commit ea6a9e8b6d4947c067ce6355ec2893b386380025
parent 5ae1c88853aeba861d2fb1232345c4359cce264e
Author: erai <erai@omiltem.net>
Date: Sat, 8 Jun 2024 11:22:16 -0400
just enough shell recognizing
Diffstat:
| M | sh.c | | | 667 | ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++- |
1 file changed, 661 insertions(+), 6 deletions(-)
diff --git a/sh.c b/sh.c
@@ -1,11 +1,666 @@
-// operators: < > << >> && || { } ! ; &
+struct shell {
+ a: *alloc;
+ prog: *byte;
+ argv: **byte;
+ argc: int;
+ scriptfd: int;
+ script: *byte;
+ c: int;
+ tt: int;
+ buf: *byte;
+ len: int;
+ cap: int;
+ quoted: int;
+ status: int;
+}
+
+enum {
+ T_EOF,
+ T_LF,
+ T_IN,
+ T_OUT,
+ T_PIPE,
+ T_OR,
+ T_AND,
+ T_BG,
+ T_WORD,
+ T_NOT,
+ T_LPAR,
+ T_RPAR,
+ T_LBRA,
+ T_RBRA,
+}
+
+feedc(s: *shell) {
+ if s.script[0] {
+ s.c = s.script[0]:int;
+ s.script = &s.script[1];
+ return;
+ }
+
+ if s.scriptfd >= 0 {
+ s.c = fdgetc(s.scriptfd);
+ return;
+ }
+
+ s.c = -1;
+}
+
+feedw(s: *shell) {
+ if s.len == s.cap {
+ die("too long");
+ }
+ if s.c == -1 {
+ die("unexpected EOF");
+ }
+ s.buf[s.len] = s.c:byte;
+ s.len = s.len + 1;
+ feedc(s);
+}
+
+feed_quote(s: *shell) {
+ feedc(s);
+ loop {
+ if s.c == '\"' {
+ feedc(s);
+ break;
+ }
+
+ if s.c == '\\' {
+ feedc(s);
+ feedw(s);
+ continue;
+ }
+
+ if s.c == '$' {
+ feed_var(s);
+ continue;
+ }
+
+ feedw(s);
+ }
+}
+
+feed_var(s: *shell) {
+ feedw(s);
+
+ if s.c != '{' {
+ die("variable missing {");
+ }
+ feedw(s);
+
+ if !(
+ (s.c >= 'A' && s.c <= 'Z')
+ || (s.c >= 'a' && s.c <= 'z')
+ || (s.c == '_' && s.c <= 'z')
+ ) {
+ die("invalid name");
+ }
+
+ loop {
+ if s.c == '}' {
+ feedw(s);
+ break;
+ }
+
+ if !(
+ (s.c >= 'A' && s.c <= 'Z')
+ || (s.c >= 'a' && s.c <= 'z')
+ || (s.c >= '0' && s.c <= '9')
+ || (s.c == '_' && s.c <= 'z')
+ ) {
+ die("invalid name");
+ }
+
+ feedw(s);
+ }
+}
+
+feed(s: *shell) {
+ loop {
+ if s.c < 0 {
+ s.tt = T_EOF;
+ return;
+ }
+
+ if s.c == '#' {
+ loop {
+ feedc(s);
+ if s.c == '\n' || s.c < 0 {
+ break;
+ }
+ }
+ continue;
+ }
+
+ if s.c == '\n' {
+ feedc(s);
+ s.tt = T_LF;
+ return;
+ }
+
+ if s.c == ' ' || s.c == '\t' || s.c == '\r' {
+ feedc(s);
+ continue;
+ }
+
+ break;
+ }
+
+ if s.c == '<' {
+ feedc(s);
+ s.tt = T_IN;
+ return;
+ }
+
+ if s.c == '>' {
+ feedc(s);
+ s.tt = T_OUT;
+ return;
+ }
+
+ if s.c == '&' {
+ feedc(s);
+ s.tt = T_BG;
+ if s.c == '&' {
+ feedc(s);
+ s.tt = T_AND;
+ }
+ return;
+ }
+
+ if s.c == '|' {
+ feedc(s);
+ s.tt = T_PIPE;
+ if s.c == '|' {
+ feedc(s);
+ s.tt = T_OR;
+ }
+ return;
+ }
+
+ if s.c == '!' {
+ feedc(s);
+ s.tt = T_NOT;
+ return;
+ }
+
+ if s.c == ';' {
+ feedc(s);
+ s.tt = T_LF;
+ return;
+ }
+
+ if s.c == '(' {
+ feedc(s);
+ s.tt = T_LPAR;
+ return;
+ }
+
+ if s.c == '{' {
+ feedc(s);
+ s.tt = T_LBRA;
+ return;
+ }
+
+ if s.c == ')' {
+ feedc(s);
+ s.tt = T_RPAR;
+ return;
+ }
+
+ if s.c == '}' {
+ feedc(s);
+ s.tt = T_RBRA;
+ return;
+ }
+
+ s.len = 0;
+ s.quoted = 0;
+
+ s.tt = T_WORD;
+ loop {
+ if (
+ s.c > ' ' && s.c < '~'
+ && s.c != '&' && s.c != '|' && s.c != ';'
+ && s.c != '<' && s.c != '>' && s.c != '"'
+ && s.c != '\'' && s.c != '\\' && s.c != '*'
