parser.c.org

/*-

• Copyright (c) 1991 The Regents of the University of California.
• All rights reserved.

*

• This code is derived from software contributed to Berkeley by
• Kenneth Almquist.

*

• Redistribution and use in source and binary forms, with or without
• modification, are permitted provided that the following conditions
• are met:
• 1. Redistributions of source code must retain the above copyright
• notice, this list of conditions and the following disclaimer.
• 2. Redistributions in binary form must reproduce the above copyright
• notice, this list of conditions and the following disclaimer in the
• documentation and/or other materials provided with the distribution.
• 3. All advertising materials mentioning features or use of this software
• must display the following acknowledgement:
• This product includes software developed by the University of
• California, Berkeley and its contributors.
• 4. Neither the name of the University nor the names of its contributors
• may be used to endorse or promote products derived from this software
• without specific prior written permission.

*

• THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS “AS IS” AND
• ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
• IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
• ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
• FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
• DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
• OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
• HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
• LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
• OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
• SUCH DAMAGE.

*/

#ifndef lint *static char sccsid[] = “from: @(#)parser.c 5.3 (Berkeley) 4/12/91”;* static char rcsid[] = “parser.c,v 1.10 1993/09/09 01:21:43 cgd Exp”; #endif * not lint *

#include “shell.h” #include “parser.h” #include “nodes.h” #include “expand.h” * defines rmescapes() * #include “redir.h” * defines copyfd() * #include “syntax.h” #include “options.h” #include “input.h” #include “output.h” #include “var.h” #include “error.h” #include “memalloc.h” #include “mystring.h”

/*

• Shell command parser.

*/

#define EOFMARKLEN 79

* values returned by readtoken * #include “token.def”

struct heredoc { struct heredoc next; / next here document in list / union node *here; / redirection node / char *eofmark; / string indicating end of input / int striptabs; / if set, strip leading tabs */ };

struct heredoc heredoclist; / list of here documents to read / int parsebackquote; / nonzero if we are inside backquotes / int doprompt; / if set, prompt the user / int needprompt; / true if interactive and at start of line / int lasttoken; / last token read / MKINIT int tokpushback; / last token pushed back / char *wordtext; / text of last word returned by readtoken / int checkkwd; / 1 == check for kwds, 2 == also eat newlines */ struct nodelist *backquotelist; union node *redirnode; struct heredoc heredoc; int quoteflag; / set if (part of) last token was quoted / int startlinno; / line # where last token started */

#define GDB_HACK 1 * avoid local declarations which gdb can’t handle * #ifdef GDB_HACK static const char argvars[5] = {CTLVAR, VSNORMAL|VSQUOTE, ‘@’, ‘=’, ‘\0’}; static const char types[] = “}-+?=”; #endif

STATIC union node *list __P((int)); STATIC union node *andor __P((void)); STATIC union node *pipeline __P((void)); STATIC union node command __P((void)); STATIC union node *simplecmd __P((union node *, union node *)); STATIC void parsefname __P((void)); STATIC void parseheredoc __P((void)); STATIC int readtoken __P((void)); STATIC int readtoken1 __P((int, char const *, char *, int)); STATIC void attyline __P((void)); STATIC int noexpand __P((char *)); STATIC void synexpect __P((int)); STATIC void synerror __P((char *));

#if ATTY STATIC void putprompt __P((char )); #else / not ATTY */ #define putprompt(s) out2str(s) #endif

/*

• Read and parse a command. Returns NEOF on end of file. (NULL is a
• valid parse tree indicating a blank line.)

