thodg/got/lib/privsep.c

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• Hash : a7403916
  Author :
  Date : 2018-12-24T14:33:38
  

  wrap overlong line
  

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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;
  }
  
  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);
  
  	ierr = imsg->data;
  	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);
  }
  
  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);
  
  	if (imsg->hdr.type == GOT_IMSG_ERROR) {
  		size_t datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
  		return recv_imsg_error(imsg, datalen);
  	}
  
  	return NULL;
  }
  
  /* 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;
  }
  
  const struct got_error *
  got_privsep_send_obj_req(struct imsgbuf *ibuf, int fd)
  {
  	if (imsg_compose(ibuf, GOT_IMSG_OBJECT_REQUEST, 0, 0, fd, NULL, 0)
  	    == -1)
  		return got_error_from_errno();
  
  	return flush_imsg(ibuf);
  }
  
  const struct got_error *
  got_privsep_send_commit_req(struct imsgbuf *ibuf, int fd,
      struct got_object_id *id, int pack_idx)
  {
  	struct got_imsg_packed_object iobj, *iobjp;
  	size_t len;
  
  	if (id) { /* commit is packed */
  		iobj.idx = pack_idx;
  		memcpy(iobj.id, id->sha1, sizeof(iobj.id));
  		iobjp = &iobj;
  		len = sizeof(iobj);
  	} else {
  		iobjp = NULL;
  		len = 0;
  	}
  
  	if (imsg_compose(ibuf, GOT_IMSG_COMMIT_REQUEST, 0, 0, fd, iobjp, len)
  	    == -1)
  		return got_error_from_errno();
  
  	return flush_imsg(ibuf);
  }
  
  const struct got_error *
  got_privsep_send_tree_req(struct imsgbuf *ibuf, int fd,
      struct got_object_id *id, int pack_idx)
  {
  	struct got_imsg_packed_object iobj, *iobjp;
  	size_t len;
  
  	if (id) { /* tree is packed */
  		iobj.idx = pack_idx;
  		memcpy(iobj.id, id->sha1, sizeof(iobj.id));
  		iobjp = &iobj;
  		len = sizeof(iobj);
  	} else {
  		iobjp = NULL;
  		len = 0;
  	}
  
  	if (imsg_compose(ibuf, GOT_IMSG_TREE_REQUEST, 0, 0, fd, iobjp, len)
  	    == -1)
  		return got_error_from_errno();
  
  	return flush_imsg(ibuf);
  }
  
  const struct got_error *
  got_privsep_send_tag_req(struct imsgbuf *ibuf, int fd,
      struct got_object_id *id, int pack_idx)
  {
  	struct got_imsg_packed_object iobj, *iobjp;
  	size_t len;
  
  	if (id) { /* tag is packed */
  		iobj.idx = pack_idx;
  		memcpy(iobj.id, id->sha1, sizeof(iobj.id));
  		iobjp = &iobj;
  		len = sizeof(iobj);
  	} else {
  		iobjp = NULL;
  		len = 0;
  	}
  
  	if (imsg_compose(ibuf, GOT_IMSG_TAG_REQUEST, 0, 0, fd, iobjp, len)
  	    == -1)
  		return got_error_from_errno();
  
  	return flush_imsg(ibuf);
  }
  
  const struct got_error *
  got_privsep_send_blob_req(struct imsgbuf *ibuf, int infd,
      struct got_object_id *id, int pack_idx)
  {
  	struct got_imsg_packed_object iobj, *iobjp;
  	size_t len;
  
  	if (id) { /* blob is packed */
  		iobj.idx = pack_idx;
  		memcpy(iobj.id, id->sha1, sizeof(iobj.id));
  		iobjp = &iobj;
  		len = sizeof(iobj);
  	} else {
  		iobjp = NULL;
  		len = 0;
  	}
  
  	if (imsg_compose(ibuf, GOT_IMSG_BLOB_REQUEST, 0, 0, infd, iobjp, len)
  	    == -1)
  		return got_error_from_errno();
  
