[PATCH v4 4/4] string-list: document iterator behavior on NULL input
- From
Derrick Stolee via GitGitGadget <gitgitgadget@gmail.com>
- Date
- Sep 27, 2022, 13:57 UTC
- Message-ID
- <73a262cdca46a45aeeda6f47ea3357aaeb937e7b.1664287021.git.gitgitgadget@gmail.com>
- In-Reply-To
- <pull.1358.v4.git.1664287021.gitgitgadget@gmail.com>
From: Derrick Stolee <derrickstolee@github.com>
The for_each_string_list_item() macro takes a string_list and automatically constructs a for loop to iterate over its contents. This macro will segfault if the list is non-NULL.
We cannot change the macro to be careful around NULL values because there are many callers that use the address of a local variable, which will never be NULL and will cause compile errors with -Werror=address.
For now, leave a documentation comment to try to avoid mistakes in the future where a caller does not check for a NULL list.
Signed-off-by: Derrick Stolee <derrickstolee@github.com> --- string-list.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/string-list.h b/string-list.h index d5a744e1438..c7b0d5d0008 100644 --- a/string-list.h +++ b/string-list.h @@ -141,7 +141,12 @@ void string_list_clear_func(struct string_list *list, string_list_clear_func_t c int for_each_string_list(struct string_list *list, string_list_each_func_t func, void *cb_data); -/** Iterate over each item, as a macro. */ +/** + * Iterate over each item, as a macro. + * + * Be sure that 'list' is non-NULL. The macro cannot perform NULL + * checks due to -Werror=address errors. + */ #define for_each_string_list_item(item,list) \ for (item = (list)->items; \ item && item < (list)->items + (list)->nr; \
-- gitgitgadget