Workaround for bug #7172: patchelf (branch yem/patchelf)

PATCH New Yann E. MORIN 4 participants 9 messages Jul 30, 2014 – Jul 31, 2014

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Yann E. MORIN

author

2014-07-30 22:57 UTC #0 lore raw

v2 cover Workaround for bug #7172: patchelf (branch yem/patchelf)

Hello All!

This series introduces a workaround for the limitations expressed in bug #7172 [0], which explains that a variable containing a $ sign is incorrectly expanded.

Since it is not trivial to actually fix #7172, this series implements a workaround, by:
- explaining the limitation in the menuconfig and the manual
- adding patchelf as a host-package, so users can tweak ELF files after the build (e.g. in a post-build script)

[0] https://bugs.buildroot.org/show_bug.cgi?id=7172

Changes v1 -> v2:
- fix typoes (Thomas DS)

Regards,
Yann E. MORIN.

The following changes since commit 26aefa672c96caefc17adf59a9ab3d327114ad36:

bind: fix static openssl linking (2014-07-30 23:51:51 +0200)

are available in the git repository at:

git://gitorious.org/buildroot/buildroot.git yem/patchelf

for you to fetch changes up to fc8f5090621f94da255a6191eec78125047eb318:

package/patchelf: new host package (2014-07-31 00:44:25 +0200)

----------------------------------------------------------------
Yann E. MORIN (2):
toolchain: linker options with a $ sign are not supported package/patchelf: new host package

 docs/manual/known-issues.txt    |  4 ++++
 package/Config.in.host          |  1 +
 package/patchelf/Config.in.host |  7 +++++++
 package/patchelf/patchelf.mk    | 12 ++++++++++++
 toolchain/toolchain-common.in   |  3 +++
 5 files changed, 27 insertions(+)
 create mode 100644 package/patchelf/Config.in.host
 create mode 100644 package/patchelf/patchelf.mk

Signature · 6 lines

.-----------------.--------------------.------------------.--------------------.
|  Yann E. MORIN  | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
| +33 662 376 056 | Software  Designer | \ / CAMPAIGN     |  ___               |
| +33 223 225 172 `------------.-------:  X  AGAINST      |  \e/  There is no  |
| http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL    |   v   conspiracy.  |
'------------------------------^-------^------------------^--------------------'

Yann E. MORIN

author

2014-07-30 22:57 UTC #1 lore raw

PATCH v2 1/2 toolchain: linker options with a $ sign are not supported

As reported in bug #7172 [0], setting BR2_TARGET_LDFLAGS to a value containing a $ sign can lead to unexpected results.

This is because it is very hard to know when the $ sign gets evaluated:
- in the Buildroot-level make
- in the shell called by the Buildroot-level make
- in the package's own build-system, either at configure time, in the Makefile, in a shell in the Makefile...

So, it is very difficult to know how much escaping that would need.

A proposal is to use a shell variable to pass such values unmolested. But it is not that simple either, since it still contains a $ sign, and there is not much certainty as to when it would be evaluated.

Instead, just document this limitation, both in the help text for BR2_TARGET_LDFLAGS, and in the known-issues section in the manual.

Does not really fix #7172, but at least the limitation is documented.

[0] https://bugs.buildroot.org/show_bug.cgi?id=7172

Signed-off-by "Yann E. MORIN" <[email protected]>

Cc Mike Zick <[email protected]>

---
 docs/manual/known-issues.txt  | 4 ++++
 toolchain/toolchain-common.in | 3 +++
 2 files changed, 7 insertions(+)

docs/manual/known-issues.txt +4 -0

index 08469e9..5eaded9 100644
@@ -3,6 +3,10 @@
 
 = Known issues
 
+* It is not possible to pass extra linker options via +BR2_TARGET_LDFLAGS+
+  if such options contain a +$+ sign. For example, the following is known
+  to break: +BR2_TARGET_LDFLAGS="-Wl,-rpath=\'$ORIGIN/../lib'"+
+
 * The +ltp-testsuite+ package does not build with the default uClibc
   configuration used by the Buildroot toolchain backend. The LTP
   testsuite uses several functions that are considered obsolete, such

toolchain/toolchain-common.in +3 -0

index 13de9e5..2df8ddb 100644
@@ -132,6 +132,9 @@ config BR2_TARGET_LDFLAGS
 	help
 	  Extra options to pass to the linker when building for the target.
 
