readelf: Reset file position to beginning for thin archive members

* readelf.c (process_archive): Reset file position to the
	beginning when calling process_object for thin archive members.
	* testsuite/binutils-all/readelf.exp: Add test.
	* testsuite/binutils-all/readelf.h.thin: New file.

binutils/ChangeLog

@@ -1,3 +1,10 @@
+2021-07-01  Andrei Homescu  <ah@immunant.com>
+
+	* readelf.c (process_archive): Reset file position to the
+	beginning when calling process_object for thin archive members.
+	* testsuite/binutils-all/readelf.exp: Add test.
+	* testsuite/binutils-all/readelf.h.thin: New file.
+
 2021-06-30  Tom Tromey  <tom@tromey.com>
 
 	* dwarf.c (read_and_display_attr_value): Handle

binutils/readelf.c

@@ -21792,6 +21792,9 @@ process_archive (Filedata * filedata, bool is_thin_archive)
 	  filedata->archive_file_offset = arch.nested_member_origin;
 	  member_filedata->file_name = qualified_name;
 
+	  /* The call to process_object() expects the file to be at the beginning.  */
+	  rewind (member_filedata->handle);
+
 	  if (! process_object (member_filedata))
 	    ret = false;
 

binutils/testsuite/binutils-all/readelf.exp

@@ -310,6 +310,32 @@ proc readelf_dump_test {} {
     # XXX FIXME: Add test of readelf -x here
 }
 
+# Tests whether readelf can read thin archives
+proc readelf_thin_archive_test {} {
+    global AR
+
+    if ![is_remote host] {
+	set tempfile tmpdir/bintest.o
+        set templib  tmpdir/bintest.thin.a
+        set libname  tmpdir/bintest.thin.a
+    } else {
+	set tempfile [remote_download host tmpdir/bintest.o]
+        set templib  [remote_download host tmpdir/bintest.thin.a]
+        set libname  bintest.thin.a
+    }
+
+    set testname "readelf -h bintest.thin"
+    set got [binutils_run $AR "rcT $libname ${tempfile}"]
+    if ![string match "" $got] {
+        fail $testname
+        return
+    }
+
+    readelf_test -h $templib readelf.h.thin
+
+    pass $testname
+}
+
 if ![is_remote host] {
     if {[which $READELF] == 0} then {
         perror "$READELF does not exist"
@@ -344,6 +370,8 @@ if {![binutils_assemble $srcdir/$subdir/bintest.s tmpdir/bintest.o]} then {
     setup_xfail "mips-*-*irix*"
     readelf_test -s $tempfile readelf.ss
     readelf_test -r $tempfile readelf.r
+
+    readelf_thin_archive_test
 }
 
 # Test demangling symbol names.

binutils/testsuite/binutils-all/readelf.h.thin

@@ -0,0 +1,22 @@
+
+File: .*bintest\.thin\.a.*
+ELF Header:
+  Magic:   7f 45 4c 46 0[12] 0[12] 01 .. .. 00 00 00 00 00 00 00 
+  Class:                             ELF[36][24]
+  Data:                              2's complement,.* endian
+  Version:                           1 \(current\)
+  OS/ABI:                            .*
+  ABI Version:                       .*
+  Type:                              REL \(Relocatable file\)
+  Machine:                           .*
+  Version:                           0x1
+  Entry point address:               0x0
+  Start of program headers:          0 \(bytes into file\)
+  Start of section headers:          .* \(bytes into file\)
+  Flags:                             .*
+  Size of this header:               .* \(bytes\)
+  Size of program headers:           0 \(bytes\)
+  Number of program headers:         0
+  Size of section headers:           .* \(bytes\)
+  Number of section headers:         .*
+  Section header string table index: .*