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authorRich Felker <dalias@aerifal.cx>2012-06-20 22:16:47 -0400
committerRich Felker <dalias@aerifal.cx>2012-06-20 22:16:47 -0400
commit4e8b0938d90793d6e1e200d6b25e6581b72bd4d0 (patch)
treecb0255413023716592eebc9f7978d7c1a1b00179
parente5fb6820a42a1f675ba09c15273953e1ace65777 (diff)
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proper error handling for fcntl F_GETOWN on modern kernels
on old kernels, there's no way to detect errors; we must assume negative syscall return values are pgrp ids. but if the F_GETOWN_EX fcntl works, we can get a reliable answer.
-rw-r--r--arch/arm/bits/fcntl.h3
-rw-r--r--arch/i386/bits/fcntl.h3
-rw-r--r--arch/x86_64/bits/fcntl.h3
-rw-r--r--include/fcntl.h11
-rw-r--r--src/fcntl/fcntl.c10
5 files changed, 29 insertions, 1 deletions
diff --git a/arch/arm/bits/fcntl.h b/arch/arm/bits/fcntl.h
index fc65ebcc..9595f9ca 100644
--- a/arch/arm/bits/fcntl.h
+++ b/arch/arm/bits/fcntl.h
@@ -31,3 +31,6 @@
#define F_GETLK 12
#define F_SETLK 13
#define F_SETLKW 14
+
+#define F_SETOWN_EX 15
+#define F_GETOWN_EX 16
diff --git a/arch/i386/bits/fcntl.h b/arch/i386/bits/fcntl.h
index 7f09b95c..69f3a8f5 100644
--- a/arch/i386/bits/fcntl.h
+++ b/arch/i386/bits/fcntl.h
@@ -31,3 +31,6 @@
#define F_GETLK 12
#define F_SETLK 13
#define F_SETLKW 14
+
+#define F_SETOWN_EX 15
+#define F_GETOWN_EX 16
diff --git a/arch/x86_64/bits/fcntl.h b/arch/x86_64/bits/fcntl.h
index 7b300210..9e07229e 100644
--- a/arch/x86_64/bits/fcntl.h
+++ b/arch/x86_64/bits/fcntl.h
@@ -31,3 +31,6 @@
#define F_GETLK 5
#define F_SETLK 6
#define F_SETLKW 7
+
+#define F_SETOWN_EX 15
+#define F_GETOWN_EX 16
diff --git a/include/fcntl.h b/include/fcntl.h
index 36fb24bc..fcb622a2 100644
--- a/include/fcntl.h
+++ b/include/fcntl.h
@@ -99,6 +99,17 @@ int posix_fallocate(int, off_t, off_t);
int lockf(int, int, off_t);
#endif
+#if defined(_GNU_SOURCE)
+#define F_OWNER_TID 0
+#define F_OWNER_PID 1
+#define F_OWNER_PGRP 2
+#define F_OWNER_GID 2
+struct f_owner_ex {
+ int type;
+ pid_t pid;
+};
+#endif
+
#if defined(_LARGEFILE64_SOURCE) || defined(_GNU_SOURCE)
#define open64 open
#define openat64 openat
diff --git a/src/fcntl/fcntl.c b/src/fcntl/fcntl.c
index fa5ad32f..fb7806a3 100644
--- a/src/fcntl/fcntl.c
+++ b/src/fcntl/fcntl.c
@@ -1,6 +1,8 @@
+#define _GNU_SOURCE
#include <fcntl.h>
#include <unistd.h>
#include <stdarg.h>
+#include <errno.h>
#include "syscall.h"
#include "libc.h"
@@ -13,6 +15,12 @@ int fcntl(int fd, int cmd, ...)
va_end(ap);
if (cmd == F_SETFL) arg |= O_LARGEFILE;
if (cmd == F_SETLKW) return syscall_cp(SYS_fcntl, fd, cmd, arg);
- if (cmd == F_GETOWN) return __syscall(SYS_fcntl, fd, cmd, arg);
+ if (cmd == F_GETOWN) {
+ struct f_owner_ex ex;
+ int ret = __syscall(SYS_fcntl, fd, F_GETOWN_EX, &ex);
+ if (ret == -EINVAL) return __syscall(SYS_fcntl, fd, cmd, arg);
+ if (ret) return __syscall_ret(ret);
+ return ex.type == F_OWNER_PGRP ? -ex.pid : ex.pid;
+ }
return syscall(SYS_fcntl, fd, cmd, arg);
}