Commit af861dea authored by Filip Bozuta's avatar Filip Bozuta Committed by Laurent Vivier
Browse files

linux-user: Add strace support for printing arguments of lseek() 

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: default avatarFilip Bozuta <Filip.Bozuta@syrmia.com>
Reviewed-by: default avatarLaurent Vivier <laurent@vivier.eu>
Message-Id: <20200619123331.17387-5-filip.bozuta@syrmia.com>
Signed-off-by: default avatarLaurent Vivier <laurent@vivier.eu>
parent 4fc3cdde

linux-user/strace.c

+31 −0
Original line number Diff line number Diff line
@@ -1833,6 +1833,37 @@ 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(TARGET_ABI_FMT_ld, arg1, 0);

    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);

    }

    print_syscall_epilogue(name);

}

#endif



#if defined(TARGET_NR_socket)

static void

print_socket(const struct syscallname *name,

linux-user/strace.list

+1 −1
Original line number Diff line number Diff line
@@ -516,7 +516,7 @@ 
{ TARGET_NR_lremovexattr, "lremovexattr" , NULL, print_lremovexattr, 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 },