* [PATCH] improve error handling of ttyname_r and isatty
@ 2018-09-13 16:27 Benjamin Peterson
2018-09-13 18:25 ` Rich Felker
0 siblings, 1 reply; 5+ messages in thread
From: Benjamin Peterson @ 2018-09-13 16:27 UTC (permalink / raw)
To: musl
POSIX allows ttyname(_r) and isatty to return EBADF if passed file descriptor is
invalid.
---
src/unistd/isatty.c | 6 +++++-
src/unistd/ttyname_r.c | 5 ++++-
2 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/src/unistd/isatty.c b/src/unistd/isatty.c
index c8badaf5..3d5213c6 100644
--- a/src/unistd/isatty.c
+++ b/src/unistd/isatty.c
@@ -1,9 +1,13 @@
#include <unistd.h>
+#include <errno.h>
#include <sys/ioctl.h>
#include "syscall.h"
int isatty(int fd)
{
struct winsize wsz;
- return !__syscall(SYS_ioctl, fd, TIOCGWINSZ, &wsz);
+ unsigned long r = __syscall_ret(__syscall(SYS_ioctl, fd, TIOCGWINSZ, &wsz));
+ if (r == 0) return 1;
+ if (errno != EBADF) errno = ENOTTY;
+ return 0;
}
diff --git a/src/unistd/ttyname_r.c b/src/unistd/ttyname_r.c
index 33aa4ae1..3f836a6a 100644
--- a/src/unistd/ttyname_r.c
+++ b/src/unistd/ttyname_r.c
@@ -10,7 +10,10 @@ int ttyname_r(int fd, char *name, size_t size)
char procname[sizeof "/proc/self/fd/" + 3*sizeof(int) + 2];
ssize_t l;
- if (!isatty(fd)) return ENOTTY;
+ if (!isatty(fd)) {
+ if (errno != EBADF) errno = ENOTTY;
+ return errno;
+ }
__procfdname(procname, fd);
l = readlink(procname, name, size);
--
2.17.1
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] improve error handling of ttyname_r and isatty
2018-09-13 16:27 [PATCH] improve error handling of ttyname_r and isatty Benjamin Peterson
@ 2018-09-13 18:25 ` Rich Felker
2018-09-13 21:23 ` Benjamin Peterson
0 siblings, 1 reply; 5+ messages in thread
From: Rich Felker @ 2018-09-13 18:25 UTC (permalink / raw)
To: musl
On Thu, Sep 13, 2018 at 09:27:55AM -0700, Benjamin Peterson wrote:
> POSIX allows ttyname(_r) and isatty to return EBADF if passed file descriptor is
> invalid.
> ---
> src/unistd/isatty.c | 6 +++++-
> src/unistd/ttyname_r.c | 5 ++++-
> 2 files changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/src/unistd/isatty.c b/src/unistd/isatty.c
> index c8badaf5..3d5213c6 100644
> --- a/src/unistd/isatty.c
> +++ b/src/unistd/isatty.c
> @@ -1,9 +1,13 @@
> #include <unistd.h>
> +#include <errno.h>
> #include <sys/ioctl.h>
> #include "syscall.h"
>
> int isatty(int fd)
> {
> struct winsize wsz;
> - return !__syscall(SYS_ioctl, fd, TIOCGWINSZ, &wsz);
> + unsigned long r = __syscall_ret(__syscall(SYS_ioctl, fd, TIOCGWINSZ, &wsz));
> + if (r == 0) return 1;
> + if (errno != EBADF) errno = ENOTTY;
> + return 0;
> }
__syscall_ret(__syscall(...)) is just an ugly way of writing
syscall(). :-)
But the whole reason __syscall_ret exists is for the sake of setting
errno via a tailcall after the __syscall returns. When you have to
patch up the value, rather than shuffling it in and out of errno and
breaking the tailcall, a cleaner method is something like:
int r = __syscall(...);
if (r && r!=-EBADF) r=-ENOTTY;
return __syscall_ret(r);
> diff --git a/src/unistd/ttyname_r.c b/src/unistd/ttyname_r.c
> index 33aa4ae1..3f836a6a 100644
> --- a/src/unistd/ttyname_r.c
> +++ b/src/unistd/ttyname_r.c
> @@ -10,7 +10,10 @@ int ttyname_r(int fd, char *name, size_t size)
> char procname[sizeof "/proc/self/fd/" + 3*sizeof(int) + 2];
> ssize_t l;
>
> - if (!isatty(fd)) return ENOTTY;
> + if (!isatty(fd)) {
> + if (errno != EBADF) errno = ENOTTY;
> + return errno;
> + }
>
> __procfdname(procname, fd);
> l = readlink(procname, name, size);
> --
> 2.17.1
With isatty setting errno reasonably, there's no need for errno fixup
here. Just::
if (!isatty(fd)) return errno;
suffices.
