/*
 * pseudo.c, main pseudo utility program
 *
 * Copyright (c) 2008-2013 Wind River Systems, Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the Lesser GNU General Public License version 2.1 as
 * published by the Free Software Foundation.
 *
 * 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 Lesser GNU General Public License for more details.
 *
 * You should have received a copy of the Lesser GNU General Public License
 * version 2.1 along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 
 *
 */
#include <stdlib.h>
#include <ctype.h>
#include <signal.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <time.h>
#include <limits.h>

#include <unistd.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/wait.h>
#include <sys/xattr.h>

#include "pseudo.h"
#include "pseudo_ipc.h"
#include "pseudo_client.h"
#include "pseudo_server.h"
#include "pseudo_db.h"

int opt_B = 0;
int opt_C = 0;
int opt_d = 0;
int opt_f = 0;
char *opt_i = NULL;
int opt_l = 0;
char *opt_m = NULL;
char *opt_M = NULL;
long opt_p = 0;
char *opt_r = NULL;
int opt_S = 0;

static int pseudo_op(pseudo_msg_t *msg, const char *program, const char *tag, char **response_path, size_t *response_len);
static int pseudo_db_check(int fix);

void
usage(int status) {
	FILE *f = status ? stderr : stdout;
	fputs("Usage: pseudo [-dflv] [-x flags] [-P prefix] [-rR root] [-t timeout] [command]\n", f);
	fputs("       pseudo -h\n", f);
	fputs("       pseudo [-dflv] [-x flags] [-P prefix] [-BC] -i path\n", f);
	fputs("       pseudo [-dflv] [-x flags] [-P prefix] [-BC] -m from -M to\n", f);
	fputs("       pseudo [-dflv] [-x flags] [-P prefix] -C\n", f);
	fputs("       pseudo [-dflv] [-x flags] [-P prefix] -S\n", f);
	fputs("       pseudo [-dflv] [-x flags] [-P prefix] -V\n", f);
	fputs("Debugging flags:\n", f);
	for (int i = 1; i < PDBG_MAX; i += 2) {
		unsigned char symbolics[2];
		const char *descriptions[2];
		symbolics[0] = pseudo_debug_type_symbolic(i);
		symbolics[1] = pseudo_debug_type_symbolic(i + 1);
		descriptions[0] = pseudo_debug_type_description(i);
		descriptions[1] = pseudo_debug_type_description(i + 1);
		if (symbolics[1]) {
			fprintf(f, "       %c %-32s  %c %-32s\n",
				symbolics[0], descriptions[0],
				symbolics[1], descriptions[1]);
		} else {
			fprintf(f, "       %c %-32s\n",
				symbolics[0], descriptions[0]);
		}
	}
	exit(status);
}


/* main server process */
int
main(int argc, char *argv[]) {
	int o;
	char *s;
	char *ld_env = getenv(PRELINK_LIBRARIES);
	int rc = 0;
	char opts[pseudo_path_max()], *optptr = opts;
	sigset_t blocked, saved;

	opts[0] = '\0';

	pseudo_init_util();

	/* The pseudo client will have blocked these, and sigprocmask
	 * is inherited, but we want them to work.
	 */
	sigemptyset(&blocked);
	sigaddset(&blocked, SIGALRM);	/* every-N-seconds tasks */
	sigaddset(&blocked, SIGCHLD);	/* reaping child processes */
	sigaddset(&blocked, SIGHUP);	/* idiomatically, reloading config */
	sigaddset(&blocked, SIGTERM);	/* shutdown/teardown operations */
	sigaddset(&blocked, SIGUSR1);	/* reopening log files, sometimes */
	sigaddset(&blocked, SIGUSR2);	/* who knows what people do */
	sigprocmask(SIG_UNBLOCK, &blocked, &saved);

	if (ld_env && strstr(ld_env, "libpseudo")) {
		pseudo_debug(PDBGF_SERVER, "[server %d] can't run daemon with libpseudo in %s\n", getpid(), PRELINK_LIBRARIES);
		s = pseudo_get_value("PSEUDO_UNLOAD");
		if (s) {
			pseudo_diag("pseudo: I can't seem to make %s go away.  Sorry.\n", PRELINK_LIBRARIES);
			pseudo_diag("pseudo: %s: %s\n", PRELINK_LIBRARIES, ld_env);
			exit(PSEUDO_EXIT_PSEUDO_LOADED);
		}
		free(s);
		pseudo_set_value("PSEUDO_UNLOAD", "YES");
		pseudo_setupenv();
		pseudo_dropenv(); /* Drop PRELINK_LIBRARIES */

		execv(argv[0], argv);
		exit(PSEUDO_EXIT_PSEUDO_LOADED);
	}

	/* Be sure to clean PSEUDO_UNLOAD so if we're asked to run any
	 * programs pseudo will be active in the process...
	 * (note: pseudo_set_value doesn't muck w/ the environment, thus
	 *  the need for the unsetenv, which is safe because "pseudo"
	 *  is the executable in this case!)
	 */
	pseudo_set_value("PSEUDO_UNLOAD", NULL);
	unsetenv("PSEUDO_UNLOAD");

	/* we need cwd to canonicalize paths */
	pseudo_client_getcwd();

