From dff94300f9bd0f3e6e33a22d480ea11380ddd039 Mon Sep 17 00:00:00 2001
From: Rob Landley <rob@landley.net>
Date: Thu, 11 Jul 2019 22:32:53 -0500
Subject: Next sh checkpoint. Not remotely load bearing yet.

---
 toys/pending/sh.c | 496 +++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 323 insertions(+), 173 deletions(-)

(limited to 'toys/pending')

diff --git a/toys/pending/sh.c b/toys/pending/sh.c
index e8a11ce7..19504383 100644
--- a/toys/pending/sh.c
+++ b/toys/pending/sh.c
@@ -212,22 +212,32 @@ void syntax_err(char *msg, ...)
   if (*toys.optargs) xexit();
 }
 
+// return length of match found at this point
+static int anyof(char *s, char **try)
+{
+  while (*try) {
+    if (strstart(&s, *try)) return strlen(*try);
+    try++;
+  }
 
-// Parse one word from the command line, appending one or more argv[] entries
-// to struct command.  Handles environment variable substitution and
-// substrings.  Returns pointer to next used byte, or NULL if it
-// hit an ending token.
-
-// caller eats leading spaces
+  return 0;
+}
 
 // parse next word from command line. Returns end, or 0 if need continuation
+// caller eats leading spaces
 static char *parse_word(char *start)
 {
   int i, quote = 0;
   char *end = start, *s;
 
-  // find end of string
+  // Skip leading whitespace/comment
+  for (;;) {
+    if (isspace(*start)) ++start;
+    else if (*start=='#') while (*start && *start != '\n') ++start;
+    else break;
+  }
 
+  // find end of this word
   while (*end) {
     i = 0;
 
@@ -243,11 +253,20 @@ static char *parse_word(char *start)
       // start quote
       if (strchr("\"'`", *end)) toybuf[quote++] = *end++;
       else if (strstart(&end, "<(") || strstart(&end,">(")) toybuf[quote++]=')';
-      else if (*end==')') return end+(end==start);
       else {
-        // control chars
-        for (s = end; strchr(";|&<>(", *s); s++);
-        if (s != end) return (end == start) ? s : end;
+        // control chars.
+        // 123<<file- parses as 2 args: "123<<" "file-".
+        // note: >&; becomes ">&" ";" because first loop, then second loop.
+        s = end;
+        if (*s == '{') s++;
+        for (s = end; isdigit(*s); s++);
+        if (*end == '{' && *s == '}') s++;
+        s += anyof(s, (char *[]){"<<<", "<<-", "<<", "<&", "<>", "<", ">>",
+          ">&", ">|", ">", 0});
+        if (s == end || isdigit(s[-1]))
+          s += anyof(s, (char *[]){";;&", ";;", ";&", ";", "||", "|&", "|",
+            "&&", "&>>", "&>", "&", "(", ")", 0});
+        if (s != end && !isdigit(*s)) return (end == start) ? s : end;
         i++;
       }
     }
@@ -259,7 +278,7 @@ static char *parse_word(char *start)
 
     // backslash escapes
     if (*end == '\\') {
-      if (!end[1]) return 0;
+      if (!end[1] || (end[1]=='\n' && !end[2])) return 0;
       end += 2;
     } else if (*end == '$') {
       // barf if we're near overloading quote stack (nesting ridiculously deep)
@@ -286,228 +305,359 @@ static char *parse_word(char *start)
   return quote ? 0 : end;
 }
 
-// Consume a line of shell script and do what it says. Returns 0 if finished,
-// pointer to start of unused part of line if it needs another line of input.
-static char *parse_line(char *line, struct double_list **pipeline)
+// Parse flow control statement(s), returns index of first statement to execute,
+// pp->arg->c if none, -1 if we need to flush due to syntax error
+int flow_control(int why, struct sh_arg *arg, struct double_list **expect,
+  char **end)
 {
-  char *start = line, *end, *s, *ex, *add;
-  struct sh_arg *arg = 0;
-  struct double_list *pl, *expect = 0;
-  unsigned i, paren = 0;
-
-  // Resume appending to last pipeline's last argument list
-  if (*pipeline) arg = (void *)(*pipeline)->prev->data;
-  if (arg) for (i = 0; i<arg->c; i++) {
-    if (!strcmp(arg->v[i], "(")) paren++;
-    else if (!strcmp(arg->v[i], ")")) paren--;
+  char *add = 0;
+  int i, pend = 0;
+
+  // Blank line shouldn't change end, but two ends in a row are an error
+  if (!arg->c) {
+    if (arg->v[0]) {
+      syntax_err("bad %s", arg->v[0]);
+      return -1;
+    }
+    return 0;
   }
 
