thodg/got/lib/privsep.c

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• Hash : e7885405
  Author :
  Date : 2018-09-10T17:26:06
  

  read packed trees with privsep
  

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• lib/privsep.c

• /*
   * Copyright (c) 2018 Stefan Sperling <stsp@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/types.h>
  #include <sys/queue.h>
  #include <sys/uio.h>
  #include <sys/syslimits.h>
  #include <sys/wait.h>
  
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <errno.h>
  #include <stdint.h>
  #include <poll.h>
  #include <imsg.h>
  #include <sha1.h>
  #include <zlib.h>
  #include <time.h>
  
  #include "got_object.h"
  #include "got_error.h"
  
  #include "got_lib_sha1.h"
  #include "got_lib_delta.h"
  #include "got_lib_inflate.h"
  #include "got_lib_object.h"
  #include "got_lib_object_parse.h"
  #include "got_lib_privsep.h"
  #include "got_lib_pack.h"
  
  #ifndef MIN
  #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
  #endif
  
  static const struct got_error *
  poll_fd(int fd, int events, int timeout)
  {
  	struct pollfd pfd[1];
  	int n;
  
  	pfd[0].fd = fd;
  	pfd[0].events = events;
  
  	n = poll(pfd, 1, timeout);
  	if (n == -1)
  		return got_error_from_errno();
  	if (n == 0)
  		return got_error(GOT_ERR_TIMEOUT);
  	if (pfd[0].revents & (POLLERR | POLLNVAL))
  		return got_error_from_errno();
  	if (pfd[0].revents & (events | POLLHUP))
  		return NULL;
  
  	return got_error(GOT_ERR_INTERRUPT);
  }
  
  static const struct got_error *
  read_imsg(struct imsgbuf *ibuf)
  {
  	const struct got_error *err;
  	size_t n;
  
  	err = poll_fd(ibuf->fd, POLLIN, INFTIM);
  	if (err)
  		return err;
  
  	n = imsg_read(ibuf);
  	if (n == -1) {
  		if (errno == EAGAIN) /* Could be a file-descriptor leak. */
  			return got_error(GOT_ERR_PRIVSEP_NO_FD);
  		return got_error(GOT_ERR_PRIVSEP_READ);
  	}
  	if (n == 0)
  		return got_error(GOT_ERR_PRIVSEP_PIPE);
  
  	return NULL;
  }
  
  const struct got_error *
  got_privsep_wait_for_child(pid_t pid)
  {
  	int child_status;
  
  	waitpid(pid, &child_status, 0);
  
  	if (!WIFEXITED(child_status))
  		return got_error(GOT_ERR_PRIVSEP_DIED);
  
  	if (WEXITSTATUS(child_status) != 0)
  		return got_error(GOT_ERR_PRIVSEP_EXIT);
  
  	return NULL;
  }
  
  const struct got_error *
  got_privsep_recv_imsg(struct imsg *imsg, struct imsgbuf *ibuf, size_t min_datalen)
  {
  	const struct got_error *err;
  	ssize_t n;
  
  	n = imsg_get(ibuf, imsg);
  	if (n == -1)
  		return got_error_from_errno();
  
  	while (n == 0) {
  		err = read_imsg(ibuf);
  		if (err)
  			return err;
  		n = imsg_get(ibuf, imsg);
  	}
  
  	if (imsg->hdr.len < IMSG_HEADER_SIZE + min_datalen)
  		return got_error(GOT_ERR_PRIVSEP_LEN);
  
  	return NULL;
  }
  
  static const struct got_error *
  recv_imsg_error(struct imsg *imsg, size_t datalen)
  {
  	struct got_imsg_error ierr;
  
  	if (datalen != sizeof(ierr))
  		return got_error(GOT_ERR_PRIVSEP_LEN);
  
  	memcpy(&ierr, imsg->data, sizeof(ierr));
  	if (ierr.code == GOT_ERR_ERRNO) {
  		static struct got_error serr;
  		serr.code = GOT_ERR_ERRNO;
  		serr.msg = strerror(ierr.errno_code);
  		return &serr;
  	}
  
