[PATCH v4 5/6] linux-user: Add strace support for printing arguments of chown()/lchown()

[Filip Bozuta]

From: Filip Bozuta <Filip.Bozuta@syrmia.com>

This patch implements strace argument printing functionality for syscalls:

    *chown, lchown - change ownership of a file

        int chown(const char *pathname, uid_t owner, gid_t group)
        int lchown(const char *pathname, uid_t owner, gid_t group)
        man page: https://www.man7.org/linux/man-pages/man2/lchown.2.html

Implementation notes:

    Both syscalls use strings as arguments and thus a separate
    printing function was stated in "strace.list" for them.
    Both syscalls share the same number and types of arguments
    and thus share a same definition in file "syscall.c".
    This defintion uses existing functions "print_string()" to
    print the string argument and "print_raw_param()" to print
    other two arguments that are of basic types.

Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
---
 linux-user/strace.c    | 15 +++++++++++++++
 linux-user/strace.list |  4 ++--
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/linux-user/strace.c b/linux-user/strace.c
index db561dc4c9..f44ab0ab84 100644
--- a/linux-user/strace.c
+++ b/linux-user/strace.c
@@ -1460,6 +1460,21 @@ print_chmod(const struct syscallname *name,
 }
 #endif
 
+#if defined(TARGET_NR_chown) || defined(TARGET_NR_lchown)
+static void
+print_chown(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_string(arg0, 0);
+    print_raw_param("%d", arg1, 0);
+    print_raw_param("%d", arg2, 1);
+    print_syscall_epilogue(name);
+}
+#define print_lchown     print_chown
+#endif
+
 #ifdef TARGET_NR_clock_adjtime
 static void
 print_clock_adjtime(const struct syscallname *name,
diff --git a/linux-user/strace.list b/linux-user/strace.list
index 905a9c395c..633f43f490 100644
--- a/linux-user/strace.list
+++ b/linux-user/strace.list
@@ -71,7 +71,7 @@
 { TARGET_NR_chmod, "chmod" , NULL, print_chmod, NULL },
 #endif
 #ifdef TARGET_NR_chown
-{ TARGET_NR_chown, "chown" , NULL, NULL, NULL },
+{ TARGET_NR_chown, "chown" , NULL, print_chown, NULL },
 #endif
 #ifdef TARGET_NR_chown32
 { TARGET_NR_chown32, "chown32" , NULL, NULL, NULL },
@@ -475,7 +475,7 @@
 { TARGET_NR_kill, "kill", NULL, print_kill, NULL },
 #endif
 #ifdef TARGET_NR_lchown
-{ TARGET_NR_lchown, "lchown" , NULL, NULL, NULL },
+{ TARGET_NR_lchown, "lchown" , NULL, print_lchown, NULL },
 #endif
 #ifdef TARGET_NR_lchown32
 { TARGET_NR_lchown32, "lchown32" , NULL, NULL, NULL },
-- 
2.17.1