[PATCH 4.9 16/47] objtool: Improve error message for bad file argument

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>

commit 385d11b152c4eb638eeb769edcb3249533bb9a00 upstream.

If a nonexistent file is supplied to objtool, it complains with a
non-helpful error:

  open: No such file or directory

Improve it to:

  objtool: Can't open 'foo': No such file or directory

Reported-by: Markus <M4rkusXXL@xxxxxx>
Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/406a3d00a21225eee2819844048e17f68523ccf6.1516025651.git.jpoimboe@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 tools/objtool/elf.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -26,6 +26,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <errno.h>
 
 #include "elf.h"
 #include "warn.h"
@@ -370,7 +371,8 @@ struct elf *elf_open(const char *name)
 
 	elf->fd = open(name, O_RDONLY);
 	if (elf->fd == -1) {
-		perror("open");
+		fprintf(stderr, "objtool: Can't open '%s': %s\n",
+			name, strerror(errno));
 		goto err;
 	}