  	return got_error(ierr.code);
  }
  
  /* Attempt to send an error in an imsg. Complain on stderr as a last resort. */
  void
  got_privsep_send_error(struct imsgbuf *ibuf, const struct got_error *err)
  {
  	const struct got_error *poll_err;
  	struct got_imsg_error ierr;
  	int ret;
  
  	ierr.code = err->code;
  	if (err->code == GOT_ERR_ERRNO)
  		ierr.errno_code = errno;
  	else
  		ierr.errno_code = 0;
  	ret = imsg_compose(ibuf, GOT_IMSG_ERROR, 0, 0, -1, &ierr, sizeof(ierr));
  	if (ret != -1) {
  		fprintf(stderr, "%s: error %d \"%s\": imsg_compose: %s\n",
  		    getprogname(), err->code, err->msg, strerror(errno));
  		return;
  	}
  
  	poll_err = poll_fd(ibuf->fd, POLLOUT, INFTIM);
  	if (poll_err) {
  		fprintf(stderr, "%s: error %d \"%s\": poll: %s\n",
  		    getprogname(), err->code, err->msg, poll_err->msg);
  		return;
  	}
  
  	ret = imsg_flush(ibuf);
  	if (ret == -1) {
  		fprintf(stderr, "%s: error %d \"%s\": imsg_flush: %s\n",
  		    getprogname(), err->code, err->msg, strerror(errno));
  		return;
  	}
  }
  
  static const struct got_error *
  flush_imsg(struct imsgbuf *ibuf)
  {
  	const struct got_error *err;
  
  	err = poll_fd(ibuf->fd, POLLOUT, INFTIM);
  	if (err)
  		return err;
  
  	if (imsg_flush(ibuf) == -1)
  		return got_error_from_errno();
  
  	return NULL;
  }
  
  const struct got_error *
  got_privsep_send_stop(int fd)
  {
  	const struct got_error *err = NULL;
  	struct imsgbuf ibuf;
  
  	imsg_init(&ibuf, fd);
  
  	if (imsg_compose(&ibuf, GOT_IMSG_STOP, 0, 0, -1, NULL, 0) == -1)
  		return got_error_from_errno();
  
  	err = flush_imsg(&ibuf);
  	imsg_clear(&ibuf);
  	return err;
  }
  
  static const struct got_error *
  send_delta(struct got_delta *delta, struct imsgbuf *ibuf)
  {
  	struct got_imsg_delta idelta;
  	size_t offset, remain;
  
  	idelta.offset = delta->offset;
  	idelta.tslen = delta->tslen;
  	idelta.type = delta->type;
  	idelta.size = delta->size;
  	idelta.data_offset = delta->data_offset;
  	idelta.delta_len = delta->delta_len;
  
  	if (imsg_compose(ibuf, GOT_IMSG_DELTA, 0, 0, -1,
  	    &idelta, sizeof(idelta)) == -1)
  		return got_error_from_errno();
  
  	if (imsg_flush(ibuf) == -1)
  		return got_error_from_errno();
  
  	offset = 0;
  	remain = delta->delta_len;
  	while (remain > 0) {
  		size_t n = MIN(MAX_IMSGSIZE - IMSG_HEADER_SIZE, remain);
  
  		if (imsg_compose(ibuf, GOT_IMSG_DELTA_STREAM, 0, 0, -1,
  		    delta->delta_buf + offset, n) == -1)
  			return got_error_from_errno();
  
  		if (imsg_flush(ibuf) == -1)
  			return got_error_from_errno();
  
  		offset += n;
  		remain -= n;
  	}
  
  	return NULL;
  }
  
  const struct got_error *
  got_privsep_send_obj_req(struct imsgbuf *ibuf, int fd, struct got_object *obj)
  {
  	const struct got_error *err = NULL;
  	struct got_imsg_object iobj, *iobjp = NULL;
  	size_t iobj_size = 0;
  	int imsg_code = GOT_IMSG_OBJECT_REQUEST;
  
  	if (obj) {
  		switch (obj->type) {
  		case GOT_OBJ_TYPE_TREE:
  			imsg_code = GOT_IMSG_TREE_REQUEST;
  			break;
  		case GOT_OBJ_TYPE_COMMIT:
  			imsg_code = GOT_IMSG_COMMIT_REQUEST;
  			break;
  		/* Blobs are handled in got_privsep_send_blob_req(). */
  		default:
  			return got_error(GOT_ERR_OBJ_TYPE);
  		}
  
