Change objcopy's --set-section-alignment option to take a byte alignment value rather than a power of two alignment value.

PR 24942
	* objcopy.c (copy_usage): Update description of
	--set-section-alignment.
	(copy_main): Interpret numeric argument of --set-section-alignment
	as a byte alignment, not a power of two alignment.
	* doc/binutils.texi: Update description of
	--set-section-alignment.
	* testsuite/binutils-all/set-section-alignment.d: New test.
	* testsuite/binutils-all/objcopy.exp: Run the new test.

binutils/ChangeLog

@@ -1,3 +1,15 @@
+2019-10-02  Niklas Gürtler  <profclonk@gmail.com>
+
+	PR 24942
+	* objcopy.c (copy_usage): Update description of
+	--set-section-alignment.
+	(copy_main): Interpret numeric argument of --set-section-alignment
+	as a byte alignment, not a power of two alignment.
+	* doc/binutils.texi: Update description of
+	--set-section-alignment.
+	* testsuite/binutils-all/set-section-alignment.d: New test.
+	* testsuite/binutils-all/objcopy.exp: Run the new test.
+
 2019-09-30  Alan Modra  <amodra@gmail.com>
 
 	PR 25046

binutils/doc/binutils.texi

@@ -1622,9 +1622,9 @@ contents--just remove the section instead.  Not all flags are
 meaningful for all object file formats.
 
 @item --set-section-alignment @var{sectionpattern}=@var{align}
-Set the alignment for any sections matching @var{sectionpattern}.  @var{align}
-specifies the alignment as the exponent for the power of two, i.e. the
-alignment in bytes will be 2^@var{align}.
+Set the alignment for any sections matching @var{sectionpattern}.
+@var{align} specifies the alignment in bytes and must be a power of
+two, i.e. 1, 2, 4, 8@dots{}. 
 
 @item --add-section @var{sectionname}=@var{filename}
 Add a new section named @var{sectionname} while copying the file.  The

binutils/objcopy.c

@@ -615,7 +615,7 @@ copy_usage (FILE *stream, int exit_status)
      --set-section-flags <name>=<flags>\n\
                                    Set section <name>'s properties to <flags>\n\
      --set-section-alignment <name>=<align>\n\
-                                   Set section <name>'s alignment to 2^<align> bytes\n\
+                                   Set section <name>'s alignment to <align> bytes\n\
      --add-section <name>=<file>   Add section <name> found in <file> to output\n\
      --update-section <name>=<file>\n\
                                    Update contents of section <name> with\n\
@@ -5280,24 +5280,37 @@ copy_main (int argc, char *argv[])
 	    const char *s;
 	    int len;
 	    char *name;
-	    int align;
+	    int palign, align;
 
 	    s = strchr (optarg, '=');
 	    if (s == NULL)
-	      fatal (_("bad format for %s"), "--set-section-alignment");
+	      fatal (_("bad format for --set-section-alignment: argument needed"));
 	    
-	    align = atoi(s+1);
-	    if (align < 0)
-	      fatal (_("bad format for %s"), "--set-section-alignment");
+	    align = atoi (s + 1);
+	    if (align <= 0)
+	      fatal (_("bad format for --set-section-alignment: numeric argument needed"));
 
+	    /* Convert integer alignment into a power-of-two alignment.  */
+	    palign = 0;
+	    while ((align & 1) == 0)
+	      {
+	    	align >>= 1;
+	    	++palign;
+	      }
+	    
+	    if (align != 1)
+	      /* Number has more than on 1, i.e. wasn't a power of 2.  */
+	      fatal (_("bad format for --set-section-alignment: alignment is not a power of two"));
+
+	    /* Add the alignment setting to the section list.  */
 	    len = s - optarg;
 	    name = (char *) xmalloc (len + 1);
 	    strncpy (name, optarg, len);
 	    name[len] = '\0';
 
 	    p = find_section_list (name, TRUE, SECTION_CONTEXT_SET_ALIGNMENT);
-
-	    p->alignment = align;
+	    if (p)
+	      p->alignment = palign;
 	  }
 	  break;
 	  

binutils/testsuite/binutils-all/objcopy.exp

@@ -1310,3 +1310,5 @@ proc objcopy_remove_relocations_from_executable { } {
 objcopy_remove_relocations_from_executable
 
 run_dump_test "pr23633"
+
+run_dump_test "set-section-alignment"

binutils/testsuite/binutils-all/set-section-alignment.d

@@ -0,0 +1,9 @@
+#source: pr23633.s
+#PROG: objcopy
+#objcopy: --set-section-alignment .text=16
+#objdump: --section-headers
+#notarget: *-*-*aout *-*-*coff *-*-cygwin* *-*-darwin *-*-mingw* *-*-go32 *-*-*pe hppa*-*-hpux* ns32k-*-* powerpc-*-aix* rs6000-*-* rx-*-* *-*-vms
+
+#...
+.*\.text.*2\*\*4
+#pass