/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1992 Diomidis Spinellis.
 * Copyright (c) 1992, 1993, 1994
 *      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.
 * 3. 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/cdefs.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/uio.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 <unistd.h>
#include <wchar.h>
#include <wctype.h>

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

static SPACE HS, PS, SS, YS;
#define pd              PS.deleted
#define ps              PS.space
#define psl             PS.len
#define psanl           PS.append_newline
#define hs              HS.space
#define hsl             HS.len

static inline int        applies(struct s_command *);
static void              do_tr(struct s_tr *);
static void              flush_appends(void);
static void              lputs(char *, size_t);
static int               regexec_e(regex_t *, const char *, int, int, size_t,
                             size_t);
static void              regsub(SPACE *, char *, char *);
static int               substitute(struct s_command *);

struct s_appends *appends;      /* Array of pointers to strings to append. */
static unsigned int appendx;    /* Index into appends array. */
unsigned int appendnum;         /* Size of appends array. */

static int lastaddr;            /* Set by applies if last address of a range. */
static int sdone;               /* If any substitutes since last line input. */
                                /* Iov structure for 'w' commands. */
static regex_t *defpreg;
size_t maxnsub;
regmatch_t *match;

#define OUT() do {                                                      \
        fwrite(ps, 1, psl, outfile);                                    \
        if (psanl) fputc('\n', outfile);                                \
} while (0)

void
process(void)
{
        struct s_command *cp;
        SPACE tspace;
        size_t oldpsl;
        char *p;
        int oldpsanl;

        p = NULL;
        oldpsanl = oldpsl = 0;

        for (linenum = 0; mf_fgets(&PS, REPLACE);) {
                pd = 0;
top:
                cp = prog;
redirect:
                while (cp != NULL) {
                        if (!applies(cp)) {
                                cp = cp->next;
                                continue;
                        }
                        switch (cp->code) {
                        case '{':
                                cp = cp->u.c;
                                goto redirect;
                        case 'a':
                                if (appendx >= appendnum)
                                        if ((appends = realloc(appends,
                                            sizeof(struct s_appends) *
                                            (appendnum *= 2))) == NULL)
                                                err(1, "realloc");
                                appends[appendx].type = AP_STRING;
                                appends[appendx].s = cp->t;
                                appends[appendx].len = strlen(cp->t);
                                appendx++;
                                break;
                        case 'b':
                                cp = cp->u.c;
                                goto redirect;
                        case 'c':
                                pd = 1;
                                psl = 0;
                                if (cp->a2 == NULL || lastaddr || lastline())
                                        (void)fprintf(outfile, "%s", cp->t);
                                goto new;
                        case 'd':
                                pd = 1;
                                goto new;
                        case 'D':
                                if (pd)
                                        goto new;
                                if (psl == 0 ||
                                    (p = memchr(ps, '\n', psl)) == NULL) {
                                        pd = 1;
                                        goto new;
                                } else {
                                        psl -= (p + 1) - ps;
                                        memmove(ps, p + 1, psl);
                                        goto top;
                                }
                        case 'g':
                                cspace(&PS, hs, hsl, REPLACE);
                                break;
                        case 'G':
                                cspace(&PS, "\n", 1, APPEND);
                                cspace(&PS, hs, hsl, APPEND);
                                break;
                        case 'h':
                                cspace(&HS, ps, psl, REPLACE);
                                break;
                        case 'H':
                                cspace(&HS, "\n", 1, APPEND);
                                cspace(&HS, ps, psl, APPEND);
                                break;
                        case 'i':
                                (void)fprintf(outfile, "%s", cp->t);
                                break;
                        case 'l':
                                lputs(ps, psl);
                                break;
                        case 'n':
                                if (!nflag && !pd)
                                        OUT();
                                flush_appends();
                                if (!mf_fgets(&PS, REPLACE))
                                        exit(0);
                                pd = 0;
                                break;
                        case 'N':
                                flush_appends();
                                cspace(&PS, "\n", 1, APPEND);
                                if (!mf_fgets(&PS, APPEND))
                                        exit(0);
                                break;
                        case 'p':
                                if (pd)
                                        break;
                                OUT();
                                break;
                        case 'P':
                                if (pd)
                                        break;
                                if ((p = memchr(ps, '\n', psl)) != NULL) {
                                        oldpsl = psl;
                                        oldpsanl = psanl;
                                        psl = p - ps;
                                        psanl = 1;
                                }
                                OUT();
                                if (p != NULL) {
                                        psl = oldpsl;
                                        psanl = oldpsanl;
                                }
                                break;
                        case 'q':
                                if (inplace == NULL) {
                                        if (!nflag && !pd)
                                                OUT();
                                        flush_appends();
                                        exit(0);
                                }
                                quit = 1;
                                break;
                        case 'r':
                                if (appendx >= appendnum)
                                        if ((appends = realloc(appends,
                                            sizeof(struct s_appends) *
                                            (appendnum *= 2))) == NULL)
                                                err(1, "realloc");
                                appends[appendx].type = AP_FILE;
                                appends[appendx].s = cp->t;
                                appends[appendx].len = strlen(cp->t);
                                appendx++;
                                break;
                        case 's':
                                sdone |= substitute(cp);
                                break;
                        case 't':
                                if (sdone) {
                                        sdone = 0;
                                        cp = cp->u.c;
                                        goto redirect;
                                }
                                break;
                        case 'w':
                                if (pd)
                                        break;
                                if (cp->u.fd == -1 && (cp->u.fd = open(cp->t,
                                    O_WRONLY|O_APPEND|O_CREAT|O_TRUNC,
                                    DEFFILEMODE)) == -1)
                                        err(1, "%s", cp->t);
                                if (write(cp->u.fd, ps, psl) != (ssize_t)psl ||
                                    write(cp->u.fd, "\n", 1) != 1)
                                        err(1, "%s", cp->t);
                                break;
                        case 'x':
                                /*
                                 * If the hold space is null, make it empty
                                 * but not null.  Otherwise the pattern space
                                 * will become null after the swap, which is
                                 * an abnormal condition.
                                 */
                                if (hs == NULL)
                                        cspace(&HS, "", 0, REPLACE);
                                tspace = PS;
                                PS = HS;
                                psanl = tspace.append_newline;
                                HS = tspace;
                                break;
                        case 'y':
                                if (pd || psl == 0)
                                        break;
                                do_tr(cp->u.y);
                                break;
                        case ':':
                        case '}':
                                break;
                        case '=':
                                (void)fprintf(outfile, "%lu\n", linenum);
                        }
                        cp = cp->next;
                } /* for all cp */

