Re-indent some code in set_file_attrs() to make the flow clearer.

[rsync.git] / exclude.c

/*
 * The filter include/exclude routines.
 *
 * Copyright (C) 1996-2001 Andrew Tridgell <tridge@samba.org>
 * Copyright (C) 1996 Paul Mackerras
 * Copyright (C) 2002 Martin Pool
 * Copyright (C) 2003-2007 Wayne Davison
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, visit the http://fsf.org website.
 */

#include "rsync.h"

extern int verbose;
extern int am_server;
extern int am_sender;
extern int eol_nulls;
extern int io_error;
extern int local_server;
extern int prune_empty_dirs;
extern int ignore_perishable;
extern int delete_mode;
extern int delete_excluded;
extern int cvs_exclude;
extern int sanitize_paths;
extern int protocol_version;
extern int module_id;

extern char curr_dir[];
extern unsigned int curr_dir_len;
extern unsigned int module_dirlen;

struct filter_list_struct filter_list = { 0, 0, "" };
struct filter_list_struct cvs_filter_list = { 0, 0, " [global CVS]" };
struct filter_list_struct server_filter_list = { 0, 0, " [daemon]" };

/* Need room enough for ":MODS " prefix plus some room to grow. */
#define MAX_RULE_PREFIX (16)

#define MODIFIERS_MERGE_FILE "-+Cenw"
#define MODIFIERS_INCL_EXCL "/!Crsp"
#define MODIFIERS_HIDE_PROTECT "/!p"

/* The dirbuf is set by push_local_filters() to the current subdirectory
 * relative to curr_dir that is being processed.  The path always has a
 * trailing slash appended, and the variable dirbuf_len contains the length
 * of this path prefix.  The path is always absolute. */
static char dirbuf[MAXPATHLEN+1];
static unsigned int dirbuf_len = 0;
static int dirbuf_depth;

/* This is True when we're scanning parent dirs for per-dir merge-files. */
static BOOL parent_dirscan = False;

/* This array contains a list of all the currently active per-dir merge
 * files.  This makes it easier to save the appropriate values when we
 * "push" down into each subdirectory. */
static struct filter_struct **mergelist_parents;
static int mergelist_cnt = 0;
static int mergelist_size = 0;

/* Each filter_list_struct describes a singly-linked list by keeping track
 * of both the head and tail pointers.  The list is slightly unusual in that
 * a parent-dir's content can be appended to the end of the local list in a
 * special way:  the last item in the local list has its "next" pointer set
 * to point to the inherited list, but the local list's tail pointer points
 * at the end of the local list.  Thus, if the local list is empty, the head
 * will be pointing at the inherited content but the tail will be NULL.  To
 * help you visualize this, here are the possible list arrangements:
 *
 * Completely Empty                     Local Content Only
 * ==================================   ====================================
 * head -> NULL                         head -> Local1 -> Local2 -> NULL
 * tail -> NULL                         tail -------------^
 *
 * Inherited Content Only               Both Local and Inherited Content
 * ==================================   ====================================
 * head -> Parent1 -> Parent2 -> NULL   head -> L1 -> L2 -> P1 -> P2 -> NULL
 * tail -> NULL                         tail ---------^
 *
 * This means that anyone wanting to traverse the whole list to use it just
 * needs to start at the head and use the "next" pointers until it goes
 * NULL.  To add new local content, we insert the item after the tail item
 * and update the tail (obviously, if "tail" was NULL, we insert it at the
 * head).  To clear the local list, WE MUST NOT FREE THE INHERITED CONTENT
 * because it is shared between the current list and our parent list(s).
 * The easiest way to handle this is to simply truncate the list after the
 * tail item and then free the local list from the head.  When inheriting
 * the list for a new local dir, we just save off the filter_list_struct
 * values (so we can pop back to them later) and set the tail to NULL.
 */

static void free_filter(struct filter_struct *ex)
{
        if (ex->match_flags & MATCHFLG_PERDIR_MERGE) {
                free(ex->u.mergelist->debug_type);
                free(ex->u.mergelist);
                mergelist_cnt--;
        }
        free(ex->pattern);
        free(ex);
}

/* Build a filter structure given a filter pattern.  The value in "pat"
 * is not null-terminated. */
static void add_rule(struct filter_list_struct *listp, const char *pat,
                     unsigned int pat_len, uint32 mflags, int xflags)
{
        struct filter_struct *ret;
        const char *cp;
        unsigned int ex_len;

        if (verbose > 2) {
                rprintf(FINFO, "[%s] add_rule(%s%.*s%s)%s\n",
                        who_am_i(), get_rule_prefix(mflags, pat, 0, NULL),
                        (int)pat_len, pat,
                        (mflags & MATCHFLG_DIRECTORY) ? "/" : "",
                        listp->debug_type);
        }

        /* These flags also indicate that we're reading a list that
         * needs to be filtered now, not post-filtered later. */
        if (xflags & (XFLG_ANCHORED2ABS|XFLG_ABS_IF_SLASH)) {
                uint32 mf = mflags & (MATCHFLG_RECEIVER_SIDE|MATCHFLG_SENDER_SIDE);
                if (am_sender) {
                        if (mf == MATCHFLG_RECEIVER_SIDE)
                                return;
                } else {
                        if (mf == MATCHFLG_SENDER_SIDE)
                                return;
                }
        }

        if (!(ret = new0(struct filter_struct)))
                out_of_memory("add_rule");

