/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 2013 Johann 'Myrkraverk' Oskarsson.
 * 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/mman.h>
#include <sys/param.h>
#include <sys/stat.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <libgen.h>
#include <limits.h>
#include <locale.h>
#include <regex.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

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

/*
 * Linked list of units (strings and files) to be compiled
 */
struct s_compunit {
        struct s_compunit *next;
        enum e_cut {CU_FILE, CU_STRING} type;
        char *s;                        /* Pointer to string or fname */
};

/*
 * Linked list pointer to compilation units and pointer to current
 * next pointer.
 */
static struct s_compunit *script, **cu_nextp = &script;

/*
 * Linked list of files to be processed
 */
struct s_flist {
        char *fname;
        struct s_flist *next;
};

/*
 * Linked list pointer to files and pointer to current
 * next pointer.
 */
static struct s_flist *files, **fl_nextp = &files;

FILE *infile;                   /* Current input file */
FILE *outfile;                  /* Current output file */

int aflag, eflag, nflag;
int rflags = 0;
int quit = 0;
static int rval;                /* Exit status */

static int ispan;               /* Whether inplace editing spans across files */

/*
 * Current file and line number; line numbers restart across compilation
 * units, but span across input files.  The latter is optional if editing
 * in place.
 */
const char *fname;              /* File name. */
const char *outfname;           /* Output file name */
static char oldfname[PATH_MAX]; /* Old file name (for in-place editing) */
static char tmpfname[PATH_MAX]; /* Temporary file name (for in-place editing) */
const char *inplace;            /* Inplace edit file extension. */
u_long linenum;

static void add_compunit(enum e_cut, char *);
static void add_file(char *);
static void usage(void) __dead2;

int
main(int argc, char *argv[])
{
        int c, fflag, fflagstdin;
        char *temp_arg;

        (void) setlocale(LC_ALL, "");

        fflag = 0;
        fflagstdin = 0;
        inplace = NULL;

        while ((c = getopt(argc, argv, "EI:ae:f:i:lnru")) != -1)
                switch (c) {
                case 'r':               /* Gnu sed compat */
                case 'E':
                        rflags = REG_EXTENDED;
                        break;
                case 'I':
                        inplace = optarg;
                        ispan = 1;      /* span across input files */
                        break;
                case 'a':
                        aflag = 1;
                        break;
                case 'e':
                        eflag = 1;
                        if (asprintf(&temp_arg, "%s\n", optarg) == -1)
                                err(1, "asprintf");
                        add_compunit(CU_STRING, temp_arg);
                        break;
                case 'f':
                        fflag = 1;
                        if (strcmp(optarg, "-") == 0)
                                fflagstdin = 1;
                        add_compunit(CU_FILE, optarg);
                        break;
                case 'i':
                        inplace = optarg;
                        ispan = 0;      /* don't span across input files */
                        break;
                case 'l':
                        if(setvbuf(stdout, NULL, _IOLBF, 0) != 0)
                                warnx("setting line buffered output failed");
                        break;
                case 'n':
                        nflag = 1;
                        break;
                case 'u':
                        if(setvbuf(stdout, NULL, _IONBF, 0) != 0)
                                warnx("setting unbuffered output failed");
                        break;
                default:
                case '?':
                        usage();
                }
        argc -= optind;
        argv += optind;

        /* First usage case; script is the first arg */
        if (!eflag && !fflag && *argv) {
                if (asprintf(&temp_arg, "%s\n", *argv) == -1)
                        err(1, "asprintf");
                add_compunit(CU_STRING, temp_arg);
                argv++;
        }

        compile();

        /* Continue with first and start second usage */
        if (*argv)
                for (; *argv; argv++)
                        add_file(*argv);
        else if (fflagstdin)
                exit(rval);
        else
                add_file(NULL);
        process();
        cfclose(prog, NULL);
        if (fclose(stdout))
                err(1, "stdout");
        exit(rval);
}

static void
usage(void)
{
        (void)fprintf(stderr,
            "usage: %s script [-Ealnru] [-i extension] [file ...]\n"
            "\t%s [-Ealnu] [-i extension] [-e script] ... [-f script_file]"
            " ... [file ...]\n", getprogname(), getprogname());
        exit(1);
}

