URL:
<http://savannah.gnu.org/bugs/?48169>
Summary: find makes unnecessary syscalls
Project: findutils
Submitted by: None
Submitted on: Wed 08 Jun 2016 01:10:23 AM UTC
Category: find
Severity: 3 - Normal
Item Group: None
Status: None
Privacy: Public
Assigned to: None
Originator Name: Tavian Barnes
Originator Email: [email protected]
Open/Closed: Open
Discussion Lock: Any
Release: 4.6.0
Fixed Release: None
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Details:
$ mkdir -p foo/bar/baz
$ strace find foo >/dev/null
...
newfstatat(5, "bar", {st_mode=S_IFDIR|0755, st_size=6, ...},
AT_SYMLINK_NOFOLLOW) = 0
fcntl(5, F_DUPFD_CLOEXEC, 0) = 4
openat(5, "bar", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_DIRECTORY|O_NOFOLLOW) = 6
fcntl(6, F_GETFD) = 0
fcntl(6, F_SETFD, FD_CLOEXEC) = 0
fstat(6, {st_mode=S_IFDIR|0755, st_size=6, ...}) = 0
fcntl(6, F_GETFL) = 0x38800 (flags
O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY|O_NOFOLLOW)
fcntl(6, F_SETFD, FD_CLOEXEC) = 0
newfstatat(5, "bar", {st_mode=S_IFDIR|0755, st_size=6, ...},
AT_SYMLINK_NOFOLLOW) = 0
fcntl(6, F_DUPFD, 3) = 7
fcntl(7, F_GETFD) = 0
fcntl(7, F_SETFD, FD_CLOEXEC) = 0
getdents(6, /* 3 entries */, 32768) = 72
getdents(6, /* 0 entries */, 32768) = 0
close(6) = 0
newfstatat(7, "baz", {st_mode=S_IFDIR|0755, st_size=0, ...},
AT_SYMLINK_NOFOLLOW) = 0
close(4) = 0
...
In particular:
- fd 4 is unused
- fcntl(6, F_SETFD, FD_CLOEXEC) happens twice, but could be totally avoided
with O_CLOEXEC (I suspect the second one is from within fdopendir() though)
- newfstatat(5, "bar", AT_SYMLINK_NOFOLLOW) happens twice
- fcntl(7, F_SETFD, FD_CLOEXEC) could be avoided if fcntl(6, F_DUPFD_CLOEXEC)
were used
This seems new with 4.6, at least 4.4 didn't do this.
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