cmd/sed/compile.c

	compile.c revision 84441f85b19f6b8080883f30109e58e43c893709
/*
 * Copyright 2010 Nexenta Systems, Inc.  All rights reserved.
 * Copyright (c) 1992 Diomidis Spinellis.
 * Copyright (c) 1992, 1993
 *  The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Diomidis Spinellis of Imperial College, University of London.
 *
 * 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.
 * 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.
 */

#include <sys/types.h>
#include <sys/stat.h>

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <regex.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <wchar.h>
#include <libintl.h>
#include <note.h>

#include "defs.h"
#include "extern.h"

#define LHSZ    128
#define LHMASK  (LHSZ - 1)
static struct labhash {
    struct  labhash *lh_next;
    uint_t  lh_hash;
    struct  s_command *lh_cmd;
    int lh_ref;
} *labels[LHSZ];

static char  *compile_addr(char *, struct s_addr *);
static char  *compile_ccl(char **, char *);
static char  *compile_delimited(char *, char *, int);
static char  *compile_flags(char *, struct s_subst *);
static regex_t   *compile_re(char *, int);
static char  *compile_subst(char *, struct s_subst *);
static char  *compile_text(void);
static char  *compile_tr(char *, struct s_tr **);
static struct s_command
        **compile_stream(struct s_command **);
static char  *duptoeol(char *, const char *);
static void   enterlabel(struct s_command *);
static struct s_command
         *findlabel(char *);
static void   fixuplabel(struct s_command *, struct s_command *);
static void   uselabel(void);

/*
 * Command specification.  This is used to drive the command parser.
 */
struct s_format {
    char code;              /* Command code */
    int naddr;              /* Number of address args */
    enum e_args args;           /* Argument type */
};

static struct s_format cmd_fmts[] = {
    {'{', 2, GROUP},
    {'}', 0, ENDGROUP},
    {'a', 1, TEXT},
    {'b', 2, BRANCH},
    {'c', 2, TEXT},
    {'d', 2, EMPTY},
    {'D', 2, EMPTY},
    {'g', 2, EMPTY},
    {'G', 2, EMPTY},
    {'h', 2, EMPTY},
    {'H', 2, EMPTY},
    {'i', 1, TEXT},
    {'l', 2, EMPTY},
    {'n', 2, EMPTY},
    {'N', 2, EMPTY},
    {'p', 2, EMPTY},
    {'P', 2, EMPTY},
    {'q', 1, EMPTY},
    {'r', 1, RFILE},
    {'s', 2, SUBST},
    {'t', 2, BRANCH},
    {'w', 2, WFILE},
    {'x', 2, EMPTY},
    {'y', 2, TR},
    {'!', 2, NONSEL},
    {':', 0, LABEL},
    {'#', 0, COMMENT},
    {'=', 1, EMPTY},
    {'\0', 0, COMMENT},
};

/* The compiled program. */
struct s_command *prog;

/*
 * Compile the program into prog.
 * Initialise appends.
 */
void
compile(void)
{
    *compile_stream(&prog) = NULL;
    fixuplabel(prog, NULL);
    uselabel();
    if (appendnum == 0)
        appends = NULL;
    else if ((appends = malloc(sizeof (struct s_appends) * appendnum)) ==
        NULL)
        err(1, "malloc");
    if ((match = malloc((maxnsub + 1) * sizeof (regmatch_t))) == NULL)
        err(1, "malloc");
}

#define EATSPACE() do {                         \
    if (p)                              \
        while (*p && isspace((unsigned char)*p))                \
            p++;                        \
    _NOTE(CONSTCOND)                        \
} while (0)

static struct s_command **
compile_stream(struct s_command **link)
{
    char *p;
    static char lbuf[_POSIX2_LINE_MAX + 1]; /* To save stack */
    struct s_command *cmd, *cmd2, *stack;
    struct s_format *fp;
    char re[_POSIX2_LINE_MAX + 1];
    int naddr;              /* Number of addresses */

    stack = 0;
    for (;;) {
        if ((p = cu_fgets(lbuf, sizeof (lbuf), NULL)) == NULL) {
            if (stack != 0)
                fatal(_("unexpected EOF (pending }'s)"));
            return (link);
        }

semicolon:  EATSPACE();
        if (p) {
            if (*p == '#' || *p == '\0')
                continue;
            else if (*p == ';') {
                p++;
                goto semicolon;
            }
        }
        if ((*link = cmd = malloc(sizeof (struct s_command))) == NULL)
            err(1, "malloc");
        link = &cmd->next;
        cmd->startline = cmd->nonsel = 0;
        /* First parse the addresses */
        naddr = 0;

