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authorHarald Hoyer <harald@redhat.com>2013-04-18 05:34:25 (GMT)
committerHarald Hoyer <harald@redhat.com>2013-04-18 05:34:25 (GMT)
commitfc6e6d245ee3989c222a2a8cc82a33475f9922f3 (patch)
tree1bac92dfa3d1575e136586f4c549d2ac312cca6c
parent5521d6985648669a65d0529bb01c7a32edc99294 (diff)
Add ugly CMP_F_TYPE() macro
On some architectures (like s390x) the kernel has the type int for f_type, but long in userspace. Assigning the 32 bit magic constants from linux/magic.h to the 31 bit signed f_type in the kernel, causes f_type to be negative for some constants. glibc extends the int to long for those architecures in 64 bit mode, so the negative int becomes a negative long, which cannot be simply compared to the original magic constant, because the compiler would automatically cast the constant to long. To workaround this issue, we also compare to the (int)MAGIC value in a macro. Of course, we could do #ifdef with the architecure, but it has to be maintained, and the magic constants are 32 bit anyway. Someday, when the int is unsigned or long for all architectures, we can remove this macro again. Until then, keep it as simple as it can be.
-rw-r--r--src/journal/sd-journal.c10
-rw-r--r--src/readahead/readahead-collect.c2
-rw-r--r--src/shared/macro.h17
-rw-r--r--src/shared/util.c5
4 files changed, 26 insertions, 8 deletions
diff --git a/src/journal/sd-journal.c b/src/journal/sd-journal.c
index 88777cb..e92f20b 100644
--- a/src/journal/sd-journal.c
+++ b/src/journal/sd-journal.c
@@ -1248,11 +1248,11 @@ static void check_network(sd_journal *j, int fd) {
return;
j->on_network =
- (unsigned __SWORD_TYPE) sfs.f_type == CIFS_MAGIC_NUMBER ||
- (unsigned __SWORD_TYPE) sfs.f_type == CODA_SUPER_MAGIC ||
- (unsigned __SWORD_TYPE) sfs.f_type == NCP_SUPER_MAGIC ||
- (unsigned __SWORD_TYPE) sfs.f_type == NFS_SUPER_MAGIC ||
- (unsigned __SWORD_TYPE) sfs.f_type == SMB_SUPER_MAGIC;
+ CMP_F_TYPE(sfs.f_type, CIFS_MAGIC_NUMBER) ||
+ CMP_F_TYPE(sfs.f_type, CODA_SUPER_MAGIC) ||
+ CMP_F_TYPE(sfs.f_type, NCP_SUPER_MAGIC) ||
+ CMP_F_TYPE(sfs.f_type, NFS_SUPER_MAGIC) ||
+ CMP_F_TYPE(sfs.f_type, SMB_SUPER_MAGIC);
}
static int add_file(sd_journal *j, const char *prefix, const char *filename) {
diff --git a/src/readahead/readahead-collect.c b/src/readahead/readahead-collect.c
index fbfa8e7..19703aa 100644
--- a/src/readahead/readahead-collect.c
+++ b/src/readahead/readahead-collect.c
@@ -505,7 +505,7 @@ done:
on_ssd = fs_on_ssd(root) > 0;
log_debug("On SSD: %s", yes_no(on_ssd));
- on_btrfs = statfs(root, &sfs) >= 0 && (unsigned __SWORD_TYPE) sfs.f_type == BTRFS_SUPER_MAGIC;
+ on_btrfs = statfs(root, &sfs) >= 0 && CMP_F_TYPE(sfs.f_type, BTRFS_SUPER_MAGIC);
log_debug("On btrfs: %s", yes_no(on_btrfs));
if (asprintf(&pack_fn_new, "%s/.readahead.new", root) < 0) {
diff --git a/src/shared/macro.h b/src/shared/macro.h
index 9bf81dc..f91f7de 100644
--- a/src/shared/macro.h
+++ b/src/shared/macro.h
@@ -264,6 +264,23 @@ do { \
} \
} while(false)
+/* Remove this macro, when the kernel has f_type as unsigned int or long
+ * for every architecure. Currently some 64bit architecures (like s390x)
+ * have int in the kernel, but long in userspace for f_type, so glibc
+ * extends the int to long and carries over the sign. Negative numbers are
+ * caused by the 32bit magic constants in linux/magic.h stuffed into the
+ * signed int in the kernel and these negative numbers are extended to
+ * long, which cannot be simply compared to the magic constants anymore.
+ */
+#define CMP_F_TYPE(f, c) \
+ __extension__ ({ \
+ __SWORD_TYPE _f = (f); \
+ const __SWORD_TYPE _c = (c); \
+ const int _c32 = (c); \
+ (_f == _c || _f == _c32 ); \
+ })
+
+
/* Returns the number of chars needed to format variables of the
* specified type as a decimal string. Adds in extra space for a
* negative '-' prefix. */
diff --git a/src/shared/util.c b/src/shared/util.c
index 386973b..2a80469 100644
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -2779,8 +2779,9 @@ int rm_rf_children_dangerous(int fd, bool only_dirs, bool honour_sticky, struct
static int is_temporary_fs(struct statfs *s) {
assert(s);
- return (unsigned __SWORD_TYPE) s->f_type == TMPFS_MAGIC ||
- (unsigned __SWORD_TYPE) s->f_type == RAMFS_MAGIC;
+ return
+ CMP_F_TYPE(s->f_type, TMPFS_MAGIC) ||
+ CMP_F_TYPE(s->f_type, RAMFS_MAGIC);
}
int rm_rf_children(int fd, bool only_dirs, bool honour_sticky, struct stat *root_dev) {