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For open/openat, if the flags parameter does not contain O_CREAT, the
3rd (variadic) mode_t parameter is irrelevant.  Many developers in the past
have passed mode_t (0, 044, 0644, or such), which might lead future people
to copy this broken idiom, and perhaps even believe this parameter has some
meaning or implication or application. Delete them all.
This comes out of a conversation where tb@ noticed that a strange (but
intentional) pledge behaviour is to always knock-out high-bits from
mode_t on a number of system calls as a safety factor, and his bewilderment
that this appeared to be happening against valid modes (at least visually),
but no sorry, they are all irrelevant junk.  They could all be 0xdeafbeef.
ok millert

/*	$OpenBSD: uploader.c,v 1.31 2021/10/24 21:24:17 deraadt Exp $ */
/*
 * Copyright (c) 2019 Kristaps Dzonsons <kristaps@bsd.lv>
 * Copyright (c) 2019 Florian Obser <florian@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
#include <sys/mman.h>
#include <sys/stat.h>

#include <assert.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

#include "extern.h"

enum	uploadst {
	UPLOAD_FIND_NEXT = 0, /* find next to upload to sender */
	UPLOAD_WRITE, /* wait to write to sender */
	UPLOAD_FINISHED /* nothing more to do in phase */
};

/*
 * Used to keep track of data flowing from the receiver to the sender.
 * This is managed by the receiver process.
 */
struct	upload {
	enum uploadst	    state;
	char		   *buf; /* if not NULL, pending upload */
	size_t		    bufsz; /* size of buf */
	size_t		    bufmax; /* maximum size of buf */
	size_t		    bufpos; /* position in buf */
	size_t		    idx; /* current transfer index */
	mode_t		    oumask; /* umask for creating files */
	char		   *root; /* destination directory path */
	int		    rootfd; /* destination directory */
	size_t		    csumlen; /* checksum length */
	int		    fdout; /* write descriptor to sender */
	const struct flist *fl; /* file list */
	size_t		    flsz; /* size of file list */
	int		   *newdir; /* non-zero if mkdir'd */
};

/*
 * Log a directory by emitting the file and a trailing slash, just to
 * show the operator that we're a directory.
 */
static void
log_dir(struct sess *sess, const struct flist *f)
{
	size_t	 sz;

	if (sess->opts->server)
		return;
	sz = strlen(f->path);
	assert(sz > 0);
	LOG1("%s%s", f->path, (f->path[sz - 1] == '/') ? "" : "/");
}

/*
 * Log a link by emitting the file and the target, just to show the
 * operator that we're a link.
 */
static void
log_symlink(struct sess *sess, const struct flist *f)
{

	if (!sess->opts->server)
		LOG1("%s -> %s", f->path, f->link);
}

/*
 * Simply log the filename.
 */
static void
log_file(struct sess *sess, const struct flist *f)
{

	if (!sess->opts->server)
		LOG1("%s", f->path);
}

/*
 * Prepare the overall block set's metadata.
 * We always have at least one block.
 * The block size is an important part of the algorithm.
 * I use the same heuristic as the reference rsync, but implemented in a
 * bit more of a straightforward way.
 * In general, the individual block length is the rounded square root of
 * the total file size.
 * The minimum block length is 700.
 */
static void
init_blkset(struct blkset *p, off_t sz)
{
	double	 v;

	if (sz >= (BLOCK_SIZE_MIN * BLOCK_SIZE_MIN)) {
		/* Simple rounded-up integer square root. */

		v = sqrt(sz);
		p->len = ceil(v);

		/*
		 * Always be a multiple of eight.
		 * There's no reason to do this, but rsync does.
		 */

		if ((p->len % 8) > 0)
			p->len += 8 - (p->len % 8);
	} else
		p->len = BLOCK_SIZE_MIN;

	p->size = sz;
	if ((p->blksz = sz / p->len) == 0)
		p->rem = sz;
	else
		p->rem = sz % p->len;