-  // Loop handling each word
-  for (;;) {
-    // Skip leading whitespace/comment
-    while (isspace(*start)) ++start;
-    if (*start=='#') {
-      while (*start && *start != '\n') start++;
-      continue;
+  // parse flow control statements in this command line
+  for (i = 0; ; i++) {
+    char *ex = *expect ? (*expect)->prev->data : 0, *s = arg->v[i];
+
+    // push word to expect at end of block, and expect a command first
+    if (add) {
+      dlist_add(expect, add);                  // end of context
+      if (why) dlist_add(expect, arg->v[i-1]); // context for command
+      dlist_add(expect, add = 0);              // expect a command
     }
 
-    // Parse next word and detect continuation/overflow.
-    if ((end = parse_word(start)) == (void *)1) return 0;
-    if (!end) return start;
+    // end of argument list?
+    if (i == arg->c) break;
 
-    // Extend pipeline and argv[], handle EOL
-    if (!arg)
-      dlist_add(pipeline, (void *)(arg = xzalloc(sizeof(struct sh_arg))));
-    if (!(31&arg->c)) arg->v = xrealloc(arg->v, (32+arg->c)*sizeof(void *));
-    if (end == start) {
-      arg->v[arg->c] = 0;
-      break;
+    // When waiting for { it must be next symbol, but can be on a new line.
+    if (ex && !strcmp(ex, "{")) {
+      if (strcmp(s, "{") || (!i && *end && strcmp(*end, ";"))) {
+        syntax_err("need {");
+        return -1;
+      }
     }
 
-    // Save argument (strdup) and check if it's special
-    s = arg->v[arg->c] = xstrndup(start, end-start);
-    if (!strcmp(s, "(")) paren++;
-    else if (!strcmp(s, ")") && !paren--) syntax_err("bad %s", s);
-    if (paren || !strchr(";|&", *start)) arg->c++;
-    else {
-      if (!arg->c) {
-        syntax_err("bad %s", arg->v[arg->c]);
-        goto flush;
+    if (!strcmp(s, "if")) add = "then";
+    else if (!strcmp(s, "for") || !strcmp(s, "select")
+        || !strcmp(s, "while") || !strcmp(s, "until")) add = "do";
+    else if (!strcmp(s, "case")) add = "esac";
+    else if (!strcmp(s, "{")) add = "}";
+    else if (!strcmp(s, "[[")) add = "]]";
+    else if (!strcmp(s, "(")) add = ")";
+
+    // function NAME () [nl] { [nl] body ; }
+    // Why can you to declare functions inside other functions?
+    else if (arg->c>i+1 && !strcmp(arg->v[i+1], "(")) goto funky;
+    else if (!strcmp(s, "function")) {
+      i++;
+funky:
+      // At this point we can only have a function: barf if it's invalid
+      if (arg->c<i+3 || !strcmp(arg->v[i+1], "(") || !strcmp(arg->v[i+2], ")")){
+        syntax_err("bad function ()");
+        return -1;
       }
-      arg = 0;
-    }
-    start = end;
-  }
+      // perform abnormal add (one extra piece of info) manually.
+      dlist_add(expect, "}");
+      dlist_add(expect, "function");
+      dlist_add(expect, 0);
+      dlist_add(expect, "{");
 
-  // We parsed to the end of the line, which ended a pipeline.
-  // Now handle flow control commands, which can also need more lines.
+      continue;
 
-  // array of command lines separated by | and such
-  // Note: don't preparse past ; because environment variables differ
+    // Expecting NULL means a statement: any otherwise unrecognized word
+    } else if (expect && !ex) {
+      free(dlist_pop(expect));
 
-  // Check for flow control continuations
-  end = 0;
-  for (pl = *pipeline; pl ; pl = (pl->next == *pipeline) ? 0 : pl->next) {
-    arg = (void *)pl->data;
-    if (!arg->c) continue;
-    add = 0;
-
-    // parse flow control statements in this command line
-    for (i = 0; ; i++) {
-      ex = expect ? expect->prev->data : 0;
-      s = arg->v[i];
-
-      // push word to expect to end this block, and expect a command first
-      if (add) {
-        dlist_add(&expect, add);
-        dlist_add(&expect, add = 0);
+      // if (why) context in which statement executes now at top of expect stack
+
+      // Does this statement end with a close parentheses?
+      if (!strcmp(")", arg->v[arg->c-1])) {
+
+        // Did we expect one?
+        if (!*expect || !strcmp(")", (*expect)->prev->data)) {
+          syntax_err("bad %s", ")");
+          return -1;
+        }
+
+        free(dlist_pop(expect));
+        // only need one statement in ( ( ( echo ) ) )
+        if (*expect && !(*expect)->prev->data) free(dlist_pop(expect));
+
+        pend++;
+        goto gotparen;
       }
+      break;
 