/* Valid characters to start an address */
#define addrchar(c) (strchr("0123456789/\\$", (c)))
        if (addrchar(*p)) {
            naddr++;
            if ((cmd->a1 = malloc(sizeof (struct s_addr))) == NULL)
                err(1, "malloc");
            p = compile_addr(p, cmd->a1);
            EATSPACE();             /* EXTENSION */
            if (*p == ',') {
                p++;
                EATSPACE();         /* EXTENSION */
                naddr++;
                if ((cmd->a2 = malloc(sizeof (struct s_addr)))
                    == NULL)
                    err(1, "malloc");
                p = compile_addr(p, cmd->a2);
                EATSPACE();
            } else
                cmd->a2 = 0;
        } else
            cmd->a1 = cmd->a2 = 0;

nonsel:     /* Now parse the command */
        if (!*p)
            fatal(_("command expected"));
        cmd->code = *p;
        for (fp = cmd_fmts; fp->code; fp++)
            if (fp->code == *p)
                break;
        if (!fp->code)
            fatal(_("invalid command code %c"), *p);
        if (naddr > fp->naddr)
            fatal(_("command %c expects up to %d address(es), "
                "found %d"), *p, fp->naddr, naddr);
        switch (fp->args) {
        case NONSEL:            /* ! */
            p++;
            EATSPACE();
            cmd->nonsel = 1;
            goto nonsel;
        case GROUP:         /* { */
            p++;
            EATSPACE();
            cmd->next = stack;
            stack = cmd;
            link = &cmd->u.c;
            if (*p)
                goto semicolon;
            break;
        case ENDGROUP:
            /*
             * Short-circuit command processing, since end of
             * group is really just a noop.
             */
            cmd->nonsel = 1;
            if (stack == 0)
                fatal(_("unexpected }"));
            cmd2 = stack;
            stack = cmd2->next;
            cmd2->next = cmd;
            /*FALLTHROUGH*/
        case EMPTY:     /* d D g G h H l n N p P q x = \0 */
            p++;
            EATSPACE();
            if (*p == ';') {
                p++;
                link = &cmd->next;
                goto semicolon;
            }
            if (*p)
                fatal(_("extra characters at the end of %c "
                    "command"), cmd->code);
            break;
        case TEXT:          /* a c i */
            p++;
            EATSPACE();
            if (*p != '\\')
                fatal(_("command %c expects \\ "
                    "followed by text"), cmd->code);
            p++;
            EATSPACE();
            if (*p)
                fatal(_("extra characters after \\ "
                    "at the end of %c command"),
                    cmd->code);
            cmd->t = compile_text();
            break;
        case COMMENT:           /* \0 # */
            break;
        case WFILE:         /* w */
            p++;
            EATSPACE();
            if (*p == '\0')
                fatal(_("filename expected"));
            cmd->t = duptoeol(p, "w command");
            if (aflag)
                cmd->u.fd = -1;
            else if ((cmd->u.fd = open(p,
                O_WRONLY|O_APPEND|O_CREAT|O_TRUNC, 0666)) == -1)
                err(1, "%s", p);
            break;
        case RFILE:         /* r */
            p++;
            EATSPACE();
            if (*p == '\0')
                fatal(_("filename expected"));
            else
                cmd->t = duptoeol(p, "read command");
            break;
        case BRANCH:            /* b t */
            p++;
            EATSPACE();
            if (*p == '\0')
                cmd->t = NULL;
            else
                cmd->t = duptoeol(p, "branch");
            break;
        case LABEL:         /* : */
            p++;
            EATSPACE();
            cmd->t = duptoeol(p, "label");
            if (strlen(p) == 0)
                fatal(_("empty label"));
            enterlabel(cmd);
            break;
        case SUBST:         /* s */
            p++;
            if (*p == '\0' || *p == '\\')
                fatal(_("substitute pattern can not "
                    "be delimited by newline or backslash"));
            if ((cmd->u.s = calloc(1, sizeof (struct s_subst))) ==
                NULL)
                err(1, "malloc");
            p = compile_delimited(p, re, 0);
            if (p == NULL)
                fatal(_("unterminated substitute pattern"));

            /* Compile RE with no case sensitivity temporarily */
            if (*re == '\0')
                cmd->u.s->re = NULL;
            else
                cmd->u.s->re = compile_re(re, 0);
            --p;
            p = compile_subst(p, cmd->u.s);
            p = compile_flags(p, cmd->u.s);