  		iobj.type = obj->type;
  		iobj.flags = obj->flags;
  		iobj.hdrlen = obj->hdrlen;
  		iobj.size = obj->size;
  		iobj.ndeltas = obj->deltas.nentries;
  		if (iobj.flags & GOT_OBJ_FLAG_PACKED)
  			iobj.pack_offset = obj->pack_offset;
  
  		iobjp = &iobj;
  		iobj_size = sizeof(iobj);
  	}
  
  	if (imsg_compose(ibuf, imsg_code, 0, 0, fd, iobjp, iobj_size) == -1)
  		return got_error_from_errno();
  
  	err = flush_imsg(ibuf);
  	if (err)
  		return err;
  
  	if (obj && obj->flags & GOT_OBJ_FLAG_DELTIFIED) {
  		struct got_delta *delta;
  		SIMPLEQ_FOREACH(delta, &obj->deltas.entries, entry) {
  			err = send_delta(delta, ibuf);
  			if (err)
  				break;
  		}
  	}
  
  	return err;
  }
  
  const struct got_error *
  got_privsep_send_blob_req(struct imsgbuf *ibuf, int outfd, int infd)
  {
  	const struct got_error *err = NULL;
  
  	if (imsg_compose(ibuf, GOT_IMSG_BLOB_REQUEST, 0, 0, infd, NULL, 0)
  	    == -1) {
  		close(infd);
  		close(outfd);
  		return got_error_from_errno();
  	}
  
  	err = flush_imsg(ibuf);
  	if (err) {
  		close(outfd);
  		return err;
  	}
  
  	if (imsg_compose(ibuf, GOT_IMSG_BLOB_OUTFD, 0, 0, outfd, NULL, 0)
  	    == -1) {
  		close(outfd);
  		return got_error_from_errno();
  	}
  
  	return flush_imsg(ibuf);
  }
  
  const struct got_error *
  got_privsep_send_obj(struct imsgbuf *ibuf, struct got_object *obj)
  {
  	const struct got_error *err = NULL;
  	struct got_imsg_object iobj;
  	struct got_delta *delta;
  
  	iobj.type = obj->type;
  	iobj.flags = obj->flags;
  	iobj.hdrlen = obj->hdrlen;
  	iobj.size = obj->size;
  	iobj.ndeltas = obj->deltas.nentries;
  	if (iobj.flags & GOT_OBJ_FLAG_PACKED)
  		iobj.pack_offset = obj->pack_offset;
  
  	if (imsg_compose(ibuf, GOT_IMSG_OBJECT, 0, 0, -1, &iobj, sizeof(iobj))
  	    == -1)
  		return got_error_from_errno();
  
  	err = flush_imsg(ibuf);
  	if (err)
  		return err;
  
  	SIMPLEQ_FOREACH(delta, &obj->deltas.entries, entry) {
  		err = send_delta(delta, ibuf);
  		if (err)
  			break;
  	}
  
  	return err;
  }
  
  static const struct got_error *
  receive_delta(struct got_delta **delta, struct imsgbuf *ibuf)
  {
  	const struct got_error *err = NULL;
  	struct imsg imsg;
  	struct got_imsg_delta idelta;
  	uint8_t *delta_buf = NULL;
  	const size_t min_datalen =
  	    MIN(sizeof(struct got_imsg_error), sizeof(struct got_imsg_delta));
  	size_t datalen, offset, remain;
  
  	err = got_privsep_recv_imsg(&imsg, ibuf, min_datalen);
  	if (err)
  		return err;
  
  	datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
  	if (imsg.hdr.type == GOT_IMSG_ERROR)
  		return recv_imsg_error(&imsg, datalen);
  
  	if (imsg.hdr.type != GOT_IMSG_DELTA)
  		return got_error(GOT_ERR_PRIVSEP_MSG);
  	if (datalen != sizeof(idelta))
  		return got_error(GOT_ERR_PRIVSEP_LEN);
  
