/*      $NetBSD: lex.c,v 1.24 2019/09/26 11:01:09 mlelstv Exp $ */

/*
 * lexical analysis and source input
 */
#include <sys/cdefs.h>

#ifndef lint
__RCSID("$NetBSD: lex.c,v 1.24 2019/09/26 11:01:09 mlelstv Exp $");
#endif


#include "sh.h"
#include <ctype.h>


/* Structure to keep track of the lexing state and the various pieces of info
 * needed for each particular state.
 */
typedef struct lex_state Lex_state;
struct lex_state {
        int ls_state;
        union {
            /* $(...) */
            struct scsparen_info {
                    int nparen;         /* count open parenthesis */
                    int csstate; /* XXX remove */
#define ls_scsparen ls_info.u_scsparen
            } u_scsparen;

            /* $((...)) */
            struct sasparen_info {
                    int nparen;         /* count open parenthesis */
                    int start;          /* marks start of $(( in output str */
#define ls_sasparen ls_info.u_sasparen
            } u_sasparen;

            /* ((...)) */
            struct sletparen_info {
                    int nparen;         /* count open parenthesis */
#define ls_sletparen ls_info.u_sletparen
            } u_sletparen;

            /* `...` */
            struct sbquote_info {
                    int indquotes;      /* true if in double quotes: "`...`" */
#define ls_sbquote ls_info.u_sbquote
            } u_sbquote;

            Lex_state *base;            /* used to point to next state block */
        } ls_info;
};

typedef struct State_info State_info;
struct State_info {
        Lex_state       *base;
        Lex_state       *end;
};


static void     readhere ARGS((struct ioword *iop));
static int      getsc__ ARGS((void));
static void     getsc_line ARGS((Source *s));
static int      getsc_bn ARGS((void));
static char     *get_brace_var ARGS((XString *wsp, char *wp));
static int      arraysub ARGS((char **strp));
static const char *ungetsc ARGS((int c));
static void     gethere ARGS((void));
static Lex_state *push_state_ ARGS((State_info *si, Lex_state *old_end));
static Lex_state *pop_state_ ARGS((State_info *si, Lex_state *old_end));

static int backslash_skip;
static int ignore_backslash_newline;

/* optimized getsc_bn() */
#define getsc()         (*source->str != '\0' && *source->str != '\\' \
                         && !backslash_skip ? *source->str++ : getsc_bn())
/* optimized getsc__() */
#define getsc_()        ((*source->str != '\0') ? *source->str++ : getsc__())

#define STATE_BSIZE     32

#define PUSH_STATE(s)   do { \
                            if (++statep == state_info.end) \
                                statep = push_state_(&state_info, statep); \
                            state = statep->ls_state = (s); \
                        } while (0)

#define POP_STATE()     do { \
                            if (--statep == state_info.base) \
                                statep = pop_state_(&state_info, statep); \
                            state = statep->ls_state; \
                        } while (0)



/*
 * Lexical analyzer
 *
 * tokens are not regular expressions, they are LL(1).
 * for example, "${var:-${PWD}}", and "$(size $(whence ksh))".
 * hence the state stack.
 */

int
yylex(cf)
        int cf;
{
        Lex_state states[STATE_BSIZE], *statep;
        State_info state_info;
        int c, state;
        XString ws;             /* expandable output word */
        char *wp;               /* output word pointer */
        char *sp, *dp;
        int c2;


  Again:
        states[0].ls_state = -1;
        states[0].ls_info.base = (Lex_state *) 0;
        statep = &states[1];
        state_info.base = states;
        state_info.end = &states[STATE_BSIZE];

        Xinit(ws, wp, 64, ATEMP);

        backslash_skip = 0;
        ignore_backslash_newline = 0;

        if (cf&ONEWORD)
                state = SWORD;
#ifdef KSH
        else if (cf&LETEXPR) {
                *wp++ = OQUOTE;  /* enclose arguments in (double) quotes */
                state = SLETPAREN;      
                statep->ls_sletparen.nparen = 0;
        }
#endif /* KSH */
        else {          /* normal lexing */
                state = (cf & HEREDELIM) ? SHEREDELIM : SBASE;
                while ((c = getsc()) == ' ' || c == '\t')
                        ;
                if (c == '#') {
                        ignore_backslash_newline++;
                        while ((c = getsc()) != '\0' && c != '\n')
                                ;
                        ignore_backslash_newline--;
                }
                ungetsc(c);
        }
        if (source->flags & SF_ALIAS) { /* trailing ' ' in alias definition */
                source->flags &= ~SF_ALIAS;
                /* In POSIX mode, a trailing space only counts if we are
                 * parsing a simple command
                 */
                if (!Flag(FPOSIX) || (cf & CMDWORD))
                        cf |= ALIAS;
        }

        /* Initial state: one of SBASE SHEREDELIM SWORD SASPAREN */
        statep->ls_state = state;