	/* If we have a remainder, then we need an extra block. */

	if (p->rem)
		p->blksz++;
}

/*
 * For each block, prepare the block's metadata.
 * We use the mapped "map" file to set our checksums.
 */
static void
init_blk(struct blk *p, const struct blkset *set, off_t offs,
	size_t idx, const void *map, const struct sess *sess)
{

	p->idx = idx;
	/* Block length inherits for all but the last. */
	p->len = idx < set->blksz - 1 ? set->len : set->rem;
	p->offs = offs;

	p->chksum_short = hash_fast(map, p->len);
	hash_slow(map, p->len, p->chksum_long, sess);
}

/*
 * Handle a symbolic link.
 * If we encounter directories existing in the symbolic link's place,
 * then try to unlink the directory.
 * Otherwise, simply overwrite with the symbolic link by renaming.
 * Return <0 on failure 0 on success.
 */
static int
pre_symlink(struct upload *p, struct sess *sess)
{
	struct stat		 st;
	const struct flist	*f;
	int			 rc, newlink = 0, updatelink = 0;
	char			*b, *temp = NULL;

	f = &p->fl[p->idx];
	assert(S_ISLNK(f->st.mode));

	if (!sess->opts->preserve_links) {
		WARNX("%s: ignoring symlink", f->path);
		return 0;
	}
	if (sess->opts->dry_run) {
		log_symlink(sess, f);
		return 0;
	}

	/*
	 * See if the symlink already exists.
	 * If it's a directory, then try to unlink the directory prior
	 * to overwriting with a symbolic link.
	 * If it's a non-directory, we just overwrite it.
	 */

	assert(p->rootfd != -1);
	rc = fstatat(p->rootfd, f->path, &st, AT_SYMLINK_NOFOLLOW);

	if (rc == -1 && errno != ENOENT) {
		ERR("%s: fstatat", f->path);
		return -1;
	}
	if (rc != -1 && !S_ISLNK(st.st_mode)) {
		if (S_ISDIR(st.st_mode) &&
		    unlinkat(p->rootfd, f->path, AT_REMOVEDIR) == -1) {
			ERR("%s: unlinkat", f->path);
			return -1;
		}
		rc = -1;
	}

	/*
	 * If the symbolic link already exists, then make sure that it
	 * points to the correct place.
	 */

	if (rc != -1) {
		b = symlinkat_read(p->rootfd, f->path);
		if (b == NULL) {
			ERRX1("symlinkat_read");
			return -1;
		}
		if (strcmp(f->link, b)) {
			free(b);
			b = NULL;
			LOG3("%s: updating symlink: %s", f->path, f->link);
			updatelink = 1;
		}
		free(b);
		b = NULL;
	}

	/*
	 * Create the temporary file as a symbolic link, then rename the
	 * temporary file as the real one, overwriting anything there.
	 */

	if (rc == -1 || updatelink) {
		LOG3("%s: creating symlink: %s", f->path, f->link);
		if (mktemplate(&temp, f->path, sess->opts->recursive) == -1) {
			ERRX1("mktemplate");
			return -1;
		}
		if (mkstemplinkat(f->link, p->rootfd, temp) == NULL) {
			ERR("mkstemplinkat");
			free(temp);
			return -1;
		}
		newlink = 1;
	}

	rsync_set_metadata_at(sess, newlink,
		p->rootfd, f, newlink ? temp : f->path);

	if (newlink) {
		if (renameat(p->rootfd, temp, p->rootfd, f->path) == -1) {
			ERR("%s: renameat %s", temp, f->path);
			(void)unlinkat(p->rootfd, temp, 0);
			free(temp);
			return -1;
		}
		free(temp);
	}

	log_symlink(sess, f);
	return 0;
}

/*
 * See pre_symlink(), but for devices.
 * FIXME: this is very similar to the other pre_xxx() functions.
 * Return <0 on failure 0 on success.
 */
static int
pre_dev(struct upload *p, struct sess *sess)
{
	struct stat		 st;
	const struct flist	*f;
	int			 rc, newdev = 0, updatedev = 0;
	char			*temp = NULL;

	f = &p->fl[p->idx];
	assert(S_ISBLK(f->st.mode) || S_ISCHR(f->st.mode));

	if (!sess->opts->devices || getuid() != 0) {
		WARNX("skipping non-regular file %s", f->path);
		return 0;
	}
	if (sess->opts->dry_run) {
		log_file(sess, f);
		return 0;
	}

