/* $Id: read.c,v 1.220 2021/06/27 17:57:54 schwarze Exp $ */
/*
 * Copyright (c) 2010-2020 Ingo Schwarze <schwarze@openbsd.org>
 * Copyright (c) 2008, 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
 * Copyright (c) 2010, 2012 Joerg Sonnenberger <joerg@netbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHORS DISCLAIM ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * Top-level functions of the mandoc(3) parser:
 * Parser and input encoding selection, decompression,
 * handling of input bytes, characters, lines, and files,
 * handling of roff(7) loops and file inclusion,
 * and steering of the various parsers.
 */
#include "config.h"

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

#include <assert.h>
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <zlib.h>

#include "mandoc_aux.h"
#include "mandoc.h"
#include "roff.h"
#include "mdoc.h"
#include "man.h"
#include "mandoc_parse.h"
#include "libmandoc.h"
#include "roff_int.h"
#include "tag.h"

#define REPARSE_LIMIT   1000

struct  mparse {
        struct roff      *roff; /* roff parser (!NULL) */
        struct roff_man  *man; /* man parser */
        struct buf       *primary; /* buffer currently being parsed */
        struct buf       *secondary; /* copy of top level input */
        struct buf       *loop; /* open .while request line */
        const char       *os_s; /* default operating system */
        int               options; /* parser options */
        int               gzip; /* current input file is gzipped */
        int               filenc; /* encoding of the current file */
        int               reparse_count; /* finite interp. stack */
        int               line; /* line number in the file */
};

static  void      choose_parser(struct mparse *);
static  void      free_buf_list(struct buf *);
static  void      resize_buf(struct buf *, size_t);
static  int       mparse_buf_r(struct mparse *, struct buf, size_t, int);
static  int       read_whole_file(struct mparse *, int, struct buf *, int *);
static  void      mparse_end(struct mparse *);


static void
resize_buf(struct buf *buf, size_t initial)
{

        buf->sz = buf->sz > initial/2 ? 2 * buf->sz : initial;
        buf->buf = mandoc_realloc(buf->buf, buf->sz);
}

static void
free_buf_list(struct buf *buf)
{
        struct buf *tmp;

        while (buf != NULL) {
                tmp = buf;
                buf = tmp->next;
                free(tmp->buf);
                free(tmp);
        }
}

static void
choose_parser(struct mparse *curp)
{
        char            *cp, *ep;
        int              format;

        /*
         * If neither command line arguments -mdoc or -man select
         * a parser nor the roff parser found a .Dd or .TH macro
         * yet, look ahead in the main input buffer.
         */

        if ((format = roff_getformat(curp->roff)) == 0) {
                cp = curp->primary->buf;
                ep = cp + curp->primary->sz;
                while (cp < ep) {
                        if (*cp == '.' || *cp == '\'') {
                                cp++;
                                if (cp[0] == 'D' && cp[1] == 'd') {
                                        format = MPARSE_MDOC;
                                        break;
                                }
                                if (cp[0] == 'T' && cp[1] == 'H') {
                                        format = MPARSE_MAN;
                                        break;
                                }
                        }
                        cp = memchr(cp, '\n', ep - cp);
                        if (cp == NULL)
                                break;
                        cp++;
                }
        }

        if (format == MPARSE_MDOC) {
                curp->man->meta.macroset = MACROSET_MDOC;
                if (curp->man->mdocmac == NULL)
                        curp->man->mdocmac = roffhash_alloc(MDOC_Dd, MDOC_MAX);
        } else {
                curp->man->meta.macroset = MACROSET_MAN;
                if (curp->man->manmac == NULL)
                        curp->man->manmac = roffhash_alloc(MAN_TH, MAN_MAX);
        }
        curp->man->meta.first->tok = TOKEN_NONE;
}

/*
 * Main parse routine for a buffer.
 * It assumes encoding and line numbering are already set up.
 * It can recurse directly (for invocations of user-defined
 * macros, inline equations, and input line traps)
 * and indirectly (for .so file inclusion).
 */
static int
mparse_buf_r(struct mparse *curp, struct buf blk, size_t i, int start)
{
        struct buf       ln;
        struct buf      *firstln, *lastln, *thisln, *loop;
        char            *cp;
        size_t           pos; /* byte number in the ln buffer */
        size_t           spos; /* at the start of the current line parse */
        int              line_result, result;
        int              of;
        int              lnn; /* line number in the real file */
        int              fd;
        int              inloop; /* Saw .while on this level. */
        unsigned char    c;

        ln.sz = 256;
        ln.buf = mandoc_malloc(ln.sz);
        ln.next = NULL;
        firstln = lastln = loop = NULL;
        lnn = curp->line;
        pos = 0;
        inloop = 0;
        result = ROFF_CONT;

        while (i < blk.sz && (blk.buf[i] != '\0' || pos != 0)) {
                if (start) {
                        curp->line = lnn;
                        curp->reparse_count = 0;