+ && s.c != '?' && s.c != '[' && s.c != '#'
+ && s.c != ']' && s.c != '%' && s.c != '$'
+ && s.c != '(' && s.c != ')' && s.c != '$'
+ ) {
+ feedw(s);
+ continue;
+ }
+
+ if s.c == '\\' {
+ s.quoted = 1;
+ feedc(s);
+ feedw(s);
+ continue;
+ }
+
+ if s.c == '"' {
+ s.quoted = 1;
+ feed_quote(s);
+ continue;
+ }
+
+ if s.c == '$' {
+ feed_var(s);
+ continue;
+ }
+
+ break;
+ }
+
+ if !s.len {
+ die("invalid char");
+ }
+}
+
+// command = LF
+// | and_or LF
+parse_command(s: *shell): int {
+ if s.tt == T_LF {
+ feed(s);
+ return 1;
+ }
+
+ if !parse_and_or(s) {
+ return 0;
+ }
+
+ if s.tt != T_LF {
+ die("command has no end");
+ }
+ feed(s);
+
+ return 1;
+}
+
+// and_or = pipeline
+// | pipeline '||' and_or
+// | pipeine '&&' and_or
+parse_and_or(s: *shell): int {
+ if !parse_pipeline(s) {
+ return 0;
+ }
+
+ loop {
+ if s.tt != T_AND && s.tt != T_OR {
+ return 1;
+ }
+ feed(s);
+
+ if !parse_pipeline(s) {
+ die("expected pipeline");
+ }
+ }
+}
+
+// pipeline = '!' pipeline
+// | compound
+// | compound '|' pipeline
+parse_pipeline(s: *shell): int {
+ if s.tt == T_NOT {
+ loop {
+ if s.tt != T_NOT {
+ break;
+ }
+ feed(s);
+ }
+
+ if !parse_compound(s) {
+ die("expected compound");
+ }
+ } else {
+ if !parse_compound(s) {
+ return 0;
+ }
+ }
+
+ loop {
+ if s.tt != T_PIPE {
+ return 1;
+ }
+ feed(s);
+
+ if !parse_compound(s) {
+ die("expected compound");
+ }
+ }
+}
+
+// compound = subshell | brace | if | for | while | simple
+parse_compound(s: *shell): int {
+ if parse_subshell(s) {
+ return 1;
+ } else if parse_brace(s) {
+ return 1;
+ } else if parse_if(s) {
+ return 1;
+ } else if parse_for(s) {
+ return 1;
+ } else if parse_while(s) {
+ return 1;
+ } else if parse_simple(s) {
+ return 1;
+ } else {
+ return 0;
+ }
+}
+
+// subshell = '(' command_list ')'
+// | subshell redir_list
+parse_subshell(s: *shell): int {
+ if s.tt != T_LPAR {
+ return 0;
+ }
+ feed(s);
+
+ loop {
+ if !parse_command(s) {
+ break;
+ }
+ }
+
+ if s.tt != T_RPAR {
+ die("expected )");
+ }
+ feed(s);
+
+ parse_redir_list(s);
+
+ return 1;
+}
+
+// brace = '{' command_list '}'
+// | brace redir_list
+parse_brace(s: *shell): int {
+ if s.tt != T_LBRA {
+ return 0;
+ }
+ feed(s);
+
+ loop {
+ if !parse_command(s) {
+ break;
+ }
+ }
+
+ if s.tt != T_RBRA {
+ die("expected }");
+ }
+ feed(s);
+
+ parse_redir_list(s);
+
+ return 1;
+}
+
+parse_keyword(s: *shell, key: *byte): int {
+ if s.tt != T_WORD {
+ return 0;
+ }
+
+ if s.quoted {
+ return 0;
+ }
+
+ if s.len != strlen(key) {
+ return 0;
+ }
+
+ if memcmp(s.buf, key, s.len) {
+ return 0;
+ }
+
+ feed(s);
+
+ return 1;
+}
+
+// if = 'if' command 'then' command_list else_fi
+// else_fi = 'elif' command 'then' command_list else_fi
+// | 'else' command_list 'fi'
+// | 'fi'
+parse_if(s: *shell): int {
+ if !parse_keyword(s, "if") {
+ return 0;
+ }
+
+ if !parse_command(s) {
+ die("expected command");
+ }
+
+ if !parse_keyword(s, "then") {
+ die("expected then");
+ }
+
+ loop {
+ if parse_keyword(s, "fi") {
+ break;
+ }
+
+ if parse_keyword(s, "elif") {
+ if !parse_command(s) {
+ die("expected command");
+ }
+
+ if !parse_keyword(s, "then") {
