* Note that ar(1) archives may also be opened using `elf_memory(3)`.

* Ignore the passed in value of the `fd` argument for ar(1) archives
  opened with elf_memory(3).

Obtained from:	elftoolchain
MFC after:		1 month

2 files changed, 10 insertions, 6 deletions

diff --git a/lib/libelf/elf_begin.3 b/lib/libelf/elf_begin.3
index dac4910..22c76ac 100644
--- a/lib/libelf/elf_begin.3
+++ b/lib/libelf/elf_begin.3
@@ -23,7 +23,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd June 21, 2006
+.Dd April 11, 2010
 .Dt ELF_BEGIN 3
 .Os
 .Sh NAME
@@ -163,7 +163,9 @@ archive may be opened in read mode (with argument
 set to
 .Dv ELF_C_READ )
 using
-.Fn elf_begin .
+.Fn elf_begin
+or
+.Fn elf_memory .
 The returned ELF descriptor can be passed into to
 subsequent calls to
 .Fn elf_begin
diff --git a/lib/libelf/elf_begin.c b/lib/libelf/elf_begin.c
index 7879dbe..6e81e32 100644
--- a/lib/libelf/elf_begin.c
+++ b/lib/libelf/elf_begin.c
@@ -131,13 +131,15 @@ elf_begin(int fd, Elf_Cmd c, Elf *a)
 	case ELF_C_READ:
 		/*
 		 * Descriptor `a' could be for a regular ELF file, or
-		 * for an ar(1) archive.
+		 * for an ar(1) archive.  If descriptor `a' was opened
+		 * using a valid file descriptor, we need to check if
+		 * the passed in `fd' value matches the original one.
 		 */
-		if (a && (a->e_fd != fd || c != a->e_cmd)) {
+		if (a &&
+		    ((a->e_fd != -1 && a->e_fd != fd) || c != a->e_cmd)) {
 			LIBELF_SET_ERROR(ARGUMENT, 0);
 			return (NULL);
 		}
-
 		break;
 
 	default:
@@ -149,7 +151,7 @@ elf_begin(int fd, Elf_Cmd c, Elf *a)
 	if (a == NULL)
 		e = _libelf_open_object(fd, c);
 	else if (a->e_kind == ELF_K_AR)
-		e = _libelf_ar_open_member(fd, c, a);
+		e = _libelf_ar_open_member(a->e_fd, c, a);
 	else
 		(e = a)->e_activations++;