/* vi: set sw=4 ts=4: */
/*
 * Utility routines.
 *
 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */
#include "libbb.h"

#undef DEBUG_RECURS_ACTION

/*
 * Walk down all the directories under the specified
 * location, and do something (something specified
 * by the fileAction and dirAction function pointers).
 *
 * Unfortunately, while nftw(3) could replace this and reduce
 * code size a bit, nftw() wasn't supported before GNU libc 2.1,
 * and so isn't sufficiently portable to take over since glibc2.1
 * is so stinking huge.
 */

static int FAST_FUNC true_action(struct recursive_state *state UNUSED_PARAM,
                const char *fileName UNUSED_PARAM,
                struct stat *statbuf UNUSED_PARAM)
{
        return TRUE;
}

/* fileName is (l)stat'ed (depending on ACTION_FOLLOWLINKS[_L0]).
 *
 * If it is a file: fileAction in run on it, its return value is returned.
 *
 * In case we are in a recursive invocation (see below):
 * normally, fileAction should return 1 (TRUE) to indicate that
 * everything is okay and processing should continue.
 * fileAction return value of 0 (FALSE) on any file in directory will make
 * recursive_action() also return 0, but it doesn't stop directory traversal
 * (fileAction/dirAction will be called on each file).
 *
 * [TODO: maybe introduce -1 to mean "stop traversal NOW and return"]
 *
 * If it is a directory:
 *
 * If !ACTION_RECURSE, dirAction is called and its
 * return value is returned from recursive_action(). No recursion.
 *
 * If ACTION_RECURSE, directory is opened, and recursive_action() is called
 * on each file/subdirectory.
 * If any one of these calls returns 0, current recursive_action() returns 0.
 *
 * If !ACTION_DEPTHFIRST, dirAction is called before recurse.
 * Return value of 0 (FALSE) is an error: prevents recursion,
 * the warning is printed (unless ACTION_QUIET) and recursive_action() returns 0.
 * Return value of 2 (SKIP) prevents recursion, instead recursive_action()
 * returns 1 (TRUE, no error).
 *
 * If ACTION_DEPTHFIRST, dirAction is called after recurse.
 * If it returns 0, the warning is printed and recursive_action() returns 0.
 *
 * ACTION_FOLLOWLINKS mainly controls handling of links to dirs.
 * 0: lstat(statbuf). Calls fileAction on link name even if points to dir.
 * 1: stat(statbuf). Calls dirAction and optionally recurse on link to dir.
 */

static int recursive_action1(recursive_state_t *state, const char *fileName)
{
        struct stat statbuf;
        unsigned follow;
        int status;
        DIR *dir;
        struct dirent *next;

        follow = ACTION_FOLLOWLINKS;
        if (state->depth == 0)
                follow = ACTION_FOLLOWLINKS | ACTION_FOLLOWLINKS_L0;
        follow &= state->flags;
        status = (follow ? stat : lstat)(fileName, &statbuf);
        if (status < 0) {
#ifdef DEBUG_RECURS_ACTION
                bb_error_msg("status=%d flags=%x", status, state->flags);
#endif
                if ((state->flags & ACTION_DANGLING_OK)
                 && errno == ENOENT
                 && lstat(fileName, &statbuf) == 0
                ) {
                        /* Dangling link */
                        return state->fileAction(state, fileName, &statbuf);
                }
                goto done_nak_warn;
        }

        /* If S_ISLNK(m), then we know that !S_ISDIR(m).
         * Then we can skip checking first part: if it is true, then
         * (!dir) is also true! */
        if ( /* (!(state->flags & ACTION_FOLLOWLINKS) && S_ISLNK(statbuf.st_mode)) || */
         !S_ISDIR(statbuf.st_mode)
        ) {
                return state->fileAction(state, fileName, &statbuf);
        }

        /* It's a directory (or a link to one, and followLinks is set) */

        if (!(state->flags & ACTION_RECURSE)) {
                return state->dirAction(state, fileName, &statbuf);
        }

        if (!(state->flags & ACTION_DEPTHFIRST)) {
                status = state->dirAction(state, fileName, &statbuf);
                if (status == FALSE)
                        goto done_nak_warn;
                if (status == SKIP)
                        return TRUE;
        }

        dir = opendir(fileName);
        if (!dir) {
                /* findutils-4.1.20 reports this */
                /* (i.e. it doesn't silently return with exit code 1) */
                /* To trigger: "find -exec rm -rf {} \;" */
                goto done_nak_warn;
        }
        status = TRUE;
        while ((next = readdir(dir)) != NULL) {
                char *nextFile;
                int s;

                nextFile = concat_subpath_file(fileName, next->d_name);
                if (nextFile == NULL)
                        continue;

                /* process every file (NB: ACTION_RECURSE is set in flags) */
                state->depth++;
                s = recursive_action1(state, nextFile);
                if (s == FALSE)
                        status = FALSE;
                free(nextFile);
                state->depth--;

//#define RECURSE_RESULT_ABORT -1
//              if (s == RECURSE_RESULT_ABORT) {
//                      closedir(dir);
//                      return s;
//              }
        }
        closedir(dir);

        if (state->flags & ACTION_DEPTHFIRST) {
                if (!state->dirAction(state, fileName, &statbuf))
                        goto done_nak_warn;
        }

        return status;

 done_nak_warn:
        if (!(state->flags & ACTION_QUIET))
                bb_simple_perror_msg(fileName);
        return FALSE;
}

int FAST_FUNC recursive_action(const char *fileName,
                unsigned flags,
                int FAST_FUNC (*fileAction)(struct recursive_state *state, const char *fileName, struct stat* statbuf),
                int FAST_FUNC  (*dirAction)(struct recursive_state *state, const char *fileName, struct stat* statbuf),
                void *userData)
{
        /* Keeping a part of variables of recusive descent in a "state structure"
         * instead of passing ALL of them down as parameters of recursive_action1()
         * relieves register pressure, both in recursive_action1()
         * and in every file/dirAction().
         */
        recursive_state_t state;
        state.flags = flags;
        state.depth = 0;
        state.userData = userData;
        state.fileAction = fileAction ? fileAction : true_action;
        state.dirAction  =  dirAction ?  dirAction : true_action;

        return recursive_action1(&state, fileName);
}