                        if (lnn < 3 &&
                            curp->filenc & MPARSE_UTF8 &&
                            curp->filenc & MPARSE_LATIN1)
                                curp->filenc = preconv_cue(&blk, i);
                }
                spos = pos;

                while (i < blk.sz && (start || blk.buf[i] != '\0')) {

                        /*
                         * When finding an unescaped newline character,
                         * leave the character loop to process the line.
                         * Skip a preceding carriage return, if any.
                         */

                        if ('\r' == blk.buf[i] && i + 1 < blk.sz &&
                            '\n' == blk.buf[i + 1])
                                ++i;
                        if ('\n' == blk.buf[i]) {
                                ++i;
                                ++lnn;
                                break;
                        }

                        /*
                         * Make sure we have space for the worst
                         * case of 12 bytes: "\\[u10ffff]\n\0"
                         */

                        if (pos + 12 > ln.sz)
                                resize_buf(&ln, 256);

                        /*
                         * Encode 8-bit input.
                         */

                        c = blk.buf[i];
                        if (c & 0x80) {
                                if ( ! (curp->filenc && preconv_encode(
                                    &blk, &i, &ln, &pos, &curp->filenc))) {
                                        mandoc_msg(MANDOCERR_CHAR_BAD,
                                            curp->line, pos, "0x%x", c);
                                        ln.buf[pos++] = '?';
                                        i++;
                                }
                                continue;
                        }

                        /*
                         * Exclude control characters.
                         */

                        if (c == 0x7f || (c < 0x20 && c != 0x09)) {
                                mandoc_msg(c == 0x00 || c == 0x04 ||
                                    c > 0x0a ? MANDOCERR_CHAR_BAD :
                                    MANDOCERR_CHAR_UNSUPP,
                                    curp->line, pos, "0x%x", c);
                                i++;
                                if (c != '\r')
                                        ln.buf[pos++] = '?';
                                continue;
                        }

                        ln.buf[pos++] = blk.buf[i++];
                }
                ln.buf[pos] = '\0';

                /*
                 * Maintain a lookaside buffer of all lines.
                 * parsed from this input source.
                 */

                thisln = mandoc_malloc(sizeof(*thisln));
                thisln->buf = mandoc_strdup(ln.buf);
                thisln->sz = strlen(ln.buf) + 1;
                thisln->next = NULL;
                if (firstln == NULL) {
                        firstln = lastln = thisln;
                        if (curp->secondary == NULL)
                                curp->secondary = firstln;
                } else {
                        lastln->next = thisln;
                        lastln = thisln;
                }

                /* XXX Ugly hack to mark the end of the input. */

                if (i == blk.sz || blk.buf[i] == '\0') {
                        if (pos + 2 > ln.sz)
                                resize_buf(&ln, 256);
                        ln.buf[pos++] = '\n';
                        ln.buf[pos] = '\0';
                }

                /*
                 * A significant amount of complexity is contained by
                 * the roff preprocessor.  It's line-oriented but can be
                 * expressed on one line, so we need at times to
                 * readjust our starting point and re-run it.  The roff
                 * preprocessor can also readjust the buffers with new
                 * data, so we pass them in wholesale.
                 */

                of = 0;
rerun:
                line_result = roff_parseln(curp->roff, curp->line,
                    &ln, &of, start && spos == 0 ? pos : 0);

