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

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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>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20200619123331.17387-5-filip.bozuta@syrmia.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
This commit is contained in:
Filip Bozuta 2020-06-19 14:33:29 +02:00 committed by Laurent Vivier
parent 4fc3cdde40
commit af861deaed
2 changed files with 32 additions and 1 deletions
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31
linux-user/strace.c
View File

@ -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,

2
linux-user/strace.list
View File

@ -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 },