lseek, lseek64: add cancellation for all THREADS

LT_OLD provides cancellable versions, do it for all THREADS.
llseek.c: use newly added macros for offset handling.
Add a comment about endianness issue around offset.
Compile llseek.c only on 32bit archs.
Provide aliases for 64bit archs or if syscall is not available.

Signed-off-by: Peter S. Mazinger <ps.m@gmx.net>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>

include/unistd.h

@@ -333,7 +333,10 @@ extern int faccessat (int __fd, __const char *__file, int __type, int __flag)
    Return the new file position.  */
 #ifndef __USE_FILE_OFFSET64
 extern __off_t lseek (int __fd, __off_t __offset, int __whence) __THROW;
+# ifdef _LIBC
+extern __typeof(lseek) __lseek_nocancel attribute_hidden;
 libc_hidden_proto(lseek)
+# endif
 #else
 # ifdef __REDIRECT_NTH
 extern __off64_t __REDIRECT_NTH (lseek,
@@ -346,7 +349,10 @@ extern __off64_t __REDIRECT_NTH (lseek,
 #ifdef __USE_LARGEFILE64
 extern __off64_t lseek64 (int __fd, __off64_t __offset, int __whence)
      __THROW;
+# ifdef _LIBC
+extern __typeof(lseek64) __lseek64_nocancel attribute_hidden;
 libc_hidden_proto(lseek64)
+# endif
 #endif
 
 /* Close the file descriptor FD.

libc/sysdeps/linux/common/llseek.c

@@ -9,30 +9,24 @@
 
 #include <_lfs_64.h>
 #include <sys/syscall.h>
-#include <unistd.h>
-#include <stdint.h>
+#include <bits/wordsize.h>
 
 /* Newer kernel ports have llseek() instead of _llseek() */
 #if !defined __NR__llseek && defined __NR_llseek
 # define __NR__llseek __NR_llseek
 #endif
 
-#ifdef __NR__llseek
-off64_t lseek64(int fd, off64_t offset, int whence)
+#if defined __NR__llseek && __WORDSIZE == 32
+# include <unistd.h>
+# include <endian.h>
+# include <cancel.h>
+off64_t __NC(lseek64)(int fd, off64_t offset, int whence)
 {
 	off64_t result;
-	return (off64_t)INLINE_SYSCALL(_llseek, 5, fd, (off_t) (offset >> 32),
-				(off_t) (offset & 0xffffffff), &result, whence) ?: result;
+	/* do we not need to handle the offset with __LONG_LONG_PAIR depending on endianness? */
+	return (off64_t)INLINE_SYSCALL(_llseek, 5, fd, (off_t) OFF64_HI(offset),
+				       (off_t) OFF64_LO(offset), &result, whence) ?: result;
 }
-#else
-off64_t lseek64(int fd, off64_t offset, int whence)
-{
-	return (off64_t)lseek(fd, (off_t) (offset), whence);
-}
-#endif
-#ifndef __LINUXTHREADS_OLD__
-libc_hidden_def(lseek64)
-#else
-libc_hidden_weak(lseek64)
-strong_alias(lseek64,__libc_lseek64)
+CANCELLABLE_SYSCALL(off64_t, lseek64, (int fd, off64_t offset, int whence), (fd, offset, whence))
+lt_libc_hidden(lseek64)
 #endif

libc/sysdeps/linux/common/lseek.c

@@ -9,19 +9,16 @@
 
 #include <sys/syscall.h>
 #include <unistd.h>
+#include <cancel.h>
 
 #ifdef __NR_lseek
-_syscall3(__off_t, lseek, int, fildes, __off_t, offset, int, whence)
-#elif defined __UCLIBC_HAS_LFS__ && defined __NR__llseek /* avoid circular dependency */
-__off_t lseek(int fildes, __off_t offset, int whence)
-{
-	return lseek64(fildes, offset, whence);
-}
+# define __NR___lseek_nocancel __NR_lseek
+_syscall3(off_t, __NC(lseek), int, fd, off_t, offset, int, whence)
 #else
 # include <errno.h>
-__off_t lseek(int fildes, __off_t offset attribute_unused, int whence)
+off_t __NC(lseek)(int fd, off_t offset attribute_unused, int whence)
 {
-	if (fildes < 0) {
+	if (fd < 0) {
 		__set_errno(EBADF);
 		return -1;
 	}
@@ -40,9 +37,10 @@ __off_t lseek(int fildes, __off_t offset attribute_unused, int whence)
 	return -1;
 }
 #endif
-#ifndef __LINUXTHREADS_OLD__
-libc_hidden_def(lseek)
-#else
-libc_hidden_weak(lseek)
-strong_alias(lseek,__libc_lseek)
+CANCELLABLE_SYSCALL(off_t, lseek, (int fd, off_t offset, int whence), (fd, offset, whence))
+lt_libc_hidden(lseek)
+#if defined __UCLIBC_HAS_LFS__ && (__WORDSIZE == 64 || !defined __NR__llseek)
+strong_alias_untyped(__NC(lseek),__NC(lseek64))
+strong_alias_untyped(lseek,lseek64)
+lt_libc_hidden(lseek64)
 #endif