	/* warning:  GNU getopt permutes arguments, which is just plain
	 * wrong.  The + suppresses this annoying behavior, but may not
	 * be compatible with sane option libraries.
	 */
	while ((o = getopt(argc, argv, "+BCdfhi:lm:M:p:P:r:R:St:vVx:")) != -1) {
		switch (o) {
		case 'B': /* rebuild database */
			opt_B = 1;
			opt_C = 1;
			break;
		case 'C': /* check database */
			opt_C = 1;
			break;
		case 'd': /* run as daemon */
			opt_d = 1;
			break;
		case 'f': /* run foregrounded */
			opt_f = 1;
			break;
		case 'h': /* help */
			usage(0);
			break;
		case 'i': /* renumber devices, assuming stable inodes */
			s = PSEUDO_ROOT_PATH(AT_FDCWD, optarg, 0);
			if (!s) {
				pseudo_diag("Can't resolve path '%s'\n", optarg);
				usage(EXIT_FAILURE);
			}
			opt_i = strdup(s);
			break;
		case 'l': /* log */
			optptr += snprintf(optptr, pseudo_path_max() - (optptr - opts),
					"%s-l", optptr > opts ? " " : "");
			opt_l = 1;
			break;
		case 'm': /* move from... (see also 'M') */
			s = PSEUDO_ROOT_PATH(AT_FDCWD, optarg, 0);
			if (!s) {
				pseudo_diag("Can't resolve move-from path '%s'\n", optarg);
				usage(EXIT_FAILURE);
			}
			opt_m = strdup(s);
			break;
		case 'M': /* move to... (see also 'm') */
			s = PSEUDO_ROOT_PATH(AT_FDCWD, optarg, 0);
			if (!s) {
				pseudo_diag("Can't resolve move-to path '%s'\n", optarg);
				usage(EXIT_FAILURE);
			}
			opt_M = strdup(s);
			break;
		case 'p': /* passwd file path */
			s = PSEUDO_ROOT_PATH(AT_FDCWD, optarg, AT_SYMLINK_NOFOLLOW);
			if (!s) {
				pseudo_diag("Can't resolve passwd path '%s'\n", optarg);
				usage(EXIT_FAILURE);
			}
			pseudo_set_value("PSEUDO_PASSWD", s);
			break;
		case 'P': /* prefix */
			s = PSEUDO_ROOT_PATH(AT_FDCWD, optarg, AT_SYMLINK_NOFOLLOW);
			if (!s) {
				pseudo_diag("Can't resolve prefix path '%s'\n", optarg);
				usage(EXIT_FAILURE);
			}
			pseudo_set_value("PSEUDO_PREFIX", s);
			break;
		case 'r':	/* chroot to... (fallthrough) */
		case 'R':	/* pseudo root path */
			s = PSEUDO_ROOT_PATH(AT_FDCWD, optarg, AT_SYMLINK_NOFOLLOW);
			if (!s) {
				pseudo_diag("Can't resolve root path '%s'\n", optarg);
				usage(EXIT_FAILURE);
			}
			pseudo_set_value("PSEUDO_CHROOT", s);
			if (o == 'r')
				opt_r = strdup(s);
			break;
		case 'S': /* stop */
			opt_S = 1;
			break;
		case 't': /* timeout */
			pseudo_server_timeout = strtol(optarg, &s, 10);
			if (*s && !isspace(*s)) {
				pseudo_diag("Timeout must be an integer value.\n");
				usage(EXIT_FAILURE);
			}
			optptr += snprintf(optptr, pseudo_path_max() - (optptr - opts),
					"%s-t %d", optptr > opts ? " " : "",
					pseudo_server_timeout);
			break;
		case 'v': /* verbosity */
			pseudo_debug_verbose();
			break;
		case 'V': /* version info */
			printf("pseudo version %s\n", pseudo_version ? pseudo_version : "<undefined>");
			printf("pseudo configuration:\n  prefix: %s\n",
				PSEUDO_PREFIX);
			printf("Set PSEUDO_PREFIX to run with a different prefix.\n");
			exit(0);
			break;
		case 'x': /* debug flags */
			pseudo_debug_set(optarg);
			break;
		case '?':
		default:
			pseudo_diag("unknown/invalid argument (option '%c').\n", optopt);
			usage(EXIT_FAILURE);
			break;
		}
	}
	pseudo_debug_flags_finalize();
	/* Options are processed, preserve them... */
	pseudo_set_value("PSEUDO_OPTS", opts);

	if (!pseudo_get_prefix(argv[0])) {
		pseudo_diag("Can't figure out prefix.  Set PSEUDO_PREFIX or invoke with full path.\n");
		exit(PSEUDO_EXIT_PSEUDO_PREFIX);
	}

	/* move database */
	if (opt_m || opt_M) {
		struct stat buf;
		pseudo_msg_t *msg;
		int rc;
		if (!(opt_m && opt_M)) {
			pseudo_diag("You cannot move the database without specifying from and to.\n");
			exit(EXIT_FAILURE);
		}
		if (stat(opt_M, &buf) < 0) {
			pseudo_diag("stat of '%s' failed: %s\n",
				opt_M, strerror(errno));
			pseudo_diag("The directory the database is being moved to must exist.\n");
			exit(EXIT_FAILURE);
		}
		msg = pseudo_msg_new(0, opt_M);
		if (!msg) {
			pseudo_diag("Can't allocate message structure.\n");
			exit(EXIT_FAILURE);
		}
		rc = pdb_rename_file(opt_m, msg);
		free(msg);
		if (rc < 0) {
			pseudo_diag("Warning: Database move may have failed.\n");
			pseudo_diag("To try to restore, you can reverse the move.\n");
			pseudo_diag("To commit to this anyway, run pseudo -C to check the database.\n");
			exit(EXIT_FAILURE);
		}
		pseudo_diag("Rename looked okay, running database sanity check.\n");
		opt_C = 1;
	}

