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dup.2: ffix 

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Michael Kerrisk 2020-06-10 11:48:44 +02:00
parent 73942082f2
commit 9562b9aee5
1 changed files with 23 additions and 21 deletions
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44
man2/dup.2
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@ -247,31 +247,33 @@ before calling
because of the race condition described above.
Instead, code something like the following could be used:
.PP
.in +4n
.EX
/* Obtain a duplicate of 'newfd' that can subsequently
be used to check for close() errors; an EBADF error
means that 'newfd' was not open. */
/* Obtain a duplicate of 'newfd' that can subsequently
be used to check for close() errors; an EBADF error
means that 'newfd' was not open. */
tmpfd = dup(newfd);
if (tmpfd == \-1 && errno != EBADF) {
/* Handle unexpected dup() error */
}
/* Atomically duplicate 'oldfd' on 'newfd' */
if (dup2(oldfd, newfd) == \-1) {
/* Handle dup2() error */
}
/* Now check for close() errors on the file originally
referred to by 'newfd' */
if (tmpfd != \-1) {
if (close(tmpfd) == \-1) {
/* Handle errors from close */
}
tmpfd = dup(newfd);
if (tmpfd == \-1 && errno != EBADF) {
/* Handle unexpected dup() error */
}
/* Atomically duplicate 'oldfd' on 'newfd' */
if (dup2(oldfd, newfd) == \-1) {
/* Handle dup2() error */
}
/* Now check for close() errors on the file originally
referred to by 'newfd' */
if (tmpfd != \-1) {
if (close(tmpfd) == \-1) {
/* Handle errors from close */
}
}
.EE
.in
.SH SEE ALSO
.BR close (2),
.BR fcntl (2),