            /* Recompile RE with case sens. from "I" flag if any */
            if (*re == '\0')
                cmd->u.s->re = NULL;
            else
                cmd->u.s->re = compile_re(re, cmd->u.s->icase);
            EATSPACE();
            if (*p == ';') {
                p++;
                link = &cmd->next;
                goto semicolon;
            }
            break;
        case TR:            /* y */
            p++;
            p = compile_tr(p, &cmd->u.y);
            EATSPACE();
            if (*p == ';') {
                p++;
                link = &cmd->next;
                goto semicolon;
            }
            if (*p)
                fatal(_("extra text at the end of a "
                    "transform command"));
            break;
        }
    }
}

/*
 * Get a delimited string.  P points to the delimeter of the string; d points
 * to a buffer area.  Newline and delimiter escapes are processed; other
 * escapes are ignored.
 *
 * Returns a pointer to the first character after the final delimiter or NULL
 * in the case of a non-terminated string.  The character array d is filled
 * with the processed string.
 */
static char *
compile_delimited(char *p, char *d, int is_tr)
{
    char c;

    c = *p++;
    if (c == '\0')
        return (NULL);
    else if (c == '\\')
        fatal(_("\\ can not be used as a string delimiter"));
    else if (c == '\n')
        fatal(_("newline can not be used as a string delimiter"));
    while (*p) {
        if (*p == '[' && *p != c) {
            if ((d = compile_ccl(&p, d)) == NULL)
                fatal(_("unbalanced brackets ([])"));
            continue;
        } else if (*p == '\\' && p[1] == '[') {
            *d++ = *p++;
        } else if (*p == '\\' && p[1] == c)
            p++;
        else if (*p == '\\' && p[1] == 'n') {
            *d++ = '\n';
            p += 2;
            continue;
        } else if (*p == '\\' && p[1] == '\\') {
            if (is_tr)
                p++;
            else
                *d++ = *p++;
        } else if (*p == c) {
            *d = '\0';
            return (p + 1);
        }
        *d++ = *p++;
    }
    return (NULL);
}


/* compile_ccl: expand a POSIX character class */
static char *
compile_ccl(char **sp, char *t)
{
    int c, d;
    char *s = *sp;

    *t++ = *s++;
    if (*s == '^')
        *t++ = *s++;
    if (*s == ']')
        *t++ = *s++;
    for (; *s && (*t = *s) != ']'; s++, t++)
        if (*s == '[' &&
            ((d = *(s+1)) == '.' || d == ':' || d == '=')) {
            *++t = *++s, t++, s++;
            for (c = *s; (*t = *s) != ']' || c != d; s++, t++)
                if ((c = *s) == '\0')
                    return (NULL);
        }
    return ((*s == ']') ? *sp = ++s, ++t : NULL);
}

/*
 * Compiles the regular expression in RE and returns a pointer to the compiled
 * regular expression.
 * Cflags are passed to regcomp.
 */
static regex_t *
compile_re(char *re, int case_insensitive)
{
    regex_t *rep;
    int eval, flags;


    flags = rflags;
    if (case_insensitive)
        flags |= REG_ICASE;
    if ((rep = malloc(sizeof (regex_t))) == NULL)
        err(1, "malloc");
    if ((eval = regcomp(rep, re, flags)) != 0)
        fatal(_("RE error: %s"), strregerror(eval, rep));
    if (maxnsub < rep->re_nsub)
        maxnsub = rep->re_nsub;
    return (rep);
}

/*
 * Compile the substitution string of a regular expression and set res to
 * point to a saved copy of it.  Nsub is the number of parenthesized regular
 * expressions.
 */
static char *
compile_subst(char *p, struct s_subst *s)
{
    static char lbuf[_POSIX2_LINE_MAX + 1];
    int asize;
    uintptr_t size;
    uchar_t ref;
    char c, *text, *op, *sp;
    int more = 1, sawesc = 0;

    c = *p++;           /* Terminator character */
    if (c == '\0')
        return (NULL);

    s->maxbref = 0;
    s->linenum = linenum;
    asize = 2 * _POSIX2_LINE_MAX + 1;
    if ((text = malloc(asize)) == NULL)
        err(1, "malloc");
    size = 0;
    do {
        op = sp = text + size;
        for (; *p; p++) {
            if (*p == '\\' || sawesc) {
                /*
                 * If this is a continuation from the last
                 * buffer, we won't have a character to
                 * skip over.
                 */
                if (sawesc)
                    sawesc = 0;
                else
                    p++;

