* Improve compatibility with existing application code by permitting the

  use of `elf_getbase()` on non-archive members. This change is needed
  for gcc LTO (-flto) to work properly.
* Style fix: paranthesize returned values.
* Document the current behaviour of `elf_getbase()`.

Tested by:	gerald, Steve Kargl (original patch)
Obtained from:	elftoolchain
MFC after:	3 days

2 files changed, 19 insertions, 13 deletions

diff --git a/lib/libelf/elf_getbase.3 b/lib/libelf/elf_getbase.3
index be9d103..c19445d 100644
--- a/lib/libelf/elf_getbase.3
+++ b/lib/libelf/elf_getbase.3
@@ -1,4 +1,4 @@
-.\" Copyright (c) 2006 Joseph Koshy.  All rights reserved.
+.\" Copyright (c) 2006,2008,2010 Joseph Koshy.  All rights reserved.
 .\"
 .\" Redistribution and use in source and binary forms, with or without
 .\" modification, are permitted provided that the following conditions
@@ -23,7 +23,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd June 11, 2006
+.Dd June 6, 2010
 .Dt ELF_GETBASE 3
 .Os
 .Sh NAME
@@ -38,17 +38,21 @@
 .Sh DESCRIPTION
 Function
 .Fn elf_getbase
-returns the file offset in the containing archive of the first byte of
-the file referenced by ELF descriptor
+returns the file offset to the first byte of the object referenced by ELF
+descriptor
 .Ar elf .
+.Pp
+For descriptors referencing members of archives, the returned offset is
+the file offset of the member in its containing archive.
+For descriptors to regular objects, the returned offset is (vacuously)
+zero.
 .Sh RETURN VALUES
 Function
 .Fn elf_getbase
-returns a valid file offset into the containing archive if successful.
-It returns -1 if argument
-.Ar elf
-is NULL or is not a member of an
-archive.
+returns a valid file offset if successful, or
+.Pq Vt off_t
+.Li -1
+in case of an error.
 .Sh ERRORS
 Function
 .Fn elf_getbase
@@ -57,7 +61,7 @@ may fail with the following errors:
 .It Bq Er ELF_E_ARGUMENT
 Argument
 .Ar elf
-is not an ELF descriptor for an archive member.
+was NULL.
 .El
 .Sh SEE ALSO
 .Xr elf 3 ,
diff --git a/lib/libelf/elf_getbase.c b/lib/libelf/elf_getbase.c
index d32fa6c..863c858 100644
--- a/lib/libelf/elf_getbase.c
+++ b/lib/libelf/elf_getbase.c
@@ -34,12 +34,14 @@ __FBSDID("$FreeBSD$");
 off_t
 elf_getbase(Elf *e)
 {
-	if (e == NULL ||
-	    e->e_parent == NULL) {
+	if (e == NULL) {
 		LIBELF_SET_ERROR(ARGUMENT, 0);
-		return (off_t) -1;
+		return ((off_t) -1);
 	}
 
+	if (e->e_parent == NULL)
+		return ((off_t) 0);
+
 	return ((off_t) ((uintptr_t) e->e_rawfile -
 	    (uintptr_t) e->e_parent->e_rawfile));
 }