CC-tea/coreutils
1
0
Fork 0
mirror of git://git.sv.gnu.org/coreutils.git synced 2026-04-21 03:12:48 +02:00
Code Issues Projects Releases Wiki Activity

(stdopen): Revert to iterating over descriptors, but

Browse Source 
rather than using fstat, use fcntl with its F_GETFD flag, which
is more efficient.  Unlike the 2-syscall dup-close approach,
this one doesn't apply any unnecessary pressure on the file
descriptor pool -- thus there is one fewer way to fail.
This commit is contained in:
Jim Meyering
2005-08-24 15:25:29 +00:00
parent 55fb58f426
commit f80cc28124
1 changed files with 22 additions and 30 deletions
Download Patch File Download Diff File Expand all files Collapse all files

52
lib/stdopen.c
View File

@@ -30,18 +30,6 @@
#include <unistd.h>
#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
every call to open, dup, fopen, etc. with tests to ensure they
@@ -51,25 +39,29 @@
bool
stdopen (void)
{
int fd = dup (STDIN_FILENO);
int fd;
bool ok = true;
if (0 <= fd)
close (fd);
else if (errno == EBADF)
fd = open ("/dev/null", O_WRONLY);
else
return false;
if (STDIN_FILENO <= fd && fd <= STDERR_FILENO)
for (fd = 0; fd <= 2; fd++)
{
fd = open ("/dev/null", O_RDONLY);
if (fd == STDOUT_FILENO)
fd = dup (fd);
if (fd < 0)
return false;
if (STDERR_FILENO < fd)
close (fd);
if (fcntl (fd, F_GETFD) < 0)
{
if (errno != EBADF)
ok = false;
else
{
static const int contrary_mode[]
= { O_WRONLY, O_RDONLY, O_RDONLY };
int new_fd = open ("/dev/null", contrary_mode[fd]);
if (new_fd != fd)
{
if (0 <= new_fd)
close (new_fd);
ok = false;
}
}
}
}
return true;
return ok;
}