                if (*p == '\0') {
                    /*
                     * This escaped character is continued
                     * in the next part of the line.  Note
                     * this fact, then cause the loop to
                     * exit w/ normal EOL case and reenter
                     * above with the new buffer.
                     */
                    sawesc = 1;
                    p--;
                    continue;
                } else if (strchr("123456789", *p) != NULL) {
                    *sp++ = '\\';
                    ref = *p - '0';
                    if (s->re != NULL &&
                        ref > s->re->re_nsub)
                        fatal(_("not defined in "
                            "the RE: \\%c"), *p);
                    if (s->maxbref < ref)
                        s->maxbref = ref;
                } else if (*p == '&' || *p == '\\')
                    *sp++ = '\\';
            } else if (*p == c) {
                if (*++p == '\0' && more) {
                    if (cu_fgets(lbuf, sizeof (lbuf),
                        &more))
                        p = lbuf;
                }
                *sp++ = '\0';
                size += (uintptr_t)sp - (uintptr_t)op;
                if ((s->new = realloc(text, size)) == NULL)
                    err(1, "realloc");
                return (p);
            } else if (*p == '\n') {
                fatal(_("unescaped newline inside "
                    "substitute pattern"));
                /* NOTREACHED */
            }
            *sp++ = *p;
        }
        size += (uintptr_t)sp - (uintptr_t)op;
        if (asize - size < _POSIX2_LINE_MAX + 1) {
            asize *= 2;
            if ((text = realloc(text, asize)) == NULL)
                err(1, "realloc");
        }
    } while (cu_fgets(p = lbuf, sizeof (lbuf), &more));
    fatal(_("unterminated substitute in regular expression"));
    return (NULL);
}

/*
 * Compile the flags of the s command
 */
static char *
compile_flags(char *p, struct s_subst *s)
{
    int gn;         /* True if we have seen g or n */
    unsigned long nval;
    char wfile[_POSIX2_LINE_MAX + 1], *q;

    s->n = 1;               /* Default */
    s->p = 0;
    s->wfile = NULL;
    s->wfd = -1;
    s->icase = 0;
    gn = 0;
    for (;;) {
        EATSPACE();         /* EXTENSION */
        switch (*p) {
        case 'g':
            if (gn)
                fatal(_("more than one number or "
                    "'g' in substitute flags"));
            gn = 1;
            s->n = 0;
            break;
        case '\0':
        case '\n':
        case ';':
            return (p);
        case 'p':
            s->p = 1;
            break;
        case 'I':
            s->icase = 1;
            break;
        case '1': case '2': case '3':
        case '4': case '5': case '6':
        case '7': case '8': case '9':
            if (gn)
                fatal(_("more than one number or "
                    "'g' in substitute flags"));
            gn = 1;
            errno = 0;
            nval = strtol(p, &p, 10);
            if (errno == ERANGE || nval > INT_MAX)
                fatal(_("overflow in the 'N' substitute flag"));
            s->n = nval;
            p--;
            break;
        case 'w':
            p++;
#ifdef HISTORIC_PRACTICE
            if (*p != ' ') {
                fatal(_("space missing before w wfile"));
                return (p);
            }
#endif
            EATSPACE();
            q = wfile;
            while (*p) {
                if (*p == '\n')
                    break;
                *q++ = *p++;
            }
            *q = '\0';
            if (q == wfile)
                fatal(_("no wfile specified"));
            s->wfile = strdup(wfile);
            if (!aflag && (s->wfd = open(wfile,
                O_WRONLY|O_APPEND|O_CREAT|O_TRUNC, 0666)) == -1)
                err(1, "%s", wfile);
            return (p);
        default:
            fatal(_("bad flag in substitute command: '%c'"), *p);
            break;
        }
        p++;
    }
}