	if (opt_i) {
		int rc;
		struct stat buf;
		pseudo_msg_t *msg;
		if (stat(opt_i, &buf) < 0) {
			pseudo_diag("stat of '%s' failed: %s\n",
				opt_i, strerror(errno));
			pseudo_diag("The file used to renumber the database must exist.\n");
			exit(EXIT_FAILURE);
		}
		msg = pseudo_msg_new(0, opt_i);
		if (!msg) {
			pseudo_diag("Couldn't allocate data structure for path.\n");
			exit(EXIT_FAILURE);
		}
		if (pdb_find_file_path(msg)) {
			pseudo_diag("Couldn't find a database entry for '%s'.\n", opt_i);
			exit(EXIT_FAILURE);
		}
		if (buf.st_ino != msg->ino) {
			pseudo_diag("The database inode entry for '%s' doesn't match; you must use -b.\n",
				opt_i);
			exit(EXIT_FAILURE);
		}
		rc = pdb_renumber_all(msg->dev, buf.st_dev);
		free(msg);
		if (rc < 0) {
			pseudo_diag("Warning: Database renumber failed.\n");
			exit(EXIT_FAILURE);
		}
		pseudo_diag("Renumber looked okay, running database sanity check.\n");
		opt_C = 1;
	}

	if (opt_C) {
		/*  if opt_B is set, try to fix database */
		return pseudo_db_check(opt_B);
	}

        /* If you didn't specify a command, opt_S shuts down here. */
	if (opt_S && argc <= optind) {
		return pseudo_client_shutdown();
	}

	if (opt_d && opt_f) {
		pseudo_diag("You cannot run a foregrounded daemon.\n");
		exit(PSEUDO_EXIT_PSEUDO_INVOCATION);
	}

	if (opt_f || opt_d) {
		if (argc > optind) {
			pseudo_diag("pseudo: running program implies spawning background daemon.\n");
			exit(PSEUDO_EXIT_PSEUDO_INVOCATION);
		}
	} else {
		char fullpath[pseudo_path_max()];
		char *path;

		if (opt_r) {
			if (chdir(opt_r) == -1) {
				pseudo_diag("failed to chdir to '%s': %s\n",
					opt_r, strerror(errno));
				exit(EXIT_FAILURE);
			}
		}
		if (argc > optind) {
			pseudo_debug(PDBGF_INVOKE, "running command: %s\n",
				argv[optind]);
			argc -= optind;
			argv += optind;
		} else {
			static char *newargv[2];
			argv = newargv;
			pseudo_debug(PDBGF_INVOKE, "running shell.\n");
			argv[0] = getenv("SHELL");
			if (!argv[0])
				argv[0] = "/bin/sh";
			argv[1] = NULL;
		}

		if (strchr(argv[0], '/')) {
			snprintf(fullpath, pseudo_path_max(), "%s", argv[0]);
		} else {
			int found = 0;
			if ((path = getenv("PATH")) == NULL)
				path = "/bin:/usr/bin";
			while (*path) {
				struct stat buf;
				int len = strcspn(path, ":");
				snprintf(fullpath, pseudo_path_max(), "%.*s/%s",
					len, path, argv[0]);
				path += len;
				if (*path == ':')
					++path;
				if (!stat(fullpath, &buf)) {
					if (buf.st_mode & 0111) {
						found = 1;
						break;
					}
				}
			}
			if (!found) {
				pseudo_diag("Can't find '%s' in $PATH.\n",
					argv[0]);
				exit(EXIT_FAILURE);
			}
		}
		pseudo_setupenv();

		rc = fork();
		if (rc) {
			waitpid(rc, &rc, 0);
			/* try to hint that we don't think we still need
			 * the server.
			 */
                        if (opt_S) {
				pseudo_client_shutdown();
                        }
			if (WIFEXITED(rc)) {
				return WEXITSTATUS(rc);
			} else if (WIFSIGNALED(rc)) {
				kill(getpid(), WTERMSIG(rc));
				exit(1);
			} else {
				exit(1);
			}
		} else {
			rc = execv(fullpath, argv);
			if (rc == -1) {
				pseudo_diag("pseudo: can't run %s: %s\n",
					argv[0], strerror(errno));
			}
			exit(EXIT_FAILURE);
		}
	}
	return pseudo_server_start(opt_d);
}

/* 
 * actually process operations.
 * This first evaluates the message, figures out what's in the DB, does some
 * sanity checks, then implements the fairly small DB changes required.
 */
int
pseudo_op(pseudo_msg_t *msg, const char *program, const char *tag, char **response_path, size_t *response_len) {
	pseudo_msg_t msg_header;
	pseudo_msg_t by_path = { .op = 0 }, by_ino = { .op = 0 };
	pseudo_msg_t db_header;
	char *path_by_ino = 0;
	char *oldpath = 0;
	size_t oldpathlen = 0;
	int found_path = 0, found_ino = 0;
	int prefer_ino = 0;
	int xattr_flags = 0;
	int trailing_slash = 0;

	if (!msg)
		return 1;
	
	msg->result = RESULT_SUCCEED;

	/* debugging message.  Primary key first. */
	switch (msg->op) {
	case OP_FCHOWN:		/* FALLTHROUGH */
	case OP_FCHMOD:		/* FALLTHROUGH */
	case OP_FSTAT:
		prefer_ino = 1;
		pseudo_debug(PDBGF_OP, "%s %llu [%s]: ", pseudo_op_name(msg->op),
			(unsigned long long) msg->ino,
			msg->pathlen ? msg->path : "no path");
		break;
	default:
		pseudo_debug(PDBGF_OP, "%s %s [%llu]: ", pseudo_op_name(msg->op),
			msg->pathlen ? msg->path : "no path",
			(unsigned long long) msg->ino);
		break;
	}