*/

union node * parsecmd(interact) { int t;

doprompt = interact; if (doprompt) putprompt(ps1val()); needprompt = 0; if ((t = readtoken()) == TEOF) return NEOF; if (t == TNL) return NULL; tokpushback++; return list(1); }

STATIC union node * list(nlflag) { union node *n1, *n2, *n3;

checkkwd = 2; if (nlflag == 0 && tokendlist[peektoken()]) return NULL; n1 = andor(); for (;;) { switch (readtoken()) { case TBACKGND: if (n1->type == NCMD || n1->type == NPIPE) { n1->ncmd.backgnd = 1; } else if (n1->type == NREDIR) { n1->type = NBACKGND; } else { n3 = (union node *)stalloc(sizeof (struct nredir)); n3->type = NBACKGND; n3->nredir.n = n1; n3->nredir.redirect = NULL; n1 = n3; } goto tsemi; case TNL: tokpushback++; * fall through * tsemi: case TSEMI: if (readtoken() == TNL) { parseheredoc(); if (nlflag) return n1; } else { tokpushback++; } checkkwd = 2; if (tokendlist[peektoken()]) return n1; n2 = andor(); n3 = (union node *)stalloc(sizeof (struct nbinary)); n3->type = NSEMI; n3->nbinary.ch1 = n1; n3->nbinary.ch2 = n2; n1 = n3; break; case TEOF: if (heredoclist) parseheredoc(); else pungetc(); * push back EOF on input * return n1; default: if (nlflag) synexpect(-1); tokpushback++; return n1; } } }

STATIC union node * andor() { union node *n1, *n2, *n3; int t;

n1 = pipeline(); for (;;) { if ((t = readtoken()) == TAND) { t = NAND; } else if (t == TOR) { t = NOR; } else { tokpushback++; return n1; } n2 = pipeline(); n3 = (union node *)stalloc(sizeof (struct nbinary)); n3->type = t; n3->nbinary.ch1 = n1; n3->nbinary.ch2 = n2; n1 = n3; } }

STATIC union node * pipeline() { union node *n1, *pipenode; struct nodelist *lp, *prev;

n1 = command(); if (readtoken() == TPIPE) { pipenode = (union node *)stalloc(sizeof (struct npipe)); pipenode->type = NPIPE; pipenode->npipe.backgnd = 0; lp = (struct nodelist *)stalloc(sizeof (struct nodelist)); pipenode->npipe.cmdlist = lp; lp->n = n1; do { prev = lp; lp = (struct nodelist *)stalloc(sizeof (struct nodelist)); lp->n = command(); prev->next = lp; } while (readtoken() == TPIPE); lp->next = NULL; n1 = pipenode; } tokpushback++; return n1; }

STATIC union node * command() { union node *n1, *n2; union node *ap, **app; union node *cp, **cpp; union node *redir, **rpp; int t;

checkkwd = 2; redir = 0; rpp = &redir; * Check for redirection which may precede command * while (readtoken() == TREDIR) { *rpp = n2 = redirnode; rpp = &n2->nfile.next; parsefname(); } tokpushback++;