new:            if (!nflag && !pd)
                        OUT();
                flush_appends();
        } /* for all lines */
}

/*
 * TRUE if the address passed matches the current program state
 * (lastline, linenumber, ps).
 */
#define MATCH(a)                                                        \
        ((a)->type == AT_RE ? regexec_e((a)->u.r, ps, 0, 1, 0, psl) :   \
            (a)->type == AT_LINE ? linenum == (a)->u.l : lastline())

/*
 * Return TRUE if the command applies to the current line.  Sets the start
 * line for process ranges.  Interprets the non-select (``!'') flag.
 */
static inline int
applies(struct s_command *cp)
{
        int r;

        lastaddr = 0;
        if (cp->a1 == NULL && cp->a2 == NULL)
                r = 1;
        else if (cp->a2)
                if (cp->startline > 0) {
                        switch (cp->a2->type) {
                        case AT_RELLINE:
                                if (linenum - cp->startline <= cp->a2->u.l)
                                        r = 1;
                                else {
                                        cp->startline = 0;
                                        r = 0;
                                }
                                break;
                        default:
                                if (MATCH(cp->a2)) {
                                        cp->startline = 0;
                                        lastaddr = 1;
                                        r = 1;
                                } else if (cp->a2->type == AT_LINE &&
                                            linenum > cp->a2->u.l) {
                                        /*
                                         * We missed the 2nd address due to a
                                         * branch, so just close the range and
                                         * return false.
                                         */
                                        cp->startline = 0;
                                        r = 0;
                                } else
                                        r = 1;
                        }
                } else if (cp->a1 && MATCH(cp->a1)) {
                        /*
                         * If the second address is a number less than or
                         * equal to the line number first selected, only
                         * one line shall be selected.
                         *      -- POSIX 1003.2
                         * Likewise if the relative second line address is zero.
                         */
                        if ((cp->a2->type == AT_LINE &&
                            linenum >= cp->a2->u.l) ||
                            (cp->a2->type == AT_RELLINE && cp->a2->u.l == 0))
                                lastaddr = 1;
                        else {
                                cp->startline = linenum;
                        }
                        r = 1;
                } else
                        r = 0;
        else
                r = MATCH(cp->a1);
        return (cp->nonsel ? ! r : r);
}

