elf2flt: add patch to fix ld.real search logic

elf2flt contains a program called ld-elf2flt, which gets installed as
a replacement for ld, with ld renamed to ld.real. This program
therefore calls ld.real internally.

The logic to find ld.real worked fine for:

 - bin/TARGET_ALIAS-ld
 - TARGET_ALIAS/bin/ld

However, it failed badly if bin/SIMPLER_TARGET_ALIAS-ld is used, as
symlink to bin/TARGET_ALIAS-ld. For example:

$ ./output/host/bin/arm-buildroot-uclinux-uclibcgnueabi-ld
/home/thomas/buildroot/buildroot/output/host/bin/../arm-buildroot-uclinux-uclibcgnueabi/bin/ld.real: no input files

$ ./output/host/bin/arm-linux-ld
arm-linux-ld (ld-elf2flt): error trying to exec '/home/thomas/buildroot/buildroot/output/host/bin/ld.real': execvp: No such file or directory

$ ./output/host/arm-buildroot-uclinux-uclibcgnueabi/bin/ld
/home/thomas/buildroot/buildroot/output/host/arm-buildroot-uclinux-uclibcgnueabi/bin/ld.real: no input files

This commit fixes that by adding a patch that adjusts the ld-elf2flt
logic to properly cope with this situation.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

diff --git a/package/elf2flt/0001-ld-elf2flt-behave-properly-when-called-with-a-name-d.patch b/package/elf2flt/0001-ld-elf2flt-behave-properly-when-called-with-a-name-d.patch
new file mode 100644 (file)
index 0000000..a27c491
--- /dev/null
+++ b/package/elf2flt/0001-ld-elf2flt-behave-properly-when-called-with-a-name-d.patch
@@ -0,0 +1,79 @@
+From b31e9b1bff6832063816b972395179859d1d4619 Mon Sep 17 00:00:00 2001
+From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
+Date: Sun, 13 Aug 2017 16:03:20 +0200
+Subject: [PATCH] ld-elf2flt: behave properly when called with a name different
+ from TARGET_ALIAS
+
+ld-elf2flt currently handles two cases:
+
+ 1 It is called as the wrapper for <TARGET_ALIAS>-ld, generally
+   installed in the bin/ directory of a toolchain.
+
+ 2 It is called as the wrapper for "ld", generally installed in the
+   TARGET_ALIAS/bin/ directory of a toolchain.
+
+Unfortunately, if for some reason it gets called using a FOOBAR-ld
+name that is different from <TARGET_ALIAS>-ld, it assumes it is in
+case (2), while it really is in case (1). Due to this, the path
+mangling logic doesn't work, and it doesn't find ld.real.
+
+This happens for example when the binary program in bin/ is named
+arm-buildroot-uclinux-uclibcgnueabi-ld, but also has a simpler symlink
+named arm-linux-ld. In this case,
+arm-buildroot-uclinux-uclibcgnueabi-ld is recognized by ld-elf2flt as
+containing TARGET_ALIAS, and therefore the proper logic to find
+ld.real is applied. However, when arm-linux-ld is used, ld-elf2flt
+doesn't find TARGET_ALIAS, and therefore assumes we're being called as
+TARGET_ALIAS/bin/ld.. and searches for a program called ld.real in
+bin/, which doesn't exist.
+
+See:
+
+$ ./output/host/bin/arm-buildroot-uclinux-uclibcgnueabi-ld
+/home/thomas/buildroot/buildroot/output/host/bin/../arm-buildroot-uclinux-uclibcgnueabi/bin/ld.real: no input files
+
+$ ./output/host/bin/arm-linux-ld
+arm-linux-ld (ld-elf2flt): error trying to exec '/home/thomas/buildroot/buildroot/output/host/bin/ld.real': execvp: No such file or directory
+
+$ ./output/host/arm-buildroot-uclinux-uclibcgnueabi/bin/ld
+/home/thomas/buildroot/buildroot/output/host/arm-buildroot-uclinux-uclibcgnueabi/bin/ld.real: no input files
+
+This commit fixes that by inverting the logic: if we're being called
+as just "ld", then we assume it's the program in
+TARGET_ALIAS/bin/. Otherwise, we're called through some variant of
+TARGET-ld.
+
+Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
+Submitted-upstream: https://github.com/uclinux-dev/elf2flt/pull/8
+---
+ ld-elf2flt.c | 10 +++++-----
+ 1 file changed, 5 insertions(+), 5 deletions(-)
+
+diff --git a/ld-elf2flt.c b/ld-elf2flt.c
+index de39fe0..c187c2e 100644
+--- a/ld-elf2flt.c
++++ b/ld-elf2flt.c
+@@ -506,15 +506,15 @@ int main(int argc, char *argv[])
+          the host while those in <TARGET_ALIAS>/lib are for the target.
+          Make bindir point to the bin dir for bin/<TARGET_ALIAS>-foo.
+          Make tooldir point to the bin dir for <TARGET_ALIAS>/bin/foo.  */
+-      if (streqn(elf2flt_progname, TARGET_ALIAS)) {
+-              tmp = concat(argv0_dir, "../" TARGET_ALIAS "/bin", NULL);
++      if (streqn(elf2flt_progname, "ld")) {
++              tmp = concat(argv0_dir, "../../bin", NULL);
+               if (stat(tmp, &buf) == 0 && S_ISDIR(buf.st_mode)) {
+-                      tooldir = concat(tmp, "/", NULL);
++                      bindir = concat(tmp, "/", NULL);
+               }
+       } else {
+-              tmp = concat(argv0_dir, "../../bin", NULL);
++              tmp = concat(argv0_dir, "../" TARGET_ALIAS "/bin", NULL);
+               if (stat(tmp, &buf) == 0 && S_ISDIR(buf.st_mode)) {
+-                      bindir = concat(tmp, "/", NULL);
++                      tooldir = concat(tmp, "/", NULL);
+               }
+       }
+ 
+-- 
+2.9.4
+