1 files changed, 180 insertions, 0 deletions
diff --git a/src/shared/uid-range.c b/src/shared/uid-range.c
new file mode 100644
index 0000000..5d5bf7f
--- /dev/null
+++ b/src/shared/uid-range.c
@@ -0,0 +1,180 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "alloc-util.h"
+#include "macro.h"
+#include "sort-util.h"
+#include "uid-range.h"
+#include "user-util.h"
+
+static bool uid_range_intersect(UidRange *range, uid_t start, uid_t nr) {
+        assert(range);
+
+        return range->start <= start + nr &&
+                range->start + range->nr >= start;
+}
+
+static void uid_range_coalesce(UidRange **p, unsigned *n) {
+        assert(p);
+        assert(n);
+
+        for (unsigned i = 0; i < *n; i++) {
+                for (unsigned j = i + 1; j < *n; j++) {
+                        UidRange *x = (*p)+i, *y = (*p)+j;
+
+                        if (uid_range_intersect(x, y->start, y->nr)) {
+                                uid_t begin, end;
+
+                                begin = MIN(x->start, y->start);
+                                end = MAX(x->start + x->nr, y->start + y->nr);
+
+                                x->start = begin;
+                                x->nr = end - begin;
+
+                                if (*n > j+1)
+                                        memmove(y, y+1, sizeof(UidRange) * (*n - j -1));
+
+                                (*n)--;
+                                j--;
+                        }
+                }
+        }
+}
+
+static int uid_range_compare(const UidRange *a, const UidRange *b) {
+        int r;
+
+        r = CMP(a->start, b->start);
+        if (r != 0)
+                return r;
+
+        return CMP(a->nr, b->nr);
+}
+
+int uid_range_add(UidRange **p, unsigned *n, uid_t start, uid_t nr) {
+        bool found = false;
+        UidRange *x;
+
+        assert(p);
+        assert(n);
+
+        if (nr <= 0)
+                return 0;
+
+        for (unsigned i = 0; i < *n; i++) {
+                x = (*p) + i;
+                if (uid_range_intersect(x, start, nr)) {
+                        found = true;
+                        break;
+                }
+        }
+
+        if (found) {
+                uid_t begin, end;
+
+                begin = MIN(x->start, start);
+                end = MAX(x->start + x->nr, start + nr);
+
+                x->start = begin;
+                x->nr = end - begin;
+        } else {
+                UidRange *t;
+
+                t = reallocarray(*p, *n + 1, sizeof(UidRange));
+                if (!t)
+                        return -ENOMEM;
+
+                *p = t;
+                x = t + ((*n) ++);
+
+                x->start = start;
+                x->nr = nr;
+        }
+
+        typesafe_qsort(*p, *n, uid_range_compare);
+        uid_range_coalesce(p, n);
+
+        return *n;
+}
+
+int uid_range_add_str(UidRange **p, unsigned *n, const char *s) {
+        uid_t start, nr;
+        const char *t;
+        int r;
+
+        assert(p);
+        assert(n);
+        assert(s);
+
+        t = strchr(s, '-');
+        if (t) {
+                char *b;
+                uid_t end;
+
+                b = strndupa(s, t - s);
+                r = parse_uid(b, &start);
+                if (r < 0)
+                        return r;
+
+                r = parse_uid(t+1, &end);
+                if (r < 0)
+                        return r;
+
+                if (end < start)
+                        return -EINVAL;
+
+                nr = end - start + 1;
+        } else {
+                r = parse_uid(s, &start);
+                if (r < 0)
+                        return r;
+
+                nr = 1;
+        }
+
+        return uid_range_add(p, n, start, nr);
+}
+
+int uid_range_next_lower(const UidRange *p, unsigned n, uid_t *uid) {
+        uid_t closest = UID_INVALID, candidate;
+
+        assert(p);
+        assert(uid);
+
+        candidate = *uid - 1;
+
+        for (unsigned i = 0; i < n; i++) {
+                uid_t begin, end;
+
+                begin = p[i].start;
+                end = p[i].start + p[i].nr - 1;
+
+                if (candidate >= begin && candidate <= end) {
+                        *uid = candidate;
+                        return 1;
+                }
+
+                if (end < candidate)
+                        closest = end;
+        }
+
+        if (closest == UID_INVALID)
+                return -EBUSY;
+
+        *uid = closest;
+        return 1;
+}
+
+bool uid_range_contains(const UidRange *p, unsigned n, uid_t uid) {
+        assert(p);
+        assert(uid);
+
+        for (unsigned i = 0; i < n; i++)
+                if (uid >= p[i].start && uid < p[i].start + p[i].nr)
+                        return true;
+
+        return false;
+}