Commit f99ca52378cf3097fb56c7dbec379b8fc4c5459b
2014-06-30T06:38:45
stash: use a transaction to modify the reflog The stash is implemented as the refs/stash reference and its reflog. In order to modify the reflog, we need avoid races by making sure we're the only ones allowed to modify the reflog. We achieve this via the transactions API. Locking the reference gives us exclusive write access, letting us modify and write it without races.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73
diff --git a/src/stash.c b/src/stash.c
index caffd0c..ea4ba1a 100644
--- a/src/stash.c
+++ b/src/stash.c
@@ -15,6 +15,7 @@
#include "git2/status.h"
#include "git2/checkout.h"
#include "git2/index.h"
+#include "git2/transaction.h"
#include "signature.h"
static int create_error(int error, const char *msg)
@@ -601,14 +602,21 @@ int git_stash_drop(
git_repository *repo,
size_t index)
{
- git_reference *stash;
+ git_transaction *tx;
+ git_reference *stash = NULL;
git_reflog *reflog = NULL;
size_t max;
int error;
- if ((error = git_reference_lookup(&stash, repo, GIT_REFS_STASH_FILE)) < 0)
+ if ((error = git_transaction_new(&tx, repo)) < 0)
return error;
+ if ((error = git_transaction_lock(tx, GIT_REFS_STASH_FILE)) < 0)
+ goto cleanup;
+
+ if ((error = git_reference_lookup(&stash, repo, GIT_REFS_STASH_FILE)) < 0)
+ goto cleanup;
+
if ((error = git_reflog_read(&reflog, repo, GIT_REFS_STASH_FILE)) < 0)
goto cleanup;
@@ -623,29 +631,25 @@ int git_stash_drop(
if ((error = git_reflog_drop(reflog, index, true)) < 0)
goto cleanup;
- if ((error = git_reflog_write(reflog)) < 0)
+ if ((error = git_transaction_set_reflog(tx, GIT_REFS_STASH_FILE, reflog)) < 0)
goto cleanup;
if (max == 1) {
- error = git_reference_delete(stash);
- git_reference_free(stash);
- stash = NULL;
+ if ((error = git_transaction_remove(tx, GIT_REFS_STASH_FILE)) < 0)
+ goto cleanup;
} else if (index == 0) {
const git_reflog_entry *entry;
entry = git_reflog_entry_byindex(reflog, 0);
-
- git_reference_free(stash);
- error = git_reference_create(&stash, repo, GIT_REFS_STASH_FILE, &entry->oid_cur, 1, NULL, NULL);
- if (error < 0)
+ if ((error = git_transaction_set_target(tx, GIT_REFS_STASH_FILE, &entry->oid_cur, NULL, NULL)) < 0)
goto cleanup;
-
- /* We need to undo the writing that we just did */
- error = git_reflog_write(reflog);
}
+ error = git_transaction_commit(tx);
+
cleanup:
git_reference_free(stash);
+ git_transaction_free(tx);
git_reflog_free(reflog);
return error;
}