                /* Process options. */

                if (line_result & ROFF_APPEND)
                        assert(line_result == (ROFF_IGN | ROFF_APPEND));

                if (line_result & ROFF_USERCALL)
                        assert((line_result & ROFF_MASK) == ROFF_REPARSE);

                if (line_result & ROFF_USERRET) {
                        assert(line_result == (ROFF_IGN | ROFF_USERRET));
                        if (start == 0) {
                                /* Return from the current macro. */
                                result = ROFF_USERRET;
                                goto out;
                        }
                }

                switch (line_result & ROFF_LOOPMASK) {
                case ROFF_IGN:
                        break;
                case ROFF_WHILE:
                        if (curp->loop != NULL) {
                                if (loop == curp->loop)
                                        break;
                                mandoc_msg(MANDOCERR_WHILE_NEST,
                                    curp->line, pos, NULL);
                        }
                        curp->loop = thisln;
                        loop = NULL;
                        inloop = 1;
                        break;
                case ROFF_LOOPCONT:
                case ROFF_LOOPEXIT:
                        if (curp->loop == NULL) {
                                mandoc_msg(MANDOCERR_WHILE_FAIL,
                                    curp->line, pos, NULL);
                                break;
                        }
                        if (inloop == 0) {
                                mandoc_msg(MANDOCERR_WHILE_INTO,
                                    curp->line, pos, NULL);
                                curp->loop = loop = NULL;
                                break;
                        }
                        if (line_result & ROFF_LOOPCONT)
                                loop = curp->loop;
                        else {
                                curp->loop = loop = NULL;
                                inloop = 0;
                        }
                        break;
                default:
                        abort();
                }

                /* Process the main instruction from the roff parser. */

                switch (line_result & ROFF_MASK) {
                case ROFF_IGN:
                        break;
                case ROFF_CONT:
                        if (curp->man->meta.macroset == MACROSET_NONE)
                                choose_parser(curp);
                        if ((curp->man->meta.macroset == MACROSET_MDOC ?
                             mdoc_parseln(curp->man, curp->line, ln.buf, of) :
                             man_parseln(curp->man, curp->line, ln.buf, of)
                            ) == 2)
                                goto out;
                        break;
                case ROFF_RERUN:
                        goto rerun;
                case ROFF_REPARSE:
                        if (++curp->reparse_count > REPARSE_LIMIT) {
                                /* Abort and return to the top level. */
                                result = ROFF_IGN;
                                mandoc_msg(MANDOCERR_ROFFLOOP,
                                    curp->line, pos, NULL);
                                goto out;
                        }
                        result = mparse_buf_r(curp, ln, of, 0);
                        if (line_result & ROFF_USERCALL) {
                                roff_userret(curp->roff);
                                /* Continue normally. */
                                if (result & ROFF_USERRET)
                                        result = ROFF_CONT;
                        }
                        if (start == 0 && result != ROFF_CONT)
                                goto out;
                        break;
                case ROFF_SO:
                        if ( ! (curp->options & MPARSE_SO) &&
                            (i >= blk.sz || blk.buf[i] == '\0')) {
                                curp->man->meta.sodest =
                                    mandoc_strdup(ln.buf + of);
                                goto out;
                        }
                        if ((fd = mparse_open(curp, ln.buf + of)) != -1) {
                                mparse_readfd(curp, fd, ln.buf + of);
                                close(fd);
                        } else {
                                mandoc_msg(MANDOCERR_SO_FAIL,
                                    curp->line, of, ".so %s: %s",
                                    ln.buf + of, strerror(errno));
                                ln.sz = mandoc_asprintf(&cp,
                                    ".sp\nSee the file %s.\n.sp",
                                    ln.buf + of);
                                free(ln.buf);
                                ln.buf = cp;
                                of = 0;
                                mparse_buf_r(curp, ln, of, 0);
                        }
                        break;
                default:
                        abort();
                }

                /* Start the next input line. */

                if (loop != NULL &&
                    (line_result & ROFF_LOOPMASK) == ROFF_IGN)
                        loop = loop->next;

                if (loop != NULL) {
                        if ((line_result & ROFF_APPEND) == 0)
                                *ln.buf = '\0';
                        if (ln.sz < loop->sz)
                                resize_buf(&ln, loop->sz);
                        (void)strlcat(ln.buf, loop->buf, ln.sz);
                        of = 0;
                        goto rerun;
                }

                pos = (line_result & ROFF_APPEND) ? strlen(ln.buf) : 0;
        }
out:
        if (inloop) {
                if (result != ROFF_USERRET)
                        mandoc_msg(MANDOCERR_WHILE_OUTOF,
                            curp->line, pos, NULL);
                curp->loop = NULL;
        }
        free(ln.buf);
        if (firstln != curp->secondary)
                free_buf_list(firstln);
        return result;
}

static int
read_whole_file(struct mparse *curp, int fd, struct buf *fb, int *with_mmap)
{
        struct stat      st;
        gzFile           gz;
        size_t           off;
        ssize_t          ssz;
        int              gzerrnum, retval;

        if (fstat(fd, &st) == -1) {
                mandoc_msg(MANDOCERR_FSTAT, 0, 0, "%s", strerror(errno));
                return -1;
        }