	/*
	 * See if the dev already exists.
	 * If a non-device exists in its place, we'll replace that.
	 * If it replaces a directory, remove the directory first.
	 */

	assert(p->rootfd != -1);
	rc = fstatat(p->rootfd, f->path, &st, AT_SYMLINK_NOFOLLOW);

	if (rc == -1 && errno != ENOENT) {
		ERR("%s: fstatat", f->path);
		return -1;
	}
	if (rc != -1 && !(S_ISBLK(st.st_mode) || S_ISCHR(st.st_mode))) {
		if (S_ISDIR(st.st_mode) &&
		    unlinkat(p->rootfd, f->path, AT_REMOVEDIR) == -1) {
			ERR("%s: unlinkat", f->path);
			return -1;
		}
		rc = -1;
	}

	/* Make sure existing device is of the correct type. */

	if (rc != -1) {
		if ((f->st.mode & (S_IFCHR|S_IFBLK)) !=
		    (st.st_mode & (S_IFCHR|S_IFBLK)) ||
		    f->st.rdev != st.st_rdev) {
			LOG3("%s: updating device", f->path);
			updatedev = 1;
		}
	}

	if (rc == -1 || updatedev) {
		newdev = 1;
		if (mktemplate(&temp, f->path, sess->opts->recursive) == -1) {
			ERRX1("mktemplate");
			return -1;
		}
		if (mkstempnodat(p->rootfd, temp,
		    f->st.mode & (S_IFCHR|S_IFBLK), f->st.rdev) == NULL) {
			ERR("mkstempnodat");
			free(temp);
			return -1;
		}
	}

	rsync_set_metadata_at(sess, newdev,
	    p->rootfd, f, newdev ? temp : f->path);

	if (newdev) {
		if (renameat(p->rootfd, temp, p->rootfd, f->path) == -1) {
			ERR("%s: renameat %s", temp, f->path);
			(void)unlinkat(p->rootfd, temp, 0);
			free(temp);
			return -1;
		}
		free(temp);
	}

	log_file(sess, f);
	return 0;
}

/*
 * See pre_symlink(), but for FIFOs.
 * FIXME: this is very similar to the other pre_xxx() functions.
 * Return <0 on failure 0 on success.
 */
static int
pre_fifo(struct upload *p, struct sess *sess)
{
	struct stat		 st;
	const struct flist	*f;
	int			 rc, newfifo = 0;
	char			*temp = NULL;

	f = &p->fl[p->idx];
	assert(S_ISFIFO(f->st.mode));

	if (!sess->opts->specials) {
		WARNX("skipping non-regular file %s", f->path);
		return 0;
	}
	if (sess->opts->dry_run) {
		log_file(sess, f);
		return 0;
	}

	/*
	 * See if the fifo already exists.
	 * If it exists as a non-FIFO, unlink it (if a directory) then
	 * mark it from replacement.
	 */

	assert(p->rootfd != -1);
	rc = fstatat(p->rootfd, f->path, &st, AT_SYMLINK_NOFOLLOW);

	if (rc == -1 && errno != ENOENT) {
		ERR("%s: fstatat", f->path);
		return -1;
	}
	if (rc != -1 && !S_ISFIFO(st.st_mode)) {
		if (S_ISDIR(st.st_mode) &&
		    unlinkat(p->rootfd, f->path, AT_REMOVEDIR) == -1) {
			ERR("%s: unlinkat", f->path);
			return -1;
		}
		rc = -1;
	}

	if (rc == -1) {
		newfifo = 1;
		if (mktemplate(&temp, f->path, sess->opts->recursive) == -1) {
			ERRX1("mktemplate");
			return -1;
		}
		if (mkstempfifoat(p->rootfd, temp) == NULL) {
			ERR("mkstempfifoat");
			free(temp);
			return -1;
		}
	}

