/*
 * Copyright © 2006 Sean Estabrooks <seanlkml@sympatico.ca>
 * Copyright © 2006 Keith Packard <keithp@keithp.com>
 *
 *  SPDX-License-Identifier: GPL-2.0+
 *
 * Large portions of code contained in this file were obtained from
 * the original RCS application under GPLv2 or later license, it retains
 * the copyright of the original authors listed below:
 *
 * Copyright 1982, 1988, 1989 Walter Tichy
 *   Copyright 1990, 1991, 1992, 1993, 1994, 1995 Paul Eggert
 *      Distributed under license by the Free Software Foundation, Inc.
 */

/*
 * The entire aim of this module is the last function, which turns
 * the in-core revision history of a CVS/RCS master file and materializes
 * all of its revision levels through a specified export hook.
 */

#include <limits.h>
#include <stdarg.h>
#include "cvs.h"

typedef unsigned char uchar;

struct alloclist {
    void* alloc;
    struct alloclist *nextalloc;
};

struct diffcmd {
	long line1, nlines, adprev, dafter;
};

const int initial_out_buffer_size = 1024;
char const ciklog[] = "checked in with -k by ";

#define KEYLENGTH 8 /* max length of any of the above keywords */
#define KDELIM '$' /* keyword delimiter */
#define VDELIM ':' /* separates keywords from values */
#define SDELIM '@' /* string delimiter */
#define min(a,b) ((a) < (b) ? (a) : (b))
#define max(a,b) ((a) > (b) ? (a) : (b))

char const *const Keyword[] = {
	0, "Author", "Date", "Header", "Id", "Locker", "Log",
	"Name", "RCSfile", "Revision", "Source", "State"
};
enum markers { Nomatch, Author, Date, Header, Id, Locker, Log,
	Name, RCSfile, Revision, Source, State };
enum stringwork {ENTER, EDIT};

/* backup one position in the input buffer, unless at start of buffer
 *   return character at new position, or EOF if we could not back up
 */
static int in_buffer_ungetc(editbuffer_t *eb)
{
    int c;
    if (Ginbuf(eb)->read_count == 0)
	return EOF;
    --Ginbuf(eb)->read_count;
    --Ginbuf(eb)->ptr;
    c = *Ginbuf(eb)->ptr;
    if (c == SDELIM) {
	--Ginbuf(eb)->ptr;
	c = *Ginbuf(eb)->ptr;
    }
    return c;
}

static int in_buffer_getc(editbuffer_t *eb)
{
    int c;
    c = *(Ginbuf(eb)->ptr++);
    ++Ginbuf(eb)->read_count;
    if (c == SDELIM) {
	c = *(Ginbuf(eb)->ptr++);
	if (c != SDELIM) {
	    Ginbuf(eb)->ptr -= 2;
	    --Ginbuf(eb)->read_count;
	    return EOF;
#ifdef LINESTATS
	} else {
	eb->has_stringdelim = true;
#endif
	}
    }
    return c ;
}

static uchar *in_get_line(editbuffer_t *eb)
{
    int c;
    uchar *ptr = Ginbuf(eb)->ptr;
#ifdef LINESTATS
    eb->has_stringdelim = false;
#endif
    c=in_buffer_getc(eb);
    if (c == EOF)
	return NULL;
    while (c != EOF && c != '\n')
	c = in_buffer_getc(eb);
#ifdef LINESTATS
    eb->line_len = Ginbuf(eb)->ptr - ptr;
#endif
    return ptr;
}

static const uchar *in_buffer_loc(const editbuffer_t *const eb)
{
	return(Ginbuf(eb)->ptr);
}

static void in_buffer_init(editbuffer_t *eb, 
			   const uchar * const text, 
			   const bool bypass_initial)
{
    Ginbuf(eb)->ptr = Ginbuf(eb)->buffer = (uchar *)text;
    Ginbuf(eb)->read_count=0;
    if (bypass_initial && *Ginbuf(eb)->ptr++ != SDELIM)
	fatal_error("Illegal buffer, missing @ %s", text);
}

static void out_buffer_init(editbuffer_t *eb)
{
    char *t;
    eb->Goutbuf = xmalloc(sizeof(struct out_buffer_type), "out_buffer_init");
    eb->Goutbuf->size = initial_out_buffer_size;
    t = xmalloc(eb->Goutbuf->size, "out+buffer_init");
    eb->Goutbuf->text = t;
    eb->Goutbuf->ptr = t;
    eb->Goutbuf->end_of_text = t + eb->Goutbuf->size;
}

