setrlimit/getrlimit: fix prlimit64 syscall use for 32-bit CPUs

Commit 95e38b37 ("add support for systems without legacy setrlimit/getrlimit
syscalls") has added use of the prlimit64 syscall in getrlimit and setrlimit
functions. This change causes memory corruption on getrlimit call for 32-bit
CPUs like ARC, as ARC doesn't have ugetrlimit syscall and uses prlimit64.
Also, setrlimit has been broken by prlimit64 call on 32-bit CPUs like, i386,
ARM, ARC.

For the prlimit64 syscall the kernel expects an rlimit struct with 64-bit fields,
but on 32-bit CPUs without _FILE_OFFSET_BITS=64 the struct rlimit has 32-bit
fields.

Add safe implementations of getrlimit, setrlimit, prlimit for 32-bit CPUs with a
local struct rlimit64 variable for use in the prlimit64 syscall.
For 64-bit CPUs and configurations with _FILE_OFFSET_BITS=64 use
getrlimit, setrlimit, prlimit as aliases to getrlimit64, setrlimit64 and
prlimit64. Add a new function prlimit64.

Tested on aarch64, arm, i386, arc.

Fixes: 95e38b37 ("add support for systems without legacy setrlimit/getrlimit syscalls")
Signed-off-by: Pavel Kozlov <pavel.kozlov@synopsys.com>

1 files changed, 20 insertions, 4 deletions

diff --git a/libc/sysdeps/linux/common/setrlimit64.c b/libc/sysdeps/linux/common/setrlimit64.c
index fee14f4ad..3446c58fe 100644
--- a/libc/sysdeps/linux/common/setrlimit64.c
+++ b/libc/sysdeps/linux/common/setrlimit64.c
@@ -17,15 +17,31 @@
 
 #include <_lfs_64.h>
 #include <bits/wordsize.h>
+#include <sys/resource.h>
+#include <sys/syscall.h>
+#include <stddef.h> // needed for NULL to be defined
 
-/* the regular setrlimit will work just fine for 64bit users */
-#if __WORDSIZE == 32
 
-# include <sys/resource.h>
+#if defined(__NR_prlimit64)
+
+int setrlimit64 (__rlimit_resource_t resource, const struct rlimit64 *rlimits)
+{
+	return INLINE_SYSCALL (prlimit64, 4, 0, resource, rlimits, NULL);
+}
+
+# if !defined(__NR_usetrlimit) && (__WORDSIZE == 64 || defined (__USE_FILE_OFFSET64))
+/* If setrlimit is not implemented through the __NR_usetrlimit and size of
+   rlimit_t == rlimit64_t then use setrlimit as an alias to setrlimit64 */
+strong_alias_untyped(setrlimit64, setrlimit)
+libc_hidden_def(setrlimit)
+# endif
+
+#else
 
 /* Set the soft and hard limits for RESOURCE to *RLIMITS.
    Only the super-user can increase hard limits.
-   Return 0 if successful, -1 if not (and sets errno).  */
+   Return 0 if successful, -1 if not (and sets errno).
+   The regular setrlimit will work just fine for 64bit users  */
 int setrlimit64 (__rlimit_resource_t resource, const struct rlimit64 *rlimits)
 {
     struct rlimit rlimits32;