switch (readtoken()) { case TIF: n1 = (union node *)stalloc(sizeof (struct nif)); n1->type = NIF; n1->nif.test = list(0); if (readtoken() != TTHEN) synexpect(TTHEN); n1->nif.ifpart = list(0); n2 = n1; while (readtoken() == TELIF) { n2->nif.elsepart = (union node *)stalloc(sizeof (struct nif)); n2 = n2->nif.elsepart; n2->type = NIF; n2->nif.test = list(0); if (readtoken() != TTHEN) synexpect(TTHEN); n2->nif.ifpart = list(0); } if (lasttoken == TELSE) n2->nif.elsepart = list(0); else { n2->nif.elsepart = NULL; tokpushback++; } if (readtoken() != TFI) synexpect(TFI); checkkwd = 1; break; case TWHILE: case TUNTIL: { int got; n1 = (union node *)stalloc(sizeof (struct nbinary)); n1->type = (lasttoken == TWHILE)? NWHILE : NUNTIL; n1->nbinary.ch1 = list(0); if ((got=readtoken()) != TDO) { TRACE((“expecting DO got %s %s\n”, tokname[got], got == TWORD ? wordtext : “”)); synexpect(TDO); } n1->nbinary.ch2 = list(0); if (readtoken() != TDONE) synexpect(TDONE); checkkwd = 1; break; } case TFOR: if (readtoken() != TWORD || quoteflag || ! goodname(wordtext)) synerror(“Bad for loop variable”); n1 = (union node *)stalloc(sizeof (struct nfor)); n1->type = NFOR; n1->nfor.var = wordtext; if (readtoken() == TWORD && ! quoteflag && equal(wordtext, “in”)) { app = ≈ while (readtoken() == TWORD) { n2 = (union node *)stalloc(sizeof (struct narg)); n2->type = NARG; n2->narg.text = wordtext; n2->narg.backquote = backquotelist; *app = n2; app = &n2->narg.next; } *app = NULL; n1->nfor.args = ap; * A newline or semicolon is required here to end the list. * if (lasttoken != TNL && lasttoken != TSEMI) synexpect(-1); } else { #ifndef GDB_HACK static const char argvars[5] = {CTLVAR, VSNORMAL|VSQUOTE, ‘@’, ‘=’, ‘\0’}; #endif n2 = (union node *)stalloc(sizeof (struct narg)); n2->type = NARG; n2->narg.text = (char *)argvars; n2->narg.backquote = NULL; n2->narg.next = NULL; n1->nfor.args = n2; /* Many shells accept an optional semicolon here, but POSIX says we should not, so we don’t. An optional newline is OK here, but that is handled by the checkkwd = 2 assignment below. */ tokpushback++; } checkkwd = 2; if ((t = readtoken()) == TDO) t = TDONE; else if (t == TBEGIN) t = TEND; else synexpect(-1); n1->nfor.body = list(0); if (readtoken() != t) synexpect(t); checkkwd = 1; break; case TCASE: n1 = (union node *)stalloc(sizeof (struct ncase)); n1->type = NCASE; if (readtoken() != TWORD) synexpect(TWORD); n1->ncase.expr = n2 = (union node *)stalloc(sizeof (struct narg)); n2->type = NARG; n2->narg.text = wordtext; n2->narg.backquote = backquotelist; n2->narg.next = NULL; while (readtoken() == TNL); if (lasttoken != TWORD || ! equal(wordtext, “in”)) synerror(“expecting "in"”); cpp = &n1->ncase.cases; while (checkkwd = 2, readtoken() == TWORD) { *cpp = cp = (union node *)stalloc(sizeof (struct nclist)); cp->type = NCLIST; app = &cp->nclist.pattern; for (;;) { *app = ap = (union node *)stalloc(sizeof (struct narg)); ap->type = NARG; ap->narg.text = wordtext; ap->narg.backquote = backquotelist; if (readtoken() != TPIPE) break; app = &ap->narg.next; if (readtoken() != TWORD) synexpect(TWORD); } ap->narg.next = NULL; if (lasttoken != TRP) synexpect(TRP); cp->nclist.body = list(0); if ((t = readtoken()) == TESAC) tokpushback++; else if (t != TENDCASE) synexpect(TENDCASE); cpp = &cp->nclist.next; } *cpp = NULL; if (lasttoken != TESAC) synexpect(TESAC); checkkwd = 1; break; case TLP: n1 = (union node *)stalloc(sizeof (struct nredir)); n1->type = NSUBSHELL; n1->nredir.n = list(0); n1->nredir.redirect = NULL; if (readtoken() != TRP) synexpect(TRP); checkkwd = 1; break; case TBEGIN: n1 = list(0); if (readtoken() != TEND) synexpect(TEND); checkkwd = 1; break; * Handle an empty command like other simple commands. * case TSEMI: case TNL: * Handle EOF like other simple commands, too. * case TEOF: case TWORD: tokpushback++; return simplecmd(rpp, redir); default: synexpect(-1); }