+ die("expected then");
+ }
+ continue;
+ }
+
+ if parse_keyword(s, "else") {
+ loop {
+ if parse_keyword(s, "fi") {
+ break;
+ }
+
+ if !parse_command(s) {
+ die("expected command");
+ }
+ }
+ break;
+ }
+
+ if !parse_command(s) {
+ die("expected command");
+ }
+ }
+
+ parse_redir_list(s);
+
+ return 1;
+}
+
+// for = 'for' NAME 'in' word_list LF 'do' command_list 'done'
+// | for redir_list
+parse_for(s: *shell): int {
+ if !parse_keyword(s, "for") {
+ return 0;
+ }
+
+ if s.tt != T_WORD {
+ die("expceted name");
+ }
+ feed(s);
+
+ if !parse_keyword(s, "in") {
+ die("expected in");
+ }
+
+ loop {
+ if s.tt == T_LF {
+ feed(s);
+ break;
+ }
+
+ if s.tt != T_WORD {
+ die("expected word");
+ }
+
+ feed(s);
+ }
+
+ if !parse_keyword(s, "do") {
+ die("expected do");
+ }
+
+ loop {
+ if parse_keyword(s, "done") {
+ break;
+ }
+
+ if !parse_command(s) {
+ die("expected command");
+ }
+ }
+
+ parse_redir_list(s);
+
+ return 1;
+}
+
+// while = 'while' command 'do' command_list 'done'
+// | while redir_list
+parse_while(s: *shell): int {
+ if !parse_keyword(s, "while") {
+ return 0;
+ }
+
+ if !parse_command(s) {
+ die("expected command");
+ }
+
+ if !parse_keyword(s, "do") {
+ die("expceted do");
+ }
+
+ loop {
+ if !parse_keyword(s, "done") {
+ break;
+ }
+
+ if !parse_command(s) {
+ die("expected command");
+ }
+ }
+
+ parse_redir_list(s);
+
+ return 1;
+}
+
+// simple = word
+// | redir
+// | word simple
+// | redir simple
+parse_simple(s: *shell): int {
+ if s.tt == T_WORD {
+ feed(s);
+ } else if !parse_redir(s) {
+ return 0;
+ }
+
+ loop {
+ if s.tt == T_WORD {
+ feed(s);
+ } else if !parse_redir(s) {
+ return 1;
+ }
+ }
+}
+
+// redir_list =
+// | redir redir_list
+parse_redir_list(s: *shell): int {
+ loop {
+ if !parse_redir(s) {
+ return 1;
+ }
+ }
+}
+
+// redir = '>' word
+// | '<' word
+parse_redir(s: *shell): int {
+ if s.tt != T_IN && s.tt != T_OUT {
+ return 0;
+ }
+ feed(s);
+
+ if s.tt != T_WORD {
+ die("expected word");
+ }
+ feed(s);
+
+ return 1;
+}
+
+execute_command(s: *shell) {
+ die("noimpl");
+}
main(argc: int, argv: **byte, envp: **byte) {
var a: alloc;
+ var s: shell;
+ var i: int;
+ var fd: int;
setup_alloc(&a);
- // Parse args
- // Tokenize command
- // Parse command
- // Evaluate redirections
- // Execute command
+
+ bzero((&s):*byte, sizeof(s));
+ s.a = &a;
+
+ if argc <= 1 {
+ s.scriptfd = 0;
+ s.script = "";
+ s.prog = "";
+ s.argc = 0;
+ s.argv = 0:**byte;
+ } else if strcmp(argv[1], "--") == 0 {
+ s.scriptfd = 0;
+ s.script = "";
+ s.prog = "";
+ s.argc = argc - 2;
+ s.argv = &argv[2];
+ } else if argc > 2 && strcmp(argv[1], "-c") == 0 {
+ s.scriptfd = -1;
+ s.script = argv[2];
+ s.prog = "";
+ s.argc = argc - 3;
+ s.argv = &argv[3];
+ } else {
+ fd = open(argv[1], O_RDONLY, 0);
+ if fd < 0 {
+ die("could not open script");
+ }
+ s.scriptfd = fd;
+ s.script = "";
+ s.prog = argv[1];
+ s.argc = argc - 2;
+ s.argv = &argv[2];
+ }
+
+ s.buf = alloc(&a, 4096);
+ s.len = 0;
+ s.cap = 4096;
+
+ feedc(&s);
+ feed(&s);
+
+ loop {
+ if s.tt == T_EOF {
+ exit(s.status);
+ }
+
+ if !parse_command(&s) {
+ exit(127);
+ }
+
+ execute_command(&s);
+ }
}
