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diff --git a/lib/libc/gen/fts.c b/lib/libc/gen/fts.c
--- a/lib/libc/gen/fts.c
+++ b/lib/libc/gen/fts.c
@@ -41,6 +41,7 @@
#include <fcntl.h>
#include <fts.h>
#include <stdalign.h>
+#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
@@ -114,6 +115,19 @@
0
};
+/*
+ * POSIX provides nlink_t but unfortunately not NLINK_MAX.
+ */
+#define NLINK_MAX \
+ _Generic((nlink_t)0, \
+ int16_t: INT16_MAX, \
+ uint16_t: UINT16_MAX, \
+ int32_t: INT32_MAX, \
+ uint32_t: UINT32_MAX, \
+ int64_t: INT64_MAX, \
+ uint64_t: UINT64_MAX, \
+ default: 0)
+
static FTS *
__fts_open(FTS *sp, char * const *argv)
{
@@ -759,16 +773,36 @@
}
/*
- * Nlinks is the number of possible entries of type directory in the
- * directory if we're cheating on stat calls, 0 if we're not doing
- * any stat calls at all, -1 if we're doing stats on everything.
+ * In the FTS_PHYSICAL | FTS_NOSTAT case, we want to avoid calling
+ * fstat() unnecessarily, but we still need to call it for
+ * subdirectories. The current directory's link count provides an
+ * upper bound on the number of subdirectories we may encounter
+ * (including . and .. in the FTS_SEEDOT case). We initialize
+ * nlinks to the current directory's link count, then decrement it
+ * every time we encounter a directory, so when we hit zero we can
+ * save some time by not calling fstat() on subsequent entries.
+ *
+ * If FTS_NOSTAT is not set, or the link count is less than two
+ * (which should not be possible) or equal to NLINK_MAX (which
+ * suggests that the actual value could be higher), or the current
+ * filesystem is not known to provide reliable link counts, we
+ * initialize nlinks to -1 and fstat() everything.
+ *
+ * In the rare case where we don't need to stat anything, even
+ * subdirectories, we initialize nlinks to 0 regardless of the
+ * actual link count.
+ *
+ * Note that we ignore the FTS_NOSTAT flag in the FTS_LOGICAL
+ * case, although we could choose to only stat symbolic links.
+ * Implementing this is left as an exercise for the reader.
*/
if (type == BNAMES) {
nlinks = 0;
/* Be quiet about nostat, GCC. */
nostat = 0;
} else if (ISSET(FTS_NOSTAT) && ISSET(FTS_PHYSICAL)) {
- if (fts_ufslinks(sp, cur))
+ if (cur->fts_nlink >= 2 && cur->fts_nlink < NLINK_MAX &&
+ fts_ufslinks(sp, cur))
nlinks = cur->fts_nlink - (ISSET(FTS_SEEDOT) ? 0 : 2);
else
nlinks = -1;

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