  	return flush_imsg(ibuf);
  }
  
  const struct got_error *
  got_privsep_send_blob_outfd(struct imsgbuf *ibuf, int outfd)
  {
  	if (imsg_compose(ibuf, GOT_IMSG_BLOB_OUTFD, 0, 0, outfd, NULL, 0)
  	    == -1)
  		return got_error_from_errno();
  
  	return flush_imsg(ibuf);
  }
  
  const struct got_error *
  got_privsep_send_tmpfd(struct imsgbuf *ibuf, int fd)
  {
  	if (imsg_compose(ibuf, GOT_IMSG_TMPFD, 0, 0, fd, NULL, 0)
  	    == -1)
  		return got_error_from_errno();
  
  	return flush_imsg(ibuf);
  }
  
  const struct got_error *
  got_privsep_send_obj(struct imsgbuf *ibuf, struct got_object *obj)
  {
  	struct got_imsg_object iobj;
  
  	memcpy(iobj.id, obj->id.sha1, sizeof(iobj.id));
  	iobj.type = obj->type;
  	iobj.flags = obj->flags;
  	iobj.hdrlen = obj->hdrlen;
  	iobj.size = obj->size;
  	if (iobj.flags & GOT_OBJ_FLAG_PACKED) {
  		iobj.pack_offset = obj->pack_offset;
  		iobj.pack_idx = obj->pack_idx;
  	}
  
  	if (imsg_compose(ibuf, GOT_IMSG_OBJECT, 0, 0, -1, &iobj, sizeof(iobj))
  	    == -1)
  		return got_error_from_errno();
  
  	return flush_imsg(ibuf);
  }
  
  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;
  
  	if (datalen != sizeof(*iobj))
  		return got_error(GOT_ERR_PRIVSEP_LEN);
  	iobj = imsg->data;
  
  	*obj = calloc(1, sizeof(**obj));
  	if (*obj == NULL)
  		return got_error_from_errno();
  
  	memcpy((*obj)->id.sha1, iobj->id, SHA1_DIGEST_LENGTH);
  	(*obj)->type = iobj->type;
  	(*obj)->flags = iobj->flags;
  	(*obj)->hdrlen = iobj->hdrlen;
  	(*obj)->size = iobj->size;
  	/* path_packfile is handled by caller */
  	if (iobj->flags & GOT_OBJ_FLAG_PACKED) {
  		(*obj)->pack_offset = iobj->pack_offset;
  		(*obj)->pack_idx = iobj->pack_idx;
  	}
  
  	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_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;
  }
  
  static const struct got_error *
  send_commit_logmsg(struct imsgbuf *ibuf, struct got_commit_object *commit,
      size_t logmsg_len)
  {
  	const struct got_error *err = NULL;
  	size_t offset, remain;
  
  	offset = 0;
  	remain = logmsg_len;
  	while (remain > 0) {
  		size_t n = MIN(MAX_IMSGSIZE - IMSG_HEADER_SIZE, remain);
  
  		if (imsg_compose(ibuf, GOT_IMSG_COMMIT_LOGMSG, 0, 0, -1,
  		    commit->logmsg + offset, n) == -1) {
  			err = got_error_from_errno();
  			break;
  		}
  
  		err = flush_imsg(ibuf);
  		if (err)
  			break;
  
  		offset += n;
  		remain -= n;
  	}
  
  	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;
  	size_t author_len = strlen(commit->author);
  	size_t committer_len = strlen(commit->committer);
  	size_t logmsg_len = strlen(commit->logmsg);
  
  	total = sizeof(*icommit) + author_len + committer_len +
  	    commit->nparents * SHA1_DIGEST_LENGTH;
  
  	buf = malloc(total);
  	if (buf == NULL)
  		return got_error_from_errno();
  
  	icommit = (struct got_imsg_commit_object *)buf;
  	memcpy(icommit->tree_id, commit->tree_id->sha1,
  	    sizeof(icommit->tree_id));
  	icommit->author_len = author_len;
  	icommit->author_time = commit->author_time;
  	icommit->author_gmtoff = commit->author_gmtoff;
  	icommit->committer_len = committer_len;
  	icommit->committer_time = commit->committer_time;
  	icommit->committer_gmtoff = commit->committer_gmtoff;
  	icommit->logmsg_len = logmsg_len;
  	icommit->nparents = commit->nparents;
  
