diff options
| author |  Elijah Newren <newren@gmail.com> | 2021-05-20 06:09:37 +0000 |
|---|---|---|
| committer |  Junio C Hamano <gitster@pobox.com> | 2021-05-20 15:40:39 +0900 |
| commit | 19ceb486f8dd25fb5782724c454edb2f06f1ed71 (patch) | |
| tree | e4835554d8aa3e980aa56ea4f0e4b01901b6d32c | |
| parent | merge-ort: add code to check for whether cached renames can be reused (diff) | |
| download | tgif-19ceb486f8dd25fb5782724c454edb2f06f1ed71.tar.xz | |
merge-ort: avoid accidental API mis-use
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>
| -rw-r--r-- | merge-ort.c | 7 | ||||
| -rw-r--r-- | merge-ort.h | 2 |
2 files changed, 9 insertions, 0 deletions
diff --git a/merge-ort.c b/merge-ort.c index 1176bae25f..8b2c93fdcf 100644 --- a/merge-ort.c +++ b/merge-ort.c @@ -52,6 +52,8 @@ enum merge_side { MERGE_SIDE2 = 2 }; +static unsigned RESULT_INITIALIZED = 0x1abe11ed; /* unlikely accidental value */ + struct traversal_callback_data { unsigned long mask; unsigned long dirmask; @@ -3768,6 +3770,10 @@ static void merge_start(struct merge_options *opt, struct merge_result *result) assert(opt->obuf.len == 0); assert(opt->priv == NULL); + if (result->_properly_initialized != 0 && + result->_properly_initialized != RESULT_INITIALIZED) + BUG("struct merge_result passed to merge_incore_*recursive() must be zeroed or filled with values from a previous run"); + assert(!!result->priv == !!result->_properly_initialized); if (result->priv) { opt->priv = result->priv; result->priv = NULL; @@ -3927,6 +3933,7 @@ static void merge_ort_nonrecursive_internal(struct merge_options *opt, result->clean &= strmap_empty(&opt->priv->conflicted); if (!opt->priv->call_depth) { result->priv = opt->priv; + result->_properly_initialized = RESULT_INITIALIZED; opt->priv = NULL; } } diff --git a/merge-ort.h b/merge-ort.h index d53a0a339f..c011864ffe 100644 --- a/merge-ort.h +++ b/merge-ort.h @@ -29,6 +29,8 @@ struct merge_result { * !clean) and to print "CONFLICT" messages. Not for external use. */ void *priv; + /* Also private */ + unsigned _properly_initialized; }; /* |