preadv/pwritev: create compat_readv()
This patch series: Implement the preadv() and pwritev() syscalls. *BSD has this syscall for quite some time. Test code: #if 0 set -x gcc -Wall -O2 -o preadv $0 exit 0 #endif /* * preadv demo / test * * (c) 2008 Gerd Hoffmann <kraxel@redhat.com> * * build with "sh $thisfile" */ #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #include <inttypes.h> #include <sys/uio.h> /* ----------------------------------------------------------------- */ /* syscall windup */ #include <sys/syscall.h> #if 0 /* WARNING: Be sure you know what you are doing if you enable this. * linux syscall code isn't upstream yet, syscall numbers are subject * to change */ # ifndef __NR_preadv # ifdef __i386__ # define __NR_preadv 333 # define __NR_pwritev 334 # endif # ifdef __x86_64__ # define __NR_preadv 295 # define __NR_pwritev 296 # endif # endif #endif #ifndef __NR_preadv # error preadv/pwritev syscall numbers are unknown #endif static ssize_t preadv(int fd, const struct iovec *iov, int iovcnt, off_t offset) { uint32_t pos_high = (offset >> 32) & 0xffffffff; uint32_t pos_low = offset & 0xffffffff; return syscall(__NR_preadv, fd, iov, iovcnt, pos_high, pos_low); } static ssize_t pwritev(int fd, const struct iovec *iov, int iovcnt, off_t offset) { uint32_t pos_high = (offset >> 32) & 0xffffffff; uint32_t pos_low = offset & 0xffffffff; return syscall(__NR_pwritev, fd, iov, iovcnt, pos_high, pos_low); } /* ----------------------------------------------------------------- */ /* demo/test app */ static char filename[] = "/tmp/preadv-XXXXXX"; static char outbuf[11] = "0123456789"; static char inbuf[11] = "----------"; static struct iovec ovec[2] = {{ .iov_base = outbuf + 5, .iov_len = 5, },{ .iov_base = outbuf + 0, .iov_len = 5, }}; static struct iovec ivec[3] = {{ .iov_base = inbuf + 6, .iov_len = 2, },{ .iov_base = inbuf + 4, .iov_len = 2, },{ .iov_base = inbuf + 2, .iov_len = 2, }}; void cleanup(void) { unlink(filename); } int main(int argc, char **argv) { int fd, rc; fd = mkstemp(filename); if (-1 == fd) { perror("mkstemp"); exit(1); } atexit(cleanup); /* write to file: "56789-01234" */ rc = pwritev(fd, ovec, 2, 0); if (rc < 0) { perror("pwritev"); exit(1); } /* read from file: "78-90-12" */ rc = preadv(fd, ivec, 3, 2); if (rc < 0) { perror("preadv"); exit(1); } printf("result : %s\n", inbuf); printf("expected: %s\n", "--129078--"); exit(0); } This patch: Factor out some code from compat_sys_readv() which can be shared with the upcoming compat_sys_preadv(). Signed-off-by: NGerd Hoffmann <kraxel@redhat.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: <linux-api@vger.kernel.org> Cc: <linux-arch@vger.kernel.org> Cc: Ralf Baechle <ralf@linux-mips.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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