  	memcpy(&idelta, imsg.data, sizeof(idelta));
  	imsg_free(&imsg);
  
  	switch (idelta.type) {
  	case GOT_OBJ_TYPE_OFFSET_DELTA:
  	case GOT_OBJ_TYPE_REF_DELTA:
  		if (idelta.delta_len < GOT_DELTA_STREAM_LENGTH_MIN)
  			return got_error(GOT_ERR_BAD_DELTA);
  		break;
  	default:
  		if (idelta.delta_len != 0)
  			return got_error(GOT_ERR_BAD_DELTA);
  		break;
  	}
  
  	if (idelta.delta_len > 0) {
  		delta_buf = calloc(1, idelta.delta_len);
  		if (delta_buf == NULL)
  			return got_error_from_errno();
  
  		offset = 0;
  		remain = idelta.delta_len;
  		while (remain > 0) {
  			size_t n = MIN(MAX_IMSGSIZE - IMSG_HEADER_SIZE, remain);
  
  			err = got_privsep_recv_imsg(&imsg, ibuf, n);
  			if (err)
  				return err;
  
  			if (imsg.hdr.type == GOT_IMSG_ERROR)
  				return recv_imsg_error(&imsg, datalen);
  
  			if (imsg.hdr.type == GOT_IMSG_STOP)
  				break;
  
  			if (imsg.hdr.type != GOT_IMSG_DELTA_STREAM)
  				return got_error(GOT_ERR_PRIVSEP_MSG);
  
  			datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
  			if (datalen != n)
  				return got_error(GOT_ERR_PRIVSEP_LEN);
  
  			memcpy(delta_buf + offset, imsg.data, n);
  			imsg_free(&imsg);
  
  			offset += n;
  			remain -= n;
  		}
  	}
  
  	*delta = got_delta_open(idelta.offset, idelta.tslen, idelta.type,
  	    idelta.size, idelta.data_offset, delta_buf, idelta.delta_len);
  	if (*delta == NULL) {
  		err = got_error_from_errno();
  		free(delta_buf);
  	}
  
  	return err;
  }
  
  const struct got_error *
  got_privsep_get_imsg_obj(struct got_object **obj, struct imsg *imsg,
      struct imsgbuf *ibuf)
  {
  	const struct got_error *err = NULL;
  	struct got_imsg_object iobj;
  	size_t datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
  	int i;
  
  	if (datalen != sizeof(iobj))
  		return got_error(GOT_ERR_PRIVSEP_LEN);
  
  	memcpy(&iobj, imsg->data, sizeof(iobj));
  	if (iobj.ndeltas < 0 ||
  	    iobj.ndeltas > GOT_DELTA_CHAIN_RECURSION_MAX)
  		return got_error(GOT_ERR_PRIVSEP_LEN);
  
  	if (iobj.ndeltas > 0 &&
  	    (iobj.flags & GOT_OBJ_FLAG_DELTIFIED) == 0)
  		return got_error(GOT_ERR_BAD_OBJ_DATA);
  
  	*obj = calloc(1, sizeof(**obj));
  	if (*obj == NULL)
  		return got_error_from_errno();
  
  	(*obj)->type = iobj.type;
  	(*obj)->flags = iobj.flags;
  	(*obj)->hdrlen = iobj.hdrlen;
  	(*obj)->size = iobj.size;
  	/* id and path_packfile might be copied in by caller */
  	(*obj)->pack_offset = iobj.pack_offset;
  	SIMPLEQ_INIT(&(*obj)->deltas.entries);
  	for (i = 0; i < iobj.ndeltas; i++) {
  		struct got_delta *delta;
  		err = receive_delta(&delta, ibuf);
  		if (err)
  			break;
  		(*obj)->deltas.nentries++;
  		SIMPLEQ_INSERT_TAIL(&(*obj)->deltas.entries, delta,
  		    entry);
  	}
  
  	return err;
  }
  
  const struct got_error *
  got_privsep_recv_obj(struct got_object **obj, struct imsgbuf *ibuf)
  {
  	const struct got_error *err = NULL;
  	struct imsg imsg;
  	size_t datalen;
  	const size_t min_datalen =
  	    MIN(sizeof(struct got_imsg_error), sizeof(struct got_imsg_object));
  