        /* collect non-special or quoted characters to form word */
        while (!((c = getsc()) == 0
                 || ((state == SBASE || state == SHEREDELIM)
                     && ctype(c, C_LEX1))))
        {
                Xcheck(ws, wp);
                switch (state) {
                  case SBASE:
                        if (c == '[' && (cf & (VARASN|ARRAYVAR))) {
                                *wp = EOS; /* temporary */
                                if (is_wdvarname(Xstring(ws, wp), false))
                                {
                                        char *p, *tmp;

                                        if (arraysub(&tmp)) {
                                                *wp++ = CHAR;
                                                *wp++ = c;
                                                for (p = tmp; *p; ) {
                                                        Xcheck(ws, wp);
                                                        *wp++ = CHAR;
                                                        *wp++ = *p++;
                                                }
                                                afree(tmp, ATEMP);
                                                break;
                                        } else {
                                                Source *s;

                                                s = pushs(SREREAD,
                                                          source->areap);
                                                s->start = s->str
                                                        = s->u.freeme = tmp;
                                                s->next = source;
                                                source = s;
                                        }
                                }
                                *wp++ = CHAR;
                                *wp++ = c;
                                break;
                        }
                        /* fall through.. */
                  Sbase1:       /* includes *(...|...) pattern (*+?@!) */
#ifdef KSH
                        if (c == '*' || c == '@' || c == '+' || c == '?'
                            || c == '!')
                        {
                                c2 = getsc();
                                if (c2 == '(' /*)*/ ) {
                                        *wp++ = OPAT;
                                        *wp++ = c;
                                        PUSH_STATE(SPATTERN);
                                        break;
                                }
                                ungetsc(c2);
                        }
#endif /* KSH */
                        /* fall through.. */
                  Sbase2:       /* doesn't include *(...|...) pattern (*+?@!) */
                        switch (c) {
                          case '\\':
                                c = getsc();
                                if (c) /* trailing \ is lost */
                                        *wp++ = QCHAR, *wp++ = c;
                                break;
                          case '\'':
                                *wp++ = OQUOTE;
                                ignore_backslash_newline++;
                                PUSH_STATE(SSQUOTE);
                                break;
                          case '"':
                                *wp++ = OQUOTE;
                                PUSH_STATE(SDQUOTE);
                                break;
                          default:
                                goto Subst;
                        }
                        break;

                  Subst:
                        switch (c) {
                          Lex_state *s;
                          Lex_state *base;

                          case '\\':
                                c = getsc();
                                switch (c) {
                                  case '\\':
                                  case '$': case '`':
                                        *wp++ = QCHAR, *wp++ = c;
                                        break;
                                  case '"':
                                        if ((cf & HEREDOC) == 0) {
                                                *wp++ = QCHAR, *wp++ = c;
                                                break;
                                        }
                                        /* FALLTHROUGH */
                                  default:
                                        Xcheck(ws, wp);
                                        if (c) { /* trailing \ is lost */
                                                *wp++ = CHAR, *wp++ = '\\';
                                                *wp++ = CHAR, *wp++ = c;
                                        }
                                        break;
                                }
                                break;
                          case '$':
                                c = getsc();
                                if (c == '(') /*)*/ {
                                        c = getsc();
                                        if (c == '(') /*)*/ {
                                                PUSH_STATE(SASPAREN);
                                                statep->ls_sasparen.nparen = 2;
                                                statep->ls_sasparen.start =
                                                        Xsavepos(ws, wp);
                                                *wp++ = EXPRSUB;
                                        } else {
                                                ungetsc(c);
                                                PUSH_STATE(SCSPAREN);
                                                statep->ls_scsparen.nparen = 1;
                                                statep->ls_scsparen.csstate = 0;
                                                *wp++ = COMSUB;
                                        }
                                } else if (c == '{') /*}*/ {
                                        *wp++ = OSUBST;
                                        *wp++ = '{'; /*}*/
                                        wp = get_brace_var(&ws, wp);
                                        c = getsc();
                                        /* allow :# and :% (ksh88 compat) */
                                        if (c == ':') {
                                                *wp++ = CHAR, *wp++ = c;
                                                c = getsc();
                                        }
                                        /* If this is a trim operation,
                                         * treat (,|,) specially in STBRACE.
                                         */
                                        if (c == '#' || c == '%') {
                                                ungetsc(c);
                                                PUSH_STATE(STBRACE);
                                        } else {
                                                ungetsc(c);
                                                PUSH_STATE(SBRACE);
                                        }
                                } else if (ctype(c, C_ALPHA)) {
                                        *wp++ = OSUBST;
                                        *wp++ = 'X';
                                        do {
                                                Xcheck(ws, wp);
                                                *wp++ = c;
                                                c = getsc();
                                        } while (ctype(c, C_ALPHA|C_DIGIT));
                                        *wp++ = '\0';
                                        *wp++ = CSUBST;
                                        *wp++ = 'X';
                                        ungetsc(c);
                                } else if (ctype(c, C_DIGIT|C_VAR1)) {
                                        Xcheck(ws, wp);
                                        *wp++ = OSUBST;
                                        *wp++ = 'X';
                                        *wp++ = c;
                                        *wp++ = '\0';
                                        *wp++ = CSUBST;
                                        *wp++ = 'X';
                                } else {
                                        *wp++ = CHAR, *wp++ = '$';
                                        ungetsc(c);
                                }
                                break;
                          case '`':
                                PUSH_STATE(SBQUOTE);
                                *wp++ = COMSUB;
                                /* Need to know if we are inside double quotes
                                 * since sh/at&t-ksh translate the \" to " in
                                 * "`..\"..`".  POSIX also requires this.
                                 * An earlier version of ksh misinterpreted
                                 * the POSIX specification and performed
                                 * removal of backslash escapes only if
                                 * posix mode was not in effect.
                                 */
                                statep->ls_sbquote.indquotes = 0;
                                s = statep;
                                base = state_info.base;
                                while (1) {
                                        for (; s != base; s--) {
                                                if (s->ls_state == SDQUOTE) {
                                                        statep->ls_sbquote.indquotes = 1;
                                                        break;
                                                }
                                        }
                                        if (s != base)
                                                break;
                                        if (!(s = s->ls_info.base))
                                                break;
                                        base = s-- - STATE_BSIZE;
                                }
                                break;
                          default:
                                *wp++ = CHAR, *wp++ = c;
                        }
                        break;

