buildroot/support/scripts/check-kernel-headers.sh
Carlos Santos 9e546440d3 support/scripts/check-kernel-headers.sh: use a trap to remove the temporary file
The POSIX specification defines a 'trap <action> EXIT' mechanism that is
useful to perform clean-up actions in shell scripts. A trap has two main
advantages over hand-crafted clean-up mechanisms:

- It runs even if the process is terminated by a SIGTERM.
- It runs even if the script stops due to a pipeline failure (set -e).

Now we can make the script to stop immediately if a compilation error
occurs, instead of letting it try to run an unexisting program.

This change may appear to be overkill but Buildroot is an open source
project and each piece of code is a potential learning tool for other
developments. We must strive to provide good examples.

Signed-off-by: Carlos Santos <unixmania@gmail.com>
Acked-by: Yann E. MORIN <yann.morin@orange.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
2019-09-25 22:07:29 +02:00

49 lines
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Executable File

#!/bin/sh
BUILDDIR="${1}"
SYSROOT="${2}"
# Make sure we have enough version components
HDR_VER="${3}.0.0"
HDR_M="${HDR_VER%%.*}"
HDR_V="${HDR_VER#*.}"
HDR_m="${HDR_V%%.*}"
# Exit on any error, so we don't try to run an unexisting program if the
# compilation fails.
set -e
# Set the clean-up trap in advance to prevent a race condition in which we
# create the file but get a SIGTERM before setting it. Notice that we don't
# need to care about EXEC being empty, since 'rm -f ""' does nothing.
trap 'rm -f "${EXEC}"' EXIT
EXEC="$(mktemp -p "${BUILDDIR}" -t .check-headers.XXXXXX)"
# We do not want to account for the patch-level, since headers are
# not supposed to change for different patchlevels, so we mask it out.
# This only applies to kernels >= 3.0, but those are the only one
# we actually care about; we treat all 2.6.x kernels equally.
${HOSTCC} -imacros "${SYSROOT}/usr/include/linux/version.h" \
-x c -o "${EXEC}" - <<_EOF_
#include <stdio.h>
#include <stdlib.h>
int main(int argc __attribute__((unused)),
char** argv __attribute__((unused)))
{
if((LINUX_VERSION_CODE & ~0xFF)
!= KERNEL_VERSION(${HDR_M},${HDR_m},0))
{
printf("Incorrect selection of kernel headers: ");
printf("expected %d.%d.x, got %d.%d.x\n", ${HDR_M}, ${HDR_m},
((LINUX_VERSION_CODE>>16) & 0xFF),
((LINUX_VERSION_CODE>>8) & 0xFF));
return 1;
}
return 0;
}
_EOF_
"${EXEC}"