libs/printf: add support for print symbol name

Show a '%p' thing.  A nuttx extension is that the '%p' is followed
by an extra set of alphanumeric characters that are extended format
specifiers.

* - 'S' For symbolic direct pointers (or function descriptors) with offset
* - 's' For symbolic direct pointers (or function descriptors) without offset

printf("%ps %pS\n", ptr, ptr) will print:

module_start module_start+0x0/0x62

Signed-off-by: chao.an <anchao@xiaomi.com>

libs/libc/stdio/lib_libvsprintf.c

@@ -50,6 +50,7 @@
 
 #include <nuttx/compiler.h>
 #include <nuttx/streams.h>
+#include <nuttx/allsyms.h>
 
 #include "lib_dtoa_engine.h"
 #include "lib_ultoa_invert.h"
@@ -145,9 +146,34 @@ struct arg
 static const char g_nullstring[] = "(null)";
 
 /****************************************************************************
- * Public Functions
+ * Private Function Prototypes
  ****************************************************************************/
 
+static int vsprintf_internal(FAR struct lib_outstream_s *stream,
+                             FAR struct arg *arglist, int numargs,
+                             FAR const IPTR char *fmt, va_list ap);
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+#ifdef CONFIG_ALLSYMS
+static int sprintf_internal(FAR struct lib_outstream_s *stream,
+                            FAR const IPTR char *fmt, ...)
+{
+  va_list ap;
+  int     n;
+
+  /* Then let vsprintf_internal do the real work */
+
+  va_start(ap, fmt);
+  n = vsprintf_internal(stream, NULL, 0, fmt, ap);
+  va_end(ap);
+
+  return n;
+}
+#endif
+
 static int vsprintf_internal(FAR struct lib_outstream_s *stream,
                              FAR struct arg *arglist, int numargs,
                              FAR const IPTR char *fmt, va_list ap)
@@ -461,23 +487,58 @@ static int vsprintf_internal(FAR struct lib_outstream_s *stream,
 
       if (c == 'p')
         {
-          if (fmt_char(fmt) == 'V')
+          unsigned char sub_c = fmt_char(fmt);
-            {
-              FAR struct va_format *vaf = va_arg(ap, void *);
-#ifdef va_copy
-              va_list copy;
 
-              va_copy(copy, *vaf->va);
+          switch (sub_c)
-              vsprintf_internal(stream, NULL, 0, vaf->fmt, copy);
-              va_end(copy);
-#else
-              vsprintf_internal(stream, NULL, 0, vaf->fmt, *vaf->va);
-#endif
-              continue;
-            }
-          else
             {
-              fmt_ungetc(fmt);
+              case 'V':
+                {
+                  FAR struct va_format *vaf = va_arg(ap, void *);
+#ifdef va_copy
+                  va_list copy;
+
+                  va_copy(copy, *vaf->va);
+                  vsprintf_internal(stream, NULL, 0, vaf->fmt, copy);
+                  va_end(copy);
+#else
+                  vsprintf_internal(stream, NULL, 0, vaf->fmt, *vaf->va);
+#endif
+                  continue;
+                }
+#ifdef CONFIG_ALLSYMS
+
+              case 'S':
+              case 's':
+                {
+                  FAR const struct symtab_s *symbol;
+                  FAR void *addr = va_arg(ap, FAR void *);
+                  size_t symbolsize;
+
+                  symbol = allsyms_findbyvalue(addr, &symbolsize);
+                  if (symbol)
+                    {
+                      pnt = symbol->sym_name;
+                      while (*pnt)
+                        {
+                          putc(*pnt++, stream);
+                        }
+
+                      if (sub_c == 'S')
+                        {
+                          sprintf_internal(stream, "+%#x/%#x",
+                                           addr - symbol->sym_value,
+                                           symbolsize);
+                        }
+
+                      continue;
+                    }
+                }
+#endif
+
+              default:
+                {
+                  fmt_ungetc(fmt);
+                }
             }
 
           /* Determine size of pointer and set flags accordingly */