	/* Process rename path separation, there are two paths old / new
	 * stuff into a rename, break them apart (null seperated)
	 */

	if (msg->pathlen) {
		size_t initial_len;
		switch (msg->op) {
		case OP_RENAME:
		case OP_CREATE_XATTR:
		case OP_GET_XATTR:
		case OP_LIST_XATTR:
		case OP_REPLACE_XATTR:
		case OP_REMOVE_XATTR:
		case OP_SET_XATTR:
			/* In a rename there are two paths, null separated in msg->path */
			initial_len = strlen(msg->path);
			oldpath = msg->path + initial_len + 1;
			/* for rename, the path name would be null-terminated,
			 * but for *xattr, we don't want the null. */
			oldpathlen = msg->pathlen - (oldpath - msg->path) - 1;
			pseudo_debug(PDBGF_OP | PDBGF_FILE | PDBGF_XATTR, "%s: path '%s', oldpath '%s' [%d/%d]\n",
				pseudo_op_name(msg->op), msg->path, oldpath, (int) oldpathlen, (int) msg->pathlen);
			/* For a rename op, we want to strip any trailing
			 * slashes. For xattr, "oldpath" is the raw data
			 * to be stored. */
			if (oldpathlen > 0 && msg->op == OP_RENAME) {
				if (oldpath[oldpathlen - 1] == '/') {
					oldpath[--oldpathlen] = '\0';
				}
			}
			/* if we got an oldpath, but a 0-length initial
			 * path, we don't want to act as though we had
			 * a non-empty initial path.
			 */

			msg->pathlen = initial_len;
			break;
		default:
			break;
		}
	}

	/* stash original header, in case we need it later */
	msg_header = *msg;
	by_ino = msg_header;

	/* trailing slashes are kept in paths because they affect
	 * path resolution, but we don't want them in the database
	 * because they're optional. For now, any error-checking on
	 * this server-side is purely advisory, but the client should
	 * bail with ENOTDIR a lot earlier in many cases, before the
	 * server even sees anything.
	 */
	if (msg->pathlen) {
		if (msg->path[msg->pathlen - 1] == '/') {
			msg->path[--msg->pathlen] = '\0';
			trailing_slash = 1;
		}
	}

	/* There should usually be a path.  Even for f* ops, the client
	 * tries to provide a path from its table of known fd paths.
	 */
	/* Lookup the full path, with inode and dev if available */
	if (msg->pathlen && msg->dev && msg->ino) {
		if (!pdb_find_file_exact(msg)) {
			/* restore header contents */
			by_path = *msg;
			by_ino = *msg;
			*msg = msg_header;
			found_path = 1;
			found_ino = 1;
			/* note:  we have to avoid freeing this later */
			path_by_ino = msg->path;
			if (msg->op == OP_LINK) {
				pseudo_debug(PDBGF_FILE, "[matches existing link]");
			}
		}
	}

	if (!found_path && !found_ino) {
		if (msg->pathlen) {
			/* for now, don't canonicalize paths anymore */
			/* used to do it here, but now doing it in client */
			if (!pdb_find_file_path(msg)) {
				by_path = *msg;
				found_path = 1;
			} else {
				if (msg->op != OP_RENAME && msg->op != OP_LINK) {
					pseudo_debug(PDBGF_FILE, "(new?) ");
				}
			}
		}
		/* search on original inode -- in case of mismatch */
		if (msg->dev && msg->ino) {
			if (!pdb_find_file_dev(&by_ino, &path_by_ino)) {
				found_ino = 1;
			}
		}
	}

	pseudo_debug(PDBGF_OP, "incoming: '%s'%s [%llu]%s\n",
		msg->pathlen ? msg->path : "no path",
		found_path ? "+" : "-",
		(unsigned long long) msg_header.ino,
		found_ino ? "+" : "-");