        if (!(mflags & (MATCHFLG_ABS_PATH | MATCHFLG_MERGE_FILE))
         && ((xflags & (XFLG_ANCHORED2ABS|XFLG_ABS_IF_SLASH) && *pat == '/')
          || (xflags & XFLG_ABS_IF_SLASH && strchr(pat, '/') != NULL))) {
                mflags |= MATCHFLG_ABS_PATH;
                if (*pat == '/')
                        ex_len = dirbuf_len - module_dirlen - 1;
                else
                        ex_len = 0;
        } else
                ex_len = 0;
        if (!(ret->pattern = new_array(char, ex_len + pat_len + 1)))
                out_of_memory("add_rule");
        if (ex_len)
                memcpy(ret->pattern, dirbuf + module_dirlen, ex_len);
        strlcpy(ret->pattern + ex_len, pat, pat_len + 1);
        pat_len += ex_len;

        if (strpbrk(ret->pattern, "*[?")) {
                mflags |= MATCHFLG_WILD;
                if ((cp = strstr(ret->pattern, "**")) != NULL) {
                        mflags |= MATCHFLG_WILD2;
                        /* If the pattern starts with **, note that. */
                        if (cp == ret->pattern)
                                mflags |= MATCHFLG_WILD2_PREFIX;
                        /* If the pattern ends with ***, note that. */
                        if (pat_len >= 3
                         && ret->pattern[pat_len-3] == '*'
                         && ret->pattern[pat_len-2] == '*'
                         && ret->pattern[pat_len-1] == '*')
                                mflags |= MATCHFLG_WILD3_SUFFIX;
                }
        }

        if (pat_len > 1 && ret->pattern[pat_len-1] == '/') {
                ret->pattern[pat_len-1] = 0;
                mflags |= MATCHFLG_DIRECTORY;
        }

        if (mflags & MATCHFLG_PERDIR_MERGE) {
                struct filter_list_struct *lp;
                unsigned int len;
                int i;

                if ((cp = strrchr(ret->pattern, '/')) != NULL)
                        cp++;
                else
                        cp = ret->pattern;

                /* If the local merge file was already mentioned, don't
                 * add it again. */
                for (i = 0; i < mergelist_cnt; i++) {
                        struct filter_struct *ex = mergelist_parents[i];
                        const char *s = strrchr(ex->pattern, '/');
                        if (s)
                                s++;
                        else
                                s = ex->pattern;
                        len = strlen(s);
                        if (len == pat_len - (cp - ret->pattern)
                            && memcmp(s, cp, len) == 0) {
                                free_filter(ret);
                                return;
                        }
                }

                if (!(lp = new_array(struct filter_list_struct, 1)))
                        out_of_memory("add_rule");
                lp->head = lp->tail = NULL;
                if (asprintf(&lp->debug_type, " [per-dir %s]", cp) < 0)
                        out_of_memory("add_rule");
                ret->u.mergelist = lp;

                if (mergelist_cnt == mergelist_size) {
                        mergelist_size += 5;
                        mergelist_parents = realloc_array(mergelist_parents,
                                                struct filter_struct *,
                                                mergelist_size);
                        if (!mergelist_parents)
                                out_of_memory("add_rule");
                }
                mergelist_parents[mergelist_cnt++] = ret;
        } else {
                for (cp = ret->pattern; (cp = strchr(cp, '/')) != NULL; cp++)
                        ret->u.slash_cnt++;
        }

        ret->match_flags = mflags;

        if (!listp->tail) {
                ret->next = listp->head;
                listp->head = listp->tail = ret;
        } else {
                ret->next = listp->tail->next;
                listp->tail->next = ret;
                listp->tail = ret;
        }
}

static void clear_filter_list(struct filter_list_struct *listp)
{
        if (listp->tail) {
                struct filter_struct *ent, *next;
                /* Truncate any inherited items from the local list. */
                listp->tail->next = NULL;
                /* Now free everything that is left. */
                for (ent = listp->head; ent; ent = next) {
                        next = ent->next;
                        free_filter(ent);
                }
        }

        listp->head = listp->tail = NULL;
}

/* This returns an expanded (absolute) filename for the merge-file name if
 * the name has any slashes in it OR if the parent_dirscan var is True;
 * otherwise it returns the original merge_file name.  If the len_ptr value
 * is non-NULL the merge_file name is limited by the referenced length
 * value and will be updated with the length of the resulting name.  We
 * always return a name that is null terminated, even if the merge_file
 * name was not. */
static char *parse_merge_name(const char *merge_file, unsigned int *len_ptr,
                              unsigned int prefix_skip)
{
        static char buf[MAXPATHLEN];
        char *fn, tmpbuf[MAXPATHLEN];
        unsigned int fn_len;

        if (!parent_dirscan && *merge_file != '/') {
                /* Return the name unchanged it doesn't have any slashes. */
                if (len_ptr) {
                        const char *p = merge_file + *len_ptr;
                        while (--p > merge_file && *p != '/') {}
                        if (p == merge_file) {
                                strlcpy(buf, merge_file, *len_ptr + 1);
                                return buf;
                        }
                } else if (strchr(merge_file, '/') == NULL)
                        return (char *)merge_file;
        }

        fn = *merge_file == '/' ? buf : tmpbuf;
        if (sanitize_paths) {
                const char *r = prefix_skip ? "/" : NULL;
                /* null-terminate the name if it isn't already */
                if (len_ptr && merge_file[*len_ptr]) {
                        char *to = fn == buf ? tmpbuf : buf;
                        strlcpy(to, merge_file, *len_ptr + 1);
                        merge_file = to;
                }
                if (!sanitize_path(fn, merge_file, r, dirbuf_depth)) {
                        rprintf(FERROR, "merge-file name overflows: %s\n",
                                merge_file);
                        return NULL;
                }
                fn_len = strlen(fn);
        } else {
                strlcpy(fn, merge_file, len_ptr ? *len_ptr + 1 : MAXPATHLEN);
                fn_len = clean_fname(fn, CFN_COLLAPSE_DOT_DOT_DIRS);
        }