                  case SSQUOTE:
                        if (c == '\'') {
                                POP_STATE();
                                *wp++ = CQUOTE;
                                ignore_backslash_newline--;
                        } else
                                *wp++ = QCHAR, *wp++ = c;
                        break;

                  case SDQUOTE:
                        if (c == '"') {
                                POP_STATE();
                                *wp++ = CQUOTE;
                        } else
                                goto Subst;
                        break;

                  case SCSPAREN: /* $( .. ) */
                        /* todo: deal with $(...) quoting properly
                         * kludge to partly fake quoting inside $(..): doesn't
                         * really work because nested $(..) or ${..} inside
                         * double quotes aren't dealt with.
                         */
                        switch (statep->ls_scsparen.csstate) {
                          case 0: /* normal */
                                switch (c) {
                                  case '(':
                                        statep->ls_scsparen.nparen++;
                                        break;
                                  case ')':
                                        statep->ls_scsparen.nparen--;
                                        break;
                                  case '\\':
                                        statep->ls_scsparen.csstate = 1;
                                        break;
                                  case '"':
                                        statep->ls_scsparen.csstate = 2;
                                        break;
                                  case '\'':
                                        statep->ls_scsparen.csstate = 4;
                                        ignore_backslash_newline++;
                                        break;
                                }
                                break;

                          case 1: /* backslash in normal mode */
                          case 3: /* backslash in double quotes */
                                --statep->ls_scsparen.csstate;
                                break;

                          case 2: /* double quotes */
                                if (c == '"')
                                        statep->ls_scsparen.csstate = 0;
                                else if (c == '\\')
                                        statep->ls_scsparen.csstate = 3;
                                break;

                          case 4: /* single quotes */
                                if (c == '\'') {
                                        statep->ls_scsparen.csstate = 0;
                                        ignore_backslash_newline--;
                                }
                                break;
                        }
                        if (statep->ls_scsparen.nparen == 0) {
                                POP_STATE();
                                *wp++ = 0; /* end of COMSUB */
                        } else
                                *wp++ = c;
                        break;

                  case SASPAREN: /* $(( .. )) */
                        /* todo: deal with $((...); (...)) properly */
                        /* XXX should nest using existing state machine
                         *     (embed "..", $(...), etc.) */
                        if (c == '(')
                                statep->ls_sasparen.nparen++;
                        else if (c == ')') {
                                statep->ls_sasparen.nparen--;
                                if (statep->ls_sasparen.nparen == 1) {
                                        /*(*/
                                        if ((c2 = getsc()) == ')') {
                                                POP_STATE();
                                                *wp++ = 0; /* end of EXPRSUB */
                                                break;
                                        } else {
                                                char *s;

                                                ungetsc(c2);
                                                /* mismatched parenthesis -
                                                 * assume we were really
                                                 * parsing a $(..) expression
                                                 */
                                                s = Xrestpos(ws, wp,
                                                     statep->ls_sasparen.start);
                                                memmove(s + 1, s, wp - s);
                                                *s++ = COMSUB;
                                                *s = '('; /*)*/
                                                wp++;
                                                statep->ls_scsparen.nparen = 1;
                                                statep->ls_scsparen.csstate = 0;
                                                state = statep->ls_state
                                                        = SCSPAREN;
                                                