Rich
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] improve error handling of ttyname_r and isatty
2018-09-13 18:25 ` Rich Felker
@ 2018-09-13 21:23 ` Benjamin Peterson
2018-09-13 21:23 ` [PATCH v2] " Benjamin Peterson
0 siblings, 1 reply; 5+ messages in thread
From: Benjamin Peterson @ 2018-09-13 21:23 UTC (permalink / raw)
To: musl
I've made a new version with your comments addressed. I don't think we can
actually tail call through __syscall_ret in isatty(), since we need to return
nonzero if the syscall succeeded.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH v2] improve error handling of ttyname_r and isatty
2018-09-13 21:23 ` Benjamin Peterson
@ 2018-09-13 21:23 ` Benjamin Peterson
2018-09-15 6:47 ` Rich Felker
0 siblings, 1 reply; 5+ messages in thread
From: Benjamin Peterson @ 2018-09-13 21:23 UTC (permalink / raw)
To: musl
POSIX allows ttyname(_r) and isatty to return EBADF if passed file descriptor is
invalid.
---
src/unistd/isatty.c | 6 +++++-
src/unistd/ttyname_r.c | 2 +-
2 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/src/unistd/isatty.c b/src/unistd/isatty.c
index c8badaf5..75a9c186 100644
--- a/src/unistd/isatty.c
+++ b/src/unistd/isatty.c
@@ -1,9 +1,13 @@
#include <unistd.h>
+#include <errno.h>
#include <sys/ioctl.h>
#include "syscall.h"
int isatty(int fd)
{
struct winsize wsz;
- return !__syscall(SYS_ioctl, fd, TIOCGWINSZ, &wsz);
+ unsigned long r = syscall(SYS_ioctl, fd, TIOCGWINSZ, &wsz);
+ if (r == 0) return 1;
+ if (errno != EBADF) errno = ENOTTY;
+ return 0;
}
diff --git a/src/unistd/ttyname_r.c b/src/unistd/ttyname_r.c
index 33aa4ae1..24106ad8 100644
--- a/src/unistd/ttyname_r.c
+++ b/src/unistd/ttyname_r.c
@@ -10,7 +10,7 @@ int ttyname_r(int fd, char *name, size_t size)
char procname[sizeof "/proc/self/fd/" + 3*sizeof(int) + 2];
ssize_t l;
- if (!isatty(fd)) return ENOTTY;
+ if (!isatty(fd)) return errno;
__procfdname(procname, fd);
l = readlink(procname, name, size);
--
2.17.1
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] improve error handling of ttyname_r and isatty
2018-09-13 21:23 ` [PATCH v2] " Benjamin Peterson
@ 2018-09-15 6:47 ` Rich Felker
0 siblings, 0 replies; 5+ messages in thread
From: Rich Felker @ 2018-09-15 6:47 UTC (permalink / raw)
To: musl
On Thu, Sep 13, 2018 at 02:23:42PM -0700, Benjamin Peterson wrote:
> POSIX allows ttyname(_r) and isatty to return EBADF if passed file descriptor is
> invalid.
> ---
> src/unistd/isatty.c | 6 +++++-
> src/unistd/ttyname_r.c | 2 +-
> 2 files changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/src/unistd/isatty.c b/src/unistd/isatty.c
> index c8badaf5..75a9c186 100644
> --- a/src/unistd/isatty.c
> +++ b/src/unistd/isatty.c
> @@ -1,9 +1,13 @@
> #include <unistd.h>
> +#include <errno.h>
> #include <sys/ioctl.h>
> #include "syscall.h"
>
> int isatty(int fd)
> {
> struct winsize wsz;
> - return !__syscall(SYS_ioctl, fd, TIOCGWINSZ, &wsz);
> + unsigned long r = syscall(SYS_ioctl, fd, TIOCGWINSZ, &wsz);
> + if (r == 0) return 1;
> + if (errno != EBADF) errno = ENOTTY;
> + return 0;
> }
> diff --git a/src/unistd/ttyname_r.c b/src/unistd/ttyname_r.c
> index 33aa4ae1..24106ad8 100644
> --- a/src/unistd/ttyname_r.c
> +++ b/src/unistd/ttyname_r.c
> @@ -10,7 +10,7 @@ int ttyname_r(int fd, char *name, size_t size)
> char procname[sizeof "/proc/self/fd/" + 3*sizeof(int) + 2];
> ssize_t l;
>
> - if (!isatty(fd)) return ENOTTY;
> + if (!isatty(fd)) return errno;
>
> __procfdname(procname, fd);
> l = readlink(procname, name, size);
> --
> 2.17.1
Thanks, applying.
Rich
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2018-09-15 6:47 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2018-09-13 16:27 [PATCH] improve error handling of ttyname_r and isatty Benjamin Peterson
2018-09-13 18:25 ` Rich Felker
2018-09-13 21:23 ` Benjamin Peterson
2018-09-13 21:23 ` [PATCH v2] " Benjamin Peterson
2018-09-15 6:47 ` Rich Felker
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