  	*obj = NULL;
  
  	err = got_privsep_recv_imsg(&imsg, ibuf, min_datalen);
  	if (err)
  		return err;
  
  	datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
  
  	switch (imsg.hdr.type) {
  	case GOT_IMSG_ERROR:
  		err = recv_imsg_error(&imsg, datalen);
  		break;
  	case GOT_IMSG_OBJECT:
  		err = got_privsep_get_imsg_obj(obj, &imsg, ibuf);
  		break;
  	default:
  		err = got_error(GOT_ERR_PRIVSEP_MSG);
  		break;
  	}
  
  	imsg_free(&imsg);
  
  	return err;
  }
  
  const struct got_error *
  got_privsep_send_commit(struct imsgbuf *ibuf, struct got_commit_object *commit)
  {
  	const struct got_error *err = NULL;
  	struct got_imsg_commit_object icommit;
  	uint8_t *buf;
  	size_t len, total;
  	struct got_object_qid *qid;
  
  	memcpy(icommit.tree_id, commit->tree_id->sha1, sizeof(icommit.tree_id));
  	icommit.author_len = strlen(commit->author);
  	memcpy(&icommit.tm_author, &commit->tm_author,
  	    sizeof(icommit.tm_author));
  	icommit.committer_len = strlen(commit->committer);
  	memcpy(&icommit.tm_committer, &commit->tm_committer,
  	    sizeof(icommit.tm_committer));
  	icommit.logmsg_len = strlen(commit->logmsg);
  	icommit.nparents = commit->nparents;
  
  	total = sizeof(icommit) + icommit.author_len +
  	    icommit.committer_len + icommit.logmsg_len +
  	    icommit.nparents * SHA1_DIGEST_LENGTH;
  	/* XXX TODO support very large log messages properly */
  	if (total > MAX_IMSGSIZE)
  		return got_error(GOT_ERR_NO_SPACE);
  
  	buf = malloc(total);
  	if (buf == NULL)
  		return got_error_from_errno();
  
  	len = 0;
  	memcpy(buf + len, &icommit, sizeof(icommit));
  	len += sizeof(icommit);
  	memcpy(buf + len, commit->author, icommit.author_len);
  	len += icommit.author_len;
  	memcpy(buf + len, commit->committer, icommit.committer_len);
  	len += icommit.committer_len;
  	memcpy(buf + len, commit->logmsg, icommit.logmsg_len);
  	len += icommit.logmsg_len;
  	SIMPLEQ_FOREACH(qid, &commit->parent_ids, entry) {
  		memcpy(buf + len, qid->id, SHA1_DIGEST_LENGTH);
  		len += SHA1_DIGEST_LENGTH;
  	}
  
  	if (imsg_compose(ibuf, GOT_IMSG_COMMIT, 0, 0, -1, buf, len) == -1) {
  		err = got_error_from_errno();
  		goto done;
  	}
  
  	err = flush_imsg(ibuf);
  done:
  	free(buf);
  	return err;
  }
  
  const struct got_error *
  got_privsep_recv_commit(struct got_commit_object **commit, struct imsgbuf *ibuf)
  {
  	const struct got_error *err = NULL;
  	struct imsg imsg;
  	struct got_imsg_commit_object icommit;
  	size_t len, datalen;
  	int i;
  	const size_t min_datalen =
  	    MIN(sizeof(struct got_imsg_error),
  	    sizeof(struct got_imsg_commit_object));
  	uint8_t *data;
  
  	*commit = NULL;
  
  	err = got_privsep_recv_imsg(&imsg, ibuf, min_datalen);
  	if (err)
  		return err;
  
  	data = imsg.data;
  	datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
  	len = 0;
  
  	switch (imsg.hdr.type) {
  	case GOT_IMSG_ERROR:
  		err = recv_imsg_error(&imsg, datalen);
  		break;
  	case GOT_IMSG_COMMIT:
  		if (datalen < sizeof(icommit)) {
  			err = got_error(GOT_ERR_PRIVSEP_LEN);
  			break;
  		}
  
  		memcpy(&icommit, data, sizeof(icommit));
  		if (datalen != sizeof(icommit) + icommit.author_len +
  		    icommit.committer_len + icommit.logmsg_len +
  		    icommit.nparents * SHA1_DIGEST_LENGTH) {
  			err = got_error(GOT_ERR_PRIVSEP_LEN);
  			break;
  		}
  		if (icommit.nparents < 0) {
  			err = got_error(GOT_ERR_PRIVSEP_LEN);
  			break;
  		}
  		len += sizeof(icommit);
  