                                        }
                                }
                        }
                        *wp++ = c;
                        break;

                  case SBRACE:
                        /*{*/
                        if (c == '}') {
                                POP_STATE();
                                *wp++ = CSUBST;
                                *wp++ = /*{*/ '}';
                        } else
                                goto Sbase1;
                        break;

                  case STBRACE:
                        /* Same as SBRACE, except (,|,) treated specially */
                        /*{*/
                        if (c == '}') {
                                POP_STATE();
                                *wp++ = CSUBST;
                                *wp++ = /*{*/ '}';
                        } else if (c == '|') {
                                *wp++ = SPAT;
                        } else if (c == '(') {
                                *wp++ = OPAT;
                                *wp++ = ' ';    /* simile for @ */
                                PUSH_STATE(SPATTERN);
                        } else
                                goto Sbase1;
                        break;

                  case SBQUOTE:
                        if (c == '`') {
                                *wp++ = 0;
                                POP_STATE();
                        } else if (c == '\\') {
                                switch (c = getsc()) {
                                  case '\\':
                                  case '$': case '`':
                                        *wp++ = c;
                                        break;
                                  case '"':
                                        if (statep->ls_sbquote.indquotes) {
                                                *wp++ = c;
                                                break;
                                        }
                                        /* fall through.. */
                                  default:
                                        if (c) { /* trailing \ is lost */
                                                *wp++ = '\\';
                                                *wp++ = c;
                                        }
                                        break;
                                }
                        } else
                                *wp++ = c;
                        break;

                  case SWORD:   /* ONEWORD */
                        goto Subst;

#ifdef KSH
                  case SLETPAREN:       /* LETEXPR: (( ... )) */
                        /*(*/
                        if (c == ')') {
                                if (statep->ls_sletparen.nparen > 0)
                                    --statep->ls_sletparen.nparen;
                                /*(*/
                                else if ((c2 = getsc()) == ')') {
                                        c = 0;
                                        *wp++ = CQUOTE;
                                        goto Done;
                                } else
                                        ungetsc(c2);
                        } else if (c == '(')
                                /* parenthesis inside quotes and backslashes
                                 * are lost, but at&t ksh doesn't count them
                                 * either
                                 */
                                ++statep->ls_sletparen.nparen;
                        goto Sbase2;
#endif /* KSH */

                  case SHEREDELIM:      /* <<,<<- delimiter */
                        /* XXX chuck this state (and the next) - use
                         * the existing states ($ and \`..` should be
                         * stripped of their specialness after the
                         * fact).
                         */
                        /* here delimiters need a special case since
                         * $ and `..` are not to be treated specially
                         */
                        if (c == '\\') {
                                c = getsc();
                                if (c) { /* trailing \ is lost */
                                        *wp++ = QCHAR;
                                        *wp++ = c;
                                }
                        } else if (c == '\'') {
                                PUSH_STATE(SSQUOTE);
                                *wp++ = OQUOTE;
                                ignore_backslash_newline++;
                        } else if (c == '"') {
                                state = statep->ls_state = SHEREDQUOTE;
                                *wp++ = OQUOTE;
                        } else {
                                *wp++ = CHAR;
                                *wp++ = c;
                        }
                        break;

                  case SHEREDQUOTE:     /* " in <<,<<- delimiter */
                        if (c == '"') {
                                *wp++ = CQUOTE;
                                state = statep->ls_state = SHEREDELIM;
                        } else {
                                if (c == '\\') {
                                        switch (c = getsc()) {
                                          case '\\': case '"':
                                          case '$': case '`':
                                                break;
                                          default:
                                                if (c) { /* trailing \ lost */
                                                        *wp++ = CHAR;
                                                        *wp++ = '\\';
                                                }
                                                break;
                                        }
                                }
                                *wp++ = CHAR;
                                *wp++ = c;
                        }
                        break;

                  case SPATTERN:        /* in *(...|...) pattern (*+?@!) */
                        if ( /*(*/ c == ')') {
                                *wp++ = CPAT;
                                POP_STATE();
                        } else if (c == '|') {
                                *wp++ = SPAT;
                        } else if (c == '(') {
                                *wp++ = OPAT;
                                *wp++ = ' ';    /* simile for @ */
                                PUSH_STATE(SPATTERN);
                        } else
                                goto Sbase1;
                        break;
                }
        }
Done:
        Xcheck(ws, wp);
        if (statep != &states[1])
                /* XXX figure out what is missing */
                yyerror("no closing quote\n");

        /* This done to avoid tests for SHEREDELIM wherever SBASE tested */
        if (state == SHEREDELIM)
                state = SBASE;

        dp = Xstring(ws, wp);
        if ((c == '<' || c == '>') && state == SBASE
            && ((c2 = Xlength(ws, wp)) == 0
                || (c2 == 2 && dp[0] == CHAR && digit(dp[1]))))
        {
                struct ioword *iop =
                                (struct ioword *) alloc(sizeof(*iop), ATEMP);

                if (c2 == 2)
                        iop->unit = dp[1] - '0';
                else
                        iop->unit = c == '>'; /* 0 for <, 1 for > */