/*
 * Reset the sed processor to its initial state.
 */
void
resetstate(void)
{
        struct s_command *cp;

        /*
         * Reset all in-range markers.
         */
        for (cp = prog; cp; cp = cp->code == '{' ? cp->u.c : cp->next)
                if (cp->a2)
                        cp->startline = 0;

        /*
         * Clear out the hold space.
         */
        cspace(&HS, "", 0, REPLACE);
}

/*
 * substitute --
 *      Do substitutions in the pattern space.  Currently, we build a
 *      copy of the new pattern space in the substitute space structure
 *      and then swap them.
 */
static int
substitute(struct s_command *cp)
{
        SPACE tspace;
        regex_t *re;
        regoff_t slen;
        int lastempty, n;
        regoff_t le = 0;
        char *s;

        s = ps;
        re = cp->u.s->re;
        if (re == NULL) {
                if (defpreg != NULL && cp->u.s->maxbref > defpreg->re_nsub) {
                        linenum = cp->u.s->linenum;
                        errx(1, "%lu: %s: \\%u not defined in the RE",
                                        linenum, fname, cp->u.s->maxbref);
                }
        }
        if (!regexec_e(re, ps, 0, 0, 0, psl))
                return (0);

        SS.len = 0;                             /* Clean substitute space. */
        slen = psl;
        n = cp->u.s->n;
        lastempty = 1;

        do {
                /* Copy the leading retained string. */
                if (n <= 1 && (match[0].rm_so > le))
                        cspace(&SS, s, match[0].rm_so - le, APPEND);

                /* Skip zero-length matches right after other matches. */
                if (lastempty || (match[0].rm_so - le) ||
                    match[0].rm_so != match[0].rm_eo) {
                        if (n <= 1) {
                                /* Want this match: append replacement. */
                                regsub(&SS, ps, cp->u.s->new);
                                if (n == 1)
                                        n = -1;
                        } else {
                                /* Want a later match: append original. */
                                if (match[0].rm_eo - le)
                                        cspace(&SS, s, match[0].rm_eo - le,
                                            APPEND);
                                n--;
                        }
                }

                /* Move past this match. */
                s = ps + match[0].rm_eo;
                slen = psl - match[0].rm_eo;
                le = match[0].rm_eo;

                /*
                 * After a zero-length match, advance one byte,
                 * and at the end of the line, terminate.
                 */
                if (match[0].rm_so == match[0].rm_eo) {
                        if (slen > 0) {
                                cspace(&SS, s++, 1, APPEND);
                                slen--;
                                le++;
                        } else
                                slen = -1;
                        lastempty = 1;
                } else
                        lastempty = 0;

        } while (n >= 0 && slen >= 0 &&
            regexec_e(re, ps, REG_NOTBOL, 0, le, psl));

        /* Did not find the requested number of matches. */
        if (n > 0)
                return (0);

        /* Copy the trailing retained string. */
        if (slen > 0)
                cspace(&SS, s, slen, APPEND);

        /*
         * Swap the substitute space and the pattern space, and make sure
         * that any leftover pointers into stdio memory get lost.
         */
        tspace = PS;
        PS = SS;
        psanl = tspace.append_newline;
        SS = tspace;
        SS.space = SS.back;

        /* Handle the 'p' flag. */
        if (cp->u.s->p)
                OUT();

        /* Handle the 'w' flag. */
        if (cp->u.s->wfile && !pd) {
                if (cp->u.s->wfd == -1 && (cp->u.s->wfd = open(cp->u.s->wfile,
                    O_WRONLY|O_APPEND|O_CREAT|O_TRUNC, DEFFILEMODE)) == -1)
                        err(1, "%s", cp->u.s->wfile);
                if (write(cp->u.s->wfd, ps, psl) != (ssize_t)psl ||
                    write(cp->u.s->wfd, "\n", 1) != 1)
                        err(1, "%s", cp->u.s->wfile);
        }
        return (1);
}