* Now check for redirection which may follow command * while (readtoken() == TREDIR) { *rpp = n2 = redirnode; rpp = &n2->nfile.next; parsefname(); } tokpushback++; *rpp = NULL; if (redir) { if (n1->type != NSUBSHELL) { n2 = (union node *)stalloc(sizeof (struct nredir)); n2->type = NREDIR; n2->nredir.n = n1; n1 = n2; } n1->nredir.redirect = redir; } return n1; }

STATIC union node * simplecmd(rpp, redir) union node **rpp, *redir; { union node *args, **app; union node **orig_rpp = rpp; union node *n;

* If we don’t have any redirections already, then we must reset rpp to be the address of the local redir variable. * if (redir == 0) rpp = &redir;

args = NULL; app = &args; /* We save the incoming value, because we need this for shell functions. There can not be a redirect or an argument between the function name and the open parenthesis. */ orig_rpp = rpp; for (;;) { if (readtoken() == TWORD) { n = (union node *)stalloc(sizeof (struct narg)); n->type = NARG; n->narg.text = wordtext; n->narg.backquote = backquotelist; *app = n; app = &n->narg.next; } else if (lasttoken == TREDIR) { *rpp = n = redirnode; rpp = &n->nfile.next; parsefname(); * read name of redirection file * } else if (lasttoken == TLP && app == &args->narg.next && rpp == orig_rpp) { * We have a function * if (readtoken() != TRP) synexpect(TRP); #ifdef notdef if (! goodname(n->narg.text)) synerror(“Bad function name”); #endif n->type = NDEFUN; n->narg.next = command(); return n; } else { tokpushback++; break; } } *app = NULL; *rpp = NULL; n = (union node *)stalloc(sizeof (struct ncmd)); n->type = NCMD; n->ncmd.backgnd = 0; n->ncmd.args = args; n->ncmd.redirect = redir; return n; }

STATIC void parsefname() { union node *n = redirnode;

if (readtoken() != TWORD) synexpect(-1); if (n->type == NHERE) { struct heredoc *here = heredoc; struct heredoc *p; int i;

if (quoteflag == 0) n->type = NXHERE; TRACE((“Here document %d\n”, n->type)); if (here->striptabs) { while (*wordtext == ‘\t’) wordtext++; } if (! noexpand(wordtext) || (i = strlen(wordtext)) == 0 || i > EOFMARKLEN) synerror(“Illegal eof marker for << redirection”); rmescapes(wordtext); here->eofmark = wordtext; here->next = NULL; if (heredoclist == NULL) heredoclist = here; else { for (p = heredoclist ; p->next ; p = p->next); p->next = here; } } else if (n->type == NTOFD || n->type == NFROMFD) { if (is_digit(wordtext[0])) n->ndup.dupfd = digit_val(wordtext[0]); else if (wordtext[0] == ‘-‘) n->ndup.dupfd = -1; else goto bad; if (wordtext[1] != ‘\0’) { bad: synerror(“Bad fd number”); } } else { n->nfile.fname = (union node *)stalloc(sizeof (struct narg)); n = n->nfile.fname; n->type = NARG; n->narg.next = NULL; n->narg.text = wordtext; n->narg.backquote = backquotelist; } }

/*

• Input any here documents.

*/

STATIC void parseheredoc() { struct heredoc *here; union node *n;

while (heredoclist) { here = heredoclist; heredoclist = here->next; if (needprompt) { putprompt(ps2val()); needprompt = 0; } readtoken1(pgetc(), here->here->type == NHERE? SQSYNTAX : DQSYNTAX, here->eofmark, here->striptabs); n = (union node *)stalloc(sizeof (struct narg)); n->narg.type = NARG; n->narg.next = NULL; n->narg.text = wordtext; n->narg.backquote = backquotelist; here->here->nhere.doc = n; } }

STATIC int peektoken() { int t;

t = readtoken(); tokpushback++; return (t); }

STATIC int xxreadtoken();