        /* If the name isn't in buf yet, it's wasn't absolute. */
        if (fn != buf) {
                if (dirbuf_len + fn_len >= MAXPATHLEN) {
                        rprintf(FERROR, "merge-file name overflows: %s\n", fn);
                        return NULL;
                }
                memcpy(buf, dirbuf + prefix_skip, dirbuf_len - prefix_skip);
                memcpy(buf + dirbuf_len - prefix_skip, fn, fn_len + 1);
                fn_len = clean_fname(buf, CFN_COLLAPSE_DOT_DOT_DIRS);
        }

        if (len_ptr)
                *len_ptr = fn_len;
        return buf;
}

/* Sets the dirbuf and dirbuf_len values. */
void set_filter_dir(const char *dir, unsigned int dirlen)
{
        unsigned int len;
        if (*dir != '/') {
                memcpy(dirbuf, curr_dir, curr_dir_len);
                dirbuf[curr_dir_len] = '/';
                len = curr_dir_len + 1;
                if (len + dirlen >= MAXPATHLEN)
                        dirlen = 0;
        } else
                len = 0;
        memcpy(dirbuf + len, dir, dirlen);
        dirbuf[dirlen + len] = '\0';
        dirbuf_len = clean_fname(dirbuf, CFN_COLLAPSE_DOT_DOT_DIRS);
        if (dirbuf_len > 1 && dirbuf[dirbuf_len-1] == '.'
            && dirbuf[dirbuf_len-2] == '/')
                dirbuf_len -= 2;
        if (dirbuf_len != 1)
                dirbuf[dirbuf_len++] = '/';
        dirbuf[dirbuf_len] = '\0';
        if (sanitize_paths)
                dirbuf_depth = count_dir_elements(dirbuf + module_dirlen);
}

/* This routine takes a per-dir merge-file entry and finishes its setup.
 * If the name has a path portion then we check to see if it refers to a
 * parent directory of the first transfer dir.  If it does, we scan all the
 * dirs from that point through the parent dir of the transfer dir looking
 * for the per-dir merge-file in each one. */
static BOOL setup_merge_file(struct filter_struct *ex,
                             struct filter_list_struct *lp)
{
        char buf[MAXPATHLEN];
        char *x, *y, *pat = ex->pattern;
        unsigned int len;

        if (!(x = parse_merge_name(pat, NULL, 0)) || *x != '/')
                return 0;

        y = strrchr(x, '/');
        *y = '\0';
        ex->pattern = strdup(y+1);
        if (!*x)
                x = "/";
        if (*x == '/')
                strlcpy(buf, x, MAXPATHLEN);
        else
                pathjoin(buf, MAXPATHLEN, dirbuf, x);

        len = clean_fname(buf, CFN_COLLAPSE_DOT_DOT_DIRS);
        if (len != 1 && len < MAXPATHLEN-1) {
                buf[len++] = '/';
                buf[len] = '\0';
        }
        /* This ensures that the specified dir is a parent of the transfer. */
        for (x = buf, y = dirbuf; *x && *x == *y; x++, y++) {}
        if (*x)
                y += strlen(y); /* nope -- skip the scan */

        parent_dirscan = True;
        while (*y) {
                char save[MAXPATHLEN];
                strlcpy(save, y, MAXPATHLEN);
                *y = '\0';
                dirbuf_len = y - dirbuf;
                strlcpy(x, ex->pattern, MAXPATHLEN - (x - buf));
                parse_filter_file(lp, buf, ex->match_flags, XFLG_ANCHORED2ABS);
                if (ex->match_flags & MATCHFLG_NO_INHERIT)
                        lp->head = NULL;
                lp->tail = NULL;
                strlcpy(y, save, MAXPATHLEN);
                while ((*x++ = *y++) != '/') {}
        }
        parent_dirscan = False;
        free(pat);
        return 1;
}

/* Each time rsync changes to a new directory it call this function to
 * handle all the per-dir merge-files.  The "dir" value is the current path
 * relative to curr_dir (which might not be null-terminated).  We copy it
 * into dirbuf so that we can easily append a file name on the end. */
void *push_local_filters(const char *dir, unsigned int dirlen)
{
        struct filter_list_struct *ap, *push;
        int i;

        set_filter_dir(dir, dirlen);

        if (!mergelist_cnt)
                return NULL;

        push = new_array(struct filter_list_struct, mergelist_cnt);
        if (!push)
                out_of_memory("push_local_filters");

        for (i = 0, ap = push; i < mergelist_cnt; i++) {
                memcpy(ap++, mergelist_parents[i]->u.mergelist,
                       sizeof (struct filter_list_struct));
        }

        /* Note: parse_filter_file() might increase mergelist_cnt, so keep
         * this loop separate from the above loop. */
        for (i = 0; i < mergelist_cnt; i++) {
                struct filter_struct *ex = mergelist_parents[i];
                struct filter_list_struct *lp = ex->u.mergelist;

                if (verbose > 2) {
                        rprintf(FINFO, "[%s] pushing filter list%s\n",
                                who_am_i(), lp->debug_type);
                }

                lp->tail = NULL; /* Switch any local rules to inherited. */
                if (ex->match_flags & MATCHFLG_NO_INHERIT)
                        lp->head = NULL;

                if (ex->match_flags & MATCHFLG_FINISH_SETUP) {
                        ex->match_flags &= ~MATCHFLG_FINISH_SETUP;
                        if (setup_merge_file(ex, lp))
                                set_filter_dir(dir, dirlen);
                }

