PATCH: PR ld/17773: Gap between sections and section headers when ld -s is used

["H.J. Lu" <hongjiu dot lu at intel dot com>]

bfd_elf_final_link assigns the file position for the symbol string table
even when there are no symbols to be emitted.  This patch changes to
assign the file position only if needed.  OK for trunk and 2.25 branch?

Thanks.


H.J.
---
bfd/

	PR ld/17773
	* elflink.c (bfd_elf_final_link): Assign the file position for
	the symbol string table only there are symbols to be emitted.

ld/testsuite/

	PR ld/17773
	* ld-elf/binutils.exp (binutils_test): Add an optional
	readelf_options.  Replace -l with $readelf_options.  Add a
	gap test.
	* ld/testsuite/ld-elf/gap.s: New file.
---
 bfd/ChangeLog                    |  6 ++++++
 bfd/elflink.c                    | 38 ++++++++++++++++++++------------------
 ld/testsuite/ChangeLog           |  8 ++++++++
 ld/testsuite/ld-elf/binutils.exp | 15 +++++++++------
 ld/testsuite/ld-elf/gap.s        |  4 ++++
 5 files changed, 47 insertions(+), 24 deletions(-)
 create mode 100644 ld/testsuite/ld-elf/gap.s

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index b883d3c..02b1ef7 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,9 @@
+2014-12-30  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR ld/17773
+	* elflink.c (bfd_elf_final_link): Assign the file position for
+	the symbol string table only there are symbols to be emitted.
+
 2014-12-28  Alan Modra  <amodra@gmail.com>
 
 	PR 17766
diff --git a/bfd/elflink.c b/bfd/elflink.c
index 16421cf..1ceb9e5 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -10614,7 +10614,6 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
   unsigned int i;
   Elf_Internal_Shdr *symtab_hdr;
   Elf_Internal_Shdr *symtab_shndx_hdr;
-  Elf_Internal_Shdr *symstrtab_hdr;
   const struct elf_backend_data *bed = get_elf_backend_data (abfd);
   struct elf_outext_info eoinfo;
   bfd_boolean merged;
@@ -11315,25 +11314,28 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
     }
 
 
-  /* Finish up and write out the symbol string table (.strtab)
-     section.  */
-  symstrtab_hdr = &elf_tdata (abfd)->strtab_hdr;
-  /* sh_name was set in prep_headers.  */
-  symstrtab_hdr->sh_type = SHT_STRTAB;
-  symstrtab_hdr->sh_flags = 0;
-  symstrtab_hdr->sh_addr = 0;
-  symstrtab_hdr->sh_size = _bfd_stringtab_size (flinfo.symstrtab);
-  symstrtab_hdr->sh_entsize = 0;
-  symstrtab_hdr->sh_link = 0;
-  symstrtab_hdr->sh_info = 0;
-  /* sh_offset is set just below.  */
-  symstrtab_hdr->sh_addralign = 1;
-
-  off = _bfd_elf_assign_file_position_for_section (symstrtab_hdr, off, TRUE);
-  elf_next_file_pos (abfd) = off;
-
   if (bfd_get_symcount (abfd) > 0)
     {
+      /* Finish up and write out the symbol string table (.strtab)
+	 section.  */
+      Elf_Internal_Shdr *symstrtab_hdr;
+
+      symstrtab_hdr = &elf_tdata (abfd)->strtab_hdr;
+      /* sh_name was set in prep_headers.  */
+      symstrtab_hdr->sh_type = SHT_STRTAB;
+      symstrtab_hdr->sh_flags = 0;
+      symstrtab_hdr->sh_addr = 0;
+      symstrtab_hdr->sh_size = _bfd_stringtab_size (flinfo.symstrtab);
+      symstrtab_hdr->sh_entsize = 0;
+      symstrtab_hdr->sh_link = 0;
+      symstrtab_hdr->sh_info = 0;
+      /* sh_offset is set just below.  */
+      symstrtab_hdr->sh_addralign = 1;
+
+      off = _bfd_elf_assign_file_position_for_section (symstrtab_hdr,
+						       off, TRUE);
+      elf_next_file_pos (abfd) = off;
+
       if (bfd_seek (abfd, symstrtab_hdr->sh_offset, SEEK_SET) != 0
 	  || ! _bfd_stringtab_emit (abfd, flinfo.symstrtab))
 	return FALSE;
diff --git a/ld/testsuite/ChangeLog b/ld/testsuite/ChangeLog
index 6fc0318..49ab015 100644
--- a/ld/testsuite/ChangeLog
+++ b/ld/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2014-12-30  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR ld/17773
+	* ld-elf/binutils.exp (binutils_test): Add an optional
+	readelf_options.  Replace -l with $readelf_options.  Add a
+	gap test.
+	* ld/testsuite/ld-elf/gap.s: New file.
+
 2014-12-26  Alan Modra  <amodra@gmail.com>
 