STATIC int readtoken() { int t; #ifdef DEBUG int alreadyseen = tokpushback; #endif

t = xxreadtoken();

if (checkkwd) { /*

• eat newlines

*/ if (checkkwd == 2) { checkkwd = 0; while (t == TNL) { parseheredoc(); t = xxreadtoken(); } } else checkkwd = 0; /*

• check for keywords

*/ if (t == TWORD && !quoteflag) { register char *const *pp;

for (pp = parsekwd; *pp; pp++) { if (**pp == *wordtext && equal(*pp, wordtext)) { lasttoken = t = pp - parsekwd + KWDOFFSET; TRACE((“keyword %s recognized\n”, tokname[t])); break; } } } } #ifdef DEBUG if (!alreadyseen) TRACE((“token %s %s\n”, tokname[t], t == TWORD ? wordtext : “”)); else TRACE((“reread token %s %s\n”, tokname[t], t == TWORD ? wordtext : “”)); #endif return (t); }

/*

• Read the next input token.
• If the token is a word, we set backquotelist to the list of cmds in
• backquotes. We set quoteflag to true if any part of the word was
• quoted.
• If the token is TREDIR, then we set redirnode to a structure containing
• the redirection.
• In all cases, the variable startlinno is set to the number of the line
• on which the token starts.

*

• [Change comment: here documents and internal procedures]
• [Readtoken shouldn’t have any arguments. Perhaps we should make the
• word parsing code into a separate routine. In this case, readtoken
• doesn’t need to have any internal procedures, but parseword does.
• We could also make parseoperator in essence the main routine, and
• have parseword (readtoken1?) handle both words and redirection.]

*/

#define RETURN(token) return lasttoken = token

STATIC int xxreadtoken() { register c;

if (tokpushback) { tokpushback = 0; return lasttoken; } if (needprompt) { putprompt(ps2val()); needprompt = 0; } startlinno = plinno; for (;;) { * until token or start of word found * c = pgetc_macro(); if (c == ’ ’ || c == ‘\t’) continue; * quick check for white space first * switch (c) { case ’ ‘: case ‘\t’: continue; case ‘#’: while ((c = pgetc()) != ‘\n’ && c != PEOF); pungetc(); continue; case ‘\’: if (pgetc() == ‘\n’) { startlinno = ++plinno; if (doprompt) putprompt(ps2val()); continue; } pungetc(); goto breakloop; case ‘\n’: plinno++; needprompt = doprompt; RETURN(TNL); case PEOF: RETURN(TEOF); case ‘&’: if (pgetc() == ‘&’) RETURN(TAND); pungetc(); RETURN(TBACKGND); case ‘|’: if (pgetc() == ‘|’) RETURN(TOR); pungetc(); RETURN(TPIPE); case ‘;’: if (pgetc() == ‘;’) RETURN(TENDCASE); pungetc(); RETURN(TSEMI); case ‘(‘: RETURN(TLP); case ‘)’: RETURN(TRP); default: goto breakloop; } } breakloop: return readtoken1(c, BASESYNTAX, (char *)NULL, 0); #undef RETURN }

/*

• If eofmark is NULL, read a word or a redirection symbol. If eofmark
• is not NULL, read a here document. In the latter case, eofmark is the
• word which marks the end of the document and striptabs is true if
• leading tabs should be stripped from the document. The argument firstc
• is the first character of the input token or document.

*

• Because C does not have internal subroutines, I have simulated them
• using goto’s to implement the subroutine linkage. The following macros
• will run code that appears at the end of readtoken1.