                if (strlcpy(dirbuf + dirbuf_len, ex->pattern,
                    MAXPATHLEN - dirbuf_len) < MAXPATHLEN - dirbuf_len) {
                        parse_filter_file(lp, dirbuf, ex->match_flags,
                                          XFLG_ANCHORED2ABS);
                } else {
                        io_error |= IOERR_GENERAL;
                        rprintf(FINFO,
                            "cannot add local filter rules in long-named directory: %s\n",
                            full_fname(dirbuf));
                }
                dirbuf[dirbuf_len] = '\0';
        }

        return (void*)push;
}

void pop_local_filters(void *mem)
{
        struct filter_list_struct *ap, *pop = (struct filter_list_struct*)mem;
        int i;

        for (i = mergelist_cnt; i-- > 0; ) {
                struct filter_struct *ex = mergelist_parents[i];
                struct filter_list_struct *lp = ex->u.mergelist;

                if (verbose > 2) {
                        rprintf(FINFO, "[%s] popping filter list%s\n",
                                who_am_i(), lp->debug_type);
                }

                clear_filter_list(lp);
        }

        if (!pop)
                return;

        for (i = 0, ap = pop; i < mergelist_cnt; i++) {
                memcpy(mergelist_parents[i]->u.mergelist, ap++,
                       sizeof (struct filter_list_struct));
        }

        free(pop);
}

void change_local_filter_dir(const char *dname, int dlen, int dir_depth)
{
        static int cur_depth = -1;
        static void *filt_array[MAXPATHLEN/2+1];

        if (!dname) {
                for ( ; cur_depth >= 0; cur_depth--) {
                        if (filt_array[cur_depth]) {
                                pop_local_filters(filt_array[cur_depth]);
                                filt_array[cur_depth] = NULL;
                        }
                }
                return;
        }

        assert(dir_depth < MAXPATHLEN/2+1);

        for ( ; cur_depth >= dir_depth; cur_depth--) {
                if (filt_array[cur_depth]) {
                        pop_local_filters(filt_array[cur_depth]);
                        filt_array[cur_depth] = NULL;
                }
        }

        cur_depth = dir_depth;
        filt_array[cur_depth] = push_local_filters(dname, dlen);
}

static int rule_matches(char *fname, struct filter_struct *ex, int name_is_dir)
{
        int slash_handling, str_cnt = 0, anchored_match = 0;
        int ret_match = ex->match_flags & MATCHFLG_NEGATE ? 0 : 1;
        char *p, *pattern = ex->pattern;
        const char *strings[16]; /* more than enough */
        char *name = fname + (*fname == '/');

        if (!*name)
                return 0;

        if (!ex->u.slash_cnt && !(ex->match_flags & MATCHFLG_WILD2)) {
                /* If the pattern does not have any slashes AND it does
                 * not have a "**" (which could match a slash), then we
                 * just match the name portion of the path. */
                if ((p = strrchr(name,'/')) != NULL)
                        name = p+1;
        } else if (ex->match_flags & MATCHFLG_ABS_PATH && *fname != '/'
            && curr_dir_len > module_dirlen + 1) {
                /* If we're matching against an absolute-path pattern,
                 * we need to prepend our full path info. */
                strings[str_cnt++] = curr_dir + module_dirlen + 1;
                strings[str_cnt++] = "/";
        } else if (ex->match_flags & MATCHFLG_WILD2_PREFIX && *fname != '/') {
                /* Allow "**"+"/" to match at the start of the string. */
                strings[str_cnt++] = "/";
        }
        strings[str_cnt++] = name;
        if (name_is_dir) {
                /* Allow a trailing "/"+"***" to match the directory. */
                if (ex->match_flags & MATCHFLG_WILD3_SUFFIX)
                        strings[str_cnt++] = "/";
        } else if (ex->match_flags & MATCHFLG_DIRECTORY)
                return !ret_match;
        strings[str_cnt] = NULL;

        if (*pattern == '/') {
                anchored_match = 1;
                pattern++;
        }

        if (!anchored_match && ex->u.slash_cnt
            && !(ex->match_flags & MATCHFLG_WILD2)) {
                /* A non-anchored match with an infix slash and no "**"
                 * needs to match the last slash_cnt+1 name elements. */
                slash_handling = ex->u.slash_cnt + 1;
        } else if (!anchored_match && !(ex->match_flags & MATCHFLG_WILD2_PREFIX)
                                   && ex->match_flags & MATCHFLG_WILD2) {
                /* A non-anchored match with an infix or trailing "**" (but not
                 * a prefixed "**") needs to try matching after every slash. */
                slash_handling = -1;
        } else {
                /* The pattern matches only at the start of the path or name. */
                slash_handling = 0;
        }

        if (ex->match_flags & MATCHFLG_WILD) {
                if (wildmatch_array(pattern, strings, slash_handling))
                        return ret_match;
        } else if (str_cnt > 1) {
                if (litmatch_array(pattern, strings, slash_handling))
                        return ret_match;
        } else if (anchored_match) {
                if (strcmp(name, pattern) == 0)
                        return ret_match;
        } else {
                int l1 = strlen(name);
                int l2 = strlen(pattern);
                if (l2 <= l1 &&
                    strcmp(name+(l1-l2),pattern) == 0 &&
                    (l1==l2 || name[l1-(l2+1)] == '/')) {
                        return ret_match;
                }
        }

        return !ret_match;
}


static void report_filter_result(char const *name,
                                 struct filter_struct const *ent,
                                 int name_is_dir, const char *type)
{
        /* If a trailing slash is present to match only directories,
         * then it is stripped out by add_rule().  So as a special
         * case we add it back in here. */

        if (verbose >= 2) {
                static char *actions[2][2]
                    = { {"show", "hid"}, {"risk", "protect"} };
                const char *w = who_am_i();
                rprintf(FINFO, "[%s] %sing %s %s because of pattern %s%s%s\n",
                    w, actions[*w!='s'][!(ent->match_flags&MATCHFLG_INCLUDE)],
                    name_is_dir ? "directory" : "file", name, ent->pattern,
                    ent->match_flags & MATCHFLG_DIRECTORY ? "/" : "", type);
        }
}


