objcopy: add option to specify custom prefix for symbol of binary input

When using --input-target=binary, objcopy currently derives symbol names
from a mangled version of the input file name.  This approach can lead to
unpredictable results, as the generated symbols depend on the file path and
working directory.

This patch introduces a new option:

  --binary-symbol-prefix <prefix> Use <prefix> as the base symbol name for
                                    the input file (default: derived from
                                    file name)

It allows specifying an explicit symbol prefix, while preserving the existing
behavior as a fallback.

Signed-off-by: Alon Bar-Lev <alon.barlev@gmail.com>

bfd/binary.c

@@ -41,6 +41,8 @@
    a start symbol, an end symbol, and an absolute length symbol.  */
 #define BIN_SYMS 3
 
+char *bfd_binary_symbol_prefix = NULL;
+
 /* Create a binary object.  Invoked via bfd_set_format.  */
 
 static bool
@@ -122,18 +124,25 @@ static char *
 mangle_name (bfd *abfd, char *suffix)
 {
   bfd_size_type size;
+  const char *prefix;
+  const char *prefix_amend = "";
   char *buf;
   char *p;
 
-  size = (strlen (bfd_get_filename (abfd))
+  prefix = bfd_binary_symbol_prefix;
-	  + strlen (suffix)
+  if (prefix == NULL)
-	  + sizeof "_binary__");
+    {
+      prefix = "_binary_";
+      prefix_amend = bfd_get_filename (abfd);
+    }
+
+  size = strlen (prefix) + strlen (prefix_amend) + strlen (suffix) + 2;
 
   buf = (char *) bfd_alloc (abfd, size);
   if (buf == NULL)
     return "";
 
-  sprintf (buf, "_binary_%s_%s", bfd_get_filename (abfd), suffix);
+  sprintf (buf, "%s%s_%s", prefix, prefix_amend, suffix);
 
   /* Change any non-alphanumeric characters to underscores.  */
   for (p = buf; *p; p++)

binutils/doc/binutils.texi

@@ -1315,6 +1315,7 @@ objcopy [@option{-F} @var{bfdname}|@option{--target=}@var{bfdname}]
         [@option{--keep-global-symbols=}@var{filename}]
         [@option{--localize-symbols=}@var{filename}]
         [@option{--weaken-symbols=}@var{filename}]
+        [@option{--binary-symbol-prefix}@var{string}]
         [@option{--add-symbol} @var{name}=[@var{section}:]@var{value}[,@var{flags}]]
         [@option{--alt-machine-code=}@var{index}]
         [@option{--prefix-symbols=}@var{string}]
@@ -1554,6 +1555,20 @@ given more than once.  Note - unique symbols are not converted.
 @itemx --weaken-symbol=@var{symbolname}
 Make symbol @var{symbolname} weak. This option may be given more than once.
 
+@item --binary-symbol-prefix=@var{string}
+When used with @option{--input-target=binary}, sets @var{string} as the
+base name for the symbols generated for the input file.  These symbols are:
+
+@example
+@var{string}_start
+@var{string}_end
+@var{string}_size
+@end example
+
+By default, the binary input handler derives the prefix symbol name from a
+mangled version of the input file name and _binary prefix.  This option
+allows specifying it explicitly.
+
 @item --globalize-symbol=@var{symbolname}
 Give symbol @var{symbolname} global scoping so that it is visible
 outside of the file in which it is defined.  This option may be given

