fd-util: port close_all_fds() to close_range()
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@ -21,6 +21,7 @@
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#include "path-util.h"
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#include "process-util.h"
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#include "socket-util.h"
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#include "sort-util.h"
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#include "stat-util.h"
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#include "stdio-util.h"
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#include "tmpfile-util.h"
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@ -210,13 +211,102 @@ static int get_max_fd(void) {
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return (int) (m - 1);
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}
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static int cmp_int(const int *a, const int *b) {
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return CMP(*a, *b);
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}
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int close_all_fds(const int except[], size_t n_except) {
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static bool have_close_range = true; /* Assume we live in the future */
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_cleanup_closedir_ DIR *d = NULL;
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struct dirent *de;
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int r = 0;
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assert(n_except == 0 || except);
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if (have_close_range) {
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/* In the best case we have close_range() to close all fds between a start and an end fd,
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* which we can use on the "inverted" exception array, i.e. all intervals between all
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* adjacent pairs from the sorted exception array. This changes loop complexity from O(n)
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* where n is number of open fds to O(m⋅log(m)) where m is the number of fds to keep
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* open. Given that we assume n ≫ m that's preferable to us. */
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if (n_except == 0) {
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/* Close everything. Yay! */
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if (close_range(3, -1, 0) >= 0)
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return 1;
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if (!ERRNO_IS_NOT_SUPPORTED(errno) && !ERRNO_IS_PRIVILEGE(errno))
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return -errno;
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have_close_range = false;
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} else {
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_cleanup_free_ int *sorted_malloc = NULL;
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size_t n_sorted;
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int *sorted;
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assert(n_except < SIZE_MAX);
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n_sorted = n_except + 1;
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if (n_sorted > 64) /* Use heap for large numbers of fds, stack otherwise */
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sorted = sorted_malloc = new(int, n_sorted);
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else
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sorted = newa(int, n_sorted);
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if (sorted) {
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int c = 0;
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memcpy(sorted, except, n_except * sizeof(int));
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/* Let's add fd 2 to the list of fds, to simplify the loop below, as this
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* allows us to cover the head of the array the same way as the body */
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sorted[n_sorted-1] = 2;
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typesafe_qsort(sorted, n_sorted, cmp_int);
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for (size_t i = 0; i < n_sorted-1; i++) {
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int start, end;
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start = MAX(sorted[i], 2); /* The first three fds shall always remain open */
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end = MAX(sorted[i+1], 2);
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assert(end >= start);
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if (end - start <= 1)
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continue;
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/* Close everything between the start and end fds (both of which shall stay open) */
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if (close_range(start + 1, end - 1, 0) < 0) {
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if (!ERRNO_IS_NOT_SUPPORTED(errno) && !ERRNO_IS_PRIVILEGE(errno))
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return -errno;
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have_close_range = false;
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break;
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}
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c += end - start - 1;
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}
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if (have_close_range) {
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/* The loop succeeded. Let's now close everything beyond the end */
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if (sorted[n_sorted-1] >= INT_MAX) /* Dont let the addition below overflow */
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return c;
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if (close_range(sorted[n_sorted-1] + 1, -1, 0) >= 0)
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return c + 1;
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if (!ERRNO_IS_NOT_SUPPORTED(errno) && !ERRNO_IS_PRIVILEGE(errno))
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return -errno;
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have_close_range = false;
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}
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}
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}
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/* Fallback on OOM or if close_range() is not supported */
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}
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d = opendir("/proc/self/fd");
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if (!d) {
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int fd, max_fd;
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