pipe_sequence(SequenceType.Head)
cur_pipe_seq.commands, mem_err = make([dynamic]Command, 0, 1, context.temp_allocator)
log.assertf(mem_err == nil, "Memory allocation failed")
if len(c_tokens) == 0 {
return cmd_seq, nil
}
cur_cmd := Command{ name = c_tokens[0] }
cur_cmd.args, mem_err = make([dynamic]cstring, 0, 1, context.temp_allocator)
log.assertf(mem_err == nil, "Memory allocation failed")
parser_state := ParserState{
cmd_seq = cur_cmd_seq,
cur_pipe_seq = cur_pipe_seq,
cur_cmd = cur_cmd,
tokens = c_tokens,
token_idx = 1
}
for parser_state.token_idx < len(parser_state.tokens) {
parse_err := parse_token(&parser_state)
switch parse_err {
case .MissingRedirect:
fmt.printf("Error: Missing redirect target after '%s'\n", parser_state.tokens[parser_state.token_idx])
return cmd_seq, parse_err
case .MissingCommand:
fmt.printf("Error: Missing command before '%s'\n", parser_state.tokens[parser_state.token_idx])
return cmd_seq, parse_err
case .ForbiddenToken:
fmt.printf("Error: Forbidden '%s' after '%s'\n",
parser_state.tokens[parser_state.token_idx+1],
parser_state.tokens[parser_state.token_idx])
return cmd_seq, parse_err
case .None:
continue
}
}
if parser_state.cur_cmd.name != "" {
_, mem_err = append(&parser_state.cur_pipe_seq.commands, parser_state.cur_cmd)
log.assertf(mem_err == nil, "Memory allocation failed")
}
if len(parser_state.cur_pipe_seq.commands) > 0 {
_, mem_err = append(&parser_state.cmd_seq.pipe_sequences, parser_state.cur_pipe_seq)
log.assertf(mem_err == nil, "Memory allocation failed")
}
return parser_state.cmd_seq, nil
}

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shell/shell.odin Normal file
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package shell
import "core:fmt"
import "core:strings"
import "core:sys/posix"
import "core:os"
import "core:log"
import "core:mem"
import "../parser"
ShellState :: enum {
Continue,
Stop
}
get_prompt :: proc() -> string {
dir := os.get_current_directory(context.temp_allocator)
home := string(posix.getenv("HOME"))
if strings.contains(dir, home) {
dir, _ = strings.replace(dir, home, "~", 1, context.temp_allocator)
}
uid := posix.getuid()
pw := posix.getpwuid(uid)
user: string
if pw == nil {
user = "Skal"
} else {
user = string(pw.pw_name)
}
promt_parts := []string {user, " :: ", dir, " » "}
prompt, err := strings.concatenate(promt_parts[:], context.temp_allocator)
log.assertf(err == nil, "Memory allocation failed")
return prompt
}
pipe_command :: proc(pipe_seq: ^parser.PipeSequence, maybe_fd: Maybe(posix.FD), idx: int) {
cmd := pipe_seq.commands[idx]
fd, missing_fd := maybe_fd.?
if missing_fd {
dup_status := posix.dup2(fd, posix.STDOUT_FILENO)
log.assertf(dup_status > -1, "Pipe failed")
close_status := posix.close(fd)
log.assertf(close_status == .OK, "Pipe failed")
}
if idx == 0 {
if pipe_seq^.rstdin != "" {
stdin_fd := posix.open(pipe_seq^.rstdin, { .RDWR }, { .IRUSR, .IWUSR, .IRGRP, .IROTH })
log.assertf(stdin_fd > -1, "Pipe failed")
dup_status := posix.dup2(stdin_fd, posix.STDIN_FILENO)
log.assertf(dup_status > -1, "Pipe failed")
close_status := posix.close(stdin_fd)
log.assertf(close_status == .OK, "Pipe failed")
}
if pipe_seq^.rstdout != "" {
stdout_fd := posix.open(pipe_seq^.rstdout, { .WRONLY, .CREAT, .TRUNC }, { .IRUSR, .IWUSR, .IRGRP, .IROTH })
log.assertf(stdout_fd > -1, "Pipe failed")
dup_status := posix.dup2(stdout_fd, posix.STDOUT_FILENO)
log.assertf(dup_status > -1, "Pipe failed")
close_status := posix.close(stdout_fd)
log.assertf(close_status == .OK, "Pipe failed")
}
if pipe_seq^.rstderr != "" {
stderr_fd := posix.open(pipe_seq^.rstderr, { .WRONLY, .CREAT, .TRUNC }, { .IRUSR, .IWUSR, .IRGRP, .IROTH })
log.assertf(stderr_fd > -1, "Pipe failed")
dup_status := posix.dup2(stderr_fd, posix.STDERR_FILENO)
log.assertf(dup_status > -1, "Pipe failed")
close_status := posix.close(stderr_fd)
log.assertf(close_status == .OK, "Pipe failed")
}
} else {
pipe: [2]posix.FD
log.assertf(posix.pipe(&pipe) == .OK, "Pipe failed")
pid := posix.fork()
switch pid {
case -1: // Error
log.assertf(posix.pipe(&pipe) == .OK, "Fork failed")
