[PATCH] stat: Use stat64 syscall if available

Khem Raj raj.khem at gmail.com
Fri Feb 3 00:12:00 UTC 2012


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 at gmail.com>
---
 libc/sysdeps/linux/common/stat.c |   12 +++++++++---
 test/stat/stat-loop256.c         |   32 ++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 3 deletions(-)
 create mode 100644 test/stat/stat-loop256.c

diff --git a/libc/sysdeps/linux/common/stat.c b/libc/sysdeps/linux/common/stat.c
index a6ab291..5850266 100644
--- a/libc/sysdeps/linux/common/stat.c
+++ b/libc/sysdeps/linux/common/stat.c
@@ -14,18 +14,24 @@
 
 #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
+	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)
diff --git a/test/stat/stat-loop256.c b/test/stat/stat-loop256.c
new file mode 100644
index 0000000..fad4962
--- /dev/null
+++ b/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);
+}
+
-- 
1.7.5.4



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