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/*
* Oracle Linux DTrace; close a range of fds.
* Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
#include <sys/types.h>
#include <sys/resource.h>
#include <sys/syscall.h>
#include <dirent.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
/*
* This is only used if glibc does not provide an implementation, in which case
* glibc will deal with a kernel too old to implement close_range; but even if
* it doesn't, if a sufficiently new kernel is in use, we should close all fds
* using the syscall.
*/
int
close_range(unsigned int first, unsigned int last, unsigned int flags)
{
DIR *fds;
struct dirent *ent;
#ifdef __NR_close_range
int ret;
ret = syscall(__NR_close_range, first, last, flags);
if (ret >= 0)
return ret;
#endif
fds = opendir("/proc/self/fd");
if (fds == NULL) {
/*
* No /proc/self/fd: fall back to just closing blindly.
*/
struct rlimit nfiles;
if (getrlimit(RLIMIT_NOFILE, &nfiles) < 0)
return -1; /* errno is set for us. */
if (nfiles.rlim_max == 0)
return 0;
/*
* Use rlim_max rather than rlim_cur because one can
* lower rlim_cur after opening more than rlim_cur files,
* leaving files numbered higher than the limit open.
*/
if (last >= nfiles.rlim_max)
last = nfiles.rlim_max - 1;
while (first <= last)
close(first++);
return 0;
}
while (errno = 0, (ent = readdir(fds)) != NULL) {
char *err;
int fd;
fd = strtol(ent->d_name, &err, 10);
/*
* Don't close garbage, no matter what.
*/
if (*err != '\0')
continue;
if (fd < first || fd > last)
continue;
close(fd);
}
closedir(fds);
return 0;
}
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