From 6f2cac23a7e759c464ef52103fac929e1eeb6b10 Mon Sep 17 00:00:00 2001
From: Nicholas Noll <nbnoll@eml.cc>
Date: Sat, 9 Oct 2021 10:30:50 -0700
Subject: feat(rc): added shell

---
 sys/cmd/rc/lex.c | 417 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 417 insertions(+)
 create mode 100644 sys/cmd/rc/lex.c

(limited to 'sys/cmd/rc/lex.c')

diff --git a/sys/cmd/rc/lex.c b/sys/cmd/rc/lex.c
new file mode 100644
index 0000000..f6e2b4e
--- /dev/null
+++ b/sys/cmd/rc/lex.c
@@ -0,0 +1,417 @@
+#include "rc.h"
+
+#define	onebyte(c)	     ((c&0x80)==0x00)
+#define	twobyte(c)	     ((c&0xe0)==0xc0)
+#define	threebyte(c)	 ((c&0xf0)==0xe0)
+#define	fourbyte(c)	     ((c&0xf8)==0xf0)
+
+// -----------------------------------------------------------------------
+// globals
+
+static int lastc, nextc=EOF, lastdol, lastword, doprompt = 1;
+static char buf[8*1024];
+
+// -----------------------------------------------------------------------
+// utilities
+
+static uchar nwordc[256] =
+{
+	1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	1, 0, 0, 1, 1, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0,
+	1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+};
+
+int
+wordchr(int c)
+{
+	return !nwordc[c] && c!=EOF;
+}
+
+
+static uchar nquotec[256] =
+{
+	1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+};
+
+int
+quotechr(char c)
+{
+	return !nquotec[c] && c!=EOF;
+}
+
+static uchar nvarc[256] =
+{
+	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1,
+	1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0,
+	1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+};
+
+
+int
+varchr(char c)
+{
+    return !nvarc[c] && c!=EOF;
+}
+
+static
+void
+prompt(void)
+{
+    shell->cmd.line++;
+    doprompt = 0;
+}
+
+/* lookahead one byte */
+static
+int
+lookahead(void)
+{
+    int c;
+
+    if(nextc != EOF)
+        return nextc;
+    if(shell->cmd.eof)
+        return EOF;
+
+    if(doprompt)
+        prompt();
+
+    c = rchr(shell->cmd.io);
+    doprompt = c == '\n' || c == EOF;
+
+    if(c == EOF)
+        shell->cmd.eof++;
+
+    return nextc = c;
+}
+
+/* consumes the lookahead */
+static
+int
+advance(void)
+{
+    int c = lookahead();
+    lastc = nextc, nextc = EOF;
+
+    return c;
+}
+
+/* 
+ * advance until we no longer hit horizontal space 
+ * consumes all comments
+ */ 
+static
+void
+skipws(void)
+{
+    int c;
+    for(;;) {
+        c = lookahead();
+        if(c=='#'){
+            for(;;){
+                c = lookahead();
+                if(c=='\n' || c==EOF)
+                    break;
+                advance();
+            }
+        }
+        if(c==' ' || c=='\t')
+            advance();
+        else 
+            return;
+    }
+}
+
+/* advance until we no longer hit any space */
+void
+skipnl(void)
+{
+    int c;
+    for(;;) {
+        skipws();
+        if ((c = lookahead()) != '\n')
+            return;
+        advance();
+    }
+}
+
+/* advance if next char is equal to c */
+static
+int
+nextis(int c)
+{
+    if(lookahead()==c) {
+        advance();
+        return 1;
+    }
+    return 0;
+}
+
+/* functions to append to our write buffer */
+static
+char*
+putbyte(char *s, int c)
+{
+    if(!s)
+        return s;
+    if(s == arrend(buf)){
+        *s = 0;
+        rcerror("out of buffer space");
+        return nil;
+    }
+    *s++ = c;
+    return s;
+}
+
+static
+char*
+putrune(char *s, int c)
+{
+    s = putbyte(s, c);
+    if (onebyte(c))
+        return s;
+    if (twobyte(c))
+        return putbyte(s, advance());
+    if (threebyte(c)) {
+        putbyte(s, advance());
+        return putbyte(s, advance());
+    }
+    if (fourbyte(c)) {
+        putbyte(s, advance());
+        putbyte(s, advance());
+        return putbyte(s, advance());
+    }
+    rcerror("malformed utf8 stream");
+    return nil;
+}
+
+// -----------------------------------------------------------------------
+// main exports
+
+void
+rcerror(char *fmt, ...)
+{
+    va_list args;
+
+    pfmt(errio, "rc:");
+    if (shell->cmd.io)
+        pfmt(errio, "%s:%d ", shell->cmd.name, shell->cmd.line);
+
+    va_start(args, fmt);
+    vpfmt(errio, fmt, args);
+    va_end(args);
+
+    pfmt(errio, "\n");
+
+    flush(&errio);
+    lastword = lastdol = 0;
+    while (lastc != '\n' && lastc != EOF)
+        advance();
+    /* for debugging only */
+    abort();
+}
+
+/* word is only modified in the event of a lexed word */
