[binutils-gdb] libctf: make it compile for old glibc

[Jose E.Marchesi]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=a2230b5e626b301e1f5f0f7122fe4038c9eb8428

commit a2230b5e626b301e1f5f0f7122fe4038c9eb8428
Author: Hans-Peter Nilsson <hp@bitrange.com>
Date:   Thu Jul 11 00:11:09 2019 -0400

    libctf: make it compile for old glibc
    
    With a glibc before 2.9 (such as 2.8), there's <endian.h> but no
    htole64 or le64toh, so you get, compiling binutils for any target:
    
    libtool: link: gcc -W -Wall -Wstrict-prototypes -Wmissing-prototypes \
    -Wshadow -Werror -I/x/binutils/../zlib -g -O2 -o objdump \
    objdump.o dwarf.o prdbg.o rddbg.o debug.o stabs.o rdcoff.o \
    bucomm.o version.o filemode.o elfcomm.o  ../opcodes/.libs/libopcodes.a \
    ../libctf/libctf.a ../bfd/.libs/libbfd.a -L/x/obj/b/zlib -lz ../libiberty/libiberty.a -ldl
    ../libctf/libctf.a(ctf-archive.o): In function `ctf_archive_raw_iter_internal':
    /x/src/libctf/ctf-archive.c:543: undefined reference to `le64toh'
    /x/src/libctf/ctf-archive.c:550: undefined reference to `le64toh'
    /x/src/libctf/ctf-archive.c:551: undefined reference to `le64toh'
    /x/src/libctf/ctf-archive.c:551: undefined reference to `le64toh'
    /x/src/libctf/ctf-archive.c:554: undefined reference to `le64toh'
    ../libctf/libctf.a(ctf-archive.o):/x/src/libctf/ctf-archive.c:545: more undefined references to `le64toh' follow
    (etc)
    
    Also, I see no bswap_identity_64 *anywhere* except in libctf/swap.h
    (including current glibc) and I don't think calling an "identity"-
    function is better than just plain "#define foo(x) (x)" anyway.
    (Where does the idea of a bytestap.h bswap_identity_64 come from?)
    
    Speaking of that, I should mention that I instrumented the condition
    to observe that the WORDS_BIGENDIAN case passes too for a presumed
    big-endian target and glibc-2.8: there is a bswap_64 present for that
    version.  Curiously, no test-case regressed with that instrumentation.
    
    For the record, constructing binary blobs using text source to run
    tests on, can be done by linking to --oformat binary (with most ELF
    targets), but I guess that's seen as unnecessary roundabout perhaps
    checking in binary files in the test-suite would be ok these days.
    [...]
    
    [nca: trimmed commit log slightly, updated changelog]
    
    v5: fix tabdamage.
    
    libctf/
    	* ctf-endian.h: Don't assume htole64 and le64toh are always
    	present if HAVE_ENDIAN_H; also check if htole64 is defined.
    	[!WORDS_BIGENDIAN] (htole64, le64toh): Define as identity,
    	not bswap_identity_64.

Diff:
---
 libctf/ChangeLog    | 7 +++++++
 libctf/ctf-endian.h | 6 +++---
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/libctf/ChangeLog b/libctf/ChangeLog
index 8a82ed0..08eb02b 100644
--- a/libctf/ChangeLog
+++ b/libctf/ChangeLog
@@ -1,3 +1,10 @@
+2019-07-11  Hans-Peter Nilsson  <hp@bitrange.com>
+
+	* ctf-endian.h: Don't assume htole64 and le64toh are always
+	present if HAVE_ENDIAN_H; also check if htole64 is defined.
+	[!WORDS_BIGENDIAN] (htole64, le64toh): Define as identity,
+	not bswap_identity_64.
+
 2019-09-18  Alan Modra  <amodra@gmail.com>
 
 	* ctf-open-bfd.c: Update throughout for bfd section macro changes.
diff --git a/libctf/ctf-endian.h b/libctf/ctf-endian.h
index ec177d1..f1cc527 100644
--- a/libctf/ctf-endian.h
+++ b/libctf/ctf-endian.h
@@ -24,10 +24,10 @@
 #include <stdint.h>
 #include "swap.h"
 
-#ifndef HAVE_ENDIAN_H
+#if !defined (HAVE_ENDIAN_H) || !defined (htole64)
 #ifndef WORDS_BIGENDIAN
-# define htole64(x) bswap_identity_64 ((x))
-# define le64toh(x) bswap_identity_64 ((x))
+# define htole64(x) (x)
+# define le64toh(x) (x)
 #else
 # define htole64(x) bswap_64 ((x))
 # define le64toh(x) bswap_64 ((x))