[PULL 01/14] linux-user: Fix "print_fdset()" in "strace.c" to not print ", " after last value

[Laurent Vivier <laurent@vivier.eu>]

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

Function "print_fdset()" in "strace.c" is used to print the file descriptor
values in "print__newselect()" which prints arguments of syscall _newselect().
Until changes from this patch, this function was printing "," even after the
last value of the fd_set argument. This was changed in this patch by removing
this unnecessary "," after the last fd value and thus improving the estetics of
the _newselect() "-strace" print.

Implementation notes:

   The printing fix was made possible by using an existing function "get_comma()"
   which returns a "," or an empty string "" based on its argument (0 for "," and
   other for "").

Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20200702160915.9517-1-Filip.Bozuta@syrmia.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
 linux-user/strace.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/linux-user/strace.c b/linux-user/strace.c
index 13981341b327..5e380486433c 100644
--- a/linux-user/strace.c
+++ b/linux-user/strace.c
@@ -541,6 +541,7 @@ static void
 print_fdset(int n, abi_ulong target_fds_addr)
 {
     int i;
+    int first = 1;
 
     qemu_log("[");
     if( target_fds_addr ) {
@@ -555,9 +556,12 @@ print_fdset(int n, abi_ulong target_fds_addr)
             return;
 
         for (i=n; i>=0; i--) {
-            if ((tswapal(target_fds[i / TARGET_ABI_BITS]) >> (i & (TARGET_ABI_BITS - 1))) & 1)
-                qemu_log("%d,", i);
+            if ((tswapal(target_fds[i / TARGET_ABI_BITS]) >>
+                (i & (TARGET_ABI_BITS - 1))) & 1) {
+                qemu_log("%s%d", get_comma(first), i);
+                first = 0;
             }
+        }
         unlock_user(target_fds, target_fds_addr, 0);
     }
     qemu_log("]");
-- 
2.26.2