Re: [PATCH] fsck: fix strange logic
From: Andreas Dilger <hidden>
Date: 2016-08-09 20:26:25
On Aug 9, 2016, at 2:12 PM, Andreas Dilger [off-list ref] wrote:
quoted hunk ↗ jump to hunk
llvm warns about the confusingly written comparison: !strncmp(argv[i+1], "-", 1) == 0) { misc/fsck.c:1178 col 9: warning: logical not is only applied to the left hand side of comparison [-Wlogical-not-parentheses] misc/fsck.c:1178 col 9: note: add parentheses after the '!' to evaluate the comparison first misc/fsck.c:1178 col 9: note: add parentheses around left hand side expression to silence this warning It makes sense to simplify this to a character comparison rather than using strncmp() to check only one character. Signed-off-by: Andreas Dilger <redacted> --- misc/fsck.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)diff --git a/misc/fsck.c b/misc/fsck.c index 826aaeb..4f918b7 100644 --- a/misc/fsck.c +++ b/misc/fsck.c@@ -1174,8 +1174,8 @@ static void PRS(int argc, char *argv[])progress_fd = 0; else goto next_arg; - } else if ((i+1) < argc && - !strncmp(argv[i+1], "-", 1) == 0) { + } else if (argc > i + 1 && + argv[i + 1][0] == '-') { progress_fd = string_to_int(argv[i]); if (progress_fd < 0) progress_fd = 0;
Note that it isn't clear whether the original logic also contained a bug, with both "!strncmp()" and the comparison with "== 0". At first glance it appeared that this was a bug to both negate and compare with 0, but in further review I think that this should _not_ parse negative numbers and use "-" as the fd. Unfortunately, it isn't documented what "-" means. I'll push a v2 patch that keeps the original logic, and Ted can choose which one is correct. Cheers, Andreas
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