static void out_buffer_enlarge(editbuffer_t *eb)
{
    register struct out_buffer_type *ob = eb->Goutbuf;
    int ptroffset = ob->ptr - ob->text;
    ob->size *= 2;
    ob->text = xrealloc(ob->text, ob->size, "out_buffer_enlarge");
    ob->end_of_text = ob->text + ob->size;
    ob->ptr = ob->text + ptroffset;
}

static unsigned long  out_buffer_count(const editbuffer_t *const eb)
{
    return(unsigned long) (eb->Goutbuf->ptr - eb->Goutbuf->text);
}

static char *out_buffer_text(const editbuffer_t *const eb)
{
    return eb->Goutbuf->text;
}

static void out_buffer_cleanup(const editbuffer_t *eb)
{
    free(eb->Goutbuf->text);
    free(eb->Goutbuf);
}

inline static void out_putc(editbuffer_t *eb, const int c)
{
    /*
     * This function is a severe hot spot.
     */
    register struct out_buffer_type *ob = eb->Goutbuf;
    *ob->ptr++ = c;
    if (ob->ptr >= ob->end_of_text)
	out_buffer_enlarge(eb);
}

static void out_printf(editbuffer_t *eb, const char *fmt, ...)
{
    va_list ap;
    while (1) {
	int ret, room;
	room = eb->Goutbuf->end_of_text - eb->Goutbuf->ptr;
	va_start(ap, fmt);
	ret = vsnprintf(eb->Goutbuf->ptr, room, fmt, ap);
	va_end(ap);
	if (ret > -1 && ret < room) {
	    eb->Goutbuf->ptr += ret;
	    return;
	}
	out_buffer_enlarge(eb);
    }
}

static void out_fputs(editbuffer_t *eb, const char *s)
{
    while (*s)
	out_putc(eb, *s++);
}

static void out_awrite(editbuffer_t *eb, const char *s, size_t len)
{
    while (len--)
	out_putc(eb, *s++);
}

static bool latin1_alpha(const int c)
{
    if (c >= 192 && c != 215 && c != 247 ) return true;
    if ((c >= 97 && c < 123) || (c >= 65 && c < 91)) return true;
    return false;
}

static int latin1_whitespace(const uchar c)
{
    return (c == ' ' || (c >= '\b' && c <= '\r' && c != '\n'));
}

enum expand_mode expand_override(char const *s)
{
    if (s != NULL)
    {
	char *const expand_names[] = {"kv", "kvl", "k", "v", "o", "b"};
	int i;
	for (i=0; i < 6; ++i)
	    if (strcmp(s,expand_names[i]) == 0)
		return(enum expand_mode) i;
    }
    return EXPANDUNSPEC;
}

static char const *basefilename(const char* const p)
{
    char const *b = p, *q = p;
    for (;;)
	switch(*q++) {
	case '/': b = q; break;
	case 0: return b;
	}
}

static char const * getfullRCSname(editbuffer_t *eb)
/* Convert relative RCS filename to absolute path */
{
    char *wdbuf = NULL;
    int wdbuflen = 0;

    size_t dlen;

    char const *r;
    char* d;

    if (eb->Gfilename[0] == '/')
	return eb->Gfilename;

    /* If we've already calculated the absolute path, return it */
    if (eb->Gabspath)
	return eb->Gabspath;

    /* Get working directory and strip any trailing slashes */
    wdbuflen = _POSIX_PATH_MAX + 1;
    wdbuf = xmalloc(wdbuflen, "getcwd");
    while (!getcwd(wdbuf, wdbuflen)) {
	if (errno == ERANGE)
	    /* coverity[leaked_storage] */
	    xrealloc(wdbuf, wdbuflen<<1, "getcwd");
	else 
	    fatal_system_error("getcwd");
    }

    /* Trim off trailing slashes */
    dlen = strlen(wdbuf);
    while (dlen && wdbuf[dlen-1] == '/')
	--dlen;
    wdbuf[dlen] = 0;

    /* Ignore leading `./'s in Gfilename. */
    for (r = eb->Gfilename;  r[0]=='.' && r[1] == '/';  r += 2)
	while (r[2] == '/')
	    r++;