+	  Note that options with a '$' sign (eg. -Wl,-rpath='$ORIGIN/../lib')
+	  are not supported.
+
 config BR2_ECLIPSE_REGISTER
 	bool "Register toolchain within Eclipse Buildroot plug-in"
 	help

Signature · 1 line

1.9.1

Thomas De Schampheleire

2014-07-31 06:38 UTC #2 lore raw

PATCH v2 1/2 toolchain: linker options with a $ sign are not supported

Quoted 49 lines · Yann E. MORIN

As reported in bug #7172 [0], setting BR2_TARGET_LDFLAGS to a value containing a $ sign can lead to unexpected results.
This is because it is very hard to know when the $ sign gets evaluated:
- in the Buildroot-level make
- in the shell called by the Buildroot-level make
- in the package's own build-system, either at configure time, in the Makefile, in a shell in the Makefile...
So, it is very difficult to know how much escaping that would need.
A proposal is to use a shell variable to pass such values unmolested. But it is not that simple either, since it still contains a $ sign, and there is not much certainty as to when it would be evaluated.
Instead, just document this limitation, both in the help text for BR2_TARGET_LDFLAGS, and in the known-issues section in the manual.
Does not really fix #7172, but at least the limitation is documented.
[0] https://bugs.buildroot.org/show_bug.cgi?id=7172
Signed-off-by "Yann E. MORIN" <[email protected]>
Cc Mike Zick <[email protected]>
---
 docs/manual/known-issues.txt  | 4 ++++
 toolchain/toolchain-common.in | 3 +++
 2 files changed, 7 insertions(+)
docs/manual/known-issues.txt +4 -0
index 08469e9..5eaded9 100644
@@ -3,6 +3,10 @@
 
 = Known issues
 
+* It is not possible to pass extra linker options via +BR2_TARGET_LDFLAGS+
+  if such options contain a +$+ sign. For example, the following is known
+  to break: +BR2_TARGET_LDFLAGS="-Wl,-rpath=\'$ORIGIN/../lib'"+
+
 * The +ltp-testsuite+ package does not build with the default uClibc
   configuration used by the Buildroot toolchain backend. The LTP
   testsuite uses several functions that are considered obsolete, such
toolchain/toolchain-common.in +0 -0
index 13de9e5..2df8ddb 100644

toolchain/toolchain-common.in config BR2_TARGET_LDFLAGS · line 140

Quoted 9 lines

toolchain/toolchain-common.in +3 -0

@@ -132,6 +132,9 @@ config BR2_TARGET_LDFLAGS
        help
          Extra options to pass to the linker when building for the target.
 
+         Note that options with a '$' sign (eg. -Wl,-rpath='$ORIGIN/../lib')
+         are not supported.
+
 config BR2_ECLIPSE_REGISTER
        bool "Register toolchain within Eclipse Buildroot plug-in"
        help

Reviewed-by Thomas De Schampheleire <[email protected]>

Thomas Petazzoni

Applied

2014-07-31 21:54 UTC #3 lore raw

PATCH v2 1/2 toolchain: linker options with a $ sign are not supported

In reply to Yann E. MORIN

Dear Yann E. MORIN,

Quoted 20 lines · Yann E. MORIN

As reported in bug #7172 [0], setting BR2_TARGET_LDFLAGS to a value containing a $ sign can lead to unexpected results.
This is because it is very hard to know when the $ sign gets evaluated:
- in the Buildroot-level make
- in the shell called by the Buildroot-level make
- in the package's own build-system, either at configure time, in the Makefile, in a shell in the Makefile...
So, it is very difficult to know how much escaping that would need.
A proposal is to use a shell variable to pass such values unmolested. But it is not that simple either, since it still contains a $ sign, and there is not much certainty as to when it would be evaluated.
Instead, just document this limitation, both in the help text for BR2_TARGET_LDFLAGS, and in the known-issues section in the manual.
Does not really fix #7172, but at least the limitation is documented.