-      // end of statement?
-      if (i == arg->c) break;
+    // If we aren't expecting and didn't just start a new flow control block,
+    // rest of statement is a command and arguments, so stop now
+    } else if (!ex) break;
 
-      // When waiting for { it must be next symbol, but can be on a new line.
-      if (ex && !strcmp(ex, "{") && (strcmp(s, "{") || (!i && end))) {
-        syntax_err("need {");
-        goto flush;
+    if (add) continue;
+
+    // If we got here we expect a specific word to end this block: is this it?
+    if (!strcmp(arg->v[i], ex)
+      || (!strcmp(ex, ")") && !strcmp(ex, arg->v[arg->c-1])))
+    {
+      // can't "if | then" or "while && do", only ; & or newline works
+      if (*end && strcmp(*end, ";") && strcmp(*end, "&")) {
+        syntax_err("bad %s", *end);
+        return -1;
       }
 
-      if (!strcmp(s, "if")) add = "then";
-      else if (!strcmp(s, "for") || !strcmp(s, "select")
-          || !strcmp(s, "while") || !strcmp(s, "until")) add = "do";
-      else if (!strcmp(s, "case")) add = "esac";
-      else if (!strcmp(s, "{")) add = "}";
-      else if (!strcmp(s, "[[")) add = "]]";
-
-      // function NAME () [nl] { [nl] body ; }
-      // Why can you to declare functions inside other functions?
-      else if (arg->c>i+1 && !strcmp(arg->v[i+1], "(")) goto funky;
-      else if (!strcmp(s, "function")) {
-        i++;
-funky:
-        // At this point we can only have a function: barf if it's invalid
-        if (arg->c<i+3 || !strcmp(arg->v[i+1], "(")
-            || !strcmp(arg->v[i+2], ")"))
-        {
-          syntax_err("bad function ()");
-          goto flush;
+gotparen:
+      free(dlist_pop(expect));
+      // Only innermost statement needed in { { { echo ;} ;} ;} and such
+      if (*expect && !(*expect)->prev->data) free(dlist_pop(expect));
+
+      // If this was a command ending in parentheses
+      if (pend) break;
+
+      // if it's a multipart block, what comes next?
+      if (!strcmp(s, "do")) ex = "done";
+      else if (!strcmp(s, "then")) add = "fi\0A";
+    // fi could have elif, which queues a then.
+    } else if (!strcmp(ex, "fi")) {
+      if (!strcmp(s, "elif")) {
+        free(dlist_pop(expect));
+        add = "then";
+      // catch duplicate else while we're here
+      } else if (!strcmp(s, "else")) {
+        if (ex[3] != 'A') {
+          syntax_err("2 else");
+          return -1;
         }
-        dlist_add(&expect, "}");
-        dlist_add(&expect, 0);
-        dlist_add(&expect, "{");
+        free(dlist_pop(expect));
+        add = "fi\0B";
+      }
+    }
+  }
 
-      // Expecting NULL will take any otherwise unrecognized word
-      } else if (expect && !ex) {
-        free(dlist_pop(&expect));
-        continue;
+  // Record how the previous stanza ended: ; | & ;; || && ;& ;;& |& NULL
+  *end = arg->v[arg->c];
+
+  return i;
+}
 
-      // If we expect nothing and didn't just start a new flow control block,
-      // rest of statement is a command and arguments, so stop now
-      } else if (!ex) break;
+// Consume a line of shell script and do what it says. Returns 0 if finished,
+// 1 to request another line of input.
 
-      if (add) continue;
+struct sh_parse {
+  struct double_list *pipeline, *plstart, *expect, *here;
+  char *end;
+};
 
-      // If we got here we expect a word to end this block: is this it?
-      if (!strcmp(arg->v[i], ex)) {
-        free(dlist_pop(&expect));
+// pipeline and expect are scratch space, state held between calls which
+// I don't want to make global yet because this could be reentrant.
+// returns 1 to request another line (> prompt), 0 if line consumed.
+static int parse_line(char *line, struct sh_parse *sp)
+{
+  char *start = line, *delete = 0, *end, *s;
+  struct sh_arg *arg = 0;
+  struct double_list *pl;
+  long i;
 