/*
 * Like fgets, but go through the chain of compilation units chaining them
 * together.  Empty strings and files are ignored.
 */
char *
cu_fgets(char *buf, int n, int *more)
{
        static enum {ST_EOF, ST_FILE, ST_STRING} state = ST_EOF;
        static FILE *f;         /* Current open file */
        static char *s;         /* Current pointer inside string */
        static char string_ident[30];
        char *p;

again:
        switch (state) {
        case ST_EOF:
                if (script == NULL) {
                        if (more != NULL)
                                *more = 0;
                        return (NULL);
                }
                linenum = 0;
                switch (script->type) {
                case CU_FILE:
                        if (strcmp(script->s, "-") == 0) {
                                f = stdin;
                                fname = "stdin";
                        } else {
                                if ((f = fopen(script->s, "r")) == NULL)
                                        err(1, "%s", script->s);
                                fname = script->s;
                        }
                        state = ST_FILE;
                        goto again;
                case CU_STRING:
                        if (((size_t)snprintf(string_ident,
                            sizeof(string_ident), "\"%s\"", script->s)) >=
                            sizeof(string_ident) - 1)
                                (void)strcpy(string_ident +
                                    sizeof(string_ident) - 6, " ...\"");
                        fname = string_ident;
                        s = script->s;
                        state = ST_STRING;
                        goto again;
                default:
                        __unreachable();
                }
        case ST_FILE:
                if ((p = fgets(buf, n, f)) != NULL) {
                        linenum++;
                        if (linenum == 1 && buf[0] == '#' && buf[1] == 'n')
                                nflag = 1;
                        if (more != NULL)
                                *more = !feof(f);
                        return (p);
                }
                script = script->next;
                (void)fclose(f);
                state = ST_EOF;
                goto again;
        case ST_STRING:
                if (linenum == 0 && s[0] == '#' && s[1] == 'n')
                        nflag = 1;
                p = buf;
                for (;;) {
                        if (n-- <= 1) {
                                *p = '\0';
                                linenum++;
                                if (more != NULL)
                                        *more = 1;
                                return (buf);
                        }
                        switch (*s) {
                        case '\0':
                                state = ST_EOF;
                                if (s == script->s) {
                                        script = script->next;
                                        goto again;
                                } else {
                                        script = script->next;
                                        *p = '\0';
                                        linenum++;
                                        if (more != NULL)
                                                *more = 0;
                                        return (buf);
                                }
                        case '\n':
                                *p++ = '\n';
                                *p = '\0';
                                s++;
                                linenum++;
                                if (more != NULL)
                                        *more = 0;
                                return (buf);
                        default:
                                *p++ = *s++;
                        }
                }
        }
        /* NOTREACHED */
        return (NULL);
}

/*
 * Like fgets, but go through the list of files chaining them together.
 * Set len to the length of the line.
 */
int
mf_fgets(SPACE *sp, enum e_spflag spflag)
{
        struct stat sb;
        ssize_t len;
        char *dirbuf, *basebuf;
        static char *p = NULL;
        static size_t plen = 0;
        int c;
        static int firstfile;

        if (infile == NULL) {
                /* stdin? */
                if (files->fname == NULL) {
                        if (inplace != NULL)
                                errx(1, "-I or -i may not be used with stdin");
                        infile = stdin;
                        fname = "stdin";
                        outfile = stdout;
                        outfname = "stdout";
                }
                firstfile = 1;
        }