binutils/objcopy.c

@@ -334,6 +334,7 @@ enum command_line_switch
   OPTION_HEAP,
   OPTION_IMAGE_BASE,
   OPTION_IMPURE,
+  OPTION_BINARY_SYMBOL_PREFIX,
   OPTION_INTERLEAVE_WIDTH,
   OPTION_KEEPGLOBAL_SYMBOLS,
   OPTION_KEEP_FILE_SYMBOLS,
@@ -465,6 +466,7 @@ static struct option copy_options[] =
   {"info", no_argument, 0, OPTION_FORMATS_INFO},
   {"input-format", required_argument, 0, 'I'}, /* Obsolete */
   {"input-target", required_argument, 0, 'I'},
+  {"binary-symbol-prefix", required_argument, 0, OPTION_BINARY_SYMBOL_PREFIX},
   {"interleave", optional_argument, 0, 'i'},
   {"interleave-width", required_argument, 0, OPTION_INTERLEAVE_WIDTH},
   {"keep-file-symbols", no_argument, 0, OPTION_KEEP_FILE_SYMBOLS},
@@ -540,6 +542,11 @@ extern char *program_name;
 extern int is_strip;
 #endif
 
+/* The symbol prefix of a binary input blob.
+ * <p>_start, <p>_end, <p>_size
+ */
+extern char *bfd_binary_symbol_prefix;
+
 /* The maximum length of an S record.  This variable is defined in srec.c
    and can be modified by the --srec-len parameter.  */
 extern unsigned int _bfd_srec_len;
@@ -678,6 +685,9 @@ copy_usage (FILE *stream, int exit_status)
      --globalize-symbols <file>    --globalize-symbol for all in <file>\n\
      --keep-global-symbols <file>  -G for all symbols listed in <file>\n\
      --weaken-symbols <file>       -W for all symbols listed in <file>\n\
+     --binary-symbol-prefix <prefix>\n\
+                                    Use <prefix> as the base symbol name for the input file\n\
+                                     (default: derived from file name)\n\
      --add-symbol <name>=[<section>:]<value>[,<flags>]  Add a symbol\n\
      --alt-machine-code <index>    Use the target's <index>'th alternative machine\n\
      --writable-text               Mark the output text as writable\n\
@@ -5395,6 +5405,10 @@ copy_main (int argc, char *argv[])
 	  input_target = optarg;
 	  break;
 
+	case OPTION_BINARY_SYMBOL_PREFIX:
+	  bfd_binary_symbol_prefix = optarg;
+	  break;
+
 	case 'O':
 	case 'd':		/* "destination" - 'O' is preferred */
 	  output_target = optarg;

binutils/testsuite/binutils-all/objcopy.exp

@@ -1602,3 +1602,40 @@ proc objcopy_tek2bin {} {
 }
 
 objcopy_tek2bin
+
+# Test objcopy -I binary and --binary-symbol-prefix
+
+proc binary_symbol {name file args symbol} {
+    global OBJCOPY
+    global NM
+    global NMFLAGS
+
+    set test "binary symbol ($name)"
+
+    # detect a valid target, take the first supported
+    set target [lindex [split [binutils_run $OBJCOPY "--info"] \n] 1]
+
+    set out tmpdir/binary_symbol.o
+    set got [binutils_run $OBJCOPY "-I binary -O $target $args $file $out"]
+
+    set expected [list "${symbol}_end" "${symbol}_size" "${symbol}_start"]
+
+    set exec_output [binutils_run $NM "-a $NMFLAGS $out"]
+    set exec_output [prune_warnings $exec_output]
+    set actual {}
+    while {[regexp {^[0-9a-fA-F]+?[ ]+[TtDdA] ([0-9a-zA-Z_]+)[\r\n]+(.*)$} ${exec_output} all s rest]} {
+	set actual [concat $actual $s]
+	set exec_output $rest
+    }
+
+    if {[lsort $expected] ne [lsort $actual]} {
+	send_log "expected: $expected, actual: $actual\n"
+	fail $test
+	return
+    }
+
+    pass $test
+}
+
+binary_symbol implicit $srcdir/$subdir/version.s "" _binary_[regsub -all {[^0-9a-zA-Z]} $srcdir/$subdir/version.s _]
+binary_symbol explicit $srcdir/$subdir/version.s "--binary-symbol-prefix symbol1" symbol1