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![Elijah Newren](/assets/img/avatar_default.png)
Previously, callers of the merge-ort API could have passed an uninitialized value for struct merge_result *result. However, we want to check result to see if it has cached renames from a previous merge that we can reuse; such values would be found behind result->priv. However, if result->priv is uninitialized, attempting to access behind it will give a segfault. So, we need result->priv to be NULL (which will be the case if the caller does a memset(&result, 0)), or be written by a previous call to the merge-ort machinery. Documenting this requirement may help, but despite being the person who introduced this requirement, I still missed it once and it did not fail in a very clear way and led to a long debugging session. Add a _properly_initialized field to merge_result; that value will be 0 if the caller zero'ed the merge_result, it will be set to a very specific value by a previous run by the merge-ort machinery, and if it's uninitialized it will most likely either be 0 or some value that does not match the specific one we'd expect allowing us to throw a much more meaningful error. Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
78 lines
2.3 KiB
C
78 lines
2.3 KiB
C
#ifndef MERGE_ORT_H
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#define MERGE_ORT_H
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#include "merge-recursive.h"
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struct commit;
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struct tree;
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struct merge_result {
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/*
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* Whether the merge is clean; possible values:
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* 1: clean
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* 0: not clean (merge conflicts)
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* <0: operation aborted prematurely. (object database
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* unreadable, disk full, etc.) Worktree may be left in an
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* inconsistent state if operation failed near the end.
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*/
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int clean;
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/*
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* Result of merge. If !clean, represents what would go in worktree
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* (thus possibly including files containing conflict markers).
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*/
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struct tree *tree;
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/*
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* Additional metadata used by merge_switch_to_result() or future calls
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* to merge_incore_*(). Includes data needed to update the index (if
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* !clean) and to print "CONFLICT" messages. Not for external use.
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*/
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void *priv;
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/* Also private */
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unsigned _properly_initialized;
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};
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/*
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* rename-detecting three-way merge with recursive ancestor consolidation.
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* working tree and index are untouched.
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*
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* merge_bases will be consumed (emptied) so make a copy if you need it.
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*
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* NOTE: empirically, the recursive algorithm will perform better if you
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* pass the merge_bases in the order of oldest commit to the
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* newest[1][2].
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*
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* [1] https://lore.kernel.org/git/nycvar.QRO.7.76.6.1907252055500.21907@tvgsbejvaqbjf.bet/
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* [2] commit 8918b0c9c2 ("merge-recur: try to merge older merge bases
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* first", 2006-08-09)
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*/
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void merge_incore_recursive(struct merge_options *opt,
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struct commit_list *merge_bases,
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struct commit *side1,
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struct commit *side2,
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struct merge_result *result);
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/*
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* rename-detecting three-way merge, no recursion.
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* working tree and index are untouched.
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*/
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void merge_incore_nonrecursive(struct merge_options *opt,
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struct tree *merge_base,
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struct tree *side1,
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struct tree *side2,
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struct merge_result *result);
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/* Update the working tree and index from head to result after incore merge */
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void merge_switch_to_result(struct merge_options *opt,
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struct tree *head,
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struct merge_result *result,
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int update_worktree_and_index,
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int display_update_msgs);
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/* Do needed cleanup when not calling merge_switch_to_result() */
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void merge_finalize(struct merge_options *opt,
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struct merge_result *result);
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#endif
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