    /* Build full pathname.  */
    eb->Gabspath = d = xmalloc(dlen + strlen(r) + 2, "pathname building");
    memcpy(d, wdbuf, dlen);
    d += dlen;
    *d++ = '/';
    strcpy(d, r);
    free(wdbuf);

    return eb->Gabspath;
}

static enum markers trymatch(char const *const string)
/* Check if string starts with a keyword followed by a KDELIM or VDELIM */
{
    int j;
    for (j = sizeof(Keyword)/sizeof(*Keyword);  (--j);  ) {
	char const *p, *s;
	p = Keyword[j];
	s = string;
	while (*p++ == *s++) {
	    if (!*p) {
		switch(*s) {
		case KDELIM:
		case VDELIM:
		    return(enum markers)j;
		default:
		    return Nomatch;
		}
	    }
	}
    }
    return(Nomatch);
}
#ifdef LINESTATS
static void insertline(editbuffer_t *eb, const unsigned long n, uchar * l)
/* Before line N, insert line L.  N is 0-origin.  */
{
    if (n > Glinemax(eb) - Ggapsize(eb))
	fatal_error("edit script tried to insert beyond eof");
    if (!Ggapsize(eb)) {
	if (Glinemax(eb)) {
	    Ggap(eb) = Ggapsize(eb) = Glinemax(eb); Glinemax(eb) <<= 1;
	    Gline(eb) = xrealloc(Gline(eb), sizeof(editline_t) * Glinemax(eb), "insertline");
	} else {
	    Glinemax(eb) = Ggapsize(eb) = 1024;
	    Gline(eb) = xmalloc(sizeof(editline_t) *  Glinemax(eb), "insertline");
	}
    }
    if (n < Ggap(eb))
	memmove(Gline(eb)+n+Ggapsize(eb), Gline(eb)+n, (Ggap(eb)-n) * sizeof(editline_t));
    else if (Ggap(eb) < n)
	memmove(Gline(eb)+Ggap(eb), Gline(eb)+Ggap(eb)+Ggapsize(eb), (n-Ggap(eb)) * sizeof(editline_t));
    Gline(eb)[n].ptr = l;
    Gline(eb)[n].has_stringdelim = eb->has_stringdelim;
    Gline(eb)[n].length = eb->line_len;
    Ggap(eb) = n + 1;
    Ggapsize(eb)--;

}

static void deletelines(editbuffer_t *eb,
			const unsigned long n, const unsigned long nlines)
/* Delete lines N through N+NLINES-1.  N is 0-origin.  */
{
    unsigned long l = n + nlines;
    if (Glinemax(eb)-Ggapsize(eb) < l  ||  l < n)
	fatal_error("edit script tried to delete beyond eof");
    if (l < Ggap(eb))
	memmove(Gline(eb)+l+Ggapsize(eb), Gline(eb)+l, (Ggap(eb)-l) * sizeof(editline_t));
    else if (Ggap(eb) < n)
	memmove(Gline(eb)+Ggap(eb), Gline(eb)+Ggap(eb)+Ggapsize(eb), (n-Ggap(eb)) * sizeof(editline_t));
    Ggap(eb) = n;
    Ggapsize(eb) += nlines;
}

#else
static void insertline(editbuffer_t *eb, const unsigned long n, uchar * l)
/* Before line N, insert line L.  N is 0-origin.  */
{
    if (n > Glinemax(eb) - Ggapsize(eb))
	fatal_error("edit script tried to insert beyond eof");
    if (!Ggapsize(eb)) {
	if (Glinemax(eb)) {
	    Ggap(eb) = Ggapsize(eb) = Glinemax(eb); Glinemax(eb) <<= 1;
	    Gline(eb) = xrealloc(Gline(eb), sizeof(uchar *) * Glinemax(eb), "insertline");
	} else {
	    Glinemax(eb) = Ggapsize(eb) = 1024;
	    Gline(eb) = xmalloc(sizeof(uchar *) *  Glinemax(eb), "insertline");
	}
    }
    if (n < Ggap(eb))
	memmove(Gline(eb)+n+Ggapsize(eb), Gline(eb)+n, (Ggap(eb)-n) * sizeof(uchar *));
    else if (Ggap(eb) < n)
	memmove(Gline(eb)+Ggap(eb), Gline(eb)+Ggap(eb)+Ggapsize(eb), (n-Ggap(eb)) * sizeof(uchar *));
    Gline(eb)[n] = l;
    Ggap(eb) = n + 1;
    Ggapsize(eb)--;
}

