diff options
| author | Paul Eggert <eggert@cs.ucla.edu> | 2004-07-28 00:30:45 +0000 |
|---|---|---|
| committer | Paul Eggert <eggert@cs.ucla.edu> | 2004-07-28 00:30:45 +0000 |
| commit | 62ce2087cb983e60c4bd9bf7741b2f3e8e69b0c4 (patch) | |
| tree | 085d6de87f7ba7c756653c4fda4826250d2d0c40 /lib/cycle-check.c | |
| parent | 43309787ced3ec53d6cda5deaa55d75c712520cb (diff) | |
| download | coreutils-62ce2087cb983e60c4bd9bf7741b2f3e8e69b0c4.tar.xz | |
(is_zero_or_power_of_two): Renamed from
is_power_of_two, to reflect better what it really does.
All uses changed. Arg is now uintmax_t, not unsigned int
(it should have been unsigned long int -- that was a bug).
(cycle_check): Check for integer overflow in cycle count,
and report a cycle if that happens, as it must be a cycle
by this point.
Diffstat (limited to 'lib/cycle-check.c')
| -rw-r--r-- | lib/cycle-check.c | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/lib/cycle-check.c b/lib/cycle-check.c index 8c7463b2f..99a88c35e 100644 --- a/lib/cycle-check.c +++ b/lib/cycle-check.c @@ -1,5 +1,6 @@ /* help detect directory cycles efficiently - Copyright 2003 Free Software Foundation, Inc. + + Copyright (C) 2003, 2004 Free Software Foundation, Inc. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -39,8 +40,10 @@ #define CC_MAGIC 9827862 +/* Return true if I is a power of 2, or is zero. */ + static inline bool -is_power_of_two (unsigned int i) +is_zero_or_power_of_two (uintmax_t i) { return (i & (i - 1)) == 0; } @@ -73,8 +76,16 @@ cycle_check (struct cycle_check_state *state, struct stat const *sb) /* If the number of `descending' chdir calls is a power of two, record the dev/ino of the current directory. */ - if (is_power_of_two (++(state->chdir_counter))) + if (is_zero_or_power_of_two (++(state->chdir_counter))) { + /* On all architectures that we know about, if the counter + overflows then there is a directory cycle here somewhere, + even if we haven't detected it yet. Typically this happens + only after the counter is incremented 2**64 times, so it's a + fairly theoretical point. */ + if (state->chdir_counter == 0) + return true; + state->dev_ino.st_dev = sb->st_dev; state->dev_ino.st_ino = sb->st_ino; } |