lstat/stat/fstat: Use 64bit version of syscall if available

This is needed for stat'ing loop devices > 255
since otherwise kernel returns EOVERFLOW becasue
it needs st_rdev/st_dev to be larger than 16bits but
in kernel it uses __old_kernel_stat for stat
syscall which has st_rdev/st_dev as unsigned short

Add a testcase

Signed-off-by: Khem Raj <raj.khem@gmail.com>

libc/sysdeps/linux/common/fstat.c

@@ -12,18 +12,28 @@
 #include <sys/stat.h>
 #include "xstatconv.h"
 
-#define __NR___syscall_fstat __NR_fstat
-static __inline__ _syscall2(int, __syscall_fstat, int, fd, struct kernel_stat *, buf)
-
 int fstat(int fd, struct stat *buf)
 {
 	int result;
+#ifdef __NR_fstat64
+	/* normal stat call has limited values for various stat elements
+	 * e.g. uid device major/minor etc.
+	 * so we use 64 variant if available
+	 * in order to get newer versions of stat elements
+	 */
+	struct kernel_stat64 kbuf;
+	result = INLINE_SYSCALL(fstat64, 2, fd, &kbuf);
+	if (result == 0) {
+		__xstat32_conv(&kbuf, buf);
+	}
+#else
 	struct kernel_stat kbuf;
 
-	result = __syscall_fstat(fd, &kbuf);
+	result = INLINE_SYSCALL(fstat, 2, fd, &kbuf);
 	if (result == 0) {
 		__xstat_conv(&kbuf, buf);
 	}
+#endif
 	return result;
 }
 libc_hidden_def(fstat)

libc/sysdeps/linux/common/lstat.c

@@ -12,19 +12,28 @@
 #include <sys/stat.h>
 #include "xstatconv.h"
 
-#define __NR___syscall_lstat __NR_lstat
-static __inline__ _syscall2(int, __syscall_lstat,
-		const char *, file_name, struct kernel_stat *, buf)
-
 int lstat(const char *file_name, struct stat *buf)
 {
 	int result;
+#ifdef __NR_lstat64
+	/* normal stat call has limited values for various stat elements
+	 * e.g. uid device major/minor etc.
+	 * so we use 64 variant if available
+	 * in order to get newer versions of stat elements
+	 */
+	struct kernel_stat64 kbuf;
+	result = INLINE_SYSCALL(lstat64, 2, file_name, &kbuf);
+	if (result == 0) {
+		__xstat32_conv(&kbuf, buf);
+	}
+#else
 	struct kernel_stat kbuf;
 
-	result = __syscall_lstat(file_name, &kbuf);
+	result = INLINE_SYSCALL(lstat, 2, file_name, &kbuf);
 	if (result == 0) {
 		__xstat_conv(&kbuf, buf);
 	}
+#endif
 	return result;
 }
 libc_hidden_def(lstat)

libc/sysdeps/linux/common/stat.c

@@ -12,20 +12,30 @@
 #include <sys/stat.h>
 #include "xstatconv.h"
 
-#define __NR___syscall_stat __NR_stat
 #undef stat
-static __inline__ _syscall2(int, __syscall_stat,
-		const char *, file_name, struct kernel_stat *, buf)
 
 int stat(const char *file_name, struct stat *buf)
 {
 	int result;
+#ifdef __NR_stat64
+	/* normal stat call has limited values for various stat elements
+	 * e.g. uid device major/minor etc.
+	 * so we use 64 variant if available
+	 * in order to get newer versions of stat elements
+	 */
+	struct kernel_stat64 kbuf;
+	result = INLINE_SYSCALL(stat64, 2, file_name, &kbuf);
+	if (result == 0) {
+		__xstat32_conv(&kbuf, buf);
+	}
+#else
 	struct kernel_stat kbuf;
 
-	result = __syscall_stat(file_name, &kbuf);
+	result = INLINE_SYSCALL(stat, 2, file_name, &kbuf);
 	if (result == 0) {
 		__xstat_conv(&kbuf, buf);
 	}
+#endif
 	return result;
 }
 libc_hidden_def(stat)

test/stat/stat-loop256.c

@@ -0,0 +1,32 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+int main()
+{
+    struct stat statbuf;
+    int ret = 0;
+    char* loop255 = "/dev/loop255";
+    char* loop256 = "/dev/loop256";
+    mode_t mode = 0660;
+    mknod(loop255, mode, 0x7ff);
+    mknod(loop256, mode, 0x100700);
+    ret = stat(loop255, &statbuf);
+    if(ret < 0) {
+	printf("stat: Cant stat %s\n",loop255);
+	unlink(loop255);
+	exit(1);
+    }
+    ret = stat(loop256, &statbuf);
+    if(ret < 0) {
+        printf("stat: Cant stat %s\n",loop256);
+	unlink(loop255);
+	unlink(loop256);
+        exit(1);
+    }
+
+    unlink(loop255);
+    unlink(loop256);
+    exit(0);
+}
+