*/

#define CHECKEND() {goto checkend; checkend_return:;} #define PARSEREDIR() {goto parseredir; parseredir_return:;} #define PARSESUB() {goto parsesub; parsesub_return:;} #define PARSEBACKQOLD() {oldstyle = 1; goto parsebackq; parsebackq_oldreturn:;} #define PARSEBACKQNEW() {oldstyle = 0; goto parsebackq; parsebackq_newreturn:;}

STATIC int readtoken1(firstc, syntax, eofmark, striptabs) int firstc; char const *syntax; char *eofmark; int striptabs; { register c = firstc; register char *out; int len; char line[EOFMARKLEN + 1]; struct nodelist *bqlist; int quotef; int dblquote; int varnest; int oldstyle;

startlinno = plinno; dblquote = 0; if (syntax == DQSYNTAX) dblquote = 1; quotef = 0; bqlist = NULL; varnest = 0; STARTSTACKSTR(out); loop: { * for each line, until end of word * #if ATTY if (c == ‘\034’ && doprompt && attyset() && ! equal(termval(), “emacs”)) { attyline(); if (syntax == BASESYNTAX) return readtoken(); c = pgetc(); goto loop; } #endif CHECKEND(); * set c to PEOF if at end of here document * for (;;) { * until end of line or end of word * CHECKSTRSPACE(3, out); * permit 3 calls to USTPUTC * switch(syntax[c]) { case CNL: * ‘\n’ * if (syntax == BASESYNTAX) goto endword; * exit outer loop * USTPUTC(c, out); plinno++; if (doprompt) { putprompt(ps2val()); } c = pgetc(); goto loop; * continue outer loop * case CWORD: USTPUTC(c, out); break; case CCTL: if (eofmark == NULL || dblquote) USTPUTC(CTLESC, out); USTPUTC(c, out); break; case CBACK: * backslash * c = pgetc(); if (c == PEOF) { USTPUTC(‘\’, out); pungetc(); } else if (c == ‘\n’) { if (doprompt) putprompt(ps2val()); } else { if (dblquote && c != ‘\’ && c != ‘`’ && c != ‘$’ && (c != ‘”’ || eofmark != NULL)) USTPUTC(‘\’, out); if (SQSYNTAX[c] == CCTL) USTPUTC(CTLESC, out); USTPUTC(c, out); quotef++; } break; case CSQUOTE: syntax = SQSYNTAX; break; case CDQUOTE: syntax = DQSYNTAX; dblquote = 1; break; case CENDQUOTE: if (eofmark) { USTPUTC(c, out); } else { syntax = BASESYNTAX; quotef++; dblquote = 0; } break; case CVAR: * ‘$’ * PARSESUB(); * parse substitution * break; case CENDVAR: * ‘}’ * if (varnest > 0) { varnest–; USTPUTC(CTLENDVAR, out); } else { USTPUTC(c, out); } break; case CBQUOTE: * ‘`’ * PARSEBACKQOLD(); break; case CEOF: goto endword; * exit outer loop * default: if (varnest == 0) goto endword; * exit outer loop * USTPUTC(c, out); } c = pgetc_macro(); } } endword: if (syntax != BASESYNTAX && ! parsebackquote && eofmark == NULL) synerror(“Unterminated quoted string”); if (varnest != 0) { startlinno = plinno; synerror(“Missing ‘}’”); } USTPUTC(‘\0’, out); len = out - stackblock(); out = stackblock(); if (eofmark == NULL) { if ((c == ‘>’ || c == ‘<’) && quotef == 0 && len <= 2 && (*out == ‘\0’ || is_digit(*out))) { PARSEREDIR(); return lasttoken = TREDIR; } else { pungetc(); } } quoteflag = quotef; backquotelist = bqlist; grabstackblock(len); wordtext = out; return lasttoken = TWORD; * end of readtoken routine *

/*

• Check to see whether we are at the end of the here document. When this
• is called, c is set to the first character of the next input line. If
• we are at the end of the here document, this routine sets the c to PEOF.

*/

checkend: { if (eofmark) { if (striptabs) { while (c == ‘\t’) c = pgetc(); } if (c == *eofmark) { if (pfgets(line, sizeof line) != NULL) { register char *p, *q;

p = line; for (q = eofmark + 1 ; *q && *p == *q ; p++, q++); if (*p == ‘\n’ && *q == ‘\0’) { c = PEOF; plinno++; needprompt = doprompt; } else { ppushback(line, strlen(line)); } } } } goto checkend_return; }

/*

• Parse a redirection operator. The variable “out” points to a string
• specifying the fd to be redirected. The variable “c” contains the
• first character of the redirection operator.