                c2 = getsc();
                /* <<, >>, <> are ok, >< is not */
                if (c == c2 || (c == '<' && c2 == '>')) {
                        iop->flag = c == c2 ?
                                  (c == '>' ? IOCAT : IOHERE) : IORDWR;
                        if (iop->flag == IOHERE) {
                                if ((c2 = getsc()) == '-') {
                                        iop->flag |= IOSKIP;
                                } else {
                                        ungetsc(c2);
                                }
                        }
                } else if (c2 == '&')
                        iop->flag = IODUP | (c == '<' ? IORDUP : 0);
                else {
                        iop->flag = c == '>' ? IOWRITE : IOREAD;
                        if (c == '>' && c2 == '|')
                                iop->flag |= IOCLOB;
                        else
                                ungetsc(c2);
                }

                iop->name = (char *) 0;
                iop->delim = (char *) 0;
                iop->heredoc = (char *) 0;
                Xfree(ws, wp);  /* free word */
                yylval.iop = iop;
                return REDIR;
        }

        if (wp == dp && state == SBASE) {
                Xfree(ws, wp);  /* free word */
                /* no word, process LEX1 character */
                switch (c) {
                  default:
                        return c;

                  case '|':
                  case '&':
                  case ';':
                        if ((c2 = getsc()) == c)
                                c = (c == ';') ? BREAK :
                                    (c == '|') ? LOGOR :
                                    (c == '&') ? LOGAND :
                                    YYERRCODE;
#ifdef KSH
                        else if (c == '|' && c2 == '&')
                                c = COPROC;
#endif /* KSH */
                        else
                                ungetsc(c2);
                        return c;

                  case '\n':
                        gethere();
                        if (cf & CONTIN)
                                goto Again;
                        return c;

                  case '(':  /*)*/
#ifdef KSH
                        if ((c2 = getsc()) == '(') /*)*/
                                /* XXX need to handle ((...); (...)) */
                                c = MDPAREN;
                        else
                                ungetsc(c2);
#endif /* KSH */
                        return c;
                  /*(*/
                  case ')':
                        return c;
                }
        }

        *wp++ = EOS;            /* terminate word */
        yylval.cp = Xclose(ws, wp);
        if (state == SWORD
#ifdef KSH
                || state == SLETPAREN
#endif /* KSH */
                )       /* ONEWORD? */
                return LWORD;
        ungetsc(c);             /* unget terminator */

        /* copy word to unprefixed string ident */
        for (sp = yylval.cp, dp = ident; dp < ident+IDENT && (c = *sp++) == CHAR; )
                *dp++ = *sp++;
        /* Make sure the ident array stays '\0' padded */
        memset(dp, 0, (ident+IDENT) - dp + 1);
        if (c != EOS)
                *ident = '\0';  /* word is not unquoted */

        if (*ident != '\0' && (cf&(KEYWORD|ALIAS))) {
                struct tbl *p;
                int h = hash(ident);

                /* { */
                if ((cf & KEYWORD) && (p = mytsearch(&keywords, ident, h))
                    && (!(cf & ESACONLY) || p->val.i == ESAC || p->val.i == '}'))
                {
                        afree(yylval.cp, ATEMP);
                        return p->val.i;
                }
                if ((cf & ALIAS) && (p = mytsearch(&aliases, ident, h))
                    && (p->flag & ISSET))
                {
                        Source *s;

                        for (s = source; s->type == SALIAS; s = s->next)
                                if (s->u.tblp == p)
                                        return LWORD;
                        /* push alias expansion */
                        s = pushs(SALIAS, source->areap);
                        s->start = s->str = p->val.s;
                        s->u.tblp = p;
                        s->next = source;
                        source = s;
                        afree(yylval.cp, ATEMP);
                        goto Again;
                }
        }

        return LWORD;
}

static void
gethere()
{
        struct ioword **p;

        for (p = heres; p < herep; p++)
                readhere(*p);
        herep = heres;
}

/*
 * read "<<word" text into temp file
 */

static void
readhere(iop)
        struct ioword *iop;
{
        int c;
        char *volatile eof;
        char *eofp;
        int skiptabs;
        XString xs;
        char *xp;
        int xpos;

        eof = evalstr(iop->delim, 0);

        if (!(iop->flag & IOEVAL))
                ignore_backslash_newline++;

        Xinit(xs, xp, 256, ATEMP);

        for (;;) {
                eofp = eof;
                skiptabs = iop->flag & IOSKIP;
                xpos = Xsavepos(xs, xp);
                while ((c = getsc()) != 0) {
                        if (skiptabs) {
                                if (c == '\t')
                                        continue;
                                skiptabs = 0;
                        }
                        if (c != *eofp)
                                break;
                        Xcheck(xs, xp);
                        Xput(xs, xp, c);
                        eofp++;
                }
                /* Allow EOF here so commands with out trailing newlines
                 * will work (eg, ksh -c '...', $(...), etc).
                 */
                if (*eofp == '\0' && (c == 0 || c == '\n')) {
                        xp = Xrestpos(xs, xp, xpos);
                        break;
                }
                ungetsc(c);
                while ((c = getsc()) != '\n') {
                        if (c == 0)
                                yyerror("here document `%s' unclosed\n", eof);
                        Xcheck(xs, xp);
                        Xput(xs, xp, c);
                }
                Xcheck(xs, xp);
                Xput(xs, xp, c);
        }
        Xput(xs, xp, '\0');
        iop->heredoc = Xclose(xs, xp);

        if (!(iop->flag & IOEVAL))
                ignore_backslash_newline--;
}

void
yyerror(const char *fmt, ...)
{
        va_list va;