/*
 * do_tr --
 *      Perform translation ('y' command) in the pattern space.
 */
static void
do_tr(struct s_tr *y)
{
        SPACE tmp;
        char c, *p;
        size_t clen, left;
        int i;

        if (MB_CUR_MAX == 1) {
                /*
                 * Single-byte encoding: perform in-place translation
                 * of the pattern space.
                 */
                for (p = ps; p < &ps[psl]; p++)
                        *p = y->bytetab[(u_char)*p];
        } else {
                /*
                 * Multi-byte encoding: perform translation into the
                 * translation space, then swap the translation and
                 * pattern spaces.
                 */
                /* Clean translation space. */
                YS.len = 0;
                for (p = ps, left = psl; left > 0; p += clen, left -= clen) {
                        if ((c = y->bytetab[(u_char)*p]) != '\0') {
                                cspace(&YS, &c, 1, APPEND);
                                clen = 1;
                                continue;
                        }
                        for (i = 0; i < y->nmultis; i++)
                                if (left >= y->multis[i].fromlen &&
                                    memcmp(p, y->multis[i].from,
                                    y->multis[i].fromlen) == 0)
                                        break;
                        if (i < y->nmultis) {
                                cspace(&YS, y->multis[i].to,
                                    y->multis[i].tolen, APPEND);
                                clen = y->multis[i].fromlen;
                        } else {
                                cspace(&YS, p, 1, APPEND);
                                clen = 1;
                        }
                }
                /* Swap the translation space and the pattern space. */
                tmp = PS;
                PS = YS;
                psanl = tmp.append_newline;
                YS = tmp;
                YS.space = YS.back;
        }
}

/*
 * Flush append requests.  Always called before reading a line,
 * therefore it also resets the substitution done (sdone) flag.
 */
static void
flush_appends(void)
{
        FILE *f;
        unsigned int count, idx;
        char buf[8 * 1024];

        for (idx = 0; idx < appendx; idx++)
                switch (appends[idx].type) {
                case AP_STRING:
                        fwrite(appends[idx].s, sizeof(char), appends[idx].len,
                            outfile);
                        break;
                case AP_FILE:
                        /*
                         * Read files probably shouldn't be cached.  Since
                         * it's not an error to read a non-existent file,
                         * it's possible that another program is interacting
                         * with the sed script through the filesystem.  It
                         * would be truly bizarre, but possible.  It's probably
                         * not that big a performance win, anyhow.
                         */
                        if ((f = fopen(appends[idx].s, "r")) == NULL)
                                break;
                        while ((count = fread(buf, sizeof(char), sizeof(buf), f)))
                                (void)fwrite(buf, sizeof(char), count, outfile);
                        (void)fclose(f);
                        break;
                }
        if (ferror(outfile))
                errx(1, "%s: %s", outfname, strerror(errno ? errno : EIO));
        appendx = sdone = 0;
}

static void
lputs(char *s, size_t len)
{
        static const char escapes[] = "\\\a\b\f\r\t\v";
        int c, col, width;
        const char *p;
        struct winsize win;
        static int termwidth = -1;
        size_t clen, i;
        wchar_t wc;
        mbstate_t mbs;

        if (outfile != stdout)
                termwidth = 60;
        if (termwidth == -1) {
                if ((p = getenv("COLUMNS")) && *p != '\0')
                        termwidth = atoi(p);
                else if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &win) == 0 &&
                    win.ws_col > 0)
                        termwidth = win.ws_col;
                else
                        termwidth = 60;
        }
        if (termwidth <= 0)
                termwidth = 1;

        memset(&mbs, 0, sizeof(mbs));
        col = 0;
        while (len != 0) {
                clen = mbrtowc(&wc, s, len, &mbs);
                if (clen == 0)
                        clen = 1;
                if (clen == (size_t)-1 || clen == (size_t)-2) {
                        wc = (unsigned char)*s;
                        clen = 1;
                        memset(&mbs, 0, sizeof(mbs));
                }
                if (wc == '\n') {
                        if (col + 1 >= termwidth)
                                fprintf(outfile, "\\\n");
                        fputc('$', outfile);
                        fputc('\n', outfile);
                        col = 0;
                } else if (iswprint(wc)) {
                        width = wcwidth(wc);
                        if (col + width >= termwidth) {
                                fprintf(outfile, "\\\n");
                                col = 0;
                        }
                        fwrite(s, 1, clen, outfile);
                        col += width;
                } else if (wc != L'\0' && (c = wctob(wc)) != EOF &&
                    (p = strchr(escapes, c)) != NULL) {
                        if (col + 2 >= termwidth) {
                                fprintf(outfile, "\\\n");
                                col = 0;
                        }
                        fprintf(outfile, "\\%c", "\\abfrtv"[p - escapes]);
                        col += 2;
                } else {
                        if (col + 4 * clen >= (unsigned)termwidth) {
                                fprintf(outfile, "\\\n");
                                col = 0;
                        }
                        for (i = 0; i < clen; i++)
                                fprintf(outfile, "\\%03o",
                                    (int)(unsigned char)s[i]);
                        col += 4 * clen;
                }
                s += clen;
                len -= clen;
        }
        if (col + 1 >= termwidth)
                fprintf(outfile, "\\\n");
        (void)fputc('$', outfile);
        (void)fputc('\n', outfile);
        if (ferror(outfile))
                errx(1, "%s: %s", outfname, strerror(errno ? errno : EIO));
}