Quoted 8 lines

[0] https://bugs.buildroot.org/show_bug.cgi?id=7172
Signed-off-by "Yann E. MORIN" <[email protected]>
Cc Mike Zick <[email protected]>
---
 docs/manual/known-issues.txt  | 4 ++++
 toolchain/toolchain-common.in | 3 +++
 2 files changed, 7 insertions(+)

Applied, thanks.

Thomas

Signature · 3 lines

Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

Yann E. MORIN

author

2014-07-30 22:57 UTC #4 lore raw

PATCH v2 2/2 package/patchelf: new host package

In reply to Yann E. MORIN

In some situations, users may want to tweak the dynamic section of the binaries (for example to add/set the RPATH to $ORIGIN/../lib).

Because it is not trivial to do it properly from the Buildroot infrastructure, allow those users to use patchelf (e.g. from a post-build script) to tweak binaries.

patchelf is able to:
- modify an existing DT_RUNPATH tags
- add a DT_RUNPATH tag if not already present
- do the above to the DT_RPATH tag, too
- set the path to the interpreter
- remove DT_NEEDED tags
- query a binary for the DT_RUNPATH/DT_RPATH tag, or for the interpreter path

Does not really fix #7172, but this is an appropriate workaround.

Signed-off-by "Yann E. MORIN" <[email protected]>

Cc Mike Zick <[email protected]>

---
 package/Config.in.host          |  1 +
 package/patchelf/Config.in.host |  7 +++++++
 package/patchelf/patchelf.mk    | 12 ++++++++++++
 3 files changed, 20 insertions(+)
 create mode 100644 package/patchelf/Config.in.host
 create mode 100644 package/patchelf/patchelf.mk

package/Config.in.host +1 -0

index 062c6c9..e05bbfa 100644
@@ -13,6 +13,7 @@ menu "Host utilities"
 	source "package/omap-u-boot-utils/Config.in.host"
 	source "package/openocd/Config.in.host"
 	source "package/parted/Config.in.host"
+	source "package/patchelf/Config.in.host"
 	source "package/pwgen/Config.in.host"
 	source "package/sam-ba/Config.in.host"
 	source "package/squashfs/Config.in.host"

package/patchelf/Config.in.host new file +7 -0

new file mode 100644
index 0000000..d1c8375
@@ -0,0 +1,7 @@
+config BR2_PACKAGE_HOST_PATCHELF
+	bool "host patchelf"
+	help
+	  PatchELF is a small utility to modify the dynamic linker
+	  and RPATH of ELF executables.
+
+	  http://nixos.org/patchelf.html

package/patchelf/patchelf.mk new file +12 -0

new file mode 100644
index 0000000..1a8e48d
@@ -0,0 +1,12 @@
+################################################################################
+#
+# patchelf
+#
+################################################################################
+
+PATCHELF_VERSION = 0.8
+PATCHELF_SITE = http://releases.nixos.org/patchelf/patchelf-0.8/
+PATCHELF_LICENSE = GPLv3
+PATCHELF_LICENSE_FILES = COPYING
+
+$(eval $(host-autotools-package))

Signature · 1 line

1.9.1

Baruch Siach

2014-07-31 03:26 UTC #5 lore raw

PATCH v2 2/2 package/patchelf: new host package

Hi Yann,

Quoted 16 lines · Yann E. MORIN

In some situations, users may want to tweak the dynamic section of the binaries (for example to add/set the RPATH to $ORIGIN/../lib).
Because it is not trivial to do it properly from the Buildroot infrastructure, allow those users to use patchelf (e.g. from a post-build script) to tweak binaries.
patchelf is able to:
- modify an existing DT_RUNPATH tags
- add a DT_RUNPATH tag if not already present
- do the above to the DT_RPATH tag, too
- set the path to the interpreter
- remove DT_NEEDED tags
- query a binary for the DT_RUNPATH/DT_RPATH tag, or for the interpreter path

Quoted 1 line

Does not really fix #7172, but this is an appropriate workaround.