  		*commit = got_object_commit_alloc_partial();
  		if (*commit == NULL) {
  			err = got_error_from_errno();
  			break;
  		}
  
  		memcpy((*commit)->tree_id->sha1, icommit.tree_id,
  		    SHA1_DIGEST_LENGTH);
  		memcpy(&(*commit)->tm_author, &icommit.tm_author,
  		    sizeof((*commit)->tm_author));
  		memcpy(&(*commit)->tm_committer, &icommit.tm_committer,
  		    sizeof((*commit)->tm_committer));
  
  		if (icommit.author_len == 0) {
  			(*commit)->author = strdup("");
  			if ((*commit)->author == NULL) {
  				err = got_error_from_errno();
  				break;
  			}
  		} else {
  			(*commit)->author = malloc(icommit.author_len + 1);
  			if ((*commit)->author == NULL) {
  				err = got_error_from_errno();
  				break;
  			}
  			memcpy((*commit)->author, data + len,
  			    icommit.author_len);
  			(*commit)->author[icommit.author_len] = '\0';
  		}
  		len += icommit.author_len;
  
  		if (icommit.committer_len == 0) {
  			(*commit)->committer = strdup("");
  			if ((*commit)->committer == NULL) {
  				err = got_error_from_errno();
  				break;
  			}
  		} else {
  			(*commit)->committer =
  			    malloc(icommit.committer_len + 1);
  			if ((*commit)->committer == NULL) {
  				err = got_error_from_errno();
  				break;
  			}
  			memcpy((*commit)->committer, data + len,
  			    icommit.committer_len);
  			(*commit)->committer[icommit.committer_len] = '\0';
  		}
  		len += icommit.committer_len;
  
  		if (icommit.logmsg_len == 0) {
  			(*commit)->logmsg = strdup("");
  			if ((*commit)->logmsg == NULL) {
  				err = got_error_from_errno();
  				break;
  			}
  		} else {
  			(*commit)->logmsg = malloc(icommit.logmsg_len + 1);
  			if ((*commit)->logmsg == NULL) {
  				err = got_error_from_errno();
  				break;
  			}
  			memcpy((*commit)->logmsg, data + len,
  			    icommit.logmsg_len);
  			(*commit)->logmsg[icommit.logmsg_len] = '\0';
  		}
  		len += icommit.logmsg_len;
  
  		for (i = 0; i < icommit.nparents; i++) {
  			struct got_object_qid *qid;
  
  			qid = calloc(1, sizeof(*qid));
  			if (qid == NULL) {
  				err = got_error_from_errno();
  				break;
  			}
  			qid->id = calloc(1, sizeof(*qid->id));
  			if (qid->id == NULL) {
  				err = got_error_from_errno();
  				free(qid);
  				break;
  			}
  
  			memcpy(qid->id, data + len + i * SHA1_DIGEST_LENGTH,
  			    sizeof(*qid->id));
  			SIMPLEQ_INSERT_TAIL(&(*commit)->parent_ids, qid, entry);
  			(*commit)->nparents++;
  		}
  		break;
  	default:
  		err = got_error(GOT_ERR_PRIVSEP_MSG);
  		break;
  	}
  
  	imsg_free(&imsg);
  
  	return err;
  }
  
  const struct got_error *
  got_privsep_send_tree(struct imsgbuf *ibuf, struct got_tree_object *tree)
  {
  	const struct got_error *err = NULL;
  	struct got_imsg_tree_object itree;
  	struct got_tree_entry *te;
  
  	itree.nentries = tree->entries.nentries;
  	if (imsg_compose(ibuf, GOT_IMSG_TREE, 0, 0, -1, &itree, sizeof(itree))
  	    == -1)
  		return got_error_from_errno();
  
  	err = flush_imsg(ibuf);
  	if (err)
  		return err;
  