static void deletelines(editbuffer_t *eb, 
			const unsigned long n, const unsigned long nlines)
/* Delete lines N through N+NLINES-1.  N is 0-origin.  */
{
    unsigned long l = n + nlines;
    if (Glinemax(eb)-Ggapsize(eb) < l  ||  l < n)
	fatal_error("edit script tried to delete beyond eof");
    if (l < Ggap(eb))
	memmove(Gline(eb)+l+Ggapsize(eb), Gline(eb)+l, (Ggap(eb)-l) * sizeof(uchar *));
    else if (Ggap(eb) < n)
	memmove(Gline(eb)+Ggap(eb), Gline(eb)+Ggap(eb)+Ggapsize(eb), (n-Ggap(eb)) * sizeof(uchar *));
    Ggap(eb) = n;
    Ggapsize(eb) += nlines;
}
#endif
static long parsenum(editbuffer_t *eb)
/* parse and return a decimal integer */
{
    int c;
    long ret = 0;
    for (c=in_buffer_getc(eb); isdigit(c); c=in_buffer_getc(eb))
	ret = (ret * 10) + (c - '0');
    in_buffer_ungetc(eb);
    return ret;
}

enum edit_op {eof, append, delete, replace};

static enum edit_op parse_next_delta_command(editbuffer_t *eb,
					     struct diffcmd *dc)
{
    int cmd;
    long line1, nlines;

    cmd = in_buffer_getc(eb);
    if (cmd==EOF)
	return eof;

    /*
     * 1.11 sometines issues replacement text without ops at the front. Example:
     *
     * 1.40414
     * log
     * @Updating build number tracker
     * @
     * text
     * @#Build Number for ANT. Do not edit!
     * #Wed Jan 13 07:35:14 CET 2016
     * build.number=41316
     * @
     */
    if (cmd != 'a' && cmd != 'd')
	return replace;
    
    line1 = parsenum(eb);

    while (in_buffer_getc(eb) == ' ')
	;
    in_buffer_ungetc(eb);

    nlines = parsenum(eb);

    while (in_buffer_getc(eb) != '\n')
	;

    if (!nlines || line1+nlines < line1)
	fatal_error("corrupt delta in %s", eb->Gfilename);

    if (cmd == 'a') {
	if (line1 < dc->adprev)
	    fatal_error("backward insertion in delta");
	dc->adprev = line1 + 1;
    } else if (cmd == 'd') {
	if (line1 < dc->adprev  ||  line1 < dc->dafter)
	    fatal_error("backward deletion in delta");
	dc->adprev = line1;
	dc->dafter = line1 + nlines;
    }

    dc->line1 = line1;
    dc->nlines = nlines;
    return cmd == 'a' ? append : delete;
}

static void escape_string(editbuffer_t *eb, register char const *s)
{
    for (;;) {
	register char c;
	switch((c = *s++)) {
	case 0:		return;
	case '\t':	out_fputs(eb, "\\t"); break;
	case '\n':	out_fputs(eb, "\\n"); break;
	case ' ':	out_fputs(eb, "\\040"); break;
	case KDELIM:	out_fputs(eb, "\\044"); break;
	case '\\':	out_fputs(eb, "\\\\"); break;
	default:	out_putc(eb, c); break;
	}
    }
}

static void keyreplace(editbuffer_t *eb, enum markers marker)
/* output the appropriate keyword value(s) */
{
    char *leader = NULL;
    char date_string[25];
    enum expand_mode exp = eb->Gexpand;
    char const *kw = Keyword[(int)marker];
    time_t utime = RCS_EPOCH + eb->Gversion->date;

    strftime(date_string, 25, "%Y/%m/%d %H:%M:%S", localtime(&utime));

    if (exp != EXPANDKV) {
        out_printf(eb, "%c%s", KDELIM, kw);
    }

    /* bug: Locker expansion is not implemented */
    if (exp != EXPANDKK) {
#ifdef __UNUSED__
	const char *target_lockedby = NULL;
#endif /* __UNUSED__ */

	if (exp != EXPANDKV)
	    out_printf(eb, "%c%c", VDELIM, ' ');

	switch(marker) {
	case Author:
	    out_fputs(eb, eb->Gversion->author);
	    break;
	case Date:
	    out_fputs(eb, date_string);
	    break;
	case Id:
	case Header:
	    if (marker == Id )
		escape_string(eb, basefilename(eb->Gfilename));
	    else
		escape_string(eb, getfullRCSname(eb));
	    out_printf(eb, " %s %s %s %s",
		       eb->Gversion_number, date_string,
		       eb->Gversion->author, eb->Gversion->state);
#ifdef __UNUSED__
	    if (target_lockedby && exp == EXPANDKKVL)
		out_printf(eb, " %s", target_lockedby);
#endif /* __UNUSED__ */
	    break;
	case Locker:
#ifdef __UNUSED__
	    if (target_lockedby && exp == EXPANDKKVL)
		out_fputs(eb, target_lockedby);
#endif /* __UNUSED__ */
	    break;
	case Log:
	case RCSfile:
	    escape_string(eb, basefilename(eb->Gfilename));
	    break;
	case Revision:
	    out_fputs(eb, eb->Gversion_number);
	    break;
	case Source:
	    escape_string(eb, getfullRCSname(eb));
	    break;
	case State:
	    out_fputs(eb, eb->Gversion->state);
	    break;
	default:
	    break;
	}

