The maximum number of directives is already limited by the maximum
value of iovec, and current padding usage on _dl_map_object_from_fd
specifies a value of 16 (2 times sizeof (void *)) in hexa, which is
less than the INT_STRLEN_BOUND(void *) (20 for LP64).
This works if pointers are larger than 8 bytes, for instance 16.
In this case the maximum padding would be 32 and the IFMTSIZE would
be 40.
The resulting code does use a slightly larger static stack, the
output of -fstack-usage (for x86_64):
* master:
dl-printf.c:35:1:_dl_debug_vdprintf 1344 dynamic
* patch:
dl-printf.c:36:1:_dl_debug_vdprintf 2416 static
However, there is an improvement in code generation:
* master
text data bss dec hex filename
3309 0 0 3309 ced elf/dl-printf.os
* patch
text data bss dec hex filename
3151 0 0 3151 c4f elf/dl-printf.os
Checked on x86_64-linux-gnu.
Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
The alloca size did not consider the optional width parameter for
padding which could cause buffer underflow. The width is currently used
e.g. by _dl_map_object_from_fd which passes 2 * sizeof(void *) which
can be larger than the alloca buffer size on targets where
sizeof(void *) >= 2 * sizeof(unsigned long).
Even if large width is not used on existing targets it is better to fix
the formatting code to avoid surprises.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
The Z modifier is a nonstandard synonymn for z (that predates z
itself) and compiler might issue an warning for in invalid
conversion specifier.
Reviewed-by: Florian Weimer <fweimer@redhat.com>