	rsync_set_metadata_at(sess, newfifo,
		p->rootfd, f, newfifo ? temp : f->path);

	if (newfifo) {
		if (renameat(p->rootfd, temp, p->rootfd, f->path) == -1) {
			ERR("%s: renameat %s", temp, f->path);
			(void)unlinkat(p->rootfd, temp, 0);
			free(temp);
			return -1;
		}
		free(temp);
	}

	log_file(sess, f);
	return 0;
}

/*
 * See pre_symlink(), but for socket files.
 * FIXME: this is very similar to the other pre_xxx() functions.
 * Return <0 on failure 0 on success.
 */
static int
pre_sock(struct upload *p, struct sess *sess)
{
	struct stat		 st;
	const struct flist	*f;
	int			 rc, newsock = 0;
	char			*temp = NULL;

	f = &p->fl[p->idx];
	assert(S_ISSOCK(f->st.mode));

	if (!sess->opts->specials) {
		WARNX("skipping non-regular file %s", f->path);
		return 0;
	}
	if (sess->opts->dry_run) {
		log_file(sess, f);
		return 0;
	}

	/*
	 * See if the fifo already exists.
	 * If it exists as a non-FIFO, unlink it (if a directory) then
	 * mark it from replacement.
	 */

	assert(p->rootfd != -1);
	rc = fstatat(p->rootfd, f->path, &st, AT_SYMLINK_NOFOLLOW);

	if (rc == -1 && errno != ENOENT) {
		ERR("%s: fstatat", f->path);
		return -1;
	}
	if (rc != -1 && !S_ISSOCK(st.st_mode)) {
		if (S_ISDIR(st.st_mode) &&
		    unlinkat(p->rootfd, f->path, AT_REMOVEDIR) == -1) {
			ERR("%s: unlinkat", f->path);
			return -1;
		}
		rc = -1;
	}

	if (rc == -1) {
		newsock = 1;
		if (mktemplate(&temp, f->path, sess->opts->recursive) == -1) {
			ERRX1("mktemplate");
			return -1;
		}
		if (mkstempsock(p->root, temp) == NULL) {
			ERR("mkstempsock");
			free(temp);
			return -1;
		}
	}

	rsync_set_metadata_at(sess, newsock,
		p->rootfd, f, newsock ? temp : f->path);

	if (newsock) {
		if (renameat(p->rootfd, temp, p->rootfd, f->path) == -1) {
			ERR("%s: renameat %s", temp, f->path);
			(void)unlinkat(p->rootfd, temp, 0);
			free(temp);
			return -1;
		}
		free(temp);
	}

	log_file(sess, f);
	return 0;
}

/*
 * If not found, create the destination directory in prefix order.
 * Create directories using the existing umask.
 * Return <0 on failure 0 on success.
 */
static int
pre_dir(const struct upload *p, struct sess *sess)
{
	struct stat	 st;
	int		 rc;
	const struct flist *f;

	f = &p->fl[p->idx];
	assert(S_ISDIR(f->st.mode));

	if (!sess->opts->recursive) {
		WARNX("%s: ignoring directory", f->path);
		return 0;
	}
	if (sess->opts->dry_run) {
		log_dir(sess, f);
		return 0;
	}

	assert(p->rootfd != -1);
	rc = fstatat(p->rootfd, f->path, &st, AT_SYMLINK_NOFOLLOW);

	if (rc == -1 && errno != ENOENT) {
		ERR("%s: fstatat", f->path);
		return -1;
	}
	if (rc != -1 && !S_ISDIR(st.st_mode)) {
		ERRX("%s: not a directory", f->path);
		return -1;
	} else if (rc != -1) {
		/*
		 * FIXME: we should fchmod the permissions here as well,
		 * as we may locally have shut down writing into the
		 * directory and that doesn't work.
		 */
		LOG3("%s: updating directory", f->path);
		return 0;
	}

	/*
	 * We want to make the directory with default permissions (using
	 * our old umask, which we've since unset), then adjust
	 * permissions (assuming preserve_perms or new) afterward in
	 * case it's u-w or something.
	 */

