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[unleashed.git] / usr / src / cmd / filesync / ignore.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 1995 Sun Microsystems, Inc.  All Rights Reserved
 *
 * module:
 *      ignore.c
 *
 * purpose:
 *      routines to manage the ignore lists and test names against them,
 *
 * contents:
 *      ignore_check ... is a particular file covered by an ignore rule
 *      ignore_file .... add a specific file name to be ignored
 *      ignore_expr .... add a regular expression for files to be ignored
 *      ignore_pgm ..... add a rule to run a program to generate a list
 *      ignore_reset ... flush the internal optimization data structures
 *
 *      static
 *          ign_hash ... maintain a hash table of ignored names
 *          cheap_check. build up a table of safe suffixes
 *
 * notes:
 *      a much simpler implementation could have been provided, but
 *      this test (every file tested against every rule) has the
 *      potential to be EXTREMELY expensive.  This module implements
 *      an engine that attempts to optimize the process of determining
 *      that a file has not been ignored.
 *
 *      the usage scenario is
 *          per base
 *              call ignore_{file,expr,pgm} for each ignore rule
 *              call ignore_check for every file under the base
 *              call ignore_reset when you are done
 */
#ident  "%W%    %E% SMI"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <libgen.h>

#include "filesync.h"
#include "messages.h"

/*
 * routines:
 */
static struct list *ign_hash(const char *, int);
static void cheap_check(const char *);

/*
 * globals
 */
struct list {
        char *l_value;                  /* the actual string            */
        struct list *l_next;            /* pointer to next element      */
};

static struct list *expr_list;          /* list of regular expressions  */
static struct list *file_list[ HASH_SIZE ]; /* hash table of literal names */

static char cheap_last[256];            /* cheap test: last char        */
static char cheap_penu[256];            /* cheap test: penultimate char */

/*
 * routine:
 *      ignore_check
 *
 * purpose:
 *      determine whether or not a particular name matches an ignore pattern.
 *
 * parameters:
 *      file name
 *
 * returns:
 *      true/false
 *
 * note:
 *      becuse this routine is called on every single file in
 *      every single sub-directory, it is critical that we make
 *      it fail quickly for most files.  The purpose of the cheap_last
 *      and cheap_penu arrays is to quickly determine there is no chance
 *      that a name will match any expression.  Most expressions have
 *      wildcards near the front and constant suffixes, so our cheap
 *      test is to look at the last two bytes.
 */
bool_t
ignore_check(const char *name)
{       struct list *lp;
        const char *s;

        /*
         * start with the cheap test
         */
        for (s = name; *s; s++);
        if (cheap_last[ (unsigned char) s[-1] ] == 0 ||
            cheap_penu[ (unsigned char) s[-2] ] == 0)
                return (FALSE);

        /* check the literal names in the hash table            */
        if (ign_hash(name, 0)) {
                if (opt_debug & DBG_IGNORE)
                        fprintf(stderr, "IGNO: match %s\n", name);
                return (TRUE);
        }

        /* check all the regular expressions                    */
        for (lp = expr_list; lp; lp = lp->l_next) {
                if (gmatch(name, lp->l_value) == 0)
                        continue;

                if (opt_debug & DBG_IGNORE)
                        fprintf(stderr, "IGNO: regex %s : %s\n",
                                lp->l_value, name);
                return (TRUE);
        }

        return (FALSE);
}

/*
 * routine:
 *      ignore_file
 *
 * purpose:
 *      to add a specific file to an ignore list
 *
 * parameters:
 *      command to run
 */
void
ignore_file(const char *name)
{
        cheap_check(name);

        (void) ign_hash(name, 1);

        if (opt_debug & DBG_IGNORE)
                fprintf(stderr, "IGNO: add file %s\n", name);
}

/*
 * routine:
 *      ignore_expr
 *
 * purpose:
 *      to add a regular expression to an ignore list
 *
 * parameters:
 *      command to run
 */
void
ignore_expr(const char *expr)
{       struct list *lp;

        cheap_check(expr);

        /* allocate a new node and stick it on the front of the list    */
        lp = malloc(sizeof (*lp));
        if (lp == 0)
                nomem("ignore list");
        lp->l_value = strdup(expr);
        lp->l_next = expr_list;
        expr_list = lp;

        if (opt_debug & DBG_IGNORE)
                fprintf(stderr, "IGNO: add expr %s\n", expr);
}

