kpatch-build: add missing include for musl

[androw]

create-kpatch-module.c can't compile because limits.h is not included by other file with musl libc.

Adding the import permits the build to work on musl system.

https://gitlab.alpinelinux.org/alpine/aports/-/merge_requests/78844/diffs

[joe-lawrence]

Thanks @androw , do you happen to have the compilation error? Just curious, thanks.

[androw]

gcc -Os -fstack-clash-protection -Wformat -Werror=format-security -fno-plt -std=gnu11 -MMD -MP -I../kmod/patch -Iinsn -Wall -Wsign-compare -Wconversion -Wno-sign-conversion -g -Werror   -c -o create-kpatch-module.o create-kpatch-module.c
create-kpatch-module.c: In function 'create_dynamic_rela_sections':
create-kpatch-module.c:101:54: error: 'INT_MAX' undeclared (first use in this function)
  101 |                 if (type == R_X86_64_64 && (addend > INT_MAX || addend <= INT_MIN)) {
      |                                                      ^~~~~~~
create-kpatch-module.c:29:1: note: 'INT_MAX' is defined in header '<limits.h>'; this is probably fixable by adding '#include <limits.h>'
   28 | #include "kpatch-patch.h"
  +++ |+#include <limits.h>
   29 | 
create-kpatch-module.c:101:54: note: each undeclared identifier is reported only once for each function it appears in
  101 |                 if (type == R_X86_64_64 && (addend > INT_MAX || addend <= INT_MIN)) {
      |                                                      ^~~~~~~
create-kpatch-module.c:101:75: error: 'INT_MIN' undeclared (first use in this function)
  101 |                 if (type == R_X86_64_64 && (addend > INT_MAX || addend <= INT_MIN)) {
      |                                                                           ^~~~~~~
create-kpatch-module.c:101:75: note: 'INT_MIN' is defined in header '<limits.h>'; this is probably fixable by adding '#include <limits.h>'
make[1]: *** [<builtin>: create-kpatch-module.o] Error 1

Full log here: https://gist.github.com/androw/22b6ee74a6d5edb6f9ce3b926fb6237e

[joe-lawrence]

Interesting. On a Fedora system, it seems that argp.h pulls it in:

$ CFLAGS=-H make
[ ... snip ... ]
. /usr/include/argp.h
.. /usr/lib/gcc/x86_64-redhat-linux/12/include/limits.h
... /usr/lib/gcc/x86_64-redhat-linux/12/include/syslimits.h
.... /usr/lib/gcc/x86_64-redhat-linux/12/include/limits.h
..... /usr/include/limits.h