Hi guys,
(I'm not subscribed to the list, so please CC)
After digging through the buildd logs of libisoburn, we found out
interesting compiler warnings on mips and mipsel.
https://buildd.debian.org/status/fetch.php?pkg=libisoburn&arch=mips&ver=1.1.8-1&stamp=1321892998
xorriso/iso_tree.c: In function 'Xorriso_fake_stbuf':
xorriso/iso_tree.c:256:4: warning: passing argument 4 of
'Xorriso_node_get_dev' from incompatible pointer type [enabled by
default]
xorriso/iso_tree.c:204:5: note: expected 'dev_t *' but argument is of
type 'long unsigned int *'
xorriso/iso_tree.c:259:4: warning: passing argument 4 of
'Xorriso_node_get_dev' from incompatible pointer type [enabled by
default]
xorriso/iso_tree.c:204:5: note: expected 'dev_t *' but argument is of
type 'long unsigned int *'
Which basically means that st_rdev member of stat struct is not of type
dev_t on mips and mipsel, which of course deviates from man 2 stat, that
prescribes that st_rdev member (as well as st_dev member) of stat struct
must be of type dev_t.
I wonder what could be wrong with the definition of the stat struct on
mips/mipsel, it is a known flaw in libc, and whether it has anything to
do with the situation of having 64-bit kernel and 32 bit userland,
usually met on misp/mipsel.
Yes, the issue could be solved in the application side if one knows
about the problem on these particular architectures (mips/mipsel), but I
believe this is not the general case.
A simplified code demonstrating the issue:
~~~~~~~~~~~~~~~~~~~~~~~~~~
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
void func(dev_t *dev) {
*dev=2;
}
int main() {
struct stat ss;
ss.st_rdev = 1;
printf("ss.st_rdev %ld\n", ss.st_rdev);
func( & (ss.st_rdev) ); // protested on mips{el}
dev_t dummy = ss.st_rdev; // work-around with a temp dev_t
object
func(&dummy);
printf("ss.st_rdev %ld\n", ss.st_rdev);
printf("sizeof st_rdev %u\n", sizeof(ss.st_rdev));
printf("sizeof dev_t %u\n", sizeof(dev_t));
printf("sizeof __dev_t %u\n", sizeof(__dev_t));
printf("sizeof ul int %u\n", sizeof(unsigned long int));
printf("sizeof ull int %u\n", sizeof(unsigned long long int));
printf("sizeof stat %u\n", sizeof(ss));
return 0;
}
mips{el}
~~~~~~
$ gcc test.c
test.c: In function ‘main’:
test.c:14:2: warning: passing argument 1 of ‘func’ from incompatible
pointer type [enabled by default]
test.c:6:6: note: expected ‘dev_t *’ but argument is of type ‘long
unsigned int *’
$ ./a.out
ss.st_rdev 1
ss.st_rdev 2
sizeof st_rdev 4
sizeof dev_t 8
sizeof __dev_t 8
sizeof ul int 4
sizeof ull int 8
sizeof stat 144
amd64
~~~~
$ gcc test.c
$ ./a.out
ss.st_rdev 1
ss.st_rdev 2
sizeof st_rdev 8
sizeof dev_t 8
sizeof __dev_t 8
sizeof ul int 8
sizeof ull int 8
sizeof stat 144
I tried to trace this type deviation of the stat dev_t members in the
headers, but gave up, and tried to look at gcc -E output, where I
realize that dev_t type is 'unsigned long long int', where stat.st_rdev
is of type 'unsigned long int'
$ grep dev_t gcc-E
__extension__ typedef __u_quad_t __dev_t;
typedef __dev_t dev_t;
$ grep quad_t gcc-E
__extension__ typedef long long int __quad_t;
__extension__ typedef unsigned long long int __u_quad_t;
__extension__ typedef __u_quad_t __dev_t;
__extension__ typedef __u_quad_t __ino64_t;
__extension__ typedef __quad_t __off64_t;
__extension__ typedef __u_quad_t __rlim64_t;
__extension__ typedef __quad_t __blkcnt64_t;
__extension__ typedef __u_quad_t __fsblkcnt64_t;
__extension__ typedef __u_quad_t __fsfilcnt64_t;
typedef __quad_t *__qaddr_t;
typedef __quad_t quad_t;
typedef __u_quad_t u_quad_t;
--
pub 4096R/0E4BD0AB <people.fccf.net/danchev/key pgp.mit.edu>
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