        /* pop aliases and re-reads */
        while (source->type == SALIAS || source->type == SREREAD)
                source = source->next;
        source->str = null;     /* zap pending input */

        error_prefix(true);
        va_start(va, fmt);
        shf_vfprintf(shl_out, fmt, va);
        va_end(va);
        errorf("%s", null);
}

/*
 * input for yylex with alias expansion
 */

Source *
pushs(type, areap)
        int type;
        Area *areap;
{
        Source *s;

        s = (Source *) alloc(sizeof(Source), areap);
        s->type = type;
        s->str = null;
        s->start = NULL;
        s->line = 0;
        s->errline = 0;
        s->file = NULL;
        s->flags = 0;
        s->next = NULL;
        s->areap = areap;
        if (type == SFILE || type == SSTDIN) {
                char *dummy;
                Xinit(s->xs, dummy, 256, s->areap);
        } else
                memset(&s->xs, 0, sizeof(s->xs));
        return s;
}

static int
getsc__()
{
        Source *s = source;
        int c;

        while ((c = *s->str++) == 0) {
                s->str = NULL;          /* return 0 for EOF by default */
                switch (s->type) {
                  case SEOF:
                        s->str = null;
                        return 0;

                  case SSTDIN:
                  case SFILE:
                        getsc_line(s);
                        break;

                  case SWSTR:
                        break;

                  case SSTRING:
                        break;

                  case SWORDS:
                        s->start = s->str = *s->u.strv++;
                        s->type = SWORDSEP;
                        break;

                  case SWORDSEP:
                        if (*s->u.strv == NULL) {
                                s->start = s->str = newline;
                                s->type = SEOF;
                        } else {
                                s->start = s->str = space;
                                s->type = SWORDS;
                        }
                        break;

                  case SALIAS:
                        if (s->flags & SF_ALIASEND) {
                                /* pass on an unused SF_ALIAS flag */
                                source = s->next;
                                source->flags |= s->flags & SF_ALIAS;
                                s = source;
                        } else if (*s->u.tblp->val.s
                                 && isspace((unsigned char)strchr(s->u.tblp->val.s, 0)[-1]))
                        {
                                source = s = s->next;   /* pop source stack */
                                /* Note that this alias ended with a space,
                                 * enabling alias expansion on the following
                                 * word.
                                 */
                                s->flags |= SF_ALIAS;
                        } else {
                                /* At this point, we need to keep the current
                                 * alias in the source list so recursive
                                 * aliases can be detected and we also need
                                 * to return the next character.  Do this
                                 * by temporarily popping the alias to get
                                 * the next character and then put it back
                                 * in the source list with the SF_ALIASEND
                                 * flag set.
                                 */
                                source = s->next;       /* pop source stack */
                                source->flags |= s->flags & SF_ALIAS;
                                c = getsc__();
                                if (c) {
                                        s->flags |= SF_ALIASEND;
                                        s->ugbuf[0] = c; s->ugbuf[1] = '\0';
                                        s->start = s->str = s->ugbuf;
                                        s->next = source;
                                        source = s;
                                } else {
                                        s = source;
                                        /* avoid reading eof twice */
                                        s->str = NULL;
                                        break;
                                }
                        }
                        continue;

                  case SREREAD:
                        if (s->start != s->ugbuf) /* yuck */
                                afree(s->u.freeme, ATEMP);
                        source = s = s->next;
                        continue;
                }
                if (s->str == NULL) {
                        s->type = SEOF;
                        s->start = s->str = null;
                        return '\0';
                }
                if (s->flags & SF_ECHO) {
                        shf_puts(s->str, shl_out);
                        shf_flush(shl_out);
                }
        }
        return c;
}

static void
getsc_line(s)
        Source *s;
{
        char *xp = Xstring(s->xs, xp);
        int interactive = Flag(FTALKING) && s->type == SSTDIN;
        int have_tty = interactive && (s->flags & SF_TTY);

        /* Done here to ensure nothing odd happens when a timeout occurs */
        XcheckN(s->xs, xp, LINE);
        *xp = '\0';
        s->start = s->str = xp;

