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Rewritten by Paul Eggert.

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Now, the minimum overhead is just two system calls: dup and close.
This commit is contained in:
Jim Meyering 2005-06-30 20:13:40 +00:00
parent 58000d181c
commit 5754380c82
1 changed files with 32 additions and 18 deletions
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50
lib/stdopen.c
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@ -1,6 +1,24 @@
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#if HAVE_FCNTL_H
# include <fcntl.h>
#endif
#if HAVE_UNISTD_H
# include <unistd.h>
#endif
#include <errno.h>
#ifndef STDIN_FILENO
# define STDIN_FILENO 0
#endif
#ifndef STDOUT_FILENO
# define STDOUT_FILENO 1
#endif
#ifndef STDERR_FILENO
# define STDERR_FILENO 2
#endif
/* Try to ensure that each of the standard file numbers (0, 1, 2)
is in use. Without this, each application would have to guard
@ -9,23 +27,19 @@
void
stdopen (void)
{
int fd;
for (fd = 0; fd <= 2; fd++)
int fd = dup (STDIN_FILENO);
if (0 <= fd)
close (fd);
else if (errno == EBADF)
fd = open ("/dev/null", O_WRONLY);
if (STDIN_FILENO <= fd && fd <= STDERR_FILENO)
{
struct stat sb;
if (fstat (fd, &sb) < 0)
{
static const int flag[] = { O_WRONLY, O_RDONLY, O_RDONLY };
/* FIXME: worry about errno != EBADF? */
char const *file = "/dev/null";
int fd2 = open (file, flag[fd]);
if (fd2 < 0)
break;
if (fd2 != fd)
{
close (fd2);
break;
}
}
fd = open ("/dev/null", O_RDONLY);
if (fd == STDOUT_FILENO)
fd = dup (fd);
if (STDERR_FILENO < fd)
close (fd);
}
}