*/

parseredir: { char fd = *out; union node *np;

np = (union node *)stalloc(sizeof (struct nfile)); if (c == ‘>’) { np->nfile.fd = 1; c = pgetc(); if (c == ‘>’) np->type = NAPPEND; else if (c == ‘&’) np->type = NTOFD; else { np->type = NTO; pungetc(); } } else { * c == ‘<’ * np->nfile.fd = 0; c = pgetc(); if (c == ‘<’) { if (sizeof (struct nfile) != sizeof (struct nhere)) { np = (union node *)stalloc(sizeof (struct nhere)); np->nfile.fd = 0; } np->type = NHERE; heredoc = (struct heredoc *)stalloc(sizeof (struct heredoc)); heredoc->here = np; if ((c = pgetc()) == ‘-‘) { heredoc->striptabs = 1; } else { heredoc->striptabs = 0; pungetc(); } } else if (c == ‘&’) np->type = NFROMFD; else { np->type = NFROM; pungetc(); } } if (fd != ‘\0’) np->nfile.fd = digit_val(fd); redirnode = np; goto parseredir_return; }

/*

• Parse a substitution. At this point, we have read the dollar sign
• and nothing else.

*/

parsesub: { int subtype; int typeloc; int flags; char *p; #ifndef GDB_HACK static const char types[] = “}-+?=”; #endif

c = pgetc(); if (c != ‘(’ && c != ‘{’ && !is_name(c) && !is_special(c)) { USTPUTC(‘$’, out); pungetc(); } else if (c == ‘(‘) { * $(command) * PARSEBACKQNEW(); } else { USTPUTC(CTLVAR, out); typeloc = out - stackblock(); USTPUTC(VSNORMAL, out); subtype = VSNORMAL; if (c == ‘{‘) { c = pgetc(); subtype = 0; } if (is_name(c)) { do { STPUTC(c, out); c = pgetc(); } while (is_in_name(c)); } else { if (! is_special(c)) badsub: synerror(“Bad substitution”); USTPUTC(c, out); c = pgetc(); } STPUTC(‘=’, out); flags = 0; if (subtype == 0) { if (c == ‘:’) { flags = VSNUL; c = pgetc(); } p = strchr(types, c); if (p == NULL) goto badsub; subtype = p - types + VSNORMAL; } else { pungetc(); } if (dblquote) flags |= VSQUOTE; *(stackblock() + typeloc) = subtype | flags; if (subtype != VSNORMAL) varnest++; } goto parsesub_return; }

/*

• Called to parse command substitutions. Newstyle is set if the command
• is enclosed inside $(…); nlpp is a pointer to the head of the linked
• list of commands (passed by reference), and savelen is the number of
• characters on the top of the stack which must be preserved.

*/

parsebackq: { struct nodelist **nlpp; int savepbq; union node *n; char *volatile str; struct jmploc jmploc; struct jmploc *volatile savehandler; int savelen;

savepbq = parsebackquote; if (setjmp(jmploc.loc)) { if (str) ckfree(str); parsebackquote = 0; handler = savehandler; longjmp(handler->loc, 1); } INTOFF; str = NULL; savelen = out - stackblock(); if (savelen > 0) { str = ckmalloc(savelen); bcopy(stackblock(), str, savelen); } savehandler = handler; handler = &jmploc; INTON; if (oldstyle) { /* We must read until the closing backquote, giving special treatment to some slashes, and then push the string and reread it as input, interpreting it normally. */ register char *out; register c; int savelen; char *str;