case 0: // Child
close_status := posix.close(pipe[0])
log.assertf(close_status == .OK, "Pipe failed")
pipe_command(pipe_seq, pipe[1], idx-1)
case: // Parent
close_status := posix.close(pipe[1])
log.assertf(close_status == .OK, "Pipe failed")
dup_status := posix.dup2(pipe[0], posix.STDIN_FILENO)
log.assertf(dup_status > -1, "Pipe failed")
close_status = posix.close(pipe[0])
log.assertf(close_status == .OK, "Pipe failed")
_ = posix.waitpid(pid, nil, { .UNTRACED, .CONTINUED })
}
}
argv, mem_err := make([]cstring, len(cmd.args)+1, context.temp_allocator)
log.assertf(mem_err == nil, "Memory allocation failed")
argv[0] = cmd.name
for i := 0; i < len(cmd.args); i += 1 do argv[i+1] = cmd.args[i]
_ = posix.execvp(argv[0], raw_data(argv))
fmt.printfln("skal: command not found: %s", argv[0])
os.exit(1)
}
@private
change_dir :: proc(cmd: ^parser.Command) {
if len(cmd.args) > 0 {
ch_status := posix.chdir(cmd.args[0])
if ch_status != .OK do fmt.printf("cd: No such file or directory: %s\n", cmd.args[0])
} else {
ch_status := posix.chdir(posix.getenv("HOME"))
if ch_status != .OK do fmt.printf("cd: No such file or directory: %s\n", posix.getenv("HOME"))
}
}
stop_chain :: proc(sequence_type: parser.SequenceType, exec_failed: bool) -> bool {
stop_chain: bool
switch sequence_type {
case .Or:
stop_chain = !exec_failed
case .And:
stop_chain = exec_failed
case .Head:
stop_chain = false
}
return stop_chain
}
execute_cmd_seq :: proc(cmd_seq: ^parser.CommandSequence) {
for &pipe_seq in cmd_seq^.pipe_sequences {
pid := posix.fork()
switch pid {
case -1: // Error
log.assertf(true, "Fork failed")
case 0: // Child
pipe_command(&pipe_seq, nil, len(pipe_seq.commands)-1)
case: // Parent
if pipe_seq.is_background {
fmt.printf("Background process: [%d]\n", pid)
posix.waitpid(pid, nil, { .NOHANG})
} else {
status: i32
posix.waitpid(pid, &status, { .UNTRACED, .CONTINUED })
exec_failed := posix.WIFEXITED(status) && posix.WEXITSTATUS(status) != 0
if stop_chain(pipe_seq.sequence_type, exec_failed) do return
}
}
}
}
execute :: proc(cmd_seq: ^parser.CommandSequence) -> ShellState {
if len(cmd_seq^.pipe_sequences) == 0 do return .Continue
// if pipe sequence is above 0 it has at least one command
first_cmd := cmd_seq^.pipe_sequences[0].commands[0]
switch first_cmd.name {
case "cd":
change_dir(&first_cmd)
case "exit":
return .Stop
case:
execute_cmd_seq(cmd_seq)
}
return .Continue
}

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tests/test.odin Normal file
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package tests
import "../parser"
import "../shell"
import "core:testing"
@(test)
testExecution_ok :: proc(t: ^testing.T) {
INPUT :: "ls -a"
cmd_seq, err := parser.parse(INPUT)
testing.expect(t, err == nil, "Parsing of %s failed", INPUT)
shell.execute(&cmd_seq)
free_all(context.temp_allocator)
}
@(test)
testPipe_ok :: proc(t: ^testing.T) {
SINGLE_PIPE :: "ls -a | wc"
cmd_seq, err := parser.parse(SINGLE_PIPE)
testing.expect(t, err == nil, "Parsing of %s failed", SINGLE_PIPE)
shell.execute(&cmd_seq)
DOUBLE_PIPE :: "ls -a | ls -b | wc"
cmd_seq, err = parser.parse(DOUBLE_PIPE)
testing.expect(t, err == nil, "Parsing of %s failed", DOUBLE_PIPE)
shell.execute(&cmd_seq)
free_all(context.temp_allocator)
}
@(test)
testOkChain_ok :: proc(t: ^testing.T) {
SINGLE_CHAIN :: "ls -a && ls -b"
cmd_seq, err := parser.parse(SINGLE_CHAIN)
testing.expect(t, err == nil, "Parsing of %s failed", SINGLE_CHAIN)
DOUBLE_CHAIN :: "ls -a && ls -b && ls -c"
cmd_seq, err = parser.parse(DOUBLE_CHAIN)
testing.expect(t, err == nil, "Parsing of %s failed", DOUBLE_CHAIN)
shell.execute(&cmd_seq)
free_all(context.temp_allocator)
}
@(test)
testBadChain_ok :: proc(t: ^testing.T) {
SINGLE_CHAIN :: "xyz || ls -a"
cmd_seq, err := parser.parse(SINGLE_CHAIN)
testing.expect(t, err == nil, "Parsing of %s failed", SINGLE_CHAIN)
DOUBLE_CHAIN :: "xyz || xyz || ls -a"
cmd_seq, err = parser.parse(DOUBLE_CHAIN)
testing.expect(t, err == nil, "Parsing of %s failed", DOUBLE_CHAIN)
shell.execute(&cmd_seq)
free_all(context.temp_allocator)
}