| Message ID | 20200113180322.5618-1-yann.morin.1998@free.fr |
|---|---|
| State | Accepted |
| Headers | show |
| Series | package/meson: fix shabang in deep build trees | expand |
On 13/01/2020 19:03, Yann E. MORIN wrote: > The meson script includes the full path to the python interpreter. In > deep build trees, this path can be more than 128 characters long, which > is the limit a shabang might be. > > In older kernels, that was silently ignored, leading to potential bugs, > but newer kernels enforce that limit, and refuse to execve() the script, > returning with NOEXEC. Since the script is +x, the shell (any bourne > shell, as well as the C shell) will conclude from that situation that > they should interpret it as a shell script, which it obviously is not. > > Fix the problem bu replacing the shabang with a call to /usr/bin/env > which will redirect to the correct pytohn3 interpreter found in the > PATH. > > Note however that this means our meson installation can no longer be > called from outside of the meson-package infrastructure anymore (not > that we ever supported it before, but who knows what people may have > done in their br2-external), unless one does set the PATH to include > $(HOST_DIR)/bin/ earlier than a system-provided python3 would be found. Actually, since meson doesn't depend on any non-standard python package, using the system-provided python3 is fine. In fact, IIRC the idea was to use the system-provided python3 if available, but nobody ever implemented that. Regards, Arnout > > Fixes: #12331 #12461 > > Reported-by: Jean-pierre Cartal <jpcartal@free.fr> > Reported-by: Matthias Weißer <m.weisser.m@gmail.com> > Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr> > Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com> > --- > package/meson/meson.mk | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/package/meson/meson.mk b/package/meson/meson.mk > index d409ae7b52..179daaa38a 100644 > --- a/package/meson/meson.mk > +++ b/package/meson/meson.mk > @@ -49,4 +49,10 @@ HOST_MESON_SED_CFLAGS = $(if $(strip $(TARGET_CFLAGS)),`printf '"%s"$(comma) ' $ > HOST_MESON_SED_LDFLAGS = $(if $(strip $(TARGET_LDFLAGS)),`printf '"%s"$(comma) ' $(TARGET_LDFLAGS)`) > HOST_MESON_SED_CXXFLAGS = $(if $(strip $(TARGET_CXXFLAGS)),`printf '"%s"$(comma) ' $(TARGET_CXXFLAGS)`) > > +# Avoid interpreter shabang longer than 127 chars > +define HOST_MESON_SET_INTERPRETER > + $(SED) '1s:.*:#!/usr/bin/env python3:' $(HOST_DIR)/bin/meson > +endef > +HOST_MESON_POST_INSTALL_HOOKS += HOST_MESON_SET_INTERPRETER > + > $(eval $(host-python-package)) >
>>>>> "Yann" == Yann E MORIN <yann.morin.1998@free.fr> writes: > The meson script includes the full path to the python interpreter. In > deep build trees, this path can be more than 128 characters long, which > is the limit a shabang might be. NIT: It is called shebang, not shabang. NIT2: This has actually been bumped to 256 bytes in linux 5.1: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=6eb3c3d0a52dca337e327ae8868ca1f44a712e02 > +# Avoid interpreter shabang longer than 127 chars 127? Off by one? ;) In fact, 128 bytes is the size of the entire buffer read from the file, so including the leading #! and trailing \0 and the actual path can AFAIK only be 125 bytes long. I changed it to 128 for consistency. Committed with these minor fixes, thanks.
diff --git a/package/meson/meson.mk b/package/meson/meson.mk index d409ae7b52..179daaa38a 100644 --- a/package/meson/meson.mk +++ b/package/meson/meson.mk @@ -49,4 +49,10 @@ HOST_MESON_SED_CFLAGS = $(if $(strip $(TARGET_CFLAGS)),`printf '"%s"$(comma) ' $ HOST_MESON_SED_LDFLAGS = $(if $(strip $(TARGET_LDFLAGS)),`printf '"%s"$(comma) ' $(TARGET_LDFLAGS)`) HOST_MESON_SED_CXXFLAGS = $(if $(strip $(TARGET_CXXFLAGS)),`printf '"%s"$(comma) ' $(TARGET_CXXFLAGS)`) +# Avoid interpreter shabang longer than 127 chars +define HOST_MESON_SET_INTERPRETER + $(SED) '1s:.*:#!/usr/bin/env python3:' $(HOST_DIR)/bin/meson +endef +HOST_MESON_POST_INSTALL_HOOKS += HOST_MESON_SET_INTERPRETER + $(eval $(host-python-package))
The meson script includes the full path to the python interpreter. In deep build trees, this path can be more than 128 characters long, which is the limit a shabang might be. In older kernels, that was silently ignored, leading to potential bugs, but newer kernels enforce that limit, and refuse to execve() the script, returning with NOEXEC. Since the script is +x, the shell (any bourne shell, as well as the C shell) will conclude from that situation that they should interpret it as a shell script, which it obviously is not. Fix the problem bu replacing the shabang with a call to /usr/bin/env which will redirect to the correct pytohn3 interpreter found in the PATH. Note however that this means our meson installation can no longer be called from outside of the meson-package infrastructure anymore (not that we ever supported it before, but who knows what people may have done in their br2-external), unless one does set the PATH to include $(HOST_DIR)/bin/ earlier than a system-provided python3 would be found. Fixes: #12331 #12461 Reported-by: Jean-pierre Cartal <jpcartal@free.fr> Reported-by: Matthias Weißer <m.weisser.m@gmail.com> Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr> Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com> --- package/meson/meson.mk | 6 ++++++ 1 file changed, 6 insertions(+)