Maybe this is worth a mention as a workaround to the known issue of #7172 in the manual?

baruch

Signature · 3 lines

     http://baruch.siach.name/blog/                  ~. .~   Tk Open Systems
=}------------------------------------------------ooO--U--Ooo------------{=
   - baruch at tkos.co.il - tel: +972.2.679.5364, http://www.tkos.co.il -

Thomas De Schampheleire

2014-07-31 06:41 UTC #6 lore raw

PATCH v2 2/2 package/patchelf: new host package

In reply to Yann E. MORIN

Quoted 61 lines · Yann E. MORIN

In some situations, users may want to tweak the dynamic section of the binaries (for example to add/set the RPATH to $ORIGIN/../lib).
Because it is not trivial to do it properly from the Buildroot infrastructure, allow those users to use patchelf (e.g. from a post-build script) to tweak binaries.
patchelf is able to:
- modify an existing DT_RUNPATH tags
- add a DT_RUNPATH tag if not already present
- do the above to the DT_RPATH tag, too
- set the path to the interpreter
- remove DT_NEEDED tags
- query a binary for the DT_RUNPATH/DT_RPATH tag, or for the interpreter path
Does not really fix #7172, but this is an appropriate workaround.
Signed-off-by "Yann E. MORIN" <[email protected]>
Cc Mike Zick <[email protected]>
---
 package/Config.in.host          |  1 +
 package/patchelf/Config.in.host |  7 +++++++
 package/patchelf/patchelf.mk    | 12 ++++++++++++
 3 files changed, 20 insertions(+)
 create mode 100644 package/patchelf/Config.in.host
 create mode 100644 package/patchelf/patchelf.mk
package/Config.in.host +1 -0
index 062c6c9..e05bbfa 100644
@@ -13,6 +13,7 @@ menu "Host utilities"
        source "package/omap-u-boot-utils/Config.in.host"
        source "package/openocd/Config.in.host"
        source "package/parted/Config.in.host"
+       source "package/patchelf/Config.in.host"
        source "package/pwgen/Config.in.host"
        source "package/sam-ba/Config.in.host"
        source "package/squashfs/Config.in.host"
package/patchelf/Config.in.host new file +7 -0
new file mode 100644
index 0000000..d1c8375
@@ -0,0 +1,7 @@
+config BR2_PACKAGE_HOST_PATCHELF
+       bool "host patchelf"
+       help
+         PatchELF is a small utility to modify the dynamic linker
+         and RPATH of ELF executables.
+
+         http://nixos.org/patchelf.html
package/patchelf/patchelf.mk new file +2 -0
new file mode 100644
index 0000000..1a8e48d
@@ -0,0 +1,12 @@
+################################################################################
+#

package/patchelf/patchelf.mk line 12

Quoted 10 lines

package/patchelf/patchelf.mk new file +10 -0

+# patchelf
+#
+################################################################################
+
+PATCHELF_VERSION = 0.8
+PATCHELF_SITE = http://releases.nixos.org/patchelf/patchelf-0.8/
+PATCHELF_LICENSE = GPLv3
+PATCHELF_LICENSE_FILES = COPYING
+
+$(eval $(host-autotools-package))

Reviewed-by Thomas De Schampheleire <[email protected]>

I do agree with Baruch's comment that it will be helpful for users desiring to use $ in the LDFLAGS to know that patchelf exists in buildroot. This could be added in the first patch of this series, or as a third patch.