/*
 * Return -1 if file "name" is defined to be excluded by the specified
 * exclude list, 1 if it is included, and 0 if it was not matched.
 */
int check_filter(struct filter_list_struct *listp, char *name, int name_is_dir)
{
        struct filter_struct *ent;

        for (ent = listp->head; ent; ent = ent->next) {
                if (ignore_perishable && ent->match_flags & MATCHFLG_PERISHABLE)
                        continue;
                if (ent->match_flags & MATCHFLG_PERDIR_MERGE) {
                        int rc = check_filter(ent->u.mergelist, name,
                                              name_is_dir);
                        if (rc)
                                return rc;
                        continue;
                }
                if (ent->match_flags & MATCHFLG_CVS_IGNORE) {
                        int rc = check_filter(&cvs_filter_list, name,
                                              name_is_dir);
                        if (rc)
                                return rc;
                        continue;
                }
                if (rule_matches(name, ent, name_is_dir)) {
                        report_filter_result(name, ent, name_is_dir,
                                              listp->debug_type);
                        return ent->match_flags & MATCHFLG_INCLUDE ? 1 : -1;
                }
        }

        return 0;
}

#define RULE_STRCMP(s,r) rule_strcmp((s), (r), sizeof (r) - 1)

static const uchar *rule_strcmp(const uchar *str, const char *rule, int rule_len)
{
        if (strncmp((char*)str, rule, rule_len) != 0)
                return NULL;
        if (isspace(str[rule_len]) || str[rule_len] == '_' || !str[rule_len])
                return str + rule_len - 1;
        if (str[rule_len] == ',')
                return str + rule_len;
        return NULL;
}

/* Get the next include/exclude arg from the string.  The token will not
 * be '\0' terminated, so use the returned length to limit the string.
 * Also, be sure to add this length to the returned pointer before passing
 * it back to ask for the next token.  This routine parses the "!" (list-
 * clearing) token and (depending on the mflags) the various prefixes.
 * The *mflags_ptr value will be set on exit to the new MATCHFLG_* bits
 * for the current token. */
static const char *parse_rule_tok(const char *p, uint32 mflags, int xflags,
                                  unsigned int *len_ptr, uint32 *mflags_ptr)
{
        const uchar *s = (const uchar *)p;
        uint32 new_mflags;
        unsigned int len;

        if (mflags & MATCHFLG_WORD_SPLIT) {
                /* Skip over any initial whitespace. */
                while (isspace(*s))
                        s++;
                /* Update to point to real start of rule. */
                p = (const char *)s;
        }
        if (!*s)
                return NULL;

        new_mflags = mflags & MATCHFLGS_FROM_CONTAINER;

