[PATCH v2 26/46] sendfile: Use sendfile64 if arch does not have the sendfile syscall

[Markos Chandras]

From: Markos Chandras <markos.chandras at imgtec.com>

Signed-off-by: Markos Chandras <markos.chandras at imgtec.com>
---
 include/sys/sendfile.h                 |  1 +
 libc/sysdeps/linux/common/sendfile.c   | 44 +++++++++++++++++++++++++++++++---
 libc/sysdeps/linux/common/sendfile64.c |  1 +
 libc/sysdeps/linux/common/stubs.c      |  3 ++-
 4 files changed, 45 insertions(+), 4 deletions(-)

diff --git a/include/sys/sendfile.h b/include/sys/sendfile.h
index 4c1367b..6280234 100644
--- a/include/sys/sendfile.h
+++ b/include/sys/sendfile.h
@@ -45,6 +45,7 @@ extern ssize_t __REDIRECT_NTH (sendfile,
 #ifdef __USE_LARGEFILE64
 extern ssize_t sendfile64 (int __out_fd, int __in_fd, __off64_t *__offset,
 			   size_t __count) __THROW;
+libc_hidden_proto(sendfile64)
 #endif
 
 __END_DECLS
diff --git a/libc/sysdeps/linux/common/sendfile.c b/libc/sysdeps/linux/common/sendfile.c
index 89bab9f..63ce37a 100644
--- a/libc/sysdeps/linux/common/sendfile.c
+++ b/libc/sysdeps/linux/common/sendfile.c
@@ -8,16 +8,54 @@
  */
 
 #include <sys/syscall.h>
+#include <stddef.h>
 #include <unistd.h>
 #include <sys/sendfile.h>
 
-#ifdef __NR_sendfile
+#if defined(__NR_sendfile64) && !defined(__NR_sendfile)
+ssize_t sendfile(int out_fd, int in_fd, __off_t *offset, size_t count)
+{
+	__off64_t off64, *off;
+	ssize_t res;
 
+	/*
+	 * Check if valids fd and valid pointers were passed
+	 * This does not prevent the user from passing
+	 * an arbitrary pointer causing a segfault or
+	 * other security issues
+	 */
+
+	if (in_fd < 0 || out_fd < 0) {
+		__set_errno(EBADF);
+		return -1;
+	}
+
+	if (offset == NULL || (int)offset < 0) {
+		__set_errno(EFAULT);
+		return -1;
+	}
+
+	if (offset) {
+		off = &off64;
+		off64 = *offset;
+	} else {
+		off = NULL;
+	}
+
+	res = INLINE_SYSCALL(sendfile64, 4, out_fd, in_fd, off, count);
+
+	if (res >= 0)
+		*offset = off64;
+
+	return res;
+}
+
+#elif defined(__NR_sendfile)
 _syscall4(ssize_t, sendfile, int, out_fd, int, in_fd, __off_t *, offset,
 		  size_t, count)
 
-#if ! defined __NR_sendfile64 && defined __UCLIBC_HAS_LFS__
+#if ! defined(__NR_sendfile64) && defined(__UCLIBC_HAS_LFS__)
 strong_alias(sendfile,sendfile64)
 #endif
 
-#endif /* __NR_sendfile */
+#endif
diff --git a/libc/sysdeps/linux/common/sendfile64.c b/libc/sysdeps/linux/common/sendfile64.c
index fc5155f..9a59485 100644
--- a/libc/sysdeps/linux/common/sendfile64.c
+++ b/libc/sysdeps/linux/common/sendfile64.c
@@ -21,4 +21,5 @@
 
 #if defined __UCLIBC_HAS_LFS__ && defined __NR_sendfile64
 _syscall4(ssize_t,sendfile64, int, out_fd, int, in_fd, __off64_t *, offset, size_t, count)
+libc_hidden_def(sendfile64)
 #endif
diff --git a/libc/sysdeps/linux/common/stubs.c b/libc/sysdeps/linux/common/stubs.c
index 9cb8de0..1837195 100644
--- a/libc/sysdeps/linux/common/stubs.c
+++ b/libc/sysdeps/linux/common/stubs.c
@@ -278,7 +278,8 @@ make_stub(sched_setaffinity)
 make_stub(send)
 #endif
 
-#if !defined __NR_sendfile && defined __UCLIBC_LINUX_SPECIFIC__
+#if !defined __NR_sendfile && !defined(__NR_sendfile64) \
+	&& defined __UCLIBC_LINUX_SPECIFIC__
 make_stub(sendfile)
 #endif
 
-- 
1.8.0