	if (exp != EXPANDKV)
	    out_putc(eb, ' ');
    }

#if 0
/* Closing delimiter is processed again in expandline */
    if (exp != EXPANDKV)
	out_putc(eb, KDELIM);
#endif

    if (marker == Log) {
	char const *xxp;
	const uchar *kdelim_ptr = NULL;
	int c;
	size_t cs, cw, ls;
	/*
	 * "Closing delimiter is processed again in expandline"
	 * does not apply here, since we consume the input.
	 */
	if (exp != EXPANDKV)
	    out_putc(eb, KDELIM);

	kw = eb->Glog;
	ls = strlen(eb->Glog);
	if (sizeof(ciklog)-1<=ls && !memcmp(kw,ciklog,sizeof(ciklog)-1))
	    return;

	/* Back up to the start of the current input line */
	int num_kdelims = 0;
	for (;;) {
	    c = in_buffer_ungetc(eb);
	    if (c == EOF)
		break;
	    if (c == '\n') {
		in_buffer_getc(eb);
		break;
	    }
	    if (c == KDELIM) {
		num_kdelims++;
		/* It is possible to have multiple keywords
		   on one line. Make sure we don't backtrack
		   into some other keyword! */
		if (num_kdelims > 2) {
		    in_buffer_getc(eb);
		    break;
		}
		kdelim_ptr = in_buffer_loc(eb);
	    }
	}

	/* Copy characters before `$Log' into LEADER.  */
	xxp = leader = xmalloc(kdelim_ptr - in_buffer_loc(eb), "keyword expansion");
	for (cs = 0; ;  cs++) {
	    c = in_buffer_getc(eb);
	    if (c == KDELIM)
		break;
	    leader[cs] = c;
	}

	/* Convert traditional C or Pascal leader to ` *'.  */
	for (cw = 0;  cw < cs;  cw++)
	    if (!latin1_whitespace(xxp[cw]))
		break;
	if (cw+1 < cs &&  xxp[cw+1] == '*' &&
	    (xxp[cw] == '/'  ||  xxp[cw] == '(')) {
	    size_t i = cw+1;
	    for (;;) {
		if (++i == cs) {
		    leader[cw] = ' ';
		    break;
		} else if (!latin1_whitespace(xxp[i]))
		    break;
	    }
	}

	/* Skip `$Log ... $' string.  */
	do {
	    c = in_buffer_getc(eb);
	} while (c != KDELIM);

	out_putc(eb, '\n');
	out_awrite(eb, xxp, cs);
	out_printf(eb, "Revision %s  %s  %s",
		   eb->Gversion_number,
		   date_string,
		   eb->Gversion->author);

	/* Do not include state: it may change and is not updated.  */
	cw = cs;
	for (;  cw && (xxp[cw-1]==' ' || xxp[cw-1]=='\t');  --cw)
	    ;
	for (;;) {
	    out_putc(eb, '\n');
	    out_awrite(eb, xxp, cw);
	    if (!ls)
		break;
	    --ls;
	    c = *kw++;
	    if (c != '\n') {
		out_awrite(eb, xxp+cw, cs-cw);
		do {
		    out_putc(eb, c);
		    if (!ls)
			break;
		    --ls;
		    c = *kw++;
		} while (c != '\n');
	    }
	}
	free(leader);
    }
}

static int expandline(editbuffer_t *eb)
{
    register int c = 0;
    char * tp;
    register int e, r;
    char const *tlim;
    enum markers matchresult;
    int orig_size;

    if (eb->Gkvlen < KEYLENGTH+3) {
	eb->Gkvlen = KEYLENGTH + 3;
	eb->Gkeyval = xrealloc(eb->Gkeyval, eb->Gkvlen, "expandline");
    }
    e = 0;
    r = -1;

    for (;;) {
	c = in_buffer_getc(eb);
	for (;;) {
	    switch(c) {
	    case EOF:
		goto uncache_exit;
	    case '\n':
		out_putc(eb, c);
		r = 2;
		goto uncache_exit;
	    case KDELIM:
		r = 0;
		/* check for keyword */
		/* first, copy a long enough string into keystring */
		tp = eb->Gkeyval;
		*tp++ = KDELIM;
		for (;;) {
		    c = in_buffer_getc(eb);
		    if (tp <= &eb->Gkeyval[KEYLENGTH] && latin1_alpha(c))
			*tp++ = c;
		    else
			break;
		}
		*tp++ = c; *tp = '\0';
		matchresult = trymatch(eb->Gkeyval+1);
		if (matchresult==Nomatch) {
		    tp[-1] = 0;
		    out_fputs(eb, eb->Gkeyval);
		    continue;   /* last c handled properly */
		}