  	len = sizeof(*icommit);
  	memcpy(buf + len, commit->author, author_len);
  	len += author_len;
  	memcpy(buf + len, commit->committer, committer_len);
  	len += committer_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;
  	}
  
  	if (logmsg_len == 0 ||
  	    logmsg_len + len > MAX_IMSGSIZE - IMSG_HEADER_SIZE) {
  		err = flush_imsg(ibuf);
  		if (err)
  			goto done;
  	}
  	err = send_commit_logmsg(ibuf, commit, logmsg_len);
  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));
  
  	*commit = NULL;
  
  	err = got_privsep_recv_imsg(&imsg, ibuf, min_datalen);
  	if (err)
  		return err;
  
  	datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
  	len = 0;
  
  	switch (imsg.hdr.type) {
  	case GOT_IMSG_COMMIT:
  		if (datalen < sizeof(*icommit)) {
  			err = got_error(GOT_ERR_PRIVSEP_LEN);
  			break;
  		}
  		icommit = imsg.data;
  		if (datalen != sizeof(*icommit) + icommit->author_len +
  		    icommit->committer_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);
  		(*commit)->author_time = icommit->author_time;
  		(*commit)->author_gmtoff = icommit->author_gmtoff;
  		(*commit)->committer_time = icommit->committer_time;
  		(*commit)->committer_gmtoff = icommit->committer_gmtoff;
  
  		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, imsg.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, imsg.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 {
  			size_t offset = 0, remain = icommit->logmsg_len;
  
  			(*commit)->logmsg = malloc(icommit->logmsg_len + 1);
  			if ((*commit)->logmsg == NULL) {
  				err = got_error_from_errno();
  				break;
  			}
  			while (remain > 0) {
  				struct imsg imsg_log;
  				size_t n = MIN(MAX_IMSGSIZE - IMSG_HEADER_SIZE,
  				    remain);
  
  				err = got_privsep_recv_imsg(&imsg_log, ibuf, n);
  				if (err)
  					return err;
  
  				if (imsg_log.hdr.type != GOT_IMSG_COMMIT_LOGMSG)
  					return got_error(GOT_ERR_PRIVSEP_MSG);
  
  				memcpy((*commit)->logmsg + offset,
  				    imsg_log.data, n);
  				imsg_free(&imsg_log);
  				offset += n;
  				remain -= n;
  			}
  			(*commit)->logmsg[icommit->logmsg_len] = '\0';
  		}
  
  		for (i = 0; i < icommit->nparents; i++) {
  			struct got_object_qid *qid;
  
  			err = got_object_qid_alloc_partial(&qid);
  			if (err)
  				break;
  			memcpy(qid->id, imsg.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;
  	size_t totlen;
  	int nimsg; /* number of imsg queued in ibuf */
  
  	itree.nentries = tree->entries.nentries;
  	if (imsg_compose(ibuf, GOT_IMSG_TREE, 0, 0, -1, &itree, sizeof(itree))
  	    == -1)
  		return got_error_from_errno();
  
  	totlen = sizeof(itree);
  	nimsg = 1;
  	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);
  
  		nimsg++;
  		if (totlen + len >= MAX_IMSGSIZE - (IMSG_HEADER_SIZE * nimsg)) {
  			err = flush_imsg(ibuf);
  			if (err)
  				return err;
  			nimsg = 0;
  		}
  
  		buf = malloc(len);
  		if (buf == NULL)
  			return got_error_from_errno();
  
  		ite = (struct got_imsg_tree_entry *)buf;
  		memcpy(ite->id, te->id->sha1, sizeof(ite->id));
  		ite->mode = te->mode;
  		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;
  		totlen += len;
  	}
  
  	return flush_imsg(ibuf);
  }
  
  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;
  	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;
  			}
  			itree = imsg.data;
  			*tree = malloc(sizeof(**tree));
  			if (*tree == NULL) {
  				err = got_error_from_errno();
  				break;
  			}
  			(*tree)->entries.nentries = itree->nentries;
  			SIMPLEQ_INIT(&(*tree)->entries.head);
  			(*tree)->refcnt = 0;
  			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);
  			if (datalen == 0 || datalen > MAX_IMSGSIZE) {
  				err = got_error(GOT_ERR_PRIVSEP_LEN);
  				break;
  			}
  			ite = imsg.data;
  