Best regards,
Thomas

Thomas Petazzoni

2014-07-31 21:55 UTC #7 lore raw

PATCH v2 2/2 package/patchelf: new host package

In reply to Yann E. MORIN

Dear Yann E. MORIN,

Quoted 59 lines · Yann E. MORIN

In some situations, users may want to tweak the dynamic section of the binaries (for example to add/set the RPATH to $ORIGIN/../lib).
Because it is not trivial to do it properly from the Buildroot infrastructure, allow those users to use patchelf (e.g. from a post-build script) to tweak binaries.
patchelf is able to:
- modify an existing DT_RUNPATH tags
- add a DT_RUNPATH tag if not already present
- do the above to the DT_RPATH tag, too
- set the path to the interpreter
- remove DT_NEEDED tags
- query a binary for the DT_RUNPATH/DT_RPATH tag, or for the interpreter path
Does not really fix #7172, but this is an appropriate workaround.
Signed-off-by "Yann E. MORIN" <[email protected]>
Cc Mike Zick <[email protected]>
---
 package/Config.in.host          |  1 +
 package/patchelf/Config.in.host |  7 +++++++
 package/patchelf/patchelf.mk    | 12 ++++++++++++
 3 files changed, 20 insertions(+)
 create mode 100644 package/patchelf/Config.in.host
 create mode 100644 package/patchelf/patchelf.mk
package/Config.in.host +1 -0
index 062c6c9..e05bbfa 100644
@@ -13,6 +13,7 @@ menu "Host utilities"
 	source "package/omap-u-boot-utils/Config.in.host"
 	source "package/openocd/Config.in.host"
 	source "package/parted/Config.in.host"
+	source "package/patchelf/Config.in.host"
 	source "package/pwgen/Config.in.host"
 	source "package/sam-ba/Config.in.host"
 	source "package/squashfs/Config.in.host"
package/patchelf/Config.in.host new file +7 -0
new file mode 100644
index 0000000..d1c8375
@@ -0,0 +1,7 @@
+config BR2_PACKAGE_HOST_PATCHELF
+	bool "host patchelf"
+	help
+	  PatchELF is a small utility to modify the dynamic linker
+	  and RPATH of ELF executables.
+
+	  http://nixos.org/patchelf.html
package/patchelf/patchelf.mk new file +0 -0
new file mode 100644
index 0000000..1a8e48d

package/patchelf/patchelf.mk line 9

Quoted 9 lines

package/patchelf/patchelf.mk new file +9 -0

@@ -0,0 +1,12 @@
+################################################################################
+#
+# patchelf
+#
+################################################################################
+
+PATCHELF_VERSION = 0.8
+PATCHELF_SITE = http://releases.nixos.org/patchelf/patchelf-0.8/
+PATCHELF_LICENSE = GPLv3

The license is actually GPLv3+, see the README file of the project.

package/patchelf/patchelf.mk line 12

Quoted 3 lines

package/patchelf/patchelf.mk new file +3 -0
+PATCHELF_LICENSE_FILES = COPYING
+
+$(eval $(host-autotools-package))

Other than that, applied, thanks!

I think it would be good to use that to make the toolchain relocatable, instead of something like http://patchwork.ozlabs.org/patch/359841/.
What do you think?

Best regards,

Thomas

Signature · 3 lines

Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

Yann E. MORIN

author

2014-07-31 22:05 UTC #8 lore raw

PATCH v2 2/2 package/patchelf: new host package

Thomas, Samuel, All,

On 2014-07-31 23:55 +0200, Thomas Petazzoni spake thusly:

Quoted 7 lines · Yann E. MORIN

Quoted 6 lines
In some situations, users may want to tweak the dynamic section of the binaries (for example to add/set the RPATH to $ORIGIN/../lib).
Because it is not trivial to do it properly from the Buildroot infrastructure, allow those users to use patchelf (e.g. from a post-build script) to tweak binaries.

[--SNIP--]

Quoted 2 lines

Quoted 1 line
+PATCHELF_LICENSE = GPLv3
The license is actually GPLv3+, see the README file of the project.

[--SNIP--]

Quoted 1 line

Other than that, applied, thanks!

Thanks! :-)

Quoted 3 lines

I think it would be good to use that to make the toolchain relocatable, instead of something like http://patchwork.ozlabs.org/patch/359841/.
What do you think?

I think that Samuel already has a WIP branch on making a relocatable
SDK: https://github.com/tSed/buildroot/tree/sma/reloc-sdk/wip

So, Samuel, what do you think of it? ;-)

(Note how fast I was able to elude and reassign the question?)

Regards,
Yann E. MORIN.

Signature · 6 lines

.-----------------.--------------------.------------------.--------------------.
|  Yann E. MORIN  | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
| +33 662 376 056 | Software  Designer | \ / CAMPAIGN     |  ___               |
| +33 223 225 172 `------------.-------:  X  AGAINST      |  \e/  There is no  |
| http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL    |   v   conspiracy.  |
'------------------------------^-------^------------------^--------------------'