-        // can't "if | then" or "while && do", only ; or newline works
-        if (end && !strcmp(end, ";")) {
-          syntax_err("bad %s", end);
-          goto flush;
-        }
+  // Resume appending to last statement?
+  if (sp->pipeline) {
+    arg = (void *)sp->pipeline->prev->data;
 
-        // if it's a multipart block, what comes next?
-        if (!strcmp(s, "do")) ex = "done";
-        else if (!strcmp(s, "then")) add = "fi\0A";
-      // fi could have elif, which queues a then.
-      } else if (!strcmp(ex, "fi")) {
-        if (!strcmp(s, "elif")) {
-          free(dlist_pop(&expect));
-          add = "then";
-        // catch duplicate else while we're here
-        } else if (!strcmp(s, "else")) {
-          if (ex[3] != 'A') {
-            syntax_err("2 else"); 
-            goto flush;
-          }
-          free(dlist_pop(&expect));
-          add = "fi\0B";
-        }
+    // Extend/resume quoted block
+    if (arg->c<0) {
+      start = delete = xmprintf("%s%s", arg->v[arg->c = (-arg->c)-1], start);
+      free(arg->v[arg->c]);
+      arg->v[arg->c] = 0;
+
+    // is a HERE document in progress?
+    } else if (sp->here && ((struct sh_arg *)sp->here->data)->c<0) {
+      unsigned long c;
+
+      arg = (void *)sp->here->data;
+      c = -arg->c - 1;
+
+      // HERE's arg->c < 0 means still adding to it, EOF string is last entry
+      if (!(31&c)) arg->v = xrealloc(arg->v, (32+c)*sizeof(void *));
+      if (strcmp(line, arg->v[c])) {
+        // Add this line
+        arg->v[c+1] = arg->v[c];
+        arg->v[c] = xstrdup(line);
+        arg->c--;
+      } else {
+        // EOF hit, end HERE document
+        arg->v[arg->c = c] = 0;
+        sp->here = sp->here->next;
       }
+      start = 0;
     }
-    // Record how the previous stanza ended: ; | & ;; || && ;& ;;& |& NULL
-    end = arg->v[arg->c];
   }
 
-  // Do we need more lines to finish a flow control statement?
-  if (expect || paren) {
-    llist_traverse(expect, free);
-    return start;
+  // Parse words, assemble argv[] pipelines, check flow control and HERE docs
+  if (start) for (;;) {
+    s = 0;
+
+    // Parse next word and detect overflow (too many nested quotes).
+    if ((end = parse_word(start)) == (void *)1) goto flush;
+
+    // Extend pipeline and argv[] to store result
+    if (!arg)
+      dlist_add(&sp->pipeline, (void *)(arg = xzalloc(sizeof(struct sh_arg))));
+    if (!(31&arg->c)) arg->v = xrealloc(arg->v, (32+arg->c)*sizeof(void *));
+
+    // Do we need to request another line to finish word (find ending quote)?
+    if (!end) {
+      // Save unparsed bit of this line, we'll need to re-parse it.
+      arg->v[arg->c] = xstrndup(start, strlen(start));
+      arg->c = -(arg->c+1);
+      free(delete);
+
+      return 1;
+    }
+
+    // Did we hit the end of this line of input?
+    if (end == start) {
+      arg->v[arg->c] = 0;
+
+      // Parse flow control data from last statement
+      if (-1 == flow_control(0, arg, &sp->expect, &sp->end)) goto flush;
+
+      // Grab HERE document(s)
+      for (pl = sp->plstart ? sp->plstart : sp->pipeline; pl;
+           pl = (pl->next == sp->pipeline) ? 0 : pl->next)
+      {
+        struct sh_arg *here;
+
+        arg = (void *)pl->data;
+
+        for (i = 0; i<arg->c; i++) {
+          // find [n]<<[-] with an argument after it
+          s = arg->v[i];
+          if (*s == '{') s++;
+          while (isdigit(*s)) s++;
+          if (*arg->v[i] == '{' && *s == '}') s++;
+          if (strcmp(s, "<<") && strcmp(s, "<<-")) continue;
+          if (i+1 == arg->c) goto flush;
+
+          here = xzalloc(sizeof(struct sh_arg));
+          here->v = xzalloc(32*sizeof(void *));
+          *here->v = arg->v[++i];
+          here->c = -1;
+        }
+      }
+
+      // Stop reading.
+      break;
+    }
+
+    // ) only saved at start of a statement, else ends statement with NULL
+    if (arg->c && *start == ')') {
+      arg->v[arg->c] = 0;
+      end--;
+      if (-1 == flow_control(0, arg, &sp->expect, &sp->end)) goto flush;
+      arg = 0;
+    } else {
+      // Save argument (strdup) and check if it's special
+      s = arg->v[arg->c] = xstrndup(start, end-start);
+      if (!strchr(");|&", *start)) arg->c++;
+      else {
+        // end of statement due to flow control character.
+        s = 0;
+        if (!arg->c) goto flush;
+        if (-1 == flow_control(0, arg, &sp->expect, &sp->end)) goto flush;
+        arg = 0;
+      }
+    }
+    start = end;
   }
+  free(delete);
+
+  // return if HERE document or more flow control
+  if (sp->expect || (sp->pipeline && sp->pipeline->prev->data==(void *)1))
+    return 1;
+
+  // At this point, we've don't need more input and can start executing.
+
+  // **************************** do the thing *******************************
+
+  // Now we have a complete thought and can start running stuff.
 