	/* the sanity checks are inappropriate for DID_UNLINK, since it's
	 * completely legitimate to have a new database entry for the
	 * same inode.
	 */
	if (found_path && msg->op != OP_DID_UNLINK) {
		/* This is a bad sign.  We should never have a different entry
		 * for the inode...  But an inode of 0 from an EXEC is normal,
		 * we don't track those.
		 */
		if (by_path.ino != msg_header.ino && msg_header.ino != 0) {
			switch (msg->op) {
			case OP_EXEC:
				break;
			default:
				/* if the path is in the database with a
				 * different inode, but we were expecting
				 * it to get deleted, mark the old one
				 * as deleted.
				 */
				if (by_path.deleting != 0) {
					pseudo_debug(PDBGF_FILE, "inode mismatch for '%s' -- old one was marked for deletion, deleting.\n",
						msg->path);
					/* in this case, we don't trust the
					 * existing entries, so we will do the
					 * more expensive sweep for stray
					 * xattrs.
					 */
					pdb_did_unlink_file(msg->path, NULL, by_path.deleting);
				} else {
					pseudo_diag("inode mismatch: '%s' ino %llu in db, %llu in request.\n",
						msg->path,
						(unsigned long long) by_path.ino,
						(unsigned long long) msg_header.ino);
				}
			}
		}
		/* If the database entry disagrees on S_ISDIR, it's just
		 * plain wrong.  We remove the database entry, because it
		 * is absolutely certain to be wrong.  This means found_path
		 * is now 0, because there is no entry in db...
		 *
		 * This used to unlink everything with the inode from
		 * the message -- but what if the entry in the database
		 * had a different inode?  We should nuke THAT inode,
		 * and everything agreeing with it, which will also catch
		 * the bogus entry that we noticed.
		 */
		if (S_ISDIR(by_path.mode) != S_ISDIR(msg_header.mode)) {
			pseudo_diag("dir mismatch: '%s' [%llu] db mode 0%o, header mode 0%o (unlinking db)\n",
				msg->path, (unsigned long long) by_path.ino,
				(int) by_path.mode, (int) msg_header.mode);
			/* unlink everything with this inode */
			pdb_unlink_file_dev(&by_path);
			found_path = 0;
		} else if (S_ISLNK(by_path.mode) != S_ISLNK(msg_header.mode)) {
			pseudo_diag("symlink mismatch: '%s' [%llu] db mode 0%o, header mode 0%o (unlinking db)\n",
				msg->path, (unsigned long long) by_path.ino,
				(int) by_path.mode, (int) msg_header.mode);
			/* unlink everything with this inode */
			pdb_unlink_file_dev(&by_path);
			found_path = 0;
		}
		if (trailing_slash && !S_ISDIR(by_path.mode)) {
			pseudo_diag("dir quasi-mismatch: '%s' [%llu] db mode 0%o, incoming path had trailing slash. Not unlinking.\n",
				msg->path, (unsigned long long) by_path.ino,
				(int) by_path.mode);
		}
	}

	/* for OP_DID_UNLINK, the reason this op exists is that the same
	 * inode might have been reclaimed. Don't sanity-check it, and
	 * especially don't delete the database contents!
	 */
	if (found_ino && msg->op != OP_DID_UNLINK) {
		/* Not always an absolute failure case.
		 * If a file descriptor shows up unexpectedly and gets
		 * fchown()d, you could have an entry giving the inode and
		 * data, but not path.  So, we add the path to the entry.
		 * Any other changes from the incoming message will be applied
		 * at leisure.
		 */
		if (msg->pathlen && !path_by_ino) {
			pseudo_debug(PDBGF_FILE, "db path missing: ino %llu, request '%s'.\n",
				(unsigned long long) msg_header.ino, msg->path);
			pdb_update_file_path(msg);
		} else if (!msg->pathlen && path_by_ino) {
			/* harmless */
			pseudo_debug(PDBGF_FILE, "req path missing: ino %llu, db '%s'.\n",
				(unsigned long long) msg_header.ino, path_by_ino);
		} else if (msg->pathlen && path_by_ino) {
			/* this suggests a database error, except in LINK
			 * cases.  In those cases, it is normal for a
			 * mismatch to occur.  :)  (SYMLINK shouldn't,
			 * because the symlink gets its own inode number.)
			 *
			 * RENAME can get false positives on this, when
			 * link count is greater than one.  So we skip this
			 * test for OP_LINK (always) and OP_RENAME (for link
			 * count greater than one).  For RENAME, the test
			 * should be against the old name, though!
			 */
			int mismatch = 0;
			switch (msg->op) {
			case OP_LINK:
			case OP_EXEC:
				break;
			case OP_RENAME:
				if (msg->nlink == 1 && strcmp(oldpath, path_by_ino)) {
					mismatch = 1;
				}
				break;
			default:
				if (strcmp(msg->path, path_by_ino)) {
					mismatch = 1;
				}
				break;
			}
			if (mismatch) {
				/* a mismatch, but we were planning to delete
				 * the file, so it must have gotten deleted
				 * already.
				 */
				if (by_ino.deleting != 0) {
					pseudo_debug(PDBGF_FILE, "inode mismatch for '%s' -- old one was marked for deletion, deleting.\n",
						msg->path);
					pdb_did_unlink_file(path_by_ino, &by_ino, by_ino.deleting);
				} else {
					pseudo_diag("path mismatch [%d link%s]: ino %llu db '%s' req '%s'.\n",
						msg->nlink,
						msg->nlink == 1 ? "" : "s",
						(unsigned long long) msg_header.ino,
						path_by_ino ? path_by_ino : "no path",
						msg->path);
				}
			}
		} else {
			/* I don't think I've ever seen this one. */
			pseudo_debug(PDBGF_FILE, "warning: ino %llu in db (mode 0%o, owner %d), no path known.\n",
				(unsigned long long) msg_header.ino,
				(int) by_ino.mode, (int) by_ino.uid);
		}
		/* Again, in the case of a directory mismatch, nuke the DB
		 * entry.  There is no way it can be right.
		 */
		if (S_ISDIR(by_ino.mode) != S_ISDIR(msg_header.mode)) {
			pseudo_diag("dir err : %llu ['%s'] (db '%s') db mode 0%o, header mode 0%o (unlinking db)\n",
				(unsigned long long) msg_header.ino,
				msg->pathlen ? msg->path : "no path",
				path_by_ino ? path_by_ino : "no path",
				(int) by_ino.mode, (int) msg_header.mode);
			pdb_unlink_file_dev(msg);
			found_ino = 0;
		} else if (S_ISLNK(by_ino.mode) != S_ISLNK(msg_header.mode)) {
			/* In the current implementation, only msg_header.mode
			 * can ever be a symlink; the test is generic as
			 * insurance against forgetting to fix it in a future
			 * update. */
			pseudo_diag("symlink err : %llu ['%s'] (db '%s') db mode 0%o, header mode 0%o (unlinking db)\n",
				(unsigned long long) msg_header.ino,
				msg->pathlen ? msg->path : "no path",
				path_by_ino ? path_by_ino : "no path",
				(int) by_ino.mode, (int) msg_header.mode);
			pdb_unlink_file_dev(msg);
			found_ino = 0;
		}
	}

