[PATCH 1/3] linux-user: Add strace support for printing arguments of truncate()/ftruncate() and getsid()

[Filip Bozuta]

This patch implements strace argument printing functionality for following 
syscalls:

    * truncate, ftruncate - truncate a file to a specified length

        int truncate(const char *path, off_t length)
        int ftruncate(int fd, off_t length)
        man page: https://man7.org/linux/man-pages/man2/truncate.2.html

    * getsid - get session ID

        pid_t getsid(pid_t pid)
        man page: https://man7.org/linux/man-pages/man2/getsid.2.html

Implementation notes:

    Syscalls truncate/truncate64 takes string as argument type and thus a
    separate print function "print_truncate/print_truncate64" is stated in
    file "strace.list". This function is defined and implemented in "strace.c"
    by using an existing function used to print string arguments: 
"print_string()".
    The other syscalls have only primitive argument types, so the rest of the
    implementation was handled by stating an appropriate printing format in file
    "strace.list".

Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
---
 linux-user/strace.c    | 14 ++++++++++++++
 linux-user/strace.list | 10 +++++-----
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/linux-user/strace.c b/linux-user/strace.c
index 6044c66954..dccfbc46e9 100644
--- a/linux-user/strace.c
+++ b/linux-user/strace.c
@@ -1925,6 +1925,20 @@ print_lseek(const struct syscallname *name,
 }
 #endif
 
+#ifdef TARGET_NR_truncate
+static void
+print_truncate(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(TARGET_ABI_FMT_ld, arg1, 1);
+    print_syscall_epilogue(name);
+}
+#define print_truncate64     print_truncate
+#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 10e3e4a814..3b77b22daf 100644
--- a/linux-user/strace.list
+++ b/linux-user/strace.list
@@ -258,10 +258,10 @@
 { TARGET_NR_ftime, "ftime" , NULL, NULL, NULL },
 #endif
 #ifdef TARGET_NR_ftruncate
-{ TARGET_NR_ftruncate, "ftruncate" , NULL, NULL, NULL },
+{ TARGET_NR_ftruncate, "ftruncate" , "%s(%d," TARGET_ABI_FMT_ld ")", NULL, 
NULL },
 #endif
 #ifdef TARGET_NR_ftruncate64
-{ TARGET_NR_ftruncate64, "ftruncate64" , NULL, NULL, NULL },
+{ TARGET_NR_ftruncate64, "ftruncate64" , "%s(%d," TARGET_ABI_FMT_ld ")", NULL, 
NULL },
 #endif
 #ifdef TARGET_NR_futex
 { TARGET_NR_futex, "futex" , NULL, print_futex, NULL },
@@ -372,7 +372,7 @@
 { TARGET_NR_getrusage, "getrusage" , NULL, NULL, NULL },
 #endif
 #ifdef TARGET_NR_getsid
-{ TARGET_NR_getsid, "getsid" , NULL, NULL, NULL },
+{ TARGET_NR_getsid, "getsid" , "%s(%d)", NULL, NULL },
 #endif
 #ifdef TARGET_NR_getsockname
 { TARGET_NR_getsockname, "getsockname" , NULL, NULL, NULL },
@@ -1534,10 +1534,10 @@
 { TARGET_NR_tkill, "tkill" , NULL, print_tkill, NULL },
 #endif
 #ifdef TARGET_NR_truncate
-{ TARGET_NR_truncate, "truncate" , NULL, NULL, NULL },
+{ TARGET_NR_truncate, "truncate" , NULL, print_truncate, NULL },
 #endif
 #ifdef TARGET_NR_truncate64
-{ TARGET_NR_truncate64, "truncate64" , NULL, NULL, NULL },
+{ TARGET_NR_truncate64, "truncate64" , NULL, print_truncate64, NULL },
 #endif
 #ifdef TARGET_NR_tuxcall
 { TARGET_NR_tuxcall, "tuxcall" , NULL, NULL, NULL },
-- 
2.17.1