        /*
         * If we're a regular file, try just reading in the whole entry
         * via mmap().  This is faster than reading it into blocks, and
         * since each file is only a few bytes to begin with, I'm not
         * concerned that this is going to tank any machines.
         */

        if (curp->gzip == 0 && S_ISREG(st.st_mode)) {
                if (st.st_size > 0x7fffffff) {
                        mandoc_msg(MANDOCERR_TOOLARGE, 0, 0, NULL);
                        return -1;
                }
                *with_mmap = 1;
                fb->sz = (size_t)st.st_size;
                fb->buf = mmap(NULL, fb->sz, PROT_READ, MAP_SHARED, fd, 0);
                if (fb->buf != MAP_FAILED)
                        return 0;
        }

        if (curp->gzip) {
                /*
                 * Duplicating the file descriptor is required
                 * because we will have to call gzclose(3)
                 * to free memory used internally by zlib,
                 * but that will also close the file descriptor,
                 * which this function must not do.
                 */
                if ((fd = dup(fd)) == -1) {
                        mandoc_msg(MANDOCERR_DUP, 0, 0,
                            "%s", strerror(errno));
                        return -1;
                }
                if ((gz = gzdopen(fd, "rb")) == NULL) {
                        mandoc_msg(MANDOCERR_GZDOPEN, 0, 0,
                            "%s", strerror(errno));
                        close(fd);
                        return -1;
                }
        } else
                gz = NULL;

        /*
         * If this isn't a regular file (like, say, stdin), then we must
         * go the old way and just read things in bit by bit.
         */

        *with_mmap = 0;
        off = 0;
        retval = -1;
        fb->sz = 0;
        fb->buf = NULL;
        for (;;) {
                if (off == fb->sz) {
                        if (fb->sz == (1U << 31)) {
                                mandoc_msg(MANDOCERR_TOOLARGE, 0, 0, NULL);
                                break;
                        }
                        resize_buf(fb, 65536);
                }
                ssz = curp->gzip ?
                    gzread(gz, fb->buf + (int)off, fb->sz - off) :
                    read(fd, fb->buf + (int)off, fb->sz - off);
                if (ssz == 0) {
                        fb->sz = off;
                        retval = 0;
                        break;
                }
                if (ssz == -1) {
                        if (curp->gzip)
                                (void)gzerror(gz, &gzerrnum);
                        mandoc_msg(MANDOCERR_READ, 0, 0, "%s",
                            curp->gzip && gzerrnum != Z_ERRNO ?
                            zError(gzerrnum) : strerror(errno));
                        break;
                }
                off += (size_t)ssz;
        }

        if (curp->gzip && (gzerrnum = gzclose(gz)) != Z_OK)
                mandoc_msg(MANDOCERR_GZCLOSE, 0, 0, "%s",
                    gzerrnum == Z_ERRNO ? strerror(errno) :
                    zError(gzerrnum));
        if (retval == -1) {
                free(fb->buf);
                fb->buf = NULL;
        }
        return retval;
}

static void
mparse_end(struct mparse *curp)
{
        if (curp->man->meta.macroset == MACROSET_NONE)
                curp->man->meta.macroset = MACROSET_MAN;
        if (curp->man->meta.macroset == MACROSET_MDOC)
                mdoc_endparse(curp->man);
        else
                man_endparse(curp->man);
        roff_endparse(curp->roff);
}

/*
 * Read the whole file into memory and call the parsers.
 * Called recursively when an .so request is encountered.
 */
void
mparse_readfd(struct mparse *curp, int fd, const char *filename)
{
        static int       recursion_depth;

        struct buf       blk;
        struct buf      *save_primary;
        const char      *save_filename, *cp;
        size_t           offset;
        int              save_filenc, save_lineno;
        int              with_mmap;

        if (recursion_depth > 64) {
                mandoc_msg(MANDOCERR_ROFFLOOP, curp->line, 0, NULL);
                return;
        } else if (recursion_depth == 0 &&
            (cp = strrchr(filename, '.')) != NULL &&
            cp[1] >= '1' && cp[1] <= '9')
                curp->man->filesec = cp[1];
        else
                curp->man->filesec = '\0';

        if (read_whole_file(curp, fd, &blk, &with_mmap) == -1)
                return;

