graphics/wayland: standalone posix_fallocate snippet
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Authored by jbeich on Feb 27 2020, 5:39 PM.

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	F6198286: raw.txt
	Feb 27 2020, 5:40 PM

	F6198259: raw.txt
	Feb 27 2020, 5:39 PM

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	#include <err.h>
	#include <errno.h>
	#include <fcntl.h>
	#include <sys/mman.h>
	#include <unistd.h>

	#define HAVE_POSIX_FALLOCATE 1

	int
	os_resize_anonymous_file(int fd, off_t size)
	{
	#ifdef HAVE_POSIX_FALLOCATE
	/*
	* Filesystems that do support fallocate will return EINVAL or
	* EOPNOTSUPP. In this case we need to fall back to ftruncate
	*/
	errno = posix_fallocate(fd, 0, size);
	if (errno == 0)
	return 0;
	else if (errno != EINVAL && errno != EOPNOTSUPP) {
	warn("posix_fallocate failed");
	return -1;
	}
	#endif
	if (ftruncate(fd, size) < 0) {
	warn("ftruncate failed");
	return -1;
	}

	return 0;
	}

	int
	main(void)
	{
	int fd;
	off_t size = 12345;

	fd = shm_open(SHM_ANON, O_CREAT \| O_RDWR \| O_CLOEXEC, 0600); // shm_open is always CLOEXEC
	if (fd < 0)
	err(1, "shm_open(SHM_ANON) failed");

	if (os_resize_anonymous_file(fd, size) < 0) {
	close(fd);
	return -1;
	}

	return 0;
	}

jbeich changed the title of this paste from untitled to graphics/wayland: standalone posix_fallocate snippet.

jbeich updated the paste's language from autodetect to c.

graphics/wayland: standalone posix_fallocate snippetArchivedPublicActions