  	SIMPLEQ_FOREACH(te, &tree->entries.head, entry) {
  		struct got_imsg_tree_entry ite;
  		uint8_t *buf = NULL;
  		size_t len = sizeof(ite) + strlen(te->name);
  
  		if (len > MAX_IMSGSIZE)
  			return got_error(GOT_ERR_NO_SPACE);
  
  		buf = malloc(len);
  		if (buf == NULL)
  			return got_error_from_errno();
  
  		memcpy(ite.id, te->id->sha1, sizeof(ite.id));
  		ite.mode = te->mode;
  		memcpy(buf, &ite, sizeof(ite));
  		memcpy(buf + sizeof(ite), te->name, strlen(te->name));
  
  		if (imsg_compose(ibuf, GOT_IMSG_TREE_ENTRY, 0, 0, -1,
  		    buf, len) == -1)
  			err = got_error_from_errno();
  		free(buf);
  		if (err)
  			return err;
  
  		err = flush_imsg(ibuf);
  		if (err)
  			return err;
  	}
  
  	return NULL;
  }
  
  const struct got_error *
  got_privsep_recv_tree(struct got_tree_object **tree, struct imsgbuf *ibuf)
  {
  	const struct got_error *err = NULL;
  	const size_t min_datalen =
  	    MIN(sizeof(struct got_imsg_error),
  	    sizeof(struct got_imsg_tree_object));
  	struct got_imsg_tree_object itree = { 0 };
  	int nentries = 0;
  
  	*tree = NULL;
  get_more:
  	err = read_imsg(ibuf);
  	if (err)
  		goto done;
  
  	while (1) {
  		struct imsg imsg;
  		size_t n;
  		size_t datalen;
  		struct got_imsg_tree_entry ite;
  		struct got_tree_entry *te = NULL;
  
  		n = imsg_get(ibuf, &imsg);
  		if (n == 0) {
  			if (*tree && (*tree)->entries.nentries != nentries)
  				goto get_more;
  			break;
  		}
  
  		if (imsg.hdr.len < IMSG_HEADER_SIZE + min_datalen)
  			return got_error(GOT_ERR_PRIVSEP_LEN);
  
  		datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
  
  		switch (imsg.hdr.type) {
  		case GOT_IMSG_ERROR:
  			err = recv_imsg_error(&imsg, datalen);
  			break;
  		case GOT_IMSG_TREE:
  			/* This message should only appear once. */
  			if (*tree != NULL) {
  				err = got_error(GOT_ERR_PRIVSEP_MSG);
  				break;
  			}
  			if (datalen != sizeof(itree)) {
  				err = got_error(GOT_ERR_PRIVSEP_LEN);
  				break;
  			}
  			memcpy(&itree, imsg.data, sizeof(itree));
  			*tree = calloc(1, sizeof(**tree));
  			if (*tree == NULL) {
  				err = got_error_from_errno();
  				break;
  			}
  			(*tree)->entries.nentries = itree.nentries;
  			SIMPLEQ_INIT(&(*tree)->entries.head);
  			break;
  		case GOT_IMSG_TREE_ENTRY:
  			/* This message should be preceeded by GOT_IMSG_TREE. */
  			if (*tree == NULL) {
  				err = got_error(GOT_ERR_PRIVSEP_MSG);
  				break;
  			}
  			if (datalen < sizeof(ite) || datalen > MAX_IMSGSIZE) {
  				err = got_error(GOT_ERR_PRIVSEP_LEN);
  				break;
  			}
  