	/* In the case of a stat() call, if a mismatch existed, we prefer
	 * by-inode for fstat, by-path for stat.  Nothing else actually uses
	 * this...
	 */
	if (found_ino && (prefer_ino || !found_path)) {
		db_header = by_ino;
	} else if (found_path) {
		db_header = by_path;
	}

	switch (msg->op) {
	case OP_CHDIR:		/* FALLTHROUGH */
	case OP_CLOSE:
		/* these messages are handled entirely on the client side,
		 * as of this writing, but might be logged by accident: */
		pseudo_diag("error: op %s sent to server.\n", pseudo_op_name(msg->op));
		break;
	case OP_EXEC:		/* FALLTHROUGH */
	case OP_OPEN:
		/* nothing to do -- just sent in case we're logging */
		break;
	case OP_CREAT:
		/* implies a new file -- not a link, which would be OP_LINK */
		if (found_ino) {
			/* CREAT should never be sent if the file existed.
			 * So, any existing entry is an error.  Nuke it.
			 */
			pseudo_diag("creat for '%s' replaces existing %llu ['%s'].\n",
				msg->pathlen ? msg->path : "no path",
				(unsigned long long) by_ino.ino,
				path_by_ino ? path_by_ino : "no path");
			pdb_unlink_file_dev(&by_ino);
		}
		if (!found_path) {
			pseudo_debug(PDBGF_DB, "linking %s for OP_CREAT\n",
				msg->pathlen ? msg->path : "no path");
			pdb_link_file(msg);
		} else {
			/* again, an error, but leaving it alone for now. */
			pseudo_diag("creat ignored for existing file '%s'.\n",
				msg->pathlen ? msg->path : "no path");
		}
		break;
	case OP_CHMOD:		/* FALLTHROUGH */
	case OP_FCHMOD:
		pseudo_debug(PDBGF_OP, "mode 0%o ", (int) msg->mode);
		/* if the inode is known, update it */
		if (found_ino) {
			/* obtain the existing data, merge with mode */
			*msg = by_ino;
			msg->mode = (msg_header.mode & 07777) |
				    (msg->mode & ~07777);
			pdb_update_file(msg);
		} else if (found_path) {
			/* obtain the existing data, merge with mode */
			*msg = by_path;
			msg->mode = (msg_header.mode & 07777) |
				    (by_path.mode & ~07777);
			pdb_update_file(msg);
		} else {
			/* just in case find_file_path screwed up the msg */
			msg->mode = msg_header.mode;
		}
		/* if we've never seen the file at all before, link it.
		 * If we have it in the db by inode, but not by name,
		 * it got fixed during the sanity checks.
		 */
		if (!found_path && !found_ino) {
			pseudo_debug(PDBGF_FILE, "(new) ");
			pseudo_debug(PDBGF_DB, "linking %s for OP_[F]CHMOD\n",
				msg->pathlen ? msg->path : "no path");
			pdb_link_file(msg);
		}
		break;
	case OP_CHOWN:		/* FALLTHROUGH */
	case OP_FCHOWN:
		pseudo_debug(PDBGF_OP, "owner %d:%d ", (int) msg_header.uid, (int) msg_header.gid);
		/* if the inode is known, update it */
		if (found_ino) {
			/* obtain the existing data, merge with mode */
			*msg = by_ino;
			msg->uid = msg_header.uid;
			msg->gid = msg_header.gid;
			pdb_update_file(msg);
		} else if (found_path) {
			/* obtain the existing data, merge with mode */
			*msg = by_path;
			msg->uid = msg_header.uid;
			msg->gid = msg_header.gid;
			pdb_update_file(msg);
		} else {
			/* just in case find_file_path screwed up the msg */
			msg->uid = msg_header.uid;
			msg->gid = msg_header.gid;
		}
		/* if we've never seen the file at all before, link it.
		 * If we have it in the db by inode, but not by name,
		 * it got fixed during the sanity checks.
		 */
		if (!found_path && !found_ino) {
			pseudo_debug(PDBGF_FILE, "(new) ");
			pseudo_debug(PDBGF_DB, "linking %s for OP_[F]CHOWN\n",
				msg->pathlen ? msg->path : "no path");
			pdb_link_file(msg);
		}
		break;
	case OP_STAT:		/* FALLTHROUGH */
	case OP_FSTAT:
		/* db_header will be whichever one looked best, in the rare
		 * case where there might be a clash.
		 */
		if (found_ino || found_path) {
			#ifdef PSEUDO_XATTRDB
			if (db_header.uid == (uid_t) -1 &&
			    db_header.gid == (gid_t) -1) {
				/* special case: this row was created
				 * to allow xattr lookups, and it's not
				 * actually valid data.
				 */
				msg->result = RESULT_FAIL;
			} else
			#endif
			{
				*msg = db_header;
			}
		} else {
			msg->result = RESULT_FAIL;
		}
		pseudo_debug(PDBGF_OP | PDBGF_VERBOSE, "%s, ino %llu (old mode 0%o): mode 0%o\n",
			pseudo_op_name(msg->op), (unsigned long long) msg->ino,
			(int) msg_header.mode, (int) msg->mode);
		break;
	case OP_LINK:		/* FALLTHROUGH */
	case OP_SYMLINK:
		/* a successful link (client only notifies us for those)
		 * implies that the new path did not previously exist, and
		 * the old path did.  We get the stat buffer and the new path.
		 * So, we unlink it, then link it.  Neither unlink nor link
		 * touches the message, which was initialized from the