        /*
         * Save some properties of the parent file.
         */

        save_primary = curp->primary;
        save_filenc = curp->filenc;
        save_lineno = curp->line;
        save_filename = mandoc_msg_getinfilename();

        curp->primary = &blk;
        curp->filenc = curp->options & (MPARSE_UTF8 | MPARSE_LATIN1);
        curp->line = 1;
        mandoc_msg_setinfilename(filename);

        /* Skip an UTF-8 byte order mark. */
        if (curp->filenc & MPARSE_UTF8 && blk.sz > 2 &&
            (unsigned char)blk.buf[0] == 0xef &&
            (unsigned char)blk.buf[1] == 0xbb &&
            (unsigned char)blk.buf[2] == 0xbf) {
                offset = 3;
                curp->filenc &= ~MPARSE_LATIN1;
        } else
                offset = 0;

        recursion_depth++;
        mparse_buf_r(curp, blk, offset, 1);
        if (--recursion_depth == 0)
                mparse_end(curp);

        /*
         * Clean up and restore saved parent properties.
         */

        if (with_mmap)
                munmap(blk.buf, blk.sz);
        else
                free(blk.buf);

        curp->primary = save_primary;
        curp->filenc = save_filenc;
        curp->line = save_lineno;
        if (save_filename != NULL)
                mandoc_msg_setinfilename(save_filename);
}

int
mparse_open(struct mparse *curp, const char *file)
{
        char             *cp;
        int               fd, save_errno;

        cp = strrchr(file, '.');
        curp->gzip = (cp != NULL && ! strcmp(cp + 1, "gz"));

        /* First try to use the filename as it is. */

        if ((fd = open(file, O_RDONLY)) != -1)
                return fd;

        /*
         * If that doesn't work and the filename doesn't
         * already  end in .gz, try appending .gz.
         */

        if ( ! curp->gzip) {
                save_errno = errno;
                mandoc_asprintf(&cp, "%s.gz", file);
                fd = open(cp, O_RDONLY);
                free(cp);
                errno = save_errno;
                if (fd != -1) {
                        curp->gzip = 1;
                        return fd;
                }
        }

        /* Neither worked, give up. */

        return -1;
}

struct mparse *
mparse_alloc(int options, enum mandoc_os os_e, const char *os_s)
{
        struct mparse   *curp;

        curp = mandoc_calloc(1, sizeof(struct mparse));

        curp->options = options;
        curp->os_s = os_s;

        curp->roff = roff_alloc(options);
        curp->man = roff_man_alloc(curp->roff, curp->os_s,
                curp->options & MPARSE_QUICK ? 1 : 0);
        if (curp->options & MPARSE_MDOC) {
                curp->man->meta.macroset = MACROSET_MDOC;
                if (curp->man->mdocmac == NULL)
                        curp->man->mdocmac = roffhash_alloc(MDOC_Dd, MDOC_MAX);
        } else if (curp->options & MPARSE_MAN) {
                curp->man->meta.macroset = MACROSET_MAN;
                if (curp->man->manmac == NULL)
                        curp->man->manmac = roffhash_alloc(MAN_TH, MAN_MAX);
        }
        curp->man->meta.first->tok = TOKEN_NONE;
        curp->man->meta.os_e = os_e;
        tag_alloc();
        return curp;
}

void
mparse_reset(struct mparse *curp)
{
        tag_free();
        roff_reset(curp->roff);
        roff_man_reset(curp->man);
        free_buf_list(curp->secondary);
        curp->secondary = NULL;
        curp->gzip = 0;
        tag_alloc();
}

void
mparse_free(struct mparse *curp)
{
        tag_free();
        roffhash_free(curp->man->mdocmac);
        roffhash_free(curp->man->manmac);
        roff_man_free(curp->man);
        roff_free(curp->roff);
        free_buf_list(curp->secondary);
        free(curp);
}

struct roff_meta *
mparse_result(struct mparse *curp)
{
        roff_state_reset(curp->man);
        if (curp->options & MPARSE_VALIDATE) {
                if (curp->man->meta.macroset == MACROSET_MDOC)
                        mdoc_validate(curp->man);
                else
                        man_validate(curp->man);
                tag_postprocess(curp->man, curp->man->meta.first);
        }
        return &curp->man->meta;
}

void
mparse_copy(const struct mparse *p)
{
        struct buf      *buf;

        for (buf = p->secondary; buf != NULL; buf = buf->next)
                puts(buf->buf);
}