  			/* Remaining data contains the entry's name. */
  			datalen -= sizeof(ite);
  			memcpy(&ite, imsg.data, sizeof(ite));
  			if (datalen == 0 || datalen > MAX_IMSGSIZE) {
  				err = got_error(GOT_ERR_PRIVSEP_LEN);
  				break;
  			}
  
  			te = got_alloc_tree_entry_partial();
  			if (te == NULL) {
  				err = got_error_from_errno();
  				break;
  			}
  			te->name = malloc(datalen + 1);
  			if (te->name == NULL) {
  				free(te);
  				err = got_error_from_errno();
  				break;
  			}
  			memcpy(te->name, imsg.data + sizeof(ite), datalen);
  			te->name[datalen] = '\0';
  
  			memcpy(te->id->sha1, ite.id, SHA1_DIGEST_LENGTH);
  			te->mode = ite.mode;
  			SIMPLEQ_INSERT_TAIL(&(*tree)->entries.head, te, entry);
  			nentries++;
  			break;
  		default:
  			err = got_error(GOT_ERR_PRIVSEP_MSG);
  			break;
  		}
  
  		imsg_free(&imsg);
  	}
  done:
  	if (*tree && (*tree)->entries.nentries != nentries) {
  		if (err == NULL)
  			err = got_error(GOT_ERR_PRIVSEP_LEN);
  		got_object_tree_close(*tree);
  		*tree = NULL;
  	}
  
  	return err;
  }
  
  const struct got_error *
  got_privsep_send_blob(struct imsgbuf *ibuf, size_t size)
  {
  	struct got_imsg_blob iblob;
  
  	iblob.size = size;
  	/* Data has already been written to file descriptor. */
  
  	if (imsg_compose(ibuf, GOT_IMSG_BLOB, 0, 0, -1, &iblob, sizeof(iblob))
  	    == -1)
  		return got_error_from_errno();
  
  	return flush_imsg(ibuf);
  }
  
  const struct got_error *
  got_privsep_recv_blob(size_t *size, struct imsgbuf *ibuf)
  {
  	const struct got_error *err = NULL;
  	struct imsg imsg;
  	struct got_imsg_blob iblob;
  	size_t datalen;
  
  	err = got_privsep_recv_imsg(&imsg, ibuf, 0);
  	if (err)
  		return err;
  
  	datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
  
  	switch (imsg.hdr.type) {
  	case GOT_IMSG_ERROR:
  		err = recv_imsg_error(&imsg, datalen);
  		break;
  	case GOT_IMSG_BLOB:
  		if (datalen != sizeof(iblob))
  			err = got_error(GOT_ERR_PRIVSEP_LEN);
  		memcpy(&iblob, imsg.data, sizeof(iblob));
  		*size = iblob.size;
  		/* Data has been written to file descriptor. */
  		break;
  	default:
  		err = got_error(GOT_ERR_PRIVSEP_MSG);
  		break;
  	}
  
  	imsg_free(&imsg);
  
  	return err;
  }
  
  const struct got_error *
  got_privsep_init_pack_child(struct imsgbuf *ibuf, struct got_pack *pack,
      struct got_packidx *packidx)
  {
  	struct got_imsg_packidx ipackidx;
  	struct got_imsg_pack ipack;
  	int fd;
  
  	ipackidx.len = packidx->len;
  	fd = dup(packidx->fd);
  	if (fd == -1)
  		return got_error_from_errno();
  
  	if (imsg_compose(ibuf, GOT_IMSG_PACKIDX, 0, 0, fd, &ipackidx,
  	    sizeof(ipackidx)) == -1)
  		return got_error_from_errno();
  
  	if (strlcpy(ipack.path_packfile, pack->path_packfile,
  	    sizeof(ipack.path_packfile)) >= sizeof(ipack.path_packfile))
  		return got_error(GOT_ERR_NO_SPACE);
  	ipack.filesize = pack->filesize;
  
  	fd = dup(pack->fd);
  	if (fd == -1)
  		return got_error_from_errno();
  
  	if (imsg_compose(ibuf, GOT_IMSG_PACK, 0, 0, fd, &ipack, sizeof(ipack))
  	    == -1)
  		return got_error_from_errno();
  
  	return flush_imsg(ibuf);
  }
  
  const struct got_error *
  got_privsep_send_packed_obj_req(struct imsgbuf *ibuf, int idx)
  {
  	struct got_imsg_packed_object iobj;
  
  	iobj.idx = idx;
  
  	if (imsg_compose(ibuf, GOT_IMSG_PACKED_OBJECT_REQUEST, 0, 0, -1,
  	    &iobj, sizeof(iobj)) == -1)
  		return got_error_from_errno();
  
  	return flush_imsg(ibuf);
  }
  

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