        /* Figure out what kind of a filter rule "s" is pointing at.  Note
         * that if MATCHFLG_NO_PREFIXES is set, the rule is either an include
         * or an exclude based on the inheritance of the MATCHFLG_INCLUDE
         * flag (above).  XFLG_OLD_PREFIXES indicates a compatibility mode
         * for old include/exclude patterns where just "+ " and "- " are
         * allowed as optional prefixes.  */
        if (mflags & MATCHFLG_NO_PREFIXES) {
                if (*s == '!' && mflags & MATCHFLG_CVS_IGNORE)
                        new_mflags |= MATCHFLG_CLEAR_LIST; /* Tentative! */
        } else if (xflags & XFLG_OLD_PREFIXES) {
                if (*s == '-' && s[1] == ' ') {
                        new_mflags &= ~MATCHFLG_INCLUDE;
                        s += 2;
                } else if (*s == '+' && s[1] == ' ') {
                        new_mflags |= MATCHFLG_INCLUDE;
                        s += 2;
                } else if (*s == '!')
                        new_mflags |= MATCHFLG_CLEAR_LIST; /* Tentative! */
        } else {
                char ch = 0, *mods = "";
                switch (*s) {
                case 'c':
                        if ((s = RULE_STRCMP(s, "clear")) != NULL)
                                ch = '!';
                        break;
                case 'd':
                        if ((s = RULE_STRCMP(s, "dir-merge")) != NULL)
                                ch = ':';
                        break;
                case 'e':
                        if ((s = RULE_STRCMP(s, "exclude")) != NULL)
                                ch = '-';
                        break;
                case 'h':
                        if ((s = RULE_STRCMP(s, "hide")) != NULL)
                                ch = 'H';
                        break;
                case 'i':
                        if ((s = RULE_STRCMP(s, "include")) != NULL)
                                ch = '+';
                        break;
                case 'm':
                        if ((s = RULE_STRCMP(s, "merge")) != NULL)
                                ch = '.';
                        break;
                case 'p':
                        if ((s = RULE_STRCMP(s, "protect")) != NULL)
                                ch = 'P';
                        break;
                case 'r':
                        if ((s = RULE_STRCMP(s, "risk")) != NULL)
                                ch = 'R';
                        break;
                case 's':
                        if ((s = RULE_STRCMP(s, "show")) != NULL)
                                ch = 'S';
                        break;
                default:
                        ch = *s;
                        if (s[1] == ',')
                                s++;
                        break;
                }
                switch (ch) {
                case ':':
                        new_mflags |= MATCHFLG_PERDIR_MERGE
                                    | MATCHFLG_FINISH_SETUP;
                        /* FALL THROUGH */
                case '.':
                        new_mflags |= MATCHFLG_MERGE_FILE;
                        mods = MODIFIERS_INCL_EXCL MODIFIERS_MERGE_FILE;
                        break;
                case '+':
                        new_mflags |= MATCHFLG_INCLUDE;
                        /* FALL THROUGH */
                case '-':
                        mods = MODIFIERS_INCL_EXCL;
                        break;
                case 'S':
                        new_mflags |= MATCHFLG_INCLUDE;
                        /* FALL THROUGH */
                case 'H':
                        new_mflags |= MATCHFLG_SENDER_SIDE;
                        mods = MODIFIERS_HIDE_PROTECT;
                        break;
                case 'R':
                        new_mflags |= MATCHFLG_INCLUDE;
                        /* FALL THROUGH */
                case 'P':
                        new_mflags |= MATCHFLG_RECEIVER_SIDE;
                        mods = MODIFIERS_HIDE_PROTECT;
                        break;
                case '!':
                        new_mflags |= MATCHFLG_CLEAR_LIST;
                        mods = NULL;
                        break;
                default:
                        rprintf(FERROR, "Unknown filter rule: `%s'\n", p);
                        exit_cleanup(RERR_SYNTAX);
                }
                while (mods && *++s && *s != ' ' && *s != '_') {
                        if (strchr(mods, *s) == NULL) {
                                if (mflags & MATCHFLG_WORD_SPLIT && isspace(*s)) {
                                        s--;
                                        break;
                                }
                            invalid:
                                rprintf(FERROR,
                                        "invalid modifier sequence at '%c' in filter rule: %s\n",
                                        *s, p);
                                exit_cleanup(RERR_SYNTAX);
                        }
                        switch (*s) {
                        case '-':
                                if (new_mflags & MATCHFLG_NO_PREFIXES)
                                    goto invalid;
                                new_mflags |= MATCHFLG_NO_PREFIXES;
                                break;
                        case '+':
                                if (new_mflags & MATCHFLG_NO_PREFIXES)
                                    goto invalid;
                                new_mflags |= MATCHFLG_NO_PREFIXES
                                            | MATCHFLG_INCLUDE;
                                break;
                        case '/':
                                new_mflags |= MATCHFLG_ABS_PATH;
                                break;
                        case '!':
                                new_mflags |= MATCHFLG_NEGATE;
                                break;
                        case 'C':
                                if (new_mflags & MATCHFLG_NO_PREFIXES)
                                    goto invalid;
                                new_mflags |= MATCHFLG_NO_PREFIXES
                                            | MATCHFLG_WORD_SPLIT
                                            | MATCHFLG_NO_INHERIT
                                            | MATCHFLG_CVS_IGNORE;
                                break;
                        case 'e':
                                new_mflags |= MATCHFLG_EXCLUDE_SELF;
                                break;
                        case 'n':
                                new_mflags |= MATCHFLG_NO_INHERIT;
                                break;
                        case 'p':
                                new_mflags |= MATCHFLG_PERISHABLE;
                                break;
                        case 'r':
                                new_mflags |= MATCHFLG_RECEIVER_SIDE;
                                break;
                        case 's':
                                new_mflags |= MATCHFLG_SENDER_SIDE;
                                break;
                        case 'w':
                                new_mflags |= MATCHFLG_WORD_SPLIT;
                                break;
                        }
                }
                if (*s)
                        s++;
        }

        if (mflags & MATCHFLG_WORD_SPLIT) {
                const uchar *cp = s;
                /* Token ends at whitespace or the end of the string. */
                while (!isspace(*cp) && *cp != '\0')
                        cp++;
                len = cp - s;
        } else
                len = strlen((char*)s);

        if (new_mflags & MATCHFLG_CLEAR_LIST) {
                if (!(mflags & MATCHFLG_NO_PREFIXES)
                 && !(xflags & XFLG_OLD_PREFIXES) && len) {
                        rprintf(FERROR,
                                "'!' rule has trailing characters: %s\n", p);
                        exit_cleanup(RERR_SYNTAX);
                }
                if (len > 1)
                        new_mflags &= ~MATCHFLG_CLEAR_LIST;
        } else if (!len && !(new_mflags & MATCHFLG_CVS_IGNORE)) {
                rprintf(FERROR, "unexpected end of filter rule: %s\n", p);
                exit_cleanup(RERR_SYNTAX);
        }

        /* --delete-excluded turns an un-modified include/exclude into a
         * sender-side rule.  We also affect per-dir merge files that take
         * no prefixes as a simple optimization. */
        if (delete_excluded
         && !(new_mflags & (MATCHFLG_RECEIVER_SIDE|MATCHFLG_SENDER_SIDE))
         && (!(new_mflags & MATCHFLG_PERDIR_MERGE)
          || new_mflags & MATCHFLG_NO_PREFIXES))
                new_mflags |= MATCHFLG_SENDER_SIDE;

        *len_ptr = len;
        *mflags_ptr = new_mflags;
        return (const char *)s;
}


static char default_cvsignore[] =
        /* These default ignored items come from the CVS manual. */
        "RCS SCCS CVS CVS.adm RCSLOG cvslog.* tags TAGS"
        " .make.state .nse_depinfo *~ #* .#* ,* _$* *$"
        " *.old *.bak *.BAK *.orig *.rej .del-*"
        " *.a *.olb *.o *.obj *.so *.exe"
        " *.Z *.elc *.ln core"
        /* The rest we added to suit ourself. */
        " .svn/ .git/ .bzr/";

static void get_cvs_excludes(uint32 mflags)
{
        static int initialized = 0;
        char *p, fname[MAXPATHLEN];

        if (initialized)
                return;
        initialized = 1;

        parse_rule(&cvs_filter_list, default_cvsignore,
                   mflags | (protocol_version >= 30 ? MATCHFLG_PERISHABLE : 0),
                   0);

        p = module_id >= 0 && lp_use_chroot(module_id) ? "/" : getenv("HOME");
        if (p && pathjoin(fname, MAXPATHLEN, p, ".cvsignore") < MAXPATHLEN)
                parse_filter_file(&cvs_filter_list, fname, mflags, 0);