        for (;;) {
                if (infile != NULL && (c = getc(infile)) != EOF && !quit) {
                        (void)ungetc(c, infile);
                        break;
                }
                /* If we are here then either eof or no files are open yet */
                if (infile == stdin) {
                        sp->len = 0;
                        return (0);
                }
                if (infile != NULL) {
                        fclose(infile);
                        if (*oldfname != '\0') {
                                /* if there was a backup file, remove it */
                                unlink(oldfname);
                                /*
                                 * Backup the original.  Note that hard links
                                 * are not supported on all filesystems.
                                 */
                                if ((link(fname, oldfname) != 0) &&
                                   (rename(fname, oldfname) != 0)) {
                                        warn("rename()");
                                        if (*tmpfname)
                                                unlink(tmpfname);
                                        exit(1);
                                }
                                *oldfname = '\0';
                        }
                        if (*tmpfname != '\0') {
                                if (outfile != NULL && outfile != stdout)
                                        if (fclose(outfile) != 0) {
                                                warn("fclose()");
                                                unlink(tmpfname);
                                                exit(1);
                                        }
                                outfile = NULL;
                                if (rename(tmpfname, fname) != 0) {
                                        /* this should not happen really! */
                                        warn("rename()");
                                        unlink(tmpfname);
                                        exit(1);
                                }
                                *tmpfname = '\0';
                        }
                        outfname = NULL;
                }
                if (firstfile == 0)
                        files = files->next;
                else
                        firstfile = 0;
                if (files == NULL) {
                        sp->len = 0;
                        return (0);
                }
                fname = files->fname;
                if (inplace != NULL) {
                        if (lstat(fname, &sb) != 0)
                                err(1, "%s", fname);
                        if (!S_ISREG(sb.st_mode))
                                errx(1, "%s: %s %s", fname,
                                    "in-place editing only",
                                    "works for regular files");
                        if (*inplace != '\0') {
                                strlcpy(oldfname, fname,
                                    sizeof(oldfname));
                                len = strlcat(oldfname, inplace,
                                    sizeof(oldfname));
                                if (len > (ssize_t)sizeof(oldfname))
                                        errx(1, "%s: name too long", fname);
                        }
                        if ((dirbuf = strdup(fname)) == NULL ||
                            (basebuf = strdup(fname)) == NULL)
                                err(1, "strdup");
                        len = snprintf(tmpfname, sizeof(tmpfname),
                            "%s/.!%ld!%s", dirname(dirbuf), (long)getpid(),
                            basename(basebuf));
                        free(dirbuf);
                        free(basebuf);
                        if (len >= (ssize_t)sizeof(tmpfname))
                                errx(1, "%s: name too long", fname);
                        unlink(tmpfname);
                        if (outfile != NULL && outfile != stdout)
                                fclose(outfile);
                        if ((outfile = fopen(tmpfname, "w")) == NULL)
                                err(1, "%s", fname);
                        fchown(fileno(outfile), sb.st_uid, sb.st_gid);
                        fchmod(fileno(outfile), sb.st_mode & ALLPERMS);
                        outfname = tmpfname;
                        if (!ispan) {
                                linenum = 0;
                                resetstate();
                        }
                } else {
                        outfile = stdout;
                        outfname = "stdout";
                }
                if ((infile = fopen(fname, "r")) == NULL) {
                        warn("%s", fname);
                        rval = 1;
                        continue;
                }
        }
        /*
         * We are here only when infile is open and we still have something
         * to read from it.
         *
         * Use getline() so that we can handle essentially infinite input
         * data.  The p and plen are static so each invocation gives
         * getline() the same buffer which is expanded as needed.
         */
        len = getline(&p, &plen, infile);
        if (len == -1)
                err(1, "%s", fname);
        if (len != 0 && p[len - 1] == '\n') {
                sp->append_newline = 1;
                len--;
        } else if (!lastline()) {
                sp->append_newline = 1;
        } else {
                sp->append_newline = 0;
        }
        cspace(sp, p, len, spflag);

        linenum++;

        return (1);
}

/*
 * Add a compilation unit to the linked list
 */
static void
add_compunit(enum e_cut type, char *s)
{
        struct s_compunit *cu;

        if ((cu = malloc(sizeof(struct s_compunit))) == NULL)
                err(1, "malloc");
        cu->type = type;
        cu->s = s;
        cu->next = NULL;
        *cu_nextp = cu;
        cu_nextp = &cu->next;
}

/*
 * Add a file to the linked list
 */
static void
add_file(char *s)
{
        struct s_flist *fp;

        if ((fp = malloc(sizeof(struct s_flist))) == NULL)
                err(1, "malloc");
        fp->next = NULL;
        *fl_nextp = fp;
        fp->fname = s;
        fl_nextp = &fp->next;
}

static int
next_files_have_lines(void)
{
        struct s_flist *file;
        FILE *file_fd;
        int ch;

        file = files;
        while ((file = file->next) != NULL) {
                if ((file_fd = fopen(file->fname, "r")) == NULL)
                        continue;

                if ((ch = getc(file_fd)) != EOF) {
                        /*
                         * This next file has content, therefore current
                         * file doesn't contains the last line.
                         */
                        ungetc(ch, file_fd);
                        fclose(file_fd);
                        return (1);
                }

                fclose(file_fd);
        }

        return (0);
}

int
lastline(void)
{
        int ch;

        if (feof(infile)) {
                return !(
                    (inplace == NULL || ispan) &&
                    next_files_have_lines());
        }
        if ((ch = getc(infile)) == EOF) {
                return !(
                    (inplace == NULL || ispan) &&
                    next_files_have_lines());
        }
        ungetc(ch, infile);
        return (0);
}