#ifdef KSH
        if (have_tty && ksh_tmout) {
                ksh_tmout_state = TMOUT_READING;
                alarm(ksh_tmout);
        }
#endif /* KSH */
#ifdef EDIT
        if (have_tty && (0
# ifdef VI
                         || Flag(FVI)
# endif /* VI */
# ifdef EMACS
                         || Flag(FEMACS) || Flag(FGMACS)
# endif /* EMACS */
                ))
        {
                int nread;

                nread = x_read(xp, LINE);
                if (nread < 0)  /* read error */
                        nread = 0;
                xp[nread] = '\0';
                xp += nread;
        }
        else
#endif /* EDIT */
        {
                if (interactive) {
                        pprompt(prompt, 0);
                } else
                        s->line++;

                while (1) {
                        char *p = shf_getse(xp, Xnleft(s->xs, xp), s->u.shf);

                        if (!p && shf_error(s->u.shf)
                            && shf_errno(s->u.shf) == EINTR)
                        {
                                shf_clearerr(s->u.shf);
                                if (trap)
                                        runtraps(0);
                                continue;
                        }
                        if (!p || (xp = p, xp[-1] == '\n'))
                                break;
                        /* double buffer size */
                        xp++; /* move past null so doubling works... */
                        XcheckN(s->xs, xp, Xlength(s->xs, xp));
                        xp--; /* ...and move back again */
                }
                /* flush any unwanted input so other programs/builtins
                 * can read it.  Not very optimal, but less error prone
                 * than flushing else where, dealing with redirections,
                 * etc..
                 * todo: reduce size of shf buffer (~128?) if SSTDIN
                 */
                if (s->type == SSTDIN)
                        shf_flush(s->u.shf);
        }
        /* XXX: temporary kludge to restore source after a
         * trap may have been executed.
         */
        source = s;
#ifdef KSH
        if (have_tty && ksh_tmout)
        {
                ksh_tmout_state = TMOUT_EXECUTING;
                alarm(0);
        }
#endif /* KSH */
        s->start = s->str = Xstring(s->xs, xp);
        strip_nuls(Xstring(s->xs, xp), Xlength(s->xs, xp));
        /* Note: if input is all nulls, this is not eof */
        if (Xlength(s->xs, xp) == 0) { /* EOF */
                if (s->type == SFILE)
                        shf_fdclose(s->u.shf);
                s->str = NULL;
        } else if (interactive) {
#ifdef HISTORY
                char *p = Xstring(s->xs, xp);
                if (cur_prompt == PS1)
                        while (*p && ctype(*p, C_IFS) && ctype(*p, C_IFSWS))
                                p++;
                if (*p) {
# ifdef EASY_HISTORY
                        if (cur_prompt == PS2)
                                histappend(Xstring(s->xs, xp), 1);
                        else
# endif /* EASY_HISTORY */
                        {
                                s->line++;
                                histsave(s->line, s->str, 1);
                        }
                }
#endif /* HISTORY */
        }
        if (interactive)
                set_prompt(PS2, (Source *) 0);
}

void
set_prompt(to, s)
        int to;
        Source *s;
{
        cur_prompt = to;

        switch (to) {
        case PS1: /* command */
#ifdef KSH
                /* Substitute ! and !! here, before substitutions are done
                 * so ! in expanded variables are not expanded.
                 * NOTE: this is not what at&t ksh does (it does it after
                 * substitutions, POSIX doesn't say which is to be done.
                 */
                {
                        struct shf *shf;
                        char * volatile ps1;
                        Area *saved_atemp;

                        ps1 = str_val(global("PS1"));
                        shf = shf_sopen((char *) 0, strlen(ps1) * 2,
                                SHF_WR | SHF_DYNAMIC, (struct shf *) 0);
                        while (*ps1) {
                                if (*ps1 != '!' || *++ps1 == '!')
                                        shf_putchar(*ps1++, shf);
                                else
                                        shf_fprintf(shf, "%d",
                                                s ? s->line + 1 : 0);
                        }
                        ps1 = shf_sclose(shf);
                        saved_atemp = ATEMP;
                        newenv(E_ERRH);
                        if (ksh_sigsetjmp(e->jbuf, 0)) {
                                prompt = safe_prompt;
                                /* Don't print an error - assume it has already
                                 * been printed.  Reason is we may have forked
                                 * to run a command and the child may be
                                 * unwinding its stack through this code as it
                                 * exits.
                                 */
                        } else
                                prompt = str_save(substitute(ps1, 0),
                                                 saved_atemp);
                        quitenv();
                }
#else /* KSH */
                prompt = str_val(global("PS1"));
#endif /* KSH */
                break;

        case PS2: /* command continuation */
                prompt = str_val(global("PS2"));
                break;
        }
}

/* See also related routine, promptlen() in edit.c */
void
pprompt(cp, ntruncate)
        const char *cp;
        int ntruncate;
{
#if 0
        char nbuf[32];
        int c;

        while (*cp != 0) {
                if (*cp != '!')
                        c = *cp++;
                else if (*++cp == '!')
                        c = *cp++;
                else {
                        int len;
                        char *p;