        parse_rule(&cvs_filter_list, getenv("CVSIGNORE"), mflags, 0);
}


void parse_rule(struct filter_list_struct *listp, const char *pattern,
                uint32 mflags, int xflags)
{
        unsigned int pat_len;
        uint32 new_mflags;
        const char *cp, *p;

        if (!pattern)
                return;

        while (1) {
                /* Remember that the returned string is NOT '\0' terminated! */
                cp = parse_rule_tok(pattern, mflags, xflags,
                                    &pat_len, &new_mflags);
                if (!cp)
                        break;

                pattern = cp + pat_len;

                if (pat_len >= MAXPATHLEN) {
                        rprintf(FERROR, "discarding over-long filter: %.*s\n",
                                (int)pat_len, cp);
                        continue;
                }

                if (new_mflags & MATCHFLG_CLEAR_LIST) {
                        if (verbose > 2) {
                                rprintf(FINFO,
                                        "[%s] clearing filter list%s\n",
                                        who_am_i(), listp->debug_type);
                        }
                        clear_filter_list(listp);
                        continue;
                }

                if (new_mflags & MATCHFLG_MERGE_FILE) {
                        unsigned int len;
                        if (!pat_len) {
                                cp = ".cvsignore";
                                pat_len = 10;
                        }
                        len = pat_len;
                        if (new_mflags & MATCHFLG_EXCLUDE_SELF) {
                                const char *name = cp + len;
                                while (name > cp && name[-1] != '/') name--;
                                len -= name - cp;
                                add_rule(listp, name, len, 0, 0);
                                new_mflags &= ~MATCHFLG_EXCLUDE_SELF;
                                len = pat_len;
                        }
                        if (new_mflags & MATCHFLG_PERDIR_MERGE) {
                                if (parent_dirscan) {
                                        if (!(p = parse_merge_name(cp, &len,
                                                                module_dirlen)))
                                                continue;
                                        add_rule(listp, p, len, new_mflags, 0);
                                        continue;
                                }
                        } else {
                                if (!(p = parse_merge_name(cp, &len, 0)))
                                        continue;
                                parse_filter_file(listp, p, new_mflags,
                                                  XFLG_FATAL_ERRORS);
                                continue;
                        }
                }

                add_rule(listp, cp, pat_len, new_mflags, xflags);

                if (new_mflags & MATCHFLG_CVS_IGNORE
                    && !(new_mflags & MATCHFLG_MERGE_FILE))
                        get_cvs_excludes(new_mflags);
        }
}


void parse_filter_file(struct filter_list_struct *listp, const char *fname,
                       uint32 mflags, int xflags)
{
        FILE *fp;
        char line[BIGPATHBUFLEN];
        char *eob = line + sizeof line - 1;
        int word_split = mflags & MATCHFLG_WORD_SPLIT;

        if (!fname || !*fname)
                return;

        if (*fname != '-' || fname[1] || am_server) {
                if (server_filter_list.head) {
                        strlcpy(line, fname, sizeof line);
                        clean_fname(line, CFN_COLLAPSE_DOT_DOT_DIRS);
                        if (check_filter(&server_filter_list, line, 0) < 0)
                                fp = NULL;
                        else
                                fp = fopen(line, "rb");
                } else
                        fp = fopen(fname, "rb");
        } else
                fp = stdin;

        if (verbose > 2) {
                rprintf(FINFO, "[%s] parse_filter_file(%s,%x,%x)%s\n",
                        who_am_i(), fname, mflags, xflags,
                        fp ? "" : " [not found]");
        }

        if (!fp) {
                if (xflags & XFLG_FATAL_ERRORS) {
                        rsyserr(FERROR, errno,
                                "failed to open %sclude file %s",
                                mflags & MATCHFLG_INCLUDE ? "in" : "ex",
                                fname);
                        exit_cleanup(RERR_FILEIO);
                }
                return;
        }
        dirbuf[dirbuf_len] = '\0';

        while (1) {
                char *s = line;
                int ch, overflow = 0;
                while (1) {
                        if ((ch = getc(fp)) == EOF) {
                                if (ferror(fp) && errno == EINTR) {
                                        clearerr(fp);
                                        continue;
                                }
                                break;
                        }
                        if (word_split && isspace(ch))
                                break;
                        if (eol_nulls? !ch : (ch == '\n' || ch == '\r'))
                                break;
                        if (s < eob)
                                *s++ = ch;
                        else
                                overflow = 1;
                }
                if (overflow) {
                        rprintf(FERROR, "discarding over-long filter: %s...\n", line);
                        s = line;
                }
                *s = '\0';
                /* Skip an empty token and (when line parsing) comments. */
                if (*line && (word_split || (*line != ';' && *line != '#')))
                        parse_rule(listp, line, mflags, xflags);
                if (ch == EOF)
                        break;
        }
        fclose(fp);
}