/*
 * routine:
 *      ignore_pgm
 *
 * purpose:
 *      to run a program and gather up the ignore list it produces
 *
 * parameters:
 *      command to run
 */
void
ignore_pgm(const char *cmd)
{       char *s;
        FILE *fp;
        char inbuf[ MAX_LINE ];

        if (opt_debug & DBG_IGNORE)
                fprintf(stderr, "IGNO: add pgm %s\n", cmd);

        /* run the command and collect its ouput        */
        fp = popen(cmd, "r");
        if (fp == NULL) {
                fprintf(stderr, gettext(ERR_badrun), cmd);
                return;
        }

        /*
         * read each line, strip off the newline and add it to the list
         */
        while (fgets(inbuf, sizeof (inbuf), fp) != 0) {
                /* strip off any trailing newline       */
                for (s = inbuf; *s && *s != '\n'; s++);
                *s = 0;

                /* skip any leading white space         */
                for (s = inbuf; *s == ' ' || *s == '\t'; s++);

                /* add this file to the list            */
                if (*s) {
                        cheap_check(s);
                        (void) ign_hash(s, 1);

                        if (opt_debug & DBG_IGNORE)
                                fprintf(stderr, "IGNO: ... %s\n", s);
                }
        }

        pclose(fp);
}

/*
 * routine:
 *      ign_hash
 *
 * purpose:
 *      to find an entry in the hash list
 *
 * parameters:
 *      name
 *      allocate flag
 *
 * returns:
 *      pointer to new list entry or 0
 */
static struct list *
ign_hash(const char *name, int alloc)
{       const unsigned char *s;
        int i;
        struct list *lp;
        struct list **pp;

        /* perform the hash and find the chain  */
        for (s = (const unsigned char *) name, i = 0; *s; s++)
                i += *s;
        pp = &file_list[i % HASH_SIZE ];

        /* search for the specified entry       */
        for (lp = *pp; lp; lp = *pp) {
                if (strcmp(name, lp->l_value) == 0)
                        return (lp);
                pp = &(lp->l_next);
        }

        /* if caller said alloc, buy a new node and chain it in */
        if (alloc) {
                lp = malloc(sizeof (*lp));
                if (lp == 0)
                        nomem("ignore list");
                lp->l_value = strdup(name);
                lp->l_next = 0;
                *pp = lp;
        }

        return (lp);
}

/*
 * routine:
 *      cheap_check
 *
 * purpose:
 *      to update the cheap-check arrays for an ignore expression
 *
 * parameters:
 *      name/expression
 */
static void
cheap_check(const char *name)
{       const char *s;
        unsigned char c;
        int i;

        for (s = name; *s; s++);
        s--;

        /* if expr ends in a wild card, we are undone           */
        c = *s;
        if (c == '*' || c == '?' || c == ']' || c == '}') {
                for (i = 0; i < 256; i++) {
                        cheap_last[i] = 1;
                        cheap_penu[i] = 1;
                }
                return;
        } else
                cheap_last[c] = 1;

        if (s <= name)
                return;

        /* check the next to last character too         */
        c = s[-1];
        if (c == '*' || c == '?' || c == ']' || c == '}') {
                for (i = 0; i < 256; i++)
                        cheap_penu[i] = 1;
        } else
                cheap_penu[c] = 1;
}

/*
 * routine:
 *      ignore_reset
 *
 * purpose:
 *      to free up all the ignore entries so we can start anew
 */
void
ignore_reset(void)
{       int i;
        struct list *np = 0;    /* for LINT */
        struct list *lp;

        /* clear the cheap check arrays */
        for (i = 0; i < 255; i++) {
                cheap_last[i] = 0;
                cheap_penu[i] = 0;
        }

        /* free all of the literal hash chains  */
        for (i = 0; i < HASH_SIZE; i++) {
                for (lp = file_list[i]; lp; lp = np) {
                        np = lp->l_next;
                        free(lp->l_value);
                        free(lp);
                }
                file_list[i] = 0;
        }

        /* free all of the expressions on the chain     */
        for (lp = expr_list; lp; lp = np) {
                np = lp->l_next;
                free(lp->l_value);
                free(lp);
        }
        expr_list = 0;
}