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Re: [PATCH v3 3/6] linux-user: Add strace support for printing argument
From: |
Laurent Vivier |
Subject: |
Re: [PATCH v3 3/6] linux-user: Add strace support for printing argument of syscalls used for extended attributes |
Date: |
Mon, 15 Jun 2020 13:52:38 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 |
Le 11/06/2020 à 17:51, Filip Bozuta a écrit :
> From: Filip Bozuta <Filip.Bozuta@syrmia.com>
>
> This patch implements strace argument printing functionality for following
> syscalls:
>
> *getxattr, lgetxattr, fgetxattr - retrieve an extended attribute value
>
> ssize_t getxattr(const char *path, const char *name, void *value,
> size_t size)
> ssize_t lgetxattr(const char *path, const char *name, void *value,
> size_t size)
> ssize_t fgetxattr(int fd, const char *name, void *value, size_t size)
> man page: https://www.man7.org/linux/man-pages/man2/getxattr.2.html
>
> *listxattr, llistxattr, flistxattr - list extended attribute names
>
> ssize_t listxattr(const char *path, char *list, size_t size)
> ssize_t llistxattr(const char *path, char *list, size_t size)
> ssize_t flistxattr(int fd, char *list, size_t size)
> man page: https://www.man7.org/linux/man-pages/man2/listxattr.2.html
>
> *removexattr, lremovexattr, fremovexattr - remove an extended attribute
>
> int removexattr(const char *path, const char *name)
> int lremovexattr(const char *path, const char *name)
> int fremovexattr(int fd, const char *name)
> man page:
> https://www.man7.org/linux/man-pages/man2/removexattr.2.html
Compared to v2, fremovexattr, removexattr and lremovexattr are missing.
>
> Implementation notes:
>
> All of the syscalls have strings as argument types and thus a separate
> printing function was stated in file "strace.list" for every one of them.
> All of these printing functions were defined in "strace.c" using existing
> printing functions for appropriate argument types:
> "print_string()" - for (const char*) type
> "print_pointer()" - for (char*) and (void *) type
> "print_raw_param()" for (int) and (size_t) type
> Syscalls "getxattr()" and "lgetxattr()" have the same number and type of
> arguments and thus their print functions ("print_getxattr",
> "print_lgetxattr")
> share a same definition. The same statement applies to syscalls
> "listxattr()"
> and "llistxattr()".
> Function "print_syscall_ret_listxattr()" was added to print the returned
> list
> of extended attributes for syscalls "print_listxattr(),
> print_llistxattr() and
> print_flistxattr()".
>
> Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
> ---
> linux-user/strace.c | 95 ++++++++++++++++++++++++++++++++++++++++++
> linux-user/strace.list | 15 ++++---
> 2 files changed, 104 insertions(+), 6 deletions(-)
>
> diff --git a/linux-user/strace.c b/linux-user/strace.c
> index 4f85606c19..a7c3ea8df3 100644
> --- a/linux-user/strace.c
> +++ b/linux-user/strace.c
> @@ -834,6 +834,41 @@ print_syscall_ret_adjtimex(const struct syscallname
> *name, abi_long ret,
> }
> #endif
>
> +#if defined(TARGET_NR_listxattr) || defined(TARGET_NR_llistxattr) \
> + || defined(TARGGET_NR_flistxattr)
> +static void
> +print_syscall_ret_listxattr(const struct syscallname *name, abi_long ret,
> + abi_long arg0, abi_long arg1, abi_long arg2,
> + abi_long arg3, abi_long arg4, abi_long arg5)
> +{
> + const char *errstr = NULL;
> +
> + SYSCALL_RET_ERR(ret, errstr);
> +
> + if (ret >= 0) {
> + qemu_log(TARGET_ABI_FMT_ld, ret);
> + qemu_log(" (list = ");
> + if (arg1 != 0) {
> + abi_long attr = arg1;
> + while (target_strlen(attr) != 0) {
You can't rely on target_strlen(), you should rely on the value returned
by the ioctl() (ret) that is defined as the length of the returned data.
Thanks,
Laurent
- [PATCH v3 0/6] Add strace support for printing arguments of selected syscalls, Filip Bozuta, 2020/06/11
- [PATCH v3 1/6] linux-user: Extend strace support to enable argument printing after syscall execution, Filip Bozuta, 2020/06/11
- [PATCH v3 3/6] linux-user: Add strace support for printing argument of syscalls used for extended attributes, Filip Bozuta, 2020/06/11
- Re: [PATCH v3 3/6] linux-user: Add strace support for printing argument of syscalls used for extended attributes,
Laurent Vivier <=
- [PATCH v3 4/6] linux-user: Add strace support for printing arguments of lseek(), Filip Bozuta, 2020/06/11
- [PATCH v3 5/6] linux-user: Add strace support for printing arguments of chown()/lchown(), Filip Bozuta, 2020/06/11
- [PATCH v3 6/6] linux-user: Add strace support for printing arguments of fallocate(), Filip Bozuta, 2020/06/11
- [PATCH v3 2/6] linux-user: Add strace support for a group of syscalls, Filip Bozuta, 2020/06/11
- Re: [PATCH v3 0/6] Add strace support for printing arguments of selected syscalls, no-reply, 2020/06/11