STARTSTACKSTR(out); while ((c = pgetc ()) != ‘`’) { if (c == ‘\’) { c = pgetc (); if (c != ‘\’ && c != ‘`’ && c != ‘$’ && (!dblquote || c != ‘”’)) STPUTC(‘\’, out); } STPUTC(c, out); } STPUTC(‘\0’, out); savelen = out - stackblock(); if (savelen > 0) { str = ckmalloc(savelen); bcopy(stackblock(), str, savelen); } setinputstring(str, 1); } nlpp = &bqlist; while (*nlpp) nlpp = &(*nlpp)->next; *nlpp = (struct nodelist *)stalloc(sizeof (struct nodelist)); (*nlpp)->next = NULL; parsebackquote = oldstyle; n = list(0); if (!oldstyle && (readtoken() != TRP)) synexpect(TRP); (nlpp)->n = n; / Start reading from old file again, and clear tokpushback since any pushed back token from the string is no longer relevant. */ if (oldstyle) { popfile(); tokpushback = 0; } while (stackblocksize() <= savelen) growstackblock(); STARTSTACKSTR(out); if (str) { bcopy(str, out, savelen); STADJUST(savelen, out); INTOFF; ckfree(str); str = NULL; INTON; } parsebackquote = savepbq; handler = savehandler; USTPUTC(CTLBACKQ + dblquote, out); if (oldstyle) goto parsebackq_oldreturn; else goto parsebackq_newreturn; }

} * end of readtoken *

#ifdef mkinit RESET { tokpushback = 0; } #endif

#if ATTY /*

• Called to process a command generated by atty. We execute the line,
• and catch any errors that occur so they don’t propagate outside of
• this routine.

*/

STATIC void attyline() { char line[256]; struct stackmark smark; struct jmploc jmploc; struct jmploc *volatile savehandler;

if (pfgets(line, sizeof line) == NULL) return; * “can’t happen” * if (setjmp(jmploc.loc)) { if (exception == EXERROR) out2str(“\033]D\n”); handler = savehandler; longjmp(handler->loc, 1); } savehandler = handler; handler = &jmploc; setstackmark(&smark); evalstring(line); popstackmark(&smark); handler = savehandler; doprompt = 1; }

/*

• Output a prompt for atty. We output the prompt as part of the
• appropriate escape sequence.

*/

STATIC void putprompt(s) char *s; { register char *p;

if (attyset() && ! equal(termval(), “emacs”)) { if (strchr(s, ‘\7’)) out2c(‘\7’); out2str(“\033]P1;”); for (p = s ; *p ; p++) { if ((unsigned)(*p - ’ ‘) <= ‘~’ - ’ ‘) out2c(*p); } out2c(‘\n’); } else { out2str(s); } } #endif

/*

• Returns true if the text contains nothing to expand (no dollar signs
• or backquotes).

*/

STATIC int noexpand(text) char *text; { register char *p; register char c;

p = text; while ((c = *p++) != ‘\0’) { if (c == CTLESC) p++; else if (BASESYNTAX[c] == CCTL) return 0; } return 1; }

/*

• Return true if the argument is a legal variable name (a letter or
• underscore followed by zero or more letters, underscores, and digits).

*/

int goodname(name) char *name; { register char *p;

p = name; if (! is_name(*p)) return 0; while (*++p) { if (! is_in_name(*p)) return 0; } return 1; }

/*

• Called when an unexpected token is read during the parse. The argument
• is the token that is expected, or -1 if more than one type of token can
• occur at this point.

*/

STATIC void synexpect(token) { char msg[64];

if (token >= 0) { fmtstr(msg, 64, “%s unexpected (expecting %s)”, tokname[lasttoken], tokname[token]); } else { fmtstr(msg, 64, “%s unexpected”, tokname[lasttoken]); } synerror(msg); }

STATIC void synerror(msg) char *msg; { if (commandname) outfmt(&errout, “%s: %d: “, commandname, startlinno); outfmt(&errout, “Syntax error: %s\n”, msg); error((char *)NULL); }