	LOG3("%s: creating directory", f->path);
	if (mkdirat(p->rootfd, f->path, 0777 & ~p->oumask) == -1) {
		ERR("%s: mkdirat", f->path);
		return -1;
	}

	p->newdir[p->idx] = 1;
	log_dir(sess, f);
	return 0;
}

/*
 * Process the directory time and mode for "idx" in the file list.
 * Returns zero on failure, non-zero on success.
 */
static int
post_dir(struct sess *sess, const struct upload *u, size_t idx)
{
	struct timespec	 tv[2];
	int		 rc;
	struct stat	 st;
	const struct flist *f;

	f = &u->fl[idx];
	assert(S_ISDIR(f->st.mode));

	/* We already warned about the directory in pre_process_dir(). */

	if (!sess->opts->recursive)
		return 1;
	if (sess->opts->dry_run)
		return 1;

	if (fstatat(u->rootfd, f->path, &st, AT_SYMLINK_NOFOLLOW) == -1) {
		ERR("%s: fstatat", f->path);
		return 0;
	}
	if (!S_ISDIR(st.st_mode)) {
		WARNX("%s: not a directory", f->path);
		return 0;
	}

	/*
	 * Update the modification time if we're a new directory *or* if
	 * we're preserving times and the time has changed.
	 * FIXME: run rsync_set_metadata()?
	 */

	if (u->newdir[idx] ||
	    (sess->opts->preserve_times &&
	     st.st_mtime != f->st.mtime)) {
		tv[0].tv_sec = time(NULL);
		tv[0].tv_nsec = 0;
		tv[1].tv_sec = f->st.mtime;
		tv[1].tv_nsec = 0;
		rc = utimensat(u->rootfd, f->path, tv, 0);
		if (rc == -1) {
			ERR("%s: utimensat", f->path);
			return 0;
		}
		LOG4("%s: updated date", f->path);
	}

	/*
	 * Update the mode if we're a new directory *or* if we're
	 * preserving modes and it has changed.
	 */

	if (u->newdir[idx] ||
	    (sess->opts->preserve_perms && st.st_mode != f->st.mode)) {
		rc = fchmodat(u->rootfd, f->path, f->st.mode, 0);
		if (rc == -1) {
			ERR("%s: fchmodat", f->path);
			return 0;
		}
		LOG4("%s: updated mode", f->path);
	}

	return 1;
}

/*
 * Check if file exists in the specified root directory.
 * Returns:
 *    -1 on error
 *     0 if file is considered the same
 *     1 if file exists and is possible match
 *     2 if file exists but quick check failed
 *     3 if file does not exist
 * The stat pointer st is only valid for 0, 1, and 2 returns.
 */
static int
check_file(int rootfd, const struct flist *f, struct stat *st)
{ 
	if (fstatat(rootfd, f->path, st, AT_SYMLINK_NOFOLLOW) == -1) {
		if (errno == ENOENT)
			return 3;

		ERR("%s: fstatat", f->path);
		return -1;
	}

	/* non-regular file needs attention */
	if (!S_ISREG(st->st_mode))
		return 2;

	/* quick check if file is the same */
	/* TODO: add support for --checksum, --size-only and --ignore-times */
	if (st->st_size == f->st.size) {
		if (st->st_mtime == f->st.mtime)
			return 0;
		return 1;
	}

	/* file needs attention */
	return 2;
}

/*
 * Try to open the file at the current index.
 * If the file does not exist, returns with >0.
 * Return <0 on failure, 0 on success w/nothing to be done, >0 on
 * success and the file needs attention.
 */
static int
pre_file(const struct upload *p, int *filefd, off_t *size,
    struct sess *sess)
{
	const struct flist *f;
	struct stat st;
	int i, rc, match = -1;

	f = &p->fl[p->idx];
	assert(S_ISREG(f->st.mode));

	if (sess->opts->dry_run) {
		log_file(sess, f);
		if (!io_write_int(sess, p->fdout, p->idx)) {
			ERRX1("io_write_int");
			return -1;
		}
		return 0;
	}

