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df60cf5789
If the original version of `write_locked_index()` returned with an error, it didn't roll back the lockfile unless the error occured at the very end, during closing/committing. See commit03b866477(read-cache: new API write_locked_index instead of write_index/write_cache, 2014-06-13). In commit9f41c7a6b(read-cache: close index.lock in do_write_index, 2017-04-26), we learned to close the lock slightly earlier in the callstack. That was mostly a side-effect of lockfiles being implemented using temporary files, but didn't cause any real harm. Recently, commit076aa2cbd(tempfile: auto-allocate tempfiles on heap, 2017-09-05) introduced a subtle bug. If the temporary file is deleted (i.e., the lockfile is rolled back), the tempfile-pointer in the `struct lock_file` will be left dangling. Thus, an attempt to reuse the lockfile, or even just to roll it back, will induce undefined behavior -- most likely a crash. Besides not crashing, we clearly want to make things consistent. The guarantees which the lockfile-machinery itself provides is A) if we ask to commit and it fails, roll back, and B) if we ask to close and it fails, do _not_ roll back. Let's do the same for consistency. Do not delete the temporary file in `do_write_index()`. One of its callers, `write_locked_index()` will thereby avoid rolling back the lock. The other caller, `write_shared_index()`, will delete its temporary file anyway. Both of these callers will avoid undefined behavior (crashing). Teach `write_locked_index(..., COMMIT_LOCK)` to roll back the lock before returning. If we have already succeeded and committed, it will be a noop. Simplify the existing callers where we now have a superfluous call to `rollback_lockfile()`. That should keep future readers from wondering why the callers are inconsistent. Signed-off-by: Martin Ågren <martin.agren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
97 lines
2.4 KiB
C
97 lines
2.4 KiB
C
#include "cache.h"
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#include "lockfile.h"
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#include "commit.h"
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#include "run-command.h"
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#include "resolve-undo.h"
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#include "tree-walk.h"
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#include "unpack-trees.h"
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#include "dir.h"
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static const char *merge_argument(struct commit *commit)
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{
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if (commit)
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return oid_to_hex(&commit->object.oid);
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else
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return EMPTY_TREE_SHA1_HEX;
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}
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int try_merge_command(const char *strategy, size_t xopts_nr,
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const char **xopts, struct commit_list *common,
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const char *head_arg, struct commit_list *remotes)
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{
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struct argv_array args = ARGV_ARRAY_INIT;
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int i, ret;
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struct commit_list *j;
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argv_array_pushf(&args, "merge-%s", strategy);
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for (i = 0; i < xopts_nr; i++)
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argv_array_pushf(&args, "--%s", xopts[i]);
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for (j = common; j; j = j->next)
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argv_array_push(&args, merge_argument(j->item));
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argv_array_push(&args, "--");
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argv_array_push(&args, head_arg);
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for (j = remotes; j; j = j->next)
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argv_array_push(&args, merge_argument(j->item));
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ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
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argv_array_clear(&args);
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discard_cache();
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if (read_cache() < 0)
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die(_("failed to read the cache"));
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resolve_undo_clear();
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return ret;
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}
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int checkout_fast_forward(const struct object_id *head,
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const struct object_id *remote,
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int overwrite_ignore)
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{
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struct tree *trees[MAX_UNPACK_TREES];
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struct unpack_trees_options opts;
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struct tree_desc t[MAX_UNPACK_TREES];
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int i, nr_trees = 0;
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struct dir_struct dir;
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struct lock_file lock_file = LOCK_INIT;
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refresh_cache(REFRESH_QUIET);
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if (hold_locked_index(&lock_file, LOCK_REPORT_ON_ERROR) < 0)
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return -1;
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memset(&trees, 0, sizeof(trees));
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memset(&opts, 0, sizeof(opts));
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memset(&t, 0, sizeof(t));
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if (overwrite_ignore) {
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memset(&dir, 0, sizeof(dir));
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dir.flags |= DIR_SHOW_IGNORED;
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setup_standard_excludes(&dir);
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opts.dir = &dir;
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}
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opts.head_idx = 1;
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opts.src_index = &the_index;
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opts.dst_index = &the_index;
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opts.update = 1;
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opts.verbose_update = 1;
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opts.merge = 1;
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opts.fn = twoway_merge;
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setup_unpack_trees_porcelain(&opts, "merge");
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trees[nr_trees] = parse_tree_indirect(head);
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if (!trees[nr_trees++])
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return -1;
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trees[nr_trees] = parse_tree_indirect(remote);
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if (!trees[nr_trees++])
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return -1;
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for (i = 0; i < nr_trees; i++) {
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parse_tree(trees[i]);
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init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
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}
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if (unpack_trees(nr_trees, t, &opts))
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return -1;
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if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
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return error(_("unable to write new index file"));
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return 0;
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}
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