[PATCH V2] lstat/stat/fstat: Use 64bit version of syscall if available

Carmelo Amoroso carmelo73 at gmail.com
Sun Feb 5 08:23:16 UTC 2012


Please commit
Cheers
Carmelo

Inviato da iPod

Il giorno 04/feb/2012, alle ore 05:42, Khem Raj <raj.khem at gmail.com> ha scritto:

> This is needed for stat'ing loop devices > 255
> since otherwise kernel returns EOVERFLOW becasue
> it needs st_rdev/st_dev to be larger than 16bits but
> in kernel it uses __old_kernel_stat for stat
> syscall which has st_rdev/st_dev as unsigned short
> 
> Add a testcase
> 
> Signed-off-by: Khem Raj <raj.khem at gmail.com>
> ---
> libc/sysdeps/linux/common/fstat.c |   18 ++++++++++++++----
> libc/sysdeps/linux/common/lstat.c |   19 ++++++++++++++-----
> libc/sysdeps/linux/common/stat.c  |   18 ++++++++++++++----
> test/stat/stat-loop256.c          |   32 ++++++++++++++++++++++++++++++++
> 4 files changed, 74 insertions(+), 13 deletions(-)
> create mode 100644 test/stat/stat-loop256.c
> 
> diff --git a/libc/sysdeps/linux/common/fstat.c b/libc/sysdeps/linux/common/fstat.c
> index acc639b..4726a68 100644
> --- a/libc/sysdeps/linux/common/fstat.c
> +++ b/libc/sysdeps/linux/common/fstat.c
> @@ -12,18 +12,28 @@
> #include <sys/stat.h>
> #include "xstatconv.h"
> 
> -#define __NR___syscall_fstat __NR_fstat
> -static __inline__ _syscall2(int, __syscall_fstat, int, fd, struct kernel_stat *, buf)
> -
> int fstat(int fd, struct stat *buf)
> {
>    int result;
> +#ifdef __NR_fstat64
> +    /* normal stat call has limited values for various stat elements
> +     * e.g. uid device major/minor etc.
> +     * so we use 64 variant if available
> +     * in order to get newer versions of stat elements
> +     */
> +    struct kernel_stat64 kbuf;
> +    result = INLINE_SYSCALL(fstat64, 2, fd, &kbuf);
> +    if (result == 0) {
> +        __xstat32_conv(&kbuf, buf);
> +    }
> +#else
>    struct kernel_stat kbuf;
> 
> -    result = __syscall_fstat(fd, &kbuf);
> +    result = INLINE_SYSCALL(fstat, 2, fd, &kbuf);
>    if (result == 0) {
>        __xstat_conv(&kbuf, buf);
>    }
> +#endif
>    return result;
> }
> libc_hidden_def(fstat)
> diff --git a/libc/sysdeps/linux/common/lstat.c b/libc/sysdeps/linux/common/lstat.c
> index aa77447..db72d1f 100644
> --- a/libc/sysdeps/linux/common/lstat.c
> +++ b/libc/sysdeps/linux/common/lstat.c
> @@ -12,19 +12,28 @@
> #include <sys/stat.h>
> #include "xstatconv.h"
> 
> -#define __NR___syscall_lstat __NR_lstat
> -static __inline__ _syscall2(int, __syscall_lstat,
> -        const char *, file_name, struct kernel_stat *, buf)
> -
> int lstat(const char *file_name, struct stat *buf)
> {
>    int result;
> +#ifdef __NR_lstat64
> +    /* normal stat call has limited values for various stat elements
> +     * e.g. uid device major/minor etc.
> +     * so we use 64 variant if available
> +     * in order to get newer versions of stat elements
> +     */
> +    struct kernel_stat64 kbuf;
> +    result = INLINE_SYSCALL(lstat64, 2, file_name, &kbuf);
> +    if (result == 0) {
> +        __xstat32_conv(&kbuf, buf);
> +    }
> +#else
>    struct kernel_stat kbuf;
> 
> -    result = __syscall_lstat(file_name, &kbuf);
> +    result = INLINE_SYSCALL(lstat, 2, file_name, &kbuf);
>    if (result == 0) {
>        __xstat_conv(&kbuf, buf);
>    }
> +#endif
>    return result;
> }
> libc_hidden_def(lstat)
> diff --git a/libc/sysdeps/linux/common/stat.c b/libc/sysdeps/linux/common/stat.c
> index a6ab291..829f35a 100644
> --- a/libc/sysdeps/linux/common/stat.c
> +++ b/libc/sysdeps/linux/common/stat.c
> @@ -12,20 +12,30 @@
> #include <sys/stat.h>
> #include "xstatconv.h"
> 
> -#define __NR___syscall_stat __NR_stat
> #undef stat
> -static __inline__ _syscall2(int, __syscall_stat,
> -        const char *, file_name, struct kernel_stat *, buf)
> 
> int stat(const char *file_name, struct stat *buf)
> {
>    int result;
> +#ifdef __NR_stat64
> +    /* normal stat call has limited values for various stat elements
> +     * e.g. uid device major/minor etc.
> +     * so we use 64 variant if available
> +     * in order to get newer versions of stat elements
> +     */
> +    struct kernel_stat64 kbuf;
> +    result = INLINE_SYSCALL(stat64, 2, file_name, &kbuf);
> +    if (result == 0) {
> +        __xstat32_conv(&kbuf, buf);
> +    }
> +#else
>    struct kernel_stat kbuf;
> 
> -    result = __syscall_stat(file_name, &kbuf);
> +    result = INLINE_SYSCALL(stat, 2, file_name, &kbuf);
>    if (result == 0) {
>        __xstat_conv(&kbuf, buf);
>    }
> +#endif
>    return result;
> }
> libc_hidden_def(stat)
> diff --git a/test/stat/stat-loop256.c b/test/stat/stat-loop256.c
> new file mode 100644
> index 0000000..14284c1
> --- /dev/null
> +++ b/test/stat/stat-loop256.c
> @@ -0,0 +1,32 @@
> +#include <stdio.h>
> +#include <unistd.h>
> +#include <stdlib.h>
> +#include <sys/stat.h>
> +int main()
> +{
> +    struct stat statbuf;
> +    int ret = 0;
> +    char* loop255 = "/dev/loop255";
> +    char* loop256 = "/dev/loop256";
> +    mode_t mode = 0660;
> +    mknod(loop255, mode, 0x7ff);
> +    mknod(loop256, mode, 0x100700);
> +    ret = stat(loop255, &statbuf);
> +    if(ret < 0) {
> +    printf("stat: Cant stat %s\n",loop255);
> +    unlink(loop255);
> +    exit(1);
> +    }
> +    ret = stat(loop256, &statbuf);
> +    if(ret < 0) {
> +        printf("stat: Cant stat %s\n",loop256);
> +    unlink(loop255);
> +    unlink(loop256);
> +        exit(1);
> +    }
> +
> +    unlink(loop255);
> +    unlink(loop256);
> +    exit(0);
> +}
> +
> -- 
> 1.7.5.4
> 
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