	/*
	 * For non dry-run cases, we'll write the acknowledgement later
	 * in the rsync_uploader() function.
	 */

	*size = 0;
	*filefd = -1;

	rc = check_file(p->rootfd, f, &st);
	if (rc == -1)
		return -1;
	if (rc == 2 && !S_ISREG(st.st_mode)) {
		if (S_ISDIR(st.st_mode) &&
		    unlinkat(p->rootfd, f->path, AT_REMOVEDIR) == -1) {
			ERR("%s: unlinkat", f->path);
			return -1;
		}
	}
	if (rc == 0) {
		if (!rsync_set_metadata_at(sess, 0, p->rootfd, f, f->path)) {
			ERRX1("rsync_set_metadata");
			return -1;
		}
		LOG3("%s: skipping: up to date", f->path);
		return 0;
	}

	/* check alternative locations for better match */
	for (i = 0; sess->opts->basedir[i] != NULL; i++) {
		const char *root = sess->opts->basedir[i];
		int dfd, x;

		dfd = openat(p->rootfd, root, O_RDONLY | O_DIRECTORY);
		if (dfd == -1)
			err(ERR_FILE_IO, "%s: openat", root);
		x = check_file(dfd, f, &st);
		/* found a match */
		if (x == 0) {
			if (rc >= 0) {
				/* found better match, delete file in rootfd */
				if (unlinkat(p->rootfd, f->path, 0) == -1 &&
				    errno != ENOENT) {
					ERR("%s: unlinkat", f->path);
					return -1;
				}
			}
			LOG3("%s: skipping: up to date in %s", f->path, root);
			/* TODO: depending on mode link or copy file */
			close(dfd);
			return 0;
		} else if (x == 1 && match == -1) {
			/* found a local file that is a close match */
			match = i;
		}
		close(dfd);
	}
	if (match != -1) {
		/* copy match from basedir into root as a start point */
		copy_file(p->rootfd, sess->opts->basedir[match], f);
		if (fstatat(p->rootfd, f->path, &st, AT_SYMLINK_NOFOLLOW) ==
		    -1) {
			ERR("%s: fstatat", f->path);
			return -1;
		}
	}

	*size = st.st_size;
	*filefd = openat(p->rootfd, f->path, O_RDONLY | O_NOFOLLOW);
	if (*filefd == -1 && errno != ENOENT) {
		ERR("%s: openat", f->path);
		return -1;
	}

	/* file needs attention */
	return 1;
}

/*
 * Allocate an uploader object in the correct state to start.
 * Returns NULL on failure or the pointer otherwise.
 * On success, upload_free() must be called with the allocated pointer.
 */
struct upload *
upload_alloc(const char *root, int rootfd, int fdout,
	size_t clen, const struct flist *fl, size_t flsz, mode_t msk)
{
	struct upload	*p;

	if ((p = calloc(1, sizeof(struct upload))) == NULL) {
		ERR("calloc");
		return NULL;
	}

	p->state = UPLOAD_FIND_NEXT;
	p->oumask = msk;
	p->root = strdup(root);
	if (p->root == NULL) {
		ERR("strdup");
		free(p);
		return NULL;
	}
	p->rootfd = rootfd;
	p->csumlen = clen;
	p->fdout = fdout;
	p->fl = fl;
	p->flsz = flsz;
	p->newdir = calloc(flsz, sizeof(int));
	if (p->newdir == NULL) {
		ERR("calloc");
		free(p->root);
		free(p);
		return NULL;
	}
	return p;
}

/*
 * Perform all cleanups and free.
 * Passing a NULL to this function is ok.
 */
void
upload_free(struct upload *p)
{

	if (p == NULL)
		return;
	free(p->root);
	free(p->newdir);
	free(p->buf);
	free(p);
}

