gh-153400: Add syscall fallbacks for copy_file_range/memfd_create - #155520
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gh-153400: Add syscall fallbacks for copy_file_range/memfd_create#155520daandemeyer wants to merge 1 commit into
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glibc only grew copy_file_range() and memfd_create() in 2.27, and we compile the os functions out when the libc we build against doesn't have them. That loses them for good in a redistributable built against an older glibc, such as the python-build-standalone builds targeting glibc 2.17, even when the kernel it runs on implements the syscalls. Keep calling the libc wrappers when they are available, so we don't lose their symbol versioning and _FORTIFY_SOURCE checks, and issue the syscall directly when they aren't. If the syscall number is missing as well, the functions are still left out. pidfd_open() and pidfd_getfd() already use raw syscalls, so nothing changes for them. Include <sys/syscall.h> whenever it exists rather than only when the getrandom() syscall was detected, since __NR_* is now needed for more than getrandom(). Signed-off-by: Daan De Meyer <daan@amutable.com>
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glibc only grew copy_file_range() and memfd_create() in 2.27, and we compile the os functions out when the libc we build against doesn't have them. That loses them for good in a redistributable built against an older glibc, such as the python-build-standalone builds targeting glibc 2.17, even when the kernel it runs on implements the syscalls.
Keep calling the libc wrappers when they are available, so we don't lose their symbol versioning and _FORTIFY_SOURCE checks, and issue the syscall directly when they aren't. If the syscall number is missing as well, the functions are still left out. pidfd_open() and pidfd_getfd() already use raw syscalls, so nothing changes for them.
Include <sys/syscall.h> whenever it exists rather than only when the getrandom() syscall was detected, since _NR* is now needed for more than getrandom().