/*
 * Compile a translation set of strings into a lookup table.
 */
static char *
compile_tr(char *p, struct s_tr **py)
{
    struct s_tr *y;
    int i;
    const char *op, *np;
    char old[_POSIX2_LINE_MAX + 1];
    char new[_POSIX2_LINE_MAX + 1];
    size_t oclen, oldlen, nclen, newlen;
    mbstate_t mbs1, mbs2;

    if ((*py = y = malloc(sizeof (*y))) == NULL)
        err(1, NULL);
    y->multis = NULL;
    y->nmultis = 0;

    if (*p == '\0' || *p == '\\')
        fatal(_("transform pattern can not be delimited by "
            "newline or backslash"));
    p = compile_delimited(p, old, 1);
    if (p == NULL)
        fatal(_("unterminated transform source string"));
    p = compile_delimited(p - 1, new, 1);
    if (p == NULL)
        fatal(_("unterminated transform target string"));
    EATSPACE();
    op = old;
    oldlen = mbsrtowcs(NULL, &op, 0, NULL);
    if (oldlen == (size_t)-1)
        err(1, NULL);
    np = new;
    newlen = mbsrtowcs(NULL, &np, 0, NULL);
    if (newlen == (size_t)-1)
        err(1, NULL);
    if (newlen != oldlen)
        fatal(_("transform strings are not the same length"));
    if (MB_CUR_MAX == 1) {
        /*
         * The single-byte encoding case is easy: generate a
         * lookup table.
         */
        for (i = 0; i <= UCHAR_MAX; i++)
            y->bytetab[i] = (char)i;
        for (; *op; op++, np++)
            y->bytetab[(uchar_t)*op] = *np;
    } else {
        /*
         * Multi-byte encoding case: generate a lookup table as
         * above, but only for single-byte characters. The first
         * bytes of multi-byte characters have their lookup table
         * entries set to 0, which causes do_tr() to search through
         * an auxiliary vector of multi-byte mappings.
         */
        (void) memset(&mbs1, 0, sizeof (mbs1));
        (void) memset(&mbs2, 0, sizeof (mbs2));
        for (i = 0; i <= UCHAR_MAX; i++)
            y->bytetab[i] = (btowc(i) != WEOF) ? (uchar_t)i : 0;
        while (*op != '\0') {
            oclen = mbrlen(op, MB_LEN_MAX, &mbs1);
            if (oclen == (size_t)-1 || oclen == (size_t)-2)
                errx(1, "%s", strerror(EILSEQ));
            nclen = mbrlen(np, MB_LEN_MAX, &mbs2);
            if (nclen == (size_t)-1 || nclen == (size_t)-2)
                errx(1, "%s", strerror(EILSEQ));
            if (oclen == 1 && nclen == 1)
                y->bytetab[(uchar_t)*op] = *np;
            else {
                y->bytetab[(uchar_t)*op] = 0;
                y->multis = realloc(y->multis,
                    (y->nmultis + 1) * sizeof (*y->multis));
                if (y->multis == NULL)
                    err(1, NULL);
                i = y->nmultis++;
                y->multis[i].fromlen = oclen;
                (void) memcpy(y->multis[i].from, op, oclen);
                y->multis[i].tolen = nclen;
                (void) memcpy(y->multis[i].to, np, nclen);
            }
            op += oclen;
            np += nclen;
        }
    }
    return (p);
}

/*
 * Compile the text following an a or i command.
 */
static char *
compile_text(void)
{
    int esc_nl;
    uintptr_t size, asize;
    char *text, *p, *op, *s;
    char lbuf[_POSIX2_LINE_MAX + 1];

    asize = 2 * _POSIX2_LINE_MAX + 1;
    if ((text = malloc(asize)) == NULL)
        err(1, "malloc");
    size = 0;
    while (cu_fgets(lbuf, sizeof (lbuf), NULL)) {
        op = s = text + size;
        p = lbuf;
        EATSPACE();
        for (esc_nl = 0; *p != '\0'; p++) {
            if (*p == '\\' && p[1] != '\0' && *++p == '\n')
                esc_nl = 1;
            *s++ = *p;
        }
        size += (uintptr_t)s - (uintptr_t)op;
        if (!esc_nl) {
            *s = '\0';
            break;
        }
        if (asize - size < _POSIX2_LINE_MAX + 1) {
            asize *= 2;
            if ((text = realloc(text, asize)) == NULL)
                err(1, "realloc");
        }
    }
    text[size] = '\0';
    if ((p = realloc(text, size + 1)) == NULL)
        err(1, "realloc");
    return (p);
}

/*
 * Get an address and return a pointer to the first character after
 * it.  Fill the structure pointed to according to the address.
 */
static char *
compile_addr(char *p, struct s_addr *a)
{
    char *end, re[_POSIX2_LINE_MAX + 1];
    int icase;

    icase = 0;

    a->type = 0;
    switch (*p) {
    case '\\':              /* Context address */
        ++p;
        /* FALLTHROUGH */
    case '/':               /* Context address */
        p = compile_delimited(p, re, 0);
        if (p == NULL)
            fatal(_("unterminated regular expression"));