/*
 * Iterates through all available files and conditionally gets the file
 * ready for processing to check whether it's up to date.
 * If not up to date or empty, sends file information to the sender.
 * If returns 0, we've processed all files there are to process.
 * If returns >0, we're waiting for POLLIN or POLLOUT data.
 * Otherwise returns <0, which is an error.
 */
int
rsync_uploader(struct upload *u, int *fileinfd,
	struct sess *sess, int *fileoutfd)
{
	struct blkset	    blk;
	void		   *mbuf, *bufp;
	ssize_t		    msz;
	size_t		    i, pos, sz;
	off_t		    offs, filesize;
	int		    c;

	/* Once finished this should never get called again. */
	assert(u->state != UPLOAD_FINISHED);

	/*
	 * If we have an upload in progress, then keep writing until the
	 * buffer has been fully written.
	 * We must only have the output file descriptor working and also
	 * have a valid buffer to write.
	 */

	if (u->state == UPLOAD_WRITE) {
		assert(u->buf != NULL);
		assert(*fileoutfd != -1);
		assert(*fileinfd == -1);

		/*
		 * Unfortunately, we need to chunk these: if we're
		 * the server side of things, then we're multiplexing
		 * output and need to wrap this in chunks.
		 * This is a major deficiency of rsync.
		 * FIXME: add a "fast-path" mode that simply dumps out
		 * the buffer non-blocking if we're not mplexing.
		 */

		if (u->bufpos < u->bufsz) {
			sz = MAX_CHUNK < (u->bufsz - u->bufpos) ?
				MAX_CHUNK : (u->bufsz - u->bufpos);
			c = io_write_buf(sess, u->fdout,
				u->buf + u->bufpos, sz);
			if (c == 0) {
				ERRX1("io_write_nonblocking");
				return -1;
			}
			u->bufpos += sz;
			if (u->bufpos < u->bufsz)
				return 1;
		}

		/*
		 * Let the UPLOAD_FIND_NEXT state handle things if we
		 * finish, as we'll need to write a POLLOUT message and
		 * not have a writable descriptor yet.
		 */

		u->state = UPLOAD_FIND_NEXT;
		u->idx++;
		return 1;
	}

	/*
	 * If we invoke the uploader without a file currently open, then
	 * we iterate through til the next available regular file and
	 * start the opening process.
	 * This means we must have the output file descriptor working.
	 */

	if (u->state == UPLOAD_FIND_NEXT) {
		assert(*fileinfd == -1);
		assert(*fileoutfd != -1);

		for ( ; u->idx < u->flsz; u->idx++) {
			if (S_ISDIR(u->fl[u->idx].st.mode))
				c = pre_dir(u, sess);
			else if (S_ISLNK(u->fl[u->idx].st.mode))
				c = pre_symlink(u, sess);
			else if (S_ISREG(u->fl[u->idx].st.mode))
				c = pre_file(u, fileinfd, &filesize, sess);
			else if (S_ISBLK(u->fl[u->idx].st.mode) ||
			    S_ISCHR(u->fl[u->idx].st.mode))
				c = pre_dev(u, sess);
			else if (S_ISFIFO(u->fl[u->idx].st.mode))
				c = pre_fifo(u, sess);
			else if (S_ISSOCK(u->fl[u->idx].st.mode))
				c = pre_sock(u, sess);
			else
				c = 0;

			if (c < 0)
				return -1;
			else if (c > 0)
				break;
		}

		/*
		 * Whether we've finished writing files or not, we
		 * disable polling on the output channel.
		 */

		*fileoutfd = -1;
		if (u->idx == u->flsz) {
			assert(*fileinfd == -1);
			if (!io_write_int(sess, u->fdout, -1)) {
				ERRX1("io_write_int");
				return -1;
			}
			u->state = UPLOAD_FINISHED;
			LOG4("uploader: finished");
			return 0;
		}