  			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, size_t hdrlen)
  {
  	struct got_imsg_blob iblob;
  
  	iblob.size = size;
  	iblob.hdrlen = hdrlen;
  	/* 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, size_t *hdrlen, 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_BLOB:
  		if (datalen != sizeof(*iblob)) {
  			err = got_error(GOT_ERR_PRIVSEP_LEN);
  			break;
  		}
  		iblob = imsg.data;
  		*size = iblob->size;
  		*hdrlen = iblob->hdrlen;
  		/* Data has been written to file descriptor. */
  		break;
  	default:
  		err = got_error(GOT_ERR_PRIVSEP_MSG);
  		break;
  	}
  
  	imsg_free(&imsg);
  
  	return err;
  }
  
  static const struct got_error *
  send_tagmsg(struct imsgbuf *ibuf, struct got_tag_object *tag, size_t tagmsg_len)
  {
  	const struct got_error *err = NULL;
  	size_t offset, remain;
  
  	offset = 0;
  	remain = tagmsg_len;
  	while (remain > 0) {
  		size_t n = MIN(MAX_IMSGSIZE - IMSG_HEADER_SIZE, remain);
  
  		if (imsg_compose(ibuf, GOT_IMSG_TAG_TAGMSG, 0, 0, -1,
  		    tag->tagmsg + offset, n) == -1) {
  			err = got_error_from_errno();
  			break;
  		}
  
  		err = flush_imsg(ibuf);
  		if (err)
  			break;
  
  		offset += n;
  		remain -= n;
  	}
  
  	return err;
  }
  
  const struct got_error *
  got_privsep_send_tag(struct imsgbuf *ibuf, struct got_tag_object *tag)
  {
  	const struct got_error *err = NULL;
  	struct got_imsg_tag_object *itag;
  	uint8_t *buf;
  	size_t len, total;
  	size_t tag_len = strlen(tag->tag);
  	size_t tagger_len = strlen(tag->tagger);
  	size_t tagmsg_len = strlen(tag->tagmsg);
  
  	total = sizeof(*itag) + tag_len + tagger_len + tagmsg_len;
  
  	buf = malloc(total);
  	if (buf == NULL)
  		return got_error_from_errno();
  
  	itag = (struct got_imsg_tag_object *)buf;
  	memcpy(itag->id, tag->id.sha1, sizeof(itag->id));
  	itag->obj_type = tag->obj_type;
  	itag->tag_len = tag_len;
  	itag->tagger_len = tagger_len;
  	itag->tagger_time = tag->tagger_time;
  	itag->tagger_gmtoff = tag->tagger_gmtoff;
  	itag->tagmsg_len = tagmsg_len;
  
  	len = sizeof(*itag);
  	memcpy(buf + len, tag->tag, tag_len);
  	len += tag_len;
  	memcpy(buf + len, tag->tagger, tagger_len);
  	len += tagger_len;
  
  	if (imsg_compose(ibuf, GOT_IMSG_TAG, 0, 0, -1, buf, len) == -1) {
  		err = got_error_from_errno();
  		goto done;
  	}
  
  	if (tagmsg_len == 0 ||
  	    tagmsg_len + len > MAX_IMSGSIZE - IMSG_HEADER_SIZE) {
  		err = flush_imsg(ibuf);
  		if (err)
  			goto done;
  	}
  	err = send_tagmsg(ibuf, tag, tagmsg_len);
  done:
  	free(buf);
  	return err;
  }
  
  const struct got_error *
  got_privsep_recv_tag(struct got_tag_object **tag, struct imsgbuf *ibuf)
  {
  	const struct got_error *err = NULL;
  	struct imsg imsg;
  	struct got_imsg_tag_object *itag;
  	size_t len, datalen;
  	const size_t min_datalen =
  	    MIN(sizeof(struct got_imsg_error),
  	    sizeof(struct got_imsg_tag_object));
  
