Implement __fsetlocking.
The old __isthreaded hack was never very useful on Android because all user
code runs in a VM where there are lots of threads running. But __fsetlocking
lets a caller say "I'll worry about the locking for this FILE*", which is
useful for the normal case where you don't share a FILE* between threads
so you don't need any locking.
Bug: 17154740
Bug: 18593728
Change-Id: I2a8dddc29d3edff39a3d7d793387f2253608a68d
diff --git a/libc/stdio/fileext.h b/libc/stdio/fileext.h
index 25b7bda..75230cd 100644
--- a/libc/stdio/fileext.h
+++ b/libc/stdio/fileext.h
@@ -33,6 +33,7 @@
#define _FILEEXT_H_
#include <pthread.h>
+#include <stdbool.h>
__BEGIN_DECLS
@@ -40,9 +41,10 @@
* file extension
*/
struct __sfileext {
- struct __sbuf _ub; /* ungetc buffer */
+ struct __sbuf _ub; /* ungetc buffer */
struct wchar_io_data _wcio; /* wide char io status */
- pthread_mutex_t _lock; /* file lock */
+ pthread_mutex_t _lock; /* file lock */
+ bool _stdio_handles_locking; /* __fsetlocking support */
};
#define _EXT(fp) ((struct __sfileext *)((fp)->_ext._base))
@@ -54,7 +56,8 @@
_UB(fp)._base = NULL; \
_UB(fp)._size = 0; \
WCIO_INIT(fp); \
- _FLOCK(fp).value = __PTHREAD_RECURSIVE_MUTEX_INIT_VALUE; \
+ _FLOCK(fp).value = __PTHREAD_RECURSIVE_MUTEX_INIT_VALUE; \
+ _EXT(fp)->_stdio_handles_locking = true; \
} while (0)
#define _FILEEXT_SETUP(f, fext) \
diff --git a/libc/stdio/local.h b/libc/stdio/local.h
index 46b11f1..7033eda 100644
--- a/libc/stdio/local.h
+++ b/libc/stdio/local.h
@@ -111,8 +111,8 @@
(fp)->_lb._base = NULL; \
}
-#define FLOCKFILE(fp) flockfile(fp)
-#define FUNLOCKFILE(fp) funlockfile(fp)
+#define FLOCKFILE(fp) if (_EXT(fp)->_stdio_handles_locking) flockfile(fp)
+#define FUNLOCKFILE(fp) if (_EXT(fp)->_stdio_handles_locking) funlockfile(fp)
#define FLOATING_POINT
#define PRINTF_WIDE_CHAR
diff --git a/libc/stdio/stdio_ext.cpp b/libc/stdio/stdio_ext.cpp
index bfdecb8..fea44f6 100644
--- a/libc/stdio/stdio_ext.cpp
+++ b/libc/stdio/stdio_ext.cpp
@@ -27,13 +27,10 @@
*/
#include <stdio_ext.h>
+#include <stdlib.h>
-#include <stdio.h>
#include "local.h"
-
-#define FSETLOCKING_QUERY 0
-#define FSETLOCKING_INTERNAL 1
-#define FSETLOCKING_BYCALLER 2
+#include "private