		/* Go back to the event loop, if necessary. */

		u->state = UPLOAD_WRITE;
	}

	/* Initialies our blocks. */

	assert(u->state == UPLOAD_WRITE);
	memset(&blk, 0, sizeof(struct blkset));
	blk.csum = u->csumlen;

	if (*fileinfd != -1 && filesize > 0) {
		init_blkset(&blk, filesize);
		assert(blk.blksz);

		blk.blks = calloc(blk.blksz, sizeof(struct blk));
		if (blk.blks == NULL) {
			ERR("calloc");
			close(*fileinfd);
			*fileinfd = -1;
			return -1;
		}

		if ((mbuf = malloc(blk.len)) == NULL) {
			ERR("malloc");
			close(*fileinfd);
			*fileinfd = -1;
			free(blk.blks);
			return -1;
		}

		offs = 0;
		i = 0;
		do {
			msz = pread(*fileinfd, mbuf, blk.len, offs);
			if ((size_t)msz != blk.len && (size_t)msz != blk.rem) {
				ERR("pread");
				close(*fileinfd);
				*fileinfd = -1;
				free(mbuf);
				free(blk.blks);
				return -1;
			}
			init_blk(&blk.blks[i], &blk, offs, i, mbuf, sess);
			offs += blk.len;
			LOG3(
			    "i=%ld, offs=%lld, msz=%ld, blk.len=%lu, blk.rem=%lu",
			    i, offs, msz, blk.len, blk.rem);
			i++;
		} while (i < blk.blksz);

		free(mbuf);
		close(*fileinfd);
		*fileinfd = -1;
		LOG3("%s: mapped %jd B with %zu blocks",
		    u->fl[u->idx].path, (intmax_t)blk.size,
		    blk.blksz);
	} else {
		if (*fileinfd != -1) {
			close(*fileinfd);
			*fileinfd = -1;
		}
		blk.len = MAX_CHUNK; /* Doesn't matter. */
		LOG3("%s: not mapped", u->fl[u->idx].path);
	}

	assert(*fileinfd == -1);

	/* Make sure the block metadata buffer is big enough. */

	u->bufsz =
	     sizeof(int32_t) + /* identifier */
	     sizeof(int32_t) + /* block count */
	     sizeof(int32_t) + /* block length */
	     sizeof(int32_t) + /* checksum length */
	     sizeof(int32_t) + /* block remainder */
	     blk.blksz *
	     (sizeof(int32_t) + /* short checksum */
	      blk.csum); /* long checksum */

	if (u->bufsz > u->bufmax) {
		if ((bufp = realloc(u->buf, u->bufsz)) == NULL) {
			ERR("realloc");
			free(blk.blks);
			return -1;
		}
		u->buf = bufp;
		u->bufmax = u->bufsz;
	}

	u->bufpos = pos = 0;
	io_buffer_int(u->buf, &pos, u->bufsz, u->idx);
	io_buffer_int(u->buf, &pos, u->bufsz, blk.blksz);
	io_buffer_int(u->buf, &pos, u->bufsz, blk.len);
	io_buffer_int(u->buf, &pos, u->bufsz, blk.csum);
	io_buffer_int(u->buf, &pos, u->bufsz, blk.rem);
	for (i = 0; i < blk.blksz; i++) {
		io_buffer_int(u->buf, &pos, u->bufsz,
			blk.blks[i].chksum_short);
		io_buffer_buf(u->buf, &pos, u->bufsz,
			blk.blks[i].chksum_long, blk.csum);
	}
	assert(pos == u->bufsz);

	/* Reenable the output poller and clean up. */

	*fileoutfd = u->fdout;
	free(blk.blks);
	return 1;
}

/*
 * Fix up the directory permissions and times post-order.
 * We can't fix up directory permissions in place because the server may
 * want us to have overly-tight permissions---say, those that don't
 * allow writing into the directory.
 * We also need to do our directory times post-order because making
 * files within the directory will change modification times.
 * Returns zero on failure, non-zero on success.
 */
int
rsync_uploader_tail(struct upload *u, struct sess *sess)
{
	size_t	 i;


	if (!sess->opts->preserve_times &&
	    !sess->opts->preserve_perms)
		return 1;

	LOG2("fixing up directory times and permissions");

	for (i = 0; i < u->flsz; i++)
		if (S_ISDIR(u->fl[i].st.mode))
			if (!post_dir(sess, u, i))
				return 0;

	return 1;
}