[PULL 07/18] linux-user: Add an api to print enumareted argument values with strace

[Laurent Vivier <laurent@vivier.eu>]

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

This patch introduces a type 'struct enums' and function 'print_enums()'
that can be used to print enumerated argument values of some syscalls
in strace. This can be used in future strace implementations.

Also, macros 'ENUM_GENERIC()', 'ENUM_TARGET()' and 'ENUM_END', are
introduced to enable automatic generation of aproppriate enumarated
values and their repsective string representations (these macros are
exactly the same as 'FLAG_GENERIC()', 'FLAG_TARGET()' and 'FLAG_END').

Future patches are planned to modify all existing print functions in
'strace.c' that print arguments of syscalls with enumerated values to
use this new api.

Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20200811164553.27713-5-Filip.Bozuta@syrmia.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
 linux-user/strace.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/linux-user/strace.c b/linux-user/strace.c
index 4ac54ecffe9c..d0731b888d29 100644
--- a/linux-user/strace.c
+++ b/linux-user/strace.c
@@ -52,9 +52,23 @@ struct flags {
 /* end of flags array */
 #define FLAG_END           { 0, NULL }
 
+/* Structure used to translate enumerated values into strings */
+struct enums {
+    abi_long    e_value;   /* enum value */
+    const char  *e_string; /* stringified enum */
+};
+
+/* common enums for all architectures */
+#define ENUM_GENERIC(name) { name, #name }
+/* target specific enums */
+#define ENUM_TARGET(name)  { TARGET_ ## name, #name }
+/* end of enums array */
+#define ENUM_END           { 0, NULL }
+
 UNUSED static const char *get_comma(int);
 UNUSED static void print_pointer(abi_long, int);
 UNUSED static void print_flags(const struct flags *, abi_long, int);
+UNUSED static void print_enums(const struct enums *, abi_long, int);
 UNUSED static void print_at_dirfd(abi_long, int);
 UNUSED static void print_file_mode(abi_long, int);
 UNUSED static void print_open_flags(abi_long, int);
@@ -1252,6 +1266,23 @@ print_flags(const struct flags *f, abi_long flags, int last)
     }
 }
 
+static void
+print_enums(const struct enums *e, abi_long enum_arg, int last)
+{
+    for (; e->e_string != NULL; e++) {
+        if (e->e_value == enum_arg) {
+            qemu_log("%s", e->e_string);
+            break;
+        }
+    }
+
+    if (e->e_string == NULL) {
+        qemu_log("%#x", (unsigned int)enum_arg);
+    }
+
+    qemu_log("%s", get_comma(last));
+}
+
 static void
 print_at_dirfd(abi_long dirfd, int last)
 {
-- 
2.26.2