 	* ld-sh/sh64/crangerel1.rd: Update.
diff --git a/ld/testsuite/ld-elf/binutils.exp b/ld/testsuite/ld-elf/binutils.exp
index 4ade8cb..37ab6b3 100644
--- a/ld/testsuite/ld-elf/binutils.exp
+++ b/ld/testsuite/ld-elf/binutils.exp
@@ -38,8 +38,9 @@ if { [istarget *-*-linux*aout*]
 # to hardwire the test name. This is important if ld_options contains
 # absolute path names because the default test name is constructed
 # from the prog_name and ld_options and we do not want absolute paths
-# to appear in the test_name.
-proc binutils_test { prog_name ld_options test {test_name ""}} {
+# to appear in the test_name.  The optional readelf_options can be
+# used to specify different options for readelf.
+proc binutils_test { prog_name ld_options test {test_name ""} {readelf_options "-l"}} {
     global as
     global ld
     global READELF
@@ -71,8 +72,8 @@ proc binutils_test { prog_name ld_options test {test_name ""}} {
 	return
     }
 
-    send_log "$READELF -l --wide tmpdir/$test > tmpdir/$test.exp\n"
-    set got [remote_exec host "$READELF -l --wide tmpdir/$test" "" "/dev/null" "tmpdir/$test.exp"]
+    send_log "$READELF $readelf_options --wide tmpdir/$test > tmpdir/$test.exp\n"
+    set got [remote_exec host "$READELF $readelf_options --wide tmpdir/$test" "" "/dev/null" "tmpdir/$test.exp"]
     if { [lindex $got 0] != 0 || ![string match "" [lindex $got 1]] } then {
 	send_log "$got\n"
 	unresolved "$test_name"
@@ -111,8 +112,8 @@ proc binutils_test { prog_name ld_options test {test_name ""}} {
 	return
     }
 
-    send_log "$READELF -l --wide tmpdir/$test > tmpdir/$test.out\n"
-    set got [remote_exec host "$READELF -l --wide tmpdir/$test" "" "/dev/null" "tmpdir/$test.out"]
+    send_log "$READELF $readelf_options --wide tmpdir/$test > tmpdir/$test.out\n"
+    set got [remote_exec host "$READELF $readelf_options --wide tmpdir/$test" "" "/dev/null" "tmpdir/$test.out"]
     if { [lindex $got 0] != 0 || ![string match "" [lindex $got 1]] } then {
 	send_log "$got\n"
 	unresolved "$test_name"
@@ -176,3 +177,5 @@ foreach testitem $tls_tests {
 	binutils_test objcopy $testopt $testitem
     }
 }
+
+binutils_test strip "-s" gap "" "-lS"
diff --git a/ld/testsuite/ld-elf/gap.s b/ld/testsuite/ld-elf/gap.s
new file mode 100644
index 0000000..039d26b
--- /dev/null
+++ b/ld/testsuite/ld-elf/gap.s
@@ -0,0 +1,4 @@
+ .text
+ .global _start
+_start:
+ .long 0
-- 
1.9.3