Re: [PATCH 1/1] Work around architectures having statfs.f_type defined as long
From: Arnd Bergmann <arnd@arndb.de>
Date: 2014-03-19 20:43:37
On Wednesday 19 March 2014, Jes.Sorensen@redhat.com wrote:
quoted hunk ↗ jump to hunk
@@ -1946,9 +1946,13 @@ int in_initrd(void) { /* This is based on similar function in systemd. */ struct statfs s; + /* statfs.f_type is signed long on s390x and MIPS, causing all + sorts of sign extension problems with RAMFS_MAGIC being + defined as 0x858458f6 */ return statfs("/", &s) >= 0 && ((unsigned long)s.f_type == TMPFS_MAGIC || - (unsigned long)s.f_type == RAMFS_MAGIC); + ((unsigned long)s.f_type & 0xFFFFFFFFUL) == + ((unsigned long)RAMFS_MAGIC & 0xFFFFFFFFUL));
The comment is wrong: on s390x the type is actually 'unsigned int'. The fix however works on all variants as far as I can tell. Thinking about it a bit more, I guess we can also cast both sides to 'unsigned int' for the same effect and get rid of the mask. Arnd