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Diffstat (limited to 'libmailutils/msgset/sub.c')
| -rw-r--r-- | libmailutils/msgset/sub.c | 233 |
1 files changed, 233 insertions, 0 deletions
diff --git a/libmailutils/msgset/sub.c b/libmailutils/msgset/sub.c new file mode 100644 index 000000000..2840781dc --- /dev/null +++ b/libmailutils/msgset/sub.c @@ -0,0 +1,233 @@ +/* GNU Mailutils -- a suite of utilities for electronic mail + Copyright (C) 2011 Free Software Foundation, Inc. + + GNU Mailutils is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3, or (at your option) + any later version. + + GNU Mailutils 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 + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with GNU Mailutils. If not, see <http://www.gnu.org/licenses/>. */ + +#include <config.h> +#include <stdlib.h> +#include <mailutils/types.h> +#include <mailutils/errno.h> +#include <mailutils/list.h> +#include <mailutils/iterator.h> +#include <mailutils/msgset.h> +#include <mailutils/sys/msgset.h> + +/* Remove range R from the set S. + + There are following basic cases: + + 1. S does not contain R. + + Return imeediately, there is nothing to do here. + + 2. S contains a range X that matches exactly R. + + Action: Remove X entirely and return. + + 3. There is a range X in S such that R falls entirely within it. + + Action: Split X into two ranges: + + X.msg_beg : R.msg_beg-1 + R.msg_end+1 : X.msg_end + + and return. + In border cases one of the new ranges may be empty. + + 4. There is a range X which contains an initial subrange of R. + + Action: Remove the subrange from X. If the resulting range is + empty, remove it. Continue iteration with X.msg_end:R.msg_end + in place of R. + + 5. There is a range X such that its initial subrange is contained + in R. + + Action: Remove X.msg_beg:R.msg_end and return. + + 6. There is a range X that is contained within R. + + Action: Remove X and continue. + +There are two special cases. First is when R.msg_end is 0, meaning the last +available message number in the mailbox. In this case the problem is reduced +to either 2 or a combination of 4 and zero or more 6. It is handled by the +sub_msgno_last function below. + +Yet another special case is when the last element of S has msg_end == 0. If +so, the problem is reduced to either 2 or 4. +*/ + +static int +sub_msgno_last (mu_msgset_t mset, size_t beg) +{ + int rc; + struct mu_msgrange *range; + + if (beg == 1) + mu_list_clear (mset->list); + else + { + mu_iterator_t itr; + + rc = mu_list_get_iterator (mset->list, &itr); + if (rc) + return rc; + rc = 1; + rc = mu_iterator_ctl (itr, mu_itrctl_set_direction, &rc); + if (rc) + { + mu_iterator_destroy (&itr); + return rc; + } + + for (mu_iterator_first (itr); rc == 0 && !mu_iterator_is_done (itr); + mu_iterator_next (itr)) + { + mu_iterator_current (itr, (void **)&range); + if (range->msg_beg > beg) + rc = mu_iterator_ctl (itr, mu_itrctl_delete, NULL); + else if (range->msg_beg == beg) + { + rc = mu_iterator_ctl (itr, mu_itrctl_delete, NULL); + break; + } + else + break; + } + mu_iterator_destroy (&itr); + } + return 0; +} + +int +mu_msgset_sub_range (mu_msgset_t mset, size_t beg, size_t end) +{ + int rc; + mu_iterator_t itr; + struct mu_msgrange *mr; + + if (!mset) + return EINVAL; + if (mu_list_is_empty (mset->list)) + return MU_ERR_NOENT; + rc = mu_msgset_aggregate (mset); + if (rc) + return rc; + + if (end == MU_MSGNO_LAST) + return sub_msgno_last (mset, beg); + + /* Test border cases */ + rc = mu_list_head (mset->list, (void**)&mr); + if (rc) + return rc; + if (end < mr->msg_beg) + return 0; + if (beg < mr->msg_beg) + beg = mr->msg_beg; + + if (rc) + return rc; + rc = mu_list_tail (mset->list, (void**) &mr); + if (mr->msg_end != MU_MSGNO_LAST) + { + if (beg > mr->msg_end) + return 0; + if (end > mr->msg_end) + end = mr->msg_end; + } + + rc = mu_list_get_iterator (mset->list, &itr); + if (rc) + return rc; + for (mu_iterator_first (itr); rc == 0 && !mu_iterator_is_done (itr); + mu_iterator_next (itr)) + { + mu_iterator_current (itr, (void **)&mr); + + if (mr->msg_end == MU_MSGNO_LAST) + { + /* This is the last element in list. */ + if (mr->msg_beg == beg) + rc = mu_iterator_ctl (itr, mu_itrctl_delete, NULL); + else if (mr->msg_beg > beg) + mr->msg_beg = end + 1; + break; + } + + if (mr->msg_beg == beg && mr->msg_end == end) /* See case 2 above */ + { + rc = mu_iterator_ctl (itr, mu_itrctl_delete, NULL); + break; + } + else if (mr->msg_beg <= beg && beg <= mr->msg_end) + { + if (mr->msg_beg <= end && end <= mr->msg_end) /* Case 3 */ + { + /* Split the range */ + if (end != mr->msg_end) + { + struct mu_msgrange *newrange = calloc (1, + sizeof (*newrange)); + if (!newrange) + { + rc = ENOMEM; + break; + } + newrange->msg_beg = end + 1; + newrange->msg_end = mr->msg_end; + rc = mu_iterator_ctl (itr, mu_itrctl_insert, newrange); + if (rc) + { + free (newrange); + break; + } + } + + if (mr->msg_beg == beg) + rc = mu_iterator_ctl (itr, mu_itrctl_delete, NULL); + else + mr->msg_end = beg - 1; + break; + } + else if (mr->msg_beg == beg) /* Case 4 */ + { + beg = mr->msg_end; + rc = mu_iterator_ctl (itr, mu_itrctl_delete, NULL); + } + else + { + size_t n = mr->msg_end; + mr->msg_end = beg - 1; + beg = n; + } + } + else if (mr->msg_beg <= end && end <= mr->msg_end) /* Case 5 */ + { + mr->msg_beg = end + 1; + if (mr->msg_beg >= mr->msg_end) + rc = mu_iterator_ctl (itr, mu_itrctl_delete, NULL); + break; + } + else if (beg <= mr->msg_beg && mr->msg_beg <= end) + { + rc = mu_iterator_ctl (itr, mu_itrctl_delete, NULL); + } + } + mu_iterator_destroy (&itr); + + return rc; +} + |