/* If the "for_xfer" flag is set, the prefix is made compatible with the
 * current protocol_version (if possible) or a NULL is returned (if not
 * possible). */
char *get_rule_prefix(int match_flags, const char *pat, int for_xfer,
                      unsigned int *plen_ptr)
{
        static char buf[MAX_RULE_PREFIX+1];
        char *op = buf;
        int legal_len = for_xfer && protocol_version < 29 ? 1 : MAX_RULE_PREFIX-1;

        if (match_flags & MATCHFLG_PERDIR_MERGE) {
                if (legal_len == 1)
                        return NULL;
                *op++ = ':';
        } else if (match_flags & MATCHFLG_INCLUDE)
                *op++ = '+';
        else if (legal_len != 1
            || ((*pat == '-' || *pat == '+') && pat[1] == ' '))
                *op++ = '-';
        else
                legal_len = 0;

        if (match_flags & MATCHFLG_NEGATE)
                *op++ = '!';
        if (match_flags & MATCHFLG_CVS_IGNORE)
                *op++ = 'C';
        else {
                if (match_flags & MATCHFLG_NO_INHERIT)
                        *op++ = 'n';
                if (match_flags & MATCHFLG_WORD_SPLIT)
                        *op++ = 'w';
                if (match_flags & MATCHFLG_NO_PREFIXES) {
                        if (match_flags & MATCHFLG_INCLUDE)
                                *op++ = '+';
                        else
                                *op++ = '-';
                }
        }
        if (match_flags & MATCHFLG_EXCLUDE_SELF)
                *op++ = 'e';
        if (match_flags & MATCHFLG_SENDER_SIDE
            && (!for_xfer || protocol_version >= 29))
                *op++ = 's';
        if (match_flags & MATCHFLG_RECEIVER_SIDE
            && (!for_xfer || protocol_version >= 29
             || (delete_excluded && am_sender)))
                *op++ = 'r';
        if (match_flags & MATCHFLG_PERISHABLE) {
                if (!for_xfer || protocol_version >= 30)
                        *op++ = 'p';
                else if (am_sender)
                        return NULL;
        }
        if (op - buf > legal_len)
                return NULL;
        if (legal_len)
                *op++ = ' ';
        *op = '\0';
        if (plen_ptr)
                *plen_ptr = op - buf;
        return buf;
}

static void send_rules(int f_out, struct filter_list_struct *flp)
{
        struct filter_struct *ent, *prev = NULL;

        for (ent = flp->head; ent; ent = ent->next) {
                unsigned int len, plen, dlen;
                int elide = 0;
                char *p;

                /* Note we need to check delete_excluded here in addition to
                 * the code in parse_rule_tok() because some rules may have
                 * been added before we found the --delete-excluded option.
                 * We must also elide any CVS merge-file rules to avoid a
                 * backward compatibility problem, and we elide any no-prefix
                 * merge files as an optimization (since they can only have
                 * include/exclude rules). */
                if (ent->match_flags & MATCHFLG_SENDER_SIDE)
                        elide = am_sender ? 1 : -1;
                if (ent->match_flags & MATCHFLG_RECEIVER_SIDE)
                        elide = elide ? 0 : am_sender ? -1 : 1;
                else if (delete_excluded && !elide
                 && (!(ent->match_flags & MATCHFLG_PERDIR_MERGE)
                  || ent->match_flags & MATCHFLG_NO_PREFIXES))
                        elide = am_sender ? 1 : -1;
                if (elide < 0) {
                        if (prev)
                                prev->next = ent->next;
                        else
                                flp->head = ent->next;
                } else
                        prev = ent;
                if (elide > 0)
                        continue;
                if (ent->match_flags & MATCHFLG_CVS_IGNORE
                    && !(ent->match_flags & MATCHFLG_MERGE_FILE)) {
                        int f = am_sender || protocol_version < 29 ? f_out : -2;
                        send_rules(f, &cvs_filter_list);
                        if (f == f_out)
                                continue;
                }
                p = get_rule_prefix(ent->match_flags, ent->pattern, 1, &plen);
                if (!p) {
                        rprintf(FERROR,
                                "filter rules are too modern for remote rsync.\n");
                        exit_cleanup(RERR_PROTOCOL);
                }
                if (f_out < 0)
                        continue;
                len = strlen(ent->pattern);
                dlen = ent->match_flags & MATCHFLG_DIRECTORY ? 1 : 0;
                if (!(plen + len + dlen))
                        continue;
                write_int(f_out, plen + len + dlen);
                if (plen)
                        write_buf(f_out, p, plen);
                write_buf(f_out, ent->pattern, len);
                if (dlen)
                        write_byte(f_out, '/');
        }
        flp->tail = prev;
}

/* This is only called by the client. */
void send_filter_list(int f_out)
{
        int receiver_wants_list = prune_empty_dirs
            || (delete_mode && (!delete_excluded || protocol_version >= 29));

        if (local_server || (am_sender && !receiver_wants_list))
                f_out = -1;
        if (cvs_exclude && am_sender) {
                if (protocol_version >= 29)
                        parse_rule(&filter_list, ":C", 0, 0);
                parse_rule(&filter_list, "-C", 0, 0);
        }

        send_rules(f_out, &filter_list);

        if (f_out >= 0)
                write_int(f_out, 0);

        if (cvs_exclude) {
                if (!am_sender || protocol_version < 29)
                        parse_rule(&filter_list, ":C", 0, 0);
                if (!am_sender)
                        parse_rule(&filter_list, "-C", 0, 0);
        }
}

/* This is only called by the server. */
void recv_filter_list(int f_in)
{
        char line[BIGPATHBUFLEN];
        int xflags = protocol_version >= 29 ? 0 : XFLG_OLD_PREFIXES;
        int receiver_wants_list = prune_empty_dirs
            || (delete_mode
             && (!delete_excluded || protocol_version >= 29));
        unsigned int len;

        if (!local_server && (am_sender || receiver_wants_list)) {
                while ((len = read_int(f_in)) != 0) {
                        if (len >= sizeof line)
                                overflow_exit("recv_rules");
                        read_sbuf(f_in, line, len);
                        parse_rule(&filter_list, line, 0, xflags);
                }
        }

        if (cvs_exclude) {
                if (local_server || am_sender || protocol_version < 29)
                        parse_rule(&filter_list, ":C", 0, 0);
                if (local_server || am_sender)
                        parse_rule(&filter_list, "-C", 0, 0);
        }

        if (local_server) /* filter out any rules that aren't for us. */
                send_rules(-1, &filter_list);
}