  	*tag = NULL;
  
  	err = got_privsep_recv_imsg(&imsg, ibuf, min_datalen);
  	if (err)
  		return err;
  
  	datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
  	len = 0;
  
  	switch (imsg.hdr.type) {
  	case GOT_IMSG_TAG:
  		if (datalen < sizeof(*itag)) {
  			err = got_error(GOT_ERR_PRIVSEP_LEN);
  			break;
  		}
  		itag = imsg.data;
  		if (datalen != sizeof(*itag) + itag->tag_len +
  		    itag->tagger_len) {
  			err = got_error(GOT_ERR_PRIVSEP_LEN);
  			break;
  		}
  		len += sizeof(*itag);
  
  		*tag = calloc(1, sizeof(**tag));
  		if (*tag == NULL) {
  			err = got_error_from_errno();
  			break;
  		}
  
  		memcpy((*tag)->id.sha1, itag->id, SHA1_DIGEST_LENGTH);
  
  		if (itag->tag_len == 0) {
  			(*tag)->tag = strdup("");
  			if ((*tag)->tag == NULL) {
  				err = got_error_from_errno();
  				break;
  			}
  		} else {
  			(*tag)->tag = malloc(itag->tag_len + 1);
  			if ((*tag)->tag == NULL) {
  				err = got_error_from_errno();
  				break;
  			}
  			memcpy((*tag)->tag, imsg.data + len,
  			    itag->tag_len);
  			(*tag)->tag[itag->tag_len] = '\0';
  		}
  		len += itag->tag_len;
  
  		(*tag)->obj_type = itag->obj_type;
  		(*tag)->tagger_time = itag->tagger_time;
  		(*tag)->tagger_gmtoff = itag->tagger_gmtoff;
  
  		if (itag->tagger_len == 0) {
  			(*tag)->tagger = strdup("");
  			if ((*tag)->tagger == NULL) {
  				err = got_error_from_errno();
  				break;
  			}
  		} else {
  			(*tag)->tagger = malloc(itag->tagger_len + 1);
  			if ((*tag)->tagger == NULL) {
  				err = got_error_from_errno();
  				break;
  			}
  			memcpy((*tag)->tagger, imsg.data + len,
  			    itag->tagger_len);
  			(*tag)->tagger[itag->tagger_len] = '\0';
  		}
  		len += itag->tagger_len;
  
  		if (itag->tagmsg_len == 0) {
  			(*tag)->tagmsg = strdup("");
  			if ((*tag)->tagmsg == NULL) {
  				err = got_error_from_errno();
  				break;
  			}
  		} else {
  			size_t offset = 0, remain = itag->tagmsg_len;
  
  			(*tag)->tagmsg = malloc(itag->tagmsg_len + 1);
  			if ((*tag)->tagmsg == NULL) {
  				err = got_error_from_errno();
  				break;
  			}
  			while (remain > 0) {
  				struct imsg imsg_log;
  				size_t n = MIN(MAX_IMSGSIZE - IMSG_HEADER_SIZE,
  				    remain);
  
  				err = got_privsep_recv_imsg(&imsg_log, ibuf, n);
  				if (err)
  					return err;
  
  				if (imsg_log.hdr.type != GOT_IMSG_TAG_TAGMSG)
  					return got_error(GOT_ERR_PRIVSEP_MSG);
  
  				memcpy((*tag)->tagmsg + offset, imsg_log.data,
  				    n);
  				imsg_free(&imsg_log);
  				offset += n;
  				remain -= n;
  			}
  			(*tag)->tagmsg[itag->tagmsg_len] = '\0';
  		}
  
  		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_object_id *id)
  {
  	struct got_imsg_packed_object iobj;
  
  	iobj.idx = idx;
  	memcpy(iobj.id, id->sha1, sizeof(iobj.id));
  
  	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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