		 * underlying file data in the client.
		 */
		if (found_path) {
			pseudo_debug(PDBGF_OP | PDBGF_FILE, "replace %slink: path %s, old ino %llu, mode 0%o, new ino %llu, mode 0%o\n",
				msg->op == OP_SYMLINK ? "sym" : "",
				msg->path, (unsigned long long) msg->ino,
				(int) msg->mode,
				(unsigned long long) msg_header.ino,
				(int) msg_header.mode);
			pdb_unlink_file(msg);
		} else {
			pseudo_debug(PDBGF_OP | PDBGF_FILE, "new %slink: path %s, ino %llu, mode 0%o\n",
				msg->op == OP_SYMLINK ? "sym" : "",
				msg->path,
				(unsigned long long) msg_header.ino,
				(int) msg_header.mode);
		}
		if (found_ino) {
			if (msg->op == OP_SYMLINK) {
				pseudo_debug(PDBGF_OP | PDBGF_FILE, "symlink: ignoring existing file %llu ['%s']\n",
					(unsigned long long) by_ino.ino,
					path_by_ino ? path_by_ino : "no path");
			} else {
				*msg = by_ino;
				pseudo_debug(PDBGF_OP | PDBGF_FILE, "link: copying data from existing file %llu ['%s']\n",
					(unsigned long long) by_ino.ino,
					path_by_ino ? path_by_ino : "no path");
			}
		} else {
			*msg = msg_header;
		}
		pseudo_debug(PDBGF_DB, "linking %s for %s\n",
			msg->pathlen ? msg->path : "no path",
			pseudo_op_name(msg->op));
		pdb_link_file(msg);
		break;
	case OP_RENAME:
		/* a rename implies renaming an existing entry... and every
		 * database entry rooted in it, if it's a directory.
		 */
		pdb_rename_file(oldpath, msg);
		pdb_update_inode(msg);
		break;
	case OP_MAY_UNLINK:
		if (pdb_may_unlink_file(msg, msg->client)) {
			/* harmless, but client wants to know so it knows
			 * whether to follow up... */
			msg->result = RESULT_FAIL;
		}
		break;
	case OP_DID_UNLINK:
		pdb_did_unlink_file(msg->path, msg, msg->client);
		break;
	case OP_CANCEL_UNLINK:
		pdb_cancel_unlink_file(msg);
		break;
	case OP_UNLINK:
		/* this removes any entries with the given path from the
		 * database.  No response is needed.
		 * DO NOT try to fail if the entry is already gone -- if the
		 * server's response didn't make it, the client would resend.
		 */
		pdb_unlink_file(msg);
		pdb_unlink_contents(msg);
		/* If we are seeing an unlink for something with only one
		 * link, we should delete all records for that inode, even
		 * ones through different paths.  This handles the case
		 * where something is removed through the wrong path, but
		 * only if it didn't have multiple hard links.
		 *
		 * This should cease to be needed once symlinks are tracked.
		 */
		if (msg_header.nlink == 1 && found_ino) {
			pseudo_debug(PDBGF_FILE | PDBGF_OP, "link count 1, unlinking anything with ino %llu.\n",
				(unsigned long long) msg->ino);
			pdb_unlink_file_dev(msg);
		}
		msg->result = RESULT_NONE;
		break;
	case OP_MKDIR:		/* FALLTHROUGH */
	case OP_MKNOD:
		pseudo_debug(PDBGF_OP, "mode 0%o", (int) msg->mode);
		/* for us to get called, the client has to have succeeded in
		 * a creation (of a regular file, for mknod) -- meaning this
		 * file DID NOT exist before the call.  Fix database:
		 */
		if (found_path) {
			pseudo_diag("mkdir/mknod: '%s' [%llu] already existed (mode 0%o), unlinking\n",
				msg->path, (unsigned long long) by_path.ino,
				(int) by_path.mode);
			pdb_unlink_file(msg);
		}
		if (found_ino) {
			pdb_unlink_file_dev(&by_ino);
		}
		*msg = msg_header;
		pseudo_debug(PDBGF_DB, "linking %s for %s\n",
			msg->pathlen ? msg->path : "no path",
			pseudo_op_name(msg->op));
		pdb_link_file(msg);
		break;
	case OP_GET_XATTR:
		if (pdb_get_xattr(msg, &oldpath, &oldpathlen)) {
			msg->result = RESULT_FAIL;
		} else {
			*response_path = oldpath;
			*response_len = oldpathlen;
			pseudo_debug(PDBGF_XATTR, "get results: '%.*s' (%d bytes)\n",
				(int) *response_len, *response_path, (int) *response_len);
		}
		break;
	case OP_LIST_XATTR:
		if (pdb_list_xattr(msg, &oldpath, &oldpathlen)) {
			msg->result = RESULT_FAIL;
		} else {
			pseudo_debug(PDBGF_XATTR, "got %d bytes of xattrs to list: %.*s\n", (int) oldpathlen, (int) oldpathlen, oldpath);
			*response_path = oldpath;
			*response_len = oldpathlen;
		}
		break;
	case OP_CREATE_XATTR:
	case OP_REPLACE_XATTR: /* fallthrough */
		if (msg->op == OP_CREATE_XATTR) {
			xattr_flags = XATTR_CREATE;
		}
		if (msg->op == OP_REPLACE_XATTR) {
			xattr_flags = XATTR_REPLACE;
		}
	case OP_SET_XATTR:
		if (pdb_set_xattr(msg, oldpath, oldpathlen, xattr_flags)) {
			msg->result = RESULT_FAIL;
		}
		break;
	case OP_REMOVE_XATTR:
		pdb_remove_xattr(msg, oldpath, oldpathlen);
		break;
	default:
		pseudo_diag("unknown op from client %d, op %d [%s]\n",
			msg->client, msg->op,
			msg->pathlen ? msg->path : "no path");
		break;
	}