   // iterate through the commands running each one
-  for (pl = *pipeline; pl ; pl = (pl->next == *pipeline) ? 0 : pl->next) {
+
+  // run a pipeline of commands
+
+  for (pl = sp->pipeline; pl ; pl = (pl->next == sp->pipeline) ? 0 : pl->next) {
     struct sh_process *pp = xzalloc(sizeof(struct sh_process));
 
-    for (i = 0; i<((struct sh_arg *)pl->data)->c; i++)
-      expand_arg(&pp->arg, ((struct sh_arg *)pl->data)->v[i]);
+    for (i = 0; i<arg->c; i++) expand_arg(&pp->arg, arg->v[i]);
     run_command(pp);
+    llist_traverse(pp->delete, free);
   }
 
+  s = 0;
 flush:
-  while ((pl = dlist_pop(pipeline))) {
+
+  if (s) syntax_err("bad %s", s);
+  while ((pl = dlist_pop(&sp->pipeline))) {
+    arg = (void *)pl->data;
+    free(pl);
+    for (i = 0; i<arg->c; i++) free(arg->v[i]);
+    free(arg->v);
+    free(arg);
+  }
+
+  while ((pl = dlist_pop(&sp->here))) {
     arg = (void *)pl->data;
     free(pl);
+    if (arg->c<0) arg->c = -arg->c - 1;
     for (i = 0; i<arg->c; i++) free(arg->v[i]);
     free(arg->v);
     free(arg);
   }
-  *pipeline = 0;
+
+  llist_traverse(sp->expect, free);
 
   return 0;
 }
 
 void sh_main(void)
 {
-  FILE *f = 0;
-  char *command = 0, *old = 0;
-  struct double_list *scratch = 0;
+  FILE *f;
+  struct sh_parse scratch;
+  int prompt = 0;
 
   // Set up signal handlers and grab control of this tty.
-  if (isatty(0)) toys.optflags |= FLAG_i;
 
-  if (*toys.optargs) f = xfopen(*toys.optargs, "r");
-  if (TT.command) command = parse_line(TT.command, &scratch);
-  else for (;;) {
+  memset(&scratch, 0, sizeof(scratch));
+  if (TT.command) f = fmemopen(TT.command, strlen(TT.command), "r");
+  else if (*toys.optargs) f = xfopen(*toys.optargs, "r");
+  else {
+    f = stdin;
+    if (isatty(0)) toys.optflags |= FLAG_i;
+  }
+
+  for (;;) {
     char *new = 0;
     size_t linelen = 0;
 
     // Prompt and read line
-    if (!f) {
-      char *s = getenv(command ? "PS2" : "PS1");
+    if (f == stdin) {
+      char *s = getenv(prompt ? "PS2" : "PS1");
 
-      if (!s) s = command ? "> " : (getpid() ? "\\$ " : "# ");
+      if (!s) s = prompt ? "> " : (getpid() ? "\\$ " : "# ");
       do_prompt(s);
-    }
-    if (1 > getline(&new, &linelen, f ? f : stdin)) break;
-    if (f) TT.lineno++;
-
-    // Append to unused portion of previous line if any
-    if (command) {
-      command = xmprintf("%s%s", command, new);
-      free(old);
-      free(new);
-      old = command;
-    } else {
-      free(old);
-      old = new;
-    }
+    } else TT.lineno++;
+    if (1>(linelen = getline(&new, &linelen, f ? f : stdin))) break;
+    if (new[linelen-1] == '\n') new[--linelen] = 0;
 
     // returns 0 if line consumed, command if it needs more data
-    command = parse_line(old, &scratch);
+    prompt = parse_line(new, &scratch);
+    free(new);
   }
 
-  if (command) error_exit("unfinished line");
+  if (prompt) error_exit("%ld:unfinished line"+4*!TT.lineno, TT.lineno);
   toys.exitval = f && ferror(f);
 }
-- 
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