		/* Now we have a keyword terminated with a K/VDELIM */
		if (c==VDELIM) {
		    /* try to find closing KDELIM, and replace value */
		    tlim = eb->Gkeyval + eb->Gkvlen;
		    for (;;) {
			c = in_buffer_getc(eb);
			if (c=='\n' || c==KDELIM)
			    break;
			*tp++ =c;
			if (tlim <= tp) {
			    orig_size = eb->Gkvlen;
			    eb->Gkvlen *= 2;
			    eb->Gkeyval = xrealloc(eb->Gkeyval, eb->Gkvlen, "expandline");
			    tlim = eb->Gkeyval + eb->Gkvlen;
			    tp = eb->Gkeyval + orig_size;

			}
			if (c==EOF)
			    goto keystring_eof;
		    }
		    if (c!=KDELIM) {
			/* couldn't find closing KDELIM -- give up */
			*tp = 0;
			out_fputs(eb, eb->Gkeyval);
			continue;   /* last c handled properly */
		    }
		}
		if (eb->Gexpand != EXPANDKV) {
			/*
			 * CVS will expand keywords that have
			 * overlapping delimiters, eg "$Name$Id$".  To
			 * support that(mis)feature, push the closing
			 * delimiter back on the input so that the
			 * loop will resume processing starting with
			 * it.
			 */
			if (c == KDELIM)
				in_buffer_ungetc(eb);
		}
		/* now put out the new keyword value */
		keyreplace(eb, matchresult);
		e = 1;
		break;
	    default:
		out_putc(eb, c);
		r = 0;
		break;
	    }
	    break;
	}
    }

keystring_eof:
    *tp = 0;
    out_fputs(eb, eb->Gkeyval);
uncache_exit:
    return r + e;
}

#if USE_MMAP

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

static uchar *
load_text(editbuffer_t *eb, const cvs_text *text)
{
    struct stat st;
    uchar *base;
    int fd;
    size_t size;
    size_t offset = (size_t)text->offset;

    if (eb->text_map.filename == text->filename) {
	base = eb->text_map.base;
	return base + offset;
    }

    if ((fd = open(text->filename, O_RDONLY)) == -1)
        fatal_system_error("open: %s", text->filename);
    if (fstat(fd, &st) == -1)
        fatal_system_error("fstat: %s", text->filename);
#if SIZE_MAX < LONG_MAX
    /* check will always succed if sizeof(size_t) == sizeof(off_t)  */
    if (st.st_size > SIZE_MAX)
        fatal_error("%s: too big", text->filename);
#endif
    size = st.st_size;
    base = mmap(NULL, size, PROT_READ, MAP_SHARED, fd, 0);
    if (base == MAP_FAILED)
        fatal_system_error("mmap: %s %zu", text->filename, size);
    close(fd);

    munmap(eb->text_map.base, eb->text_map.size);
    eb->text_map.filename = text->filename;
    eb->text_map.base = base;
    eb->text_map.size = size;

    return base + offset;
}

static void
unload_all_text(editbuffer_t *eb)
{
    if (eb->text_map.filename) {
	munmap(eb->text_map.base, eb->text_map.size);
	eb->text_map.filename = NULL;
    }
}

static void
unload_text(editbuffer_t *eb, const cvs_text *text, uchar *data)
{
}
#else
static uchar *
load_text(editbuffer_t *eb, const cvs_text *text)
{
    FILE *f = fopen(text->filename, "rb");
    uchar *data;

    if (!f)
	fatal_error("Cannot open %s", text->filename);
    if (fseek(f, text->offset, SEEK_SET) == -1)
        fatal_system_error("fseek %s", text->filename);
    data = xmalloc(text->length + 2, __func__);
    if (fread(data, 1, text->length, f) != text->length)
        fatal_system_error("short read %s", text->filename);
    if (data[0] != '@') fatal_error("doesn't start with '@'");
    if (data[text->length - 1] != '@') fatal_error("doesn't end with '@'");
    data[text->length] = ' ';
    data[text->length + 1] = '\0';
    fclose(f);
    return data;
}

static void
unload_text(editbuffer_t *eb, const cvs_text *text, uchar *data)
{
    free(data);
}

