/*      $OpenBSD: process.c,v 1.39 2024/12/10 23:49:55 millert Exp $    */

/*-
 * 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.
 * 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/types.h>
#include <sys/stat.h>
#include <sys/uio.h>

#include <ctype.h>
#include <err.h>
#include <fcntl.h>
#include <limits.h>
#include <regex.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

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

static SPACE HS, PS, SS;
#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              flush_appends(void);
static void              lputs(char *, size_t);
static inline 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 size_t appendx;          /* Index into appends array. */
size_t 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 len, oldpsl;
        char *p;

        for (linenum = 0; mf_getline(&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) {
                                        appends = xreallocarray(appends,
                                            appendnum,
                                            2 * sizeof(struct s_appends));
                                        appendnum *= 2;
                                }
                                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, 0);
                                cspace(&PS, hs, hsl, 0);
                                break;
                        case 'h':
                                cspace(&HS, ps, psl, REPLACE);
                                break;
                        case 'H':
                                cspace(&HS, "\n", 1, 0);
                                cspace(&HS, ps, psl, 0);
                                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_getline(&PS, REPLACE))
                                        exit(0);
                                pd = 0;
                                break;
                        case 'N':
                                flush_appends();
                                cspace(&PS, "\n", 1, 0);
                                if (!mf_getline(&PS, 0))
                                        exit(0);
                                break;
                        case 'p':
                                if (pd)
                                        break;
                                OUT();
                                break;
                        case 'P':
                                if (pd)
                                        break;
                                if ((p = memchr(ps, '\n', psl)) != NULL) {
                                        oldpsl = psl;
                                        psl = p - ps;
                                        psanl = 1;
                                        OUT();
                                        psl = oldpsl;
                                } else {
                                        OUT();
                                }
                                break;
                        case 'q':
                                if (!nflag && !pd)
                                        OUT();
                                flush_appends();
                                finish_file();
                                exit(0);
                        case 'r':
                                if (appendx >= appendnum) {
                                        appends = xreallocarray(appends,
                                            appendnum,
                                            2 * sizeof(struct s_appends));
                                        appendnum *= 2;
                                }
                                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 ((size_t)write(cp->u.fd, ps, psl) != psl ||
                                    write(cp->u.fd, "\n", 1) != 1)
                                        err(1, "%s", cp->t);
                                break;
                        case 'x':
                                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;
                                for (p = ps, len = psl; len--; ++p)
                                        *p = cp->u.y[(unsigned char)*p];
                                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 inrange
 * flag to 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->inrange) {
                        if (MATCH(cp->a2)) {
                                cp->inrange = 0;
                                lastaddr = 1;
                        }
                        r = 1;
                } else if (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
                         */
                        if (cp->a2->type == AT_LINE &&
                            linenum >= cp->a2->u.l)
                                lastaddr = 1;
                        else
                                cp->inrange = 1;
                        r = 1;
                } else
                        r = 0;
        else
                r = MATCH(cp->a1);
        return (cp->nonsel ? !r : r);
}

/*
 * Reset all inrange markers.
 */
void
resetstate(void)
{
        struct s_command *cp;

        free(HS.back);
        memset(&HS, 0, sizeof(HS));

        for (cp = prog; cp; cp = cp->code == '{' ? cp->u.c : cp->next)
                if (cp->a2)
                        cp->inrange = 0;
}

/*
 * 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 n, lastempty;
        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;
                        error("\\%d not defined in the RE", 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 ((size_t)write(cp->u.s->wfd, ps, psl) != psl ||
                    write(cp->u.s->wfd, "\n", 1) != 1)
                        err(1, "%s", cp->u.s->wfile);
        }
        return (1);
}

/*
 * 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;
        size_t 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 file system.  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))
                err(1, "%s", outfname);
        appendx = sdone = 0;
}

static void
lputs(char *s, size_t len)
{
        int count;
        extern int termwidth;
        const char *escapes;
        char *p;

        for (count = 0; len > 0; len--, s++) {
                if (count >= termwidth) {
                        (void)fprintf(outfile, "\\\n");
                        count = 0;
                }
                if (isascii((unsigned char)*s) && isprint((unsigned char)*s)
                    && *s != '\\') {
                        (void)fputc(*s, outfile);
                        count++;
                } else if (*s == '\n') {
                        (void)fputc('$', outfile);
                        (void)fputc('\n', outfile);
                        count = 0;
                } else {
                        escapes = "\\\a\b\f\r\t\v";
                        (void)fputc('\\', outfile);
                        if ((p = strchr(escapes, *s)) && *s != '\0') {
                                (void)fputc("\\abfrtv"[p - escapes], outfile);
                                count += 2;
                        } else {
                                (void)fprintf(outfile, "%03o", *(u_char *)s);
                                count += 4;
                        }
                }
        }
        (void)fputc('$', outfile);
        (void)fputc('\n', outfile);
        if (ferror(outfile))
                err(1, "%s", outfname);
}

static inline 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));
}

/*
 * 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)                                                  \
        if (sp->len + (reqlen) + 1 >= sp->blen) {                       \
                size_t newlen = sp->blen + (reqlen) + 1024;             \
                sp->space = sp->back = xrealloc(sp->back, newlen);      \
                sp->blen = newlen;                                      \
                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';
}

/*
 * aspace --
 *      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) {
                size_t newlen = tlen + 1024;
                sp->space = sp->back = xrealloc(sp->back, newlen);
                sp->blen = newlen;
        }

        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;
                }
}