                        shf_snprintf(p = nbuf, sizeof(nbuf), "%d",
                                source->line + 1);
                        len = strlen(nbuf);
                        if (ntruncate) {
                                if (ntruncate >= len) {
                                        ntruncate -= len;
                                        continue;
                                }
                                p += ntruncate;
                                len -= ntruncate;
                                ntruncate = 0;
                        }
                        shf_write(p, len, shl_out);
                        continue;
                }
                if (ntruncate)
                        --ntruncate;
                else
                        shf_putc(c, shl_out);
        }
#endif /* 0 */
        shf_puts(cp + ntruncate, shl_out);
        shf_flush(shl_out);
}

/* Read the variable part of a ${...} expression (ie, up to but not including
 * the :[-+?=#%] or close-brace.
 */
static char *
get_brace_var(wsp, wp)
        XString *wsp;
        char *wp;
{
        enum parse_state {
                           PS_INITIAL, PS_SAW_HASH, PS_IDENT,
                           PS_NUMBER, PS_VAR1, PS_END
                         }
                state;
        char c;

        state = PS_INITIAL;
        while (1) {
                c = getsc();
                /* State machine to figure out where the variable part ends. */
                switch (state) {
                  case PS_INITIAL:
                        if (c == '#') {
                                state = PS_SAW_HASH;
                                break;
                        }
                        /* fall through.. */
                  case PS_SAW_HASH:
                        if (letter(c))
                                state = PS_IDENT;
                        else if (digit(c))
                                state = PS_NUMBER;
                        else if (ctype(c, C_VAR1))
                                state = PS_VAR1;
                        else
                                state = PS_END;
                        break;
                  case PS_IDENT:
                        if (!letnum(c)) {
                                state = PS_END;
                                if (c == '[') {
                                        char *tmp, *p;

                                        if (!arraysub(&tmp))
                                                yyerror("missing ]\n");
                                        *wp++ = c;
                                        for (p = tmp; *p; ) {
                                                Xcheck(*wsp, wp);
                                                *wp++ = *p++;
                                        }
                                        afree(tmp, ATEMP);
                                        c = getsc(); /* the ] */
                                }
                        }
                        break;
                  case PS_NUMBER:
                        if (!digit(c))
                                state = PS_END;
                        break;
                  case PS_VAR1:
                        state = PS_END;
                        break;
                  case PS_END: /* keep gcc happy */
                        break;
                }
                if (state == PS_END) {
                        *wp++ = '\0';   /* end of variable part */
                        ungetsc(c);
                        break;
                }
                Xcheck(*wsp, wp);
                *wp++ = c;
        }
        return wp;
}

/*
 * Save an array subscript - returns true if matching bracket found, false
 * if eof or newline was found.
 * (Returned string double null terminated)
 */
static int
arraysub(strp)
        char **strp;
{
        XString ws;
        char    *wp;
        char    c;
        int     depth = 1;      /* we are just past the initial [ */

        Xinit(ws, wp, 32, ATEMP);

        do {
                c = getsc();
                Xcheck(ws, wp);
                *wp++ = c;
                if (c == '[')
                        depth++;
                else if (c == ']')
                        depth--;
        } while (depth > 0 && c && c != '\n');

        *wp++ = '\0';
        *strp = Xclose(ws, wp);

        return depth == 0 ? 1 : 0;
}

/* Unget a char: handles case when we are already at the start of the buffer */
static const char *
ungetsc(c)
        int c;
{
        if (backslash_skip)
                backslash_skip--;
        /* Don't unget eof... */
        if (source->str == null && c == '\0')
                return source->str;
        if (source->str > source->start)
                source->str--;
        else {
                Source *s;

                s = pushs(SREREAD, source->areap);
                s->ugbuf[0] = c; s->ugbuf[1] = '\0';
                s->start = s->str = s->ugbuf;
                s->next = source;
                source = s;
        }
        return source->str;
}


/* Called to get a char that isn't a \newline sequence. */
static int
getsc_bn ARGS((void))
{
        int c, c2;

        if (ignore_backslash_newline)
                return getsc_();

        if (backslash_skip == 1) {
                backslash_skip = 2;
                return getsc_();
        }

        backslash_skip = 0;

        while (1) {
                c = getsc_();
                if (c == '\\') {
                        if ((c2 = getsc_()) == '\n')
                                /* ignore the \newline; get the next char... */
                                continue;
                        ungetsc(c2);
                        backslash_skip = 1;
                }
                return c;
        }
}

static Lex_state *
push_state_(si, old_end)
        State_info *si;
        Lex_state *old_end;
{
        Lex_state       *new = alloc(sizeof(Lex_state) * STATE_BSIZE, ATEMP);

        new[0].ls_info.base = old_end;
        si->base = &new[0];
        si->end = &new[STATE_BSIZE];
        return &new[1];
}

static Lex_state *
pop_state_(si, old_end)
        State_info *si;
        Lex_state *old_end;
{
        Lex_state *old_base = si->base;

        si->base = old_end->ls_info.base - STATE_BSIZE;
        si->end = old_end->ls_info.base;

        afree(old_base, ATEMP);

        return si->base + STATE_BSIZE - 1;
}