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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/types.h>
#include <sys/stat.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) /* Try to ensure that each of the standard file numbers (0, 1, 2)
is in use. Without this, each application would have to guard is in use. Without this, each application would have to guard
@ -9,23 +27,19 @@
void void
stdopen (void) stdopen (void)
{ {
int fd; int fd = dup (STDIN_FILENO);
for (fd = 0; fd <= 2; fd++)
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; fd = open ("/dev/null", O_RDONLY);
if (fstat (fd, &sb) < 0) if (fd == STDOUT_FILENO)
{ fd = dup (fd);
static const int flag[] = { O_WRONLY, O_RDONLY, O_RDONLY }; if (STDERR_FILENO < fd)
/* FIXME: worry about errno != EBADF? */ close (fd);
char const *file = "/dev/null";
int fd2 = open (file, flag[fd]);
if (fd2 < 0)
break;
if (fd2 != fd)
{
close (fd2);
break;
}
}
} }
} }