+int
+lex(Tree **node)
+{
+    int c;
+    char *w = buf;
+    /* 
+     * NOTE: 
+     * we inject tokens into the lexer based on context if last token = word:
+     * if we see a (, then we interpret that as a subscript
+     * otherwise, if the next character is the first char of a word, we return a ^ operator.
+     */ 
+    if(lastword){
+        lastword=0;
+        c = lookahead();
+        if(c=='('){
+            advance();
+            return Tlparen;
+        }
+        if(quotechr(c))
+            return Tcarot;
+    }
+
+    skipws();
+    switch(c=advance()) {
+    case EOF:
+        lastdol = 0;
+        return EOF;
+    case '$':
+        lastdol = 1;
+        if(nextis('#'))
+            return Tcount;
+        if (nextis('"'))
+            return Tquote;
+        return Tdol;
+    case '&':
+        lastdol = 0;
+        if(nextis('&'))
+            return Tandand;
+        return Tand;
+
+    case '!':
+        return Tbang;
+    case '@':
+        return Tsubshell;
+    case '~':
+        return Ttwiddle;
+
+    case '|':
+        lastdol = 0;
+        if(nextis('|')){
+            skipnl();
+            return Toror;
+        }
+        (*node) = newtree();
+        (*node)->type = Tpipe;
+        (*node)->redir.fd[0] = 0;
+        (*node)->redir.fd[1] = 1;
+        goto redir;
+    case '>':
+        (*node) = newtree();
+        (*node)->type = Tredir;
+        if (nextis(c))
+            (*node)->redir.type = Rappend;
+        else
+            (*node)->redir.type = Rwrite;
+        (*node)->redir.fd[0] = 1;
+        goto redir;
+    case '<':
+        (*node) = newtree();
+        (*node)->type = Tredir;
+        if(nextis(c))
+            (*node)->redir.type = Rhere;
+        else if(nextis('>'))
+            (*node)->redir.type = Rrdwr;
+        else
+            (*node)->redir.type = Rread;
+        (*node)->redir.fd[0] = 0;
+        /* fallthrough */
+    redir:
+        if(nextis('[')) {
+            c = advance();
+            if(c < '0' || '9' < c) {
+            redirerr:
+                rcerror("incorrect redirection syntax");
+                return EOF;
+            }
+            (*node)->redir.fd[0] = 0;
+            do {
+                (*node)->redir.fd[0] = 10*(*node)->redir.fd[0]+(c-'0');
+                c = advance();
+            } while('0'<=c && c<='9');
+
+            if(c == '=') {
+                if((*node)->type == Tredir)
+                    (*node)->type = Tdup;
+                c = advance();
+                if('0'<=c && c<='9') {
+                    (*node)->redir.type  = Rdupfd;
+                    (*node)->redir.fd[1] = (*node)->redir.fd[0];
+                    (*node)->redir.fd[0] = 0;
+                    do {
+                        (*node)->redir.fd[0] = 10*(*node)->redir.fd[0]+(c-'0');
+                        c = advance();
+                    } while('0'<=c && c<='9');
+                } else {
+                    if((*node)->type == Tpipe)
+                        goto redirerr;
+                    (*node)->redir.type = Rclose;
+                }
+            }
+            if (c != ']'
+            ||(*node)->type==Tdup && ((*node)->redir.type==Rhere || (*node)->redir.type==Rappend))
+                goto redirerr;
+        }
+        if ((c = ((*node)->type)) == Tpipe)
+            skipnl();
+        return c;
+
+    case '\'':
+        lastdol  = 0;
+        lastword = 1;
+        for(;;){
+            c = advance();
+            if(c==EOF)
+                break;
+            if(c=='\''){
+                if(lookahead()!='\'')
+                    break;
+                advance();
+            }
+            w = putrune(w, c);
+        }
+        *w = 0;
+        *node = wordnode(buf);
+        (*node)->quoted = 1;
+        return Tword;
+    }
+    if (!wordchr(c)) {
+        lastdol = 0;
+        return c;
+    }
+    for(;;){
+        if(c=='*'||c=='['||c=='?'||c==GLOB)
+            w = putbyte(w, GLOB);
+        w = putrune(w, c);
+        c = lookahead();
+        if(lastdol?!varchr(c):!wordchr(c))
+            break;
+        advance();
+    }
+    *w = 0;
+
+    if ((c = kwlookup(buf)) == -1) {
+        (*node) = wordnode(buf);
+        (*node)->type = c = Tword;
+        (*node)->quoted   = 0;
+        lastword = 1;
+    }
+
+    lastdol  = 0;
+    return c;
+}
-- 
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