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Re: [PATCH 3/5] linux-user: Add strace support for printing arguments of
From: |
Laurent Vivier |
Subject: |
Re: [PATCH 3/5] linux-user: Add strace support for printing arguments of lseek() |
Date: |
Wed, 3 Jun 2020 16:41:01 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 |
Le 02/06/2020 à 13:53, Filip Bozuta a écrit :
> From: Filip Bozuta <Filip.Bozuta@syrmia.com>
>
> This patch implements strace argument printing functionality for syscall:
>
> *lseek - reposition read/write file offset
>
> off_t lseek(int fd, off_t offset, int whence)
> man page: https://www.man7.org/linux/man-pages/man2/lseek.2.html
>
> Implementation notes:
>
> The syscall's third argument "whence" has predefined values:
> "SEEK_SET","SEEK_CUR","SEEK_END","SEEK_DATA","SEEK_HOLE"
> and thus a separate printing function "print_lseek" was stated
> in file "strace.list". This function is defined in "strace.c"
> by using an existing function "print_raw_param()" to print
> the first and second argument and a switch(case) statement
> for the predefined values of the third argument.
> Values "SEEK_DATA" and "SEEK_HOLE" are defined in kernel version 3.1.
> That is the reason why case statements for these values are
> enwrapped in #ifdef directive.
>
> Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
> ---
> linux-user/strace.c | 32 ++++++++++++++++++++++++++++++++
> linux-user/strace.list | 2 +-
> 2 files changed, 33 insertions(+), 1 deletion(-)
>
> diff --git a/linux-user/strace.c b/linux-user/strace.c
> index 5cf419989c..b7f012f1b5 100644
> --- a/linux-user/strace.c
> +++ b/linux-user/strace.c
> @@ -1768,6 +1768,38 @@ print__llseek(const struct syscallname *name,
> }
> #endif
>
> +#ifdef TARGET_NR_lseek
> +static void
> +print_lseek(const struct syscallname *name,
> + abi_long arg0, abi_long arg1, abi_long arg2,
> + abi_long arg3, abi_long arg4, abi_long arg5)
> +{
> + print_syscall_prologue(name);
> + print_raw_param("%d", arg0, 0);
> + print_raw_param("%ld", arg1, 0);
TARGET_ABI_FMT_ld is better than "%ld", because abi_long can be a 32bit
or a 64bit value, and be different between host and target.
> + switch (arg2) {
> + case SEEK_SET:
> + qemu_log("SEEK_SET"); break;
> + case SEEK_CUR:
> + qemu_log("SEEK_CUR"); break;
> + case SEEK_END:
> + qemu_log("SEEK_END"); break;
> +#ifdef SEEK_DATA
> + case SEEK_DATA:
> + qemu_log("SEEK_DATA"); break;
> +#endif
> +#ifdef SEEK_HOLE
> + case SEEK_HOLE:
> + qemu_log("SEEK_HOLE"); break;
> +#endif
> + default:
> + print_raw_param("%#x", arg2, 1);
> + qemu_log(" /* SEEK_??? */");
remove this line ^^^
> + }
> + print_syscall_epilogue(name);
> +}
> +#endif
> +
> #if defined(TARGET_NR_socket)
> static void
> print_socket(const struct syscallname *name,
> diff --git a/linux-user/strace.list b/linux-user/strace.list
> index 8d51c54bca..5a56212532 100644
> --- a/linux-user/strace.list
> +++ b/linux-user/strace.list
> @@ -513,7 +513,7 @@
> { TARGET_NR_lremovexattr, "lremovexattr" , NULL, NULL, NULL },
> #endif
> #ifdef TARGET_NR_lseek
> -{ TARGET_NR_lseek, "lseek" , NULL, NULL, NULL },
> +{ TARGET_NR_lseek, "lseek" , NULL, print_lseek, NULL },
> #endif
> #ifdef TARGET_NR_lsetxattr
> { TARGET_NR_lsetxattr, "lsetxattr" , NULL, NULL, NULL },
>
Thanks,
Laurent
- [PATCH 0/5] Add strace support for printing arguments of selected syscalls, Filip Bozuta, 2020/06/02
- [PATCH 2/5] linux-user: Add strace support for printing argument of syscalls used for extend attributes, Filip Bozuta, 2020/06/02
- [PATCH 1/5] linux-user: Add strace support for a group of syscalls, Filip Bozuta, 2020/06/02
- [PATCH 4/5] linux-user: Add strace support for printing arguments of chown()/lchown(), Filip Bozuta, 2020/06/02
- [PATCH 5/5] linux-user: Add strace support for printing arguments of fallocate(), Filip Bozuta, 2020/06/02
- [PATCH 3/5] linux-user: Add strace support for printing arguments of lseek(), Filip Bozuta, 2020/06/02
- Re: [PATCH 3/5] linux-user: Add strace support for printing arguments of lseek(),
Laurent Vivier <=
- Re: [PATCH 0/5] Add strace support for printing arguments of selected syscalls, no-reply, 2020/06/02
- Re: [PATCH 0/5] Add strace support for printing arguments of selected syscalls, Alex Bennée, 2020/06/03