static void
unload_all_text(editbuffer_t *eb)
{
}
#endif /* !USE_MMAP */

static void process_delta(editbuffer_t *eb, 
			  const node_t *const node, 
			  const enum stringwork func)
{
    long editline = 0, linecnt = 0, adjust = 0;
    enum edit_op editor_command;
    struct diffcmd dc;
    uchar *ptr;

    eb->Glog = node->patch->log;
    in_buffer_init(eb, Gnode_text(eb), true);
    eb->Gversion = node->version;
    cvs_number_string(eb->Gversion->number, eb->Gversion_number, sizeof(eb->Gversion_number));

    switch(func) {
    case ENTER:
	while ( (ptr=in_get_line(eb)) )
	    insertline(eb, editline++, ptr);
	/* coverity[fallthrough] */
    case EDIT:
	dc.dafter = dc.adprev = 0;
	while ((editor_command = parse_next_delta_command(eb, &dc)) != eof) {
	    switch (editor_command)
	    {
	    case append:
		editline = dc.line1 + adjust;
		linecnt = dc.nlines;
		while (linecnt--)
		    insertline(eb, editline++, in_get_line(eb));
		adjust += dc.nlines;
		break;
	    case delete:
		deletelines(eb, dc.line1 - 1 + adjust, dc.nlines);
		adjust -= dc.nlines;
		break;
	    case replace:
		fatal_error("edit operation not found in %s", eb->Gfilename);
	    case eof:
		/* should never happen */
		break;
	    }
	}
	break;
    }
}

static void expandedit(editbuffer_t *eb)
{
#ifdef LINESTATS
    editline_t *p, *lim, *l = Gline(eb);

    for (p=l, lim=l+Ggap(eb);  p<lim;  ) {
	in_buffer_init(eb, (*p++).ptr, false);
	expandline(eb);
    }
    for (p+=Ggapsize(eb), lim=l+Glinemax(eb);  p<lim;  ) {
	in_buffer_init(eb, (*p++).ptr, false);
	expandline(eb);
    }
#else
    uchar **p, **lim, **l = Gline(eb);

    for (p=l, lim=l+Ggap(eb);  p<lim;  ) {
	in_buffer_init(eb, *p++, false);
	expandline(eb);
    }
    for (p+=Ggapsize(eb), lim=l+Glinemax(eb);  p<lim;  ) {
	in_buffer_init(eb, *p++, false);
	expandline(eb);
    }
#endif
}
/*
 * The FASTOUT code is a shameless micro-optimization addressing the
 * fact that without it this out_putc() loop consistently shows up as
 * a severe hotspot.  Flattening it shaves about 1.5% off wall time,
 * which can be significant for large repositories.
 *
 * The author, Laurence Hygate <loz@flower.powernet.co.uk>, says:
 * "snapshotline is mostly called on small text lines so the buffer is
 * unlikely to get enlarged more than once and data is unlikely to
 * drop off cachelines before the memcpy"
 */
#define FASTOUT
static void snapshotline(editbuffer_t *eb, register uchar * l)
{
    register int c;
#ifdef FASTOUT
    struct out_buffer_type *ob = eb->Goutbuf;
    uchar * start = l;
#endif
    do {
#ifndef FASTOUT
	if ((c = *l++) == SDELIM  &&  *l++ != SDELIM)
	    return;
	out_putc(eb, c);
#else
	if ((c = *l++) == SDELIM  &&  *l++ != SDELIM) {
	    l = l - 2;
	    break;
	}
	if (c == SDELIM) {
	    // @@ is a memcpy barrier as we're unescaping it
	    // -1 because if we get here we skipped a SDELIM
	    while (ob->end_of_text - ob->ptr < l - start - 1) {
	    	out_buffer_enlarge(eb);
		ob = eb->Goutbuf;
	    }
	    memcpy(ob->ptr, start, l - start - 1);
	    ob->ptr += l - start - 1;
	    start = l;
	}
#endif
    } while (c != '\n');

#ifdef FASTOUT
    if (l - start != 0) {
	while (ob->end_of_text - ob->ptr < l - start) {
	    out_buffer_enlarge(eb);
            ob = eb->Goutbuf;
	}
	memcpy(ob->ptr, start, l - start);
	ob->ptr += l - start;
    }
#endif /* FASTOUT */
}