static int
regexec_e(regex_t *preg, const char *string, int eflags, int nomatch,
        size_t start, size_t stop)
{
        int eval;

        if (preg == NULL) {
                if (defpreg == NULL)
                        errx(1, "first RE may not be empty");
        } else
                defpreg = preg;

        /* Set anchors */
        match[0].rm_so = start;
        match[0].rm_eo = stop;

        eval = regexec(defpreg, string,
            nomatch ? 0 : maxnsub + 1, match, eflags | REG_STARTEND);
        switch(eval) {
        case 0:
                return (1);
        case REG_NOMATCH:
                return (0);
        }
        errx(1, "RE error: %s", strregerror(eval, defpreg));
        /* NOTREACHED */
}

/*
 * regsub - perform substitutions after a regexp match
 * Based on a routine by Henry Spencer
 */
static void
regsub(SPACE *sp, char *string, char *src)
{
        int len, no;
        char c, *dst;

#define NEEDSP(reqlen)                                                  \
        /* XXX What is the +1 for? */                                   \
        if (sp->len + (reqlen) + 1 >= sp->blen) {                       \
                sp->blen += (reqlen) + 1024;                            \
                if ((sp->space = sp->back = realloc(sp->back, sp->blen)) \
                    == NULL)                                            \
                        err(1, "realloc");                              \
                dst = sp->space + sp->len;                              \
        }

        dst = sp->space + sp->len;
        while ((c = *src++) != '\0') {
                if (c == '&')
                        no = 0;
                else if (c == '\\' && isdigit((unsigned char)*src))
                        no = *src++ - '0';
                else
                        no = -1;
                if (no < 0) {           /* Ordinary character. */
                        if (c == '\\' && (*src == '\\' || *src == '&'))
                                c = *src++;
                        NEEDSP(1);
                        *dst++ = c;
                        ++sp->len;
                } else if (match[no].rm_so != -1 && match[no].rm_eo != -1) {
                        len = match[no].rm_eo - match[no].rm_so;
                        NEEDSP(len);
                        memmove(dst, string + match[no].rm_so, len);
                        dst += len;
                        sp->len += len;
                }
        }
        NEEDSP(1);
        *dst = '\0';
}

/*
 * cspace --
 *      Concatenate space: append the source space to the destination space,
 *      allocating new space as necessary.
 */
void
cspace(SPACE *sp, const char *p, size_t len, enum e_spflag spflag)
{
        size_t tlen;

        /* Make sure SPACE has enough memory and ramp up quickly. */
        tlen = sp->len + len + 1;
        if (tlen > sp->blen) {
                sp->blen = tlen + 1024;
                if ((sp->space = sp->back = realloc(sp->back, sp->blen)) ==
                    NULL)
                        err(1, "realloc");
        }

        if (spflag == REPLACE)
                sp->len = 0;

        memmove(sp->space + sp->len, p, len);

        sp->space[sp->len += len] = '\0';
}

/*
 * Close all cached opened files and report any errors
 */
void
cfclose(struct s_command *cp, struct s_command *end)
{

        for (; cp != end; cp = cp->next)
                switch(cp->code) {
                case 's':
                        if (cp->u.s->wfd != -1 && close(cp->u.s->wfd))
                                err(1, "%s", cp->u.s->wfile);
                        cp->u.s->wfd = -1;
                        break;
                case 'w':
                        if (cp->u.fd != -1 && close(cp->u.fd))
                                err(1, "%s", cp->t);
                        cp->u.fd = -1;
                        break;
                case '{':
                        cfclose(cp->u.c, cp->next);
                        break;
                }
}