        /* Check for case insensitive regexp flag */
        if (*p == 'I') {
            icase = 1;
            p++;
        }
        if (*re == '\0')
            a->u.r = NULL;
        else
            a->u.r = compile_re(re, icase);
        a->type = AT_RE;
        return (p);

    case '$':               /* Last line */
        a->type = AT_LAST;
        return (p + 1);

    case '+':               /* Relative line number */
        a->type = AT_RELLINE;
        p++;
        /* FALLTHROUGH */
                        /* Line number */
    case '0': case '1': case '2': case '3': case '4':
    case '5': case '6': case '7': case '8': case '9':
        if (a->type == 0)
            a->type = AT_LINE;
        a->u.l = strtol(p, &end, 10);
        return (end);
    default:
        fatal(_("expected context address"));
        return (NULL);
    }
}

/*
 * duptoeol --
 *  Return a copy of all the characters up to \n or \0.
 */
static char *
duptoeol(char *s, const char *ctype)
{
    size_t len;
    int ws;
    char *p, *start;

    ws = 0;
    for (start = s; *s != '\0' && *s != '\n'; ++s)
        ws = isspace((unsigned char)*s);
    *s = '\0';
    if (ws)
        warnx(_("%lu: %s: whitespace after %s"), linenum, fname, ctype);
    len = (uintptr_t)s - (uintptr_t)start + 1;
    if ((p = malloc(len)) == NULL)
        err(1, "malloc");
    return (memmove(p, start, len));
}

/*
 * Convert goto label names to addresses, and count a and r commands, in
 * the given subset of the script.  Free the memory used by labels in b
 * and t commands (but not by :).
 *
 * TODO: Remove } nodes
 */
static void
fixuplabel(struct s_command *cp, struct s_command *end)
{

    for (; cp != end; cp = cp->next)
        switch (cp->code) {
        case 'a':
        case 'r':
            appendnum++;
            break;
        case 'b':
        case 't':
            /* Resolve branch target. */
            if (cp->t == NULL) {
                cp->u.c = NULL;
                break;
            }
            if ((cp->u.c = findlabel(cp->t)) == NULL)
                fatal(_("undefined label '%s'"), cp->t);
            free(cp->t);
            break;
        case '{':
            /* Do interior commands. */
            fixuplabel(cp->u.c, cp->next);
            break;
        }
}

/*
 * Associate the given command label for later lookup.
 */
static void
enterlabel(struct s_command *cp)
{
    struct labhash **lhp, *lh;
    uchar_t *p;
    uint_t h, c;

    for (h = 0, p = (uchar_t *)cp->t; (c = *p) != 0; p++)
        h = (h << 5) + h + c;
    lhp = &labels[h & LHMASK];
    for (lh = *lhp; lh != NULL; lh = lh->lh_next)
        if (lh->lh_hash == h && strcmp(cp->t, lh->lh_cmd->t) == 0)
            fatal(_("duplicate label '%s'"), cp->t);
    if ((lh = malloc(sizeof (*lh))) == NULL)
        err(1, "malloc");
    lh->lh_next = *lhp;
    lh->lh_hash = h;
    lh->lh_cmd = cp;
    lh->lh_ref = 0;
    *lhp = lh;
}

/*
 * Find the label contained in the command l in the command linked
 * list cp.  L is excluded from the search.  Return NULL if not found.
 */
static struct s_command *
findlabel(char *name)
{
    struct labhash *lh;
    uchar_t *p;
    uint_t h, c;

    for (h = 0, p = (uchar_t *)name; (c = *p) != 0; p++)
        h = (h << 5) + h + c;
    for (lh = labels[h & LHMASK]; lh != NULL; lh = lh->lh_next) {
        if (lh->lh_hash == h && strcmp(name, lh->lh_cmd->t) == 0) {
            lh->lh_ref = 1;
            return (lh->lh_cmd);
        }
    }
    return (NULL);
}

/*
 * Warn about any unused labels.  As a side effect, release the label hash
 * table space.
 */
static void
uselabel(void)
{
    struct labhash *lh, *next;
    int i;

    for (i = 0; i < LHSZ; i++) {
        for (lh = labels[i]; lh != NULL; lh = next) {
            next = lh->lh_next;
            if (!lh->lh_ref)
                warnx(_("%lu: %s: unused label '%s'"),
                    linenum, fname, lh->lh_cmd->t);
            free(lh);
        }
    }
}