#ifdef LINESTATS
static void snapshotline_nodelim(editbuffer_t *eb, editline_t *l)
{
    struct out_buffer_type *ob = eb->Goutbuf;
    size_t chars_read = l->length;
    if (chars_read != 0) {
	while (ob->end_of_text - ob->ptr < chars_read) {
	    out_buffer_enlarge(eb);
	    ob = eb->Goutbuf;
	}
	memcpy(ob->ptr, l->ptr, chars_read);
	ob->ptr += chars_read;
    }
}

static void snapshotedit(editbuffer_t *eb)
{
    editline_t *p, *lim, *l = Gline(eb);

    for (p=l, lim=l+Ggap(eb);  p<lim;  )
	if (p->has_stringdelim)
	    snapshotline(eb, (*p++).ptr);
	else
	    snapshotline_nodelim(eb, p++);

    for (p+=Ggapsize(eb), lim=l+Glinemax(eb);  p<lim;  )
	if (p->has_stringdelim)
	    snapshotline(eb, (*p++).ptr);
	else
	    snapshotline_nodelim(eb, p++);
}
#else
static void snapshotedit(editbuffer_t *eb)
{
    uchar **p, **lim, **l=Gline(eb);
    for (p=l, lim=l+Ggap(eb);  p<lim;  )
	snapshotline(eb, *p++);
    for (p+=Ggapsize(eb), lim=l+Glinemax(eb);  p<lim;  )
	snapshotline(eb, *p++);
}
#endif

static void enter_branch(editbuffer_t *eb, const node_t *const node)
{
#ifdef LINESTATS
    editline_t *p = xmalloc(sizeof(editline_t) * eb->current->linemax, "enter branch");
    memcpy(p, eb->current->line, sizeof(editline_t) * eb->current->linemax);
    ++eb->current;
    eb->current[0] = eb->current[-1];
    eb->current->next_branch = node->sib;
    eb->current->line = p;
#else
    uchar **p = xmalloc(sizeof(uchar *) * eb->current->linemax, "enter branch");
	memcpy(p, eb->current->line, sizeof(uchar *) * eb->current->linemax);
	++eb->current;
	eb->current[0] = eb->current[-1];
	eb->current->next_branch = node->sib;
	eb->current->line = p;
#endif
}

static node_t *generate_setup(generator_t *gen)
{
    if (gen->nodehash.head_node != NULL)
    {
	editbuffer_t *eb = &gen->editbuffer;

	eb->Gkeyval = NULL;
	eb->Gkvlen = 0;

	eb->current = eb->stack;
	eb->Gfilename = gen->master_name;
	if (gen->expand != EXPANDUNSPEC)
	    eb->Gexpand = gen->expand;
	else
	    eb->Gexpand = EXPANDKKV;
	eb->Gabspath = NULL;
	Gline(eb) = NULL; Ggap(eb) = Ggapsize(eb) = Glinemax(eb) = 0;
    }

    return gen->nodehash.head_node;
}

static void generate_wrap(generator_t *gen)
{
    editbuffer_t *eb = &gen->editbuffer;

    free(eb->Gkeyval);
    eb->Gkeyval = NULL;
    eb->Gkvlen = 0;
    free(eb->Gabspath);
    unload_all_text(eb);
}

void generate_files(generator_t *gen,
		    export_options_t *opts,
		    void(*hook)(node_t *node, void *buf, size_t len, export_options_t *opts))
/* export all the revision states of a CVS/RCS master through a hook */
{
    editbuffer_t *eb = &gen->editbuffer;
    node_t *node = generate_setup(gen);

    if (node == NULL)
	return;

    eb->current->node = node;
    eb->current->node_text = load_text(eb, &node->patch->text);
    process_delta(eb, node, ENTER);
    for (;;) {
	if (node->commit != NULL && !node->commit->dead) {
	    out_buffer_init(eb);
	    if (eb->Gexpand < EXPANDKO)
		expandedit(eb);
	    else
		snapshotedit(eb);
	    hook(node, out_buffer_text(eb), out_buffer_count(eb), opts);
	    out_buffer_cleanup(eb);
	}
	node = node->down;
	if (node) {
	    enter_branch(eb, node);
	    goto Next;
	}
	while ((node = eb->current->node->to) == NULL) {
	    unload_text(eb, &eb->current->node->patch->text,
	                eb->current->node_text);
	    free(eb->current->line);
	    if (eb->current == eb->stack)
		goto Done;
	    node = (node_t *)eb->current->next_branch;
	    --eb->current;
	    if (node) {
		enter_branch(eb, node);
		break;
	    }
	}
    Next:
	eb->current->node = node;
	eb->current->node_text = load_text(eb, &node->patch->text);
	process_delta(eb, node, EDIT);
    }
Done:
    generate_wrap(gen);
}

/* end */