	/* in the case of an exact match, we just used the pointer
	 * rather than allocating space.
	 */
	if (path_by_ino != msg->path) {
		free(path_by_ino);
	}
	pseudo_debug(PDBGF_OP, "completed %s.\n", pseudo_op_name(msg->op));
	if (opt_l)
		pdb_log_msg(SEVERITY_INFO, msg, program, tag, NULL);
	return 0;
}

/* SHUTDOWN does not get this far, it's handled in pseudo_server.c */
int
pseudo_server_response(pseudo_msg_t *msg, const char *program, const char *tag, char **response_path, size_t *response_len) {
	switch (msg->type) {
	case PSEUDO_MSG_PING:
                /* mad hackery: if we aren't logging, the client gets told
                 * not to send open/exec notifications, which have no other
                 * purpose.
                 */
		msg->result = opt_l ? RESULT_SUCCEED : RESULT_FAIL;
		if (opt_l)
			pdb_log_msg(SEVERITY_INFO, msg, program, tag, NULL);
		return 0;
		break;
	case PSEUDO_MSG_OP:
	case PSEUDO_MSG_FASTOP:
		return pseudo_op(msg, program, tag, response_path, response_len);
		break;
	case PSEUDO_MSG_ACK:		/* FALLTHROUGH */
	case PSEUDO_MSG_NAK:		/* FALLTHROUGH */
	default:
		pdb_log_msg(SEVERITY_WARN, msg, program, tag, "invalid message");
		return 1;
	}
}

int
pseudo_db_check(int fix) {
	struct stat buf;
	pseudo_msg_t *m;
	pdb_file_list l;
	int errors = 0;
	int delete_some = 0;
	/* magic cookie used to show who's deleting the files */
	int magic_cookie = (int) getpid();
	int rc = 0;

	l = pdb_files();
	if (!l) {
		pseudo_diag("Couldn't start file list, can't scan.\n");
		return EXIT_FAILURE;
	}
	while ((m = pdb_file(l)) != NULL) {
		pseudo_debug(PDBGF_DB, "m: %p (%d: %s)\n",
			(void *) m,
			m ? (int) m->pathlen : -1,
			m ? m->path : "<n/a>");
		if (m->pathlen > 0) {
			int fixup_needed = 0;
			pseudo_debug(PDBGF_DB, "Checking <%s>\n", m->path);
			if (lstat(m->path, &buf)) {
				errors = EXIT_FAILURE;
				pseudo_diag("can't stat <%s>\n", m->path);
				continue;
			}
			/* can't check for device type mismatches, uid/gid, or
			 * permissions, because those are the very things we
			 * can't really set.
			 */
			if (buf.st_ino != m->ino) {
				pseudo_debug(PDBGF_DB, "ino mismatch <%s>: ino %llu, db %llu\n",
					m->path,
					(unsigned long long) buf.st_ino,
					(unsigned long long) m->ino);
				m->ino = buf.st_ino;
				fixup_needed = 1;
			}
			if (buf.st_dev != m->dev) {
				pseudo_debug(PDBGF_DB, "dev mismatch <%s>: dev %llu, db %llu\n",
					m->path,
					(unsigned long long) buf.st_dev,
					(unsigned long long) m->dev);
				m->dev = buf.st_dev;
				fixup_needed = 1;
			}
			if (S_ISLNK(buf.st_mode) != S_ISLNK(m->mode)) {
				pseudo_debug(PDBGF_DB, "symlink mismatch <%s>: file %d, db %d\n",
					m->path,
					S_ISLNK(buf.st_mode),
					S_ISLNK(m->mode));
				fixup_needed = 2;
			}
			if (S_ISDIR(buf.st_mode) != S_ISDIR(m->mode)) {
				pseudo_debug(PDBGF_DB, "symlink mismatch <%s>: file %d, db %d\n",
					m->path,
					S_ISDIR(buf.st_mode),
					S_ISDIR(m->mode));
				fixup_needed = 2;
			}
			if (fixup_needed) {
				/* in fixup mode, either delete (mismatches) or
				 * correct (dev/ino).
				 */
				if (fix) {
					if (fixup_needed == 1) {
						rc = pdb_update_inode(m);
					} else if (fixup_needed == 2) {
						/* mark for deletion */
						delete_some = 1;
						rc = pdb_may_unlink_file(m, magic_cookie);
					}
					if (rc) {
						pseudo_diag("error updating file %s\n",
							m->path);
						errors = EXIT_FAILURE;
					}
				} else {
					errors = EXIT_FAILURE;
				}
			}
		}
	}
	pdb_files_done(l);
	/* and now delete files marked for deletion */
	if (delete_some) {
		rc = pdb_did_unlink_files(magic_cookie);
		if (rc) {
			pseudo_diag("error nuking mismatched files.\n");
			pseudo_diag("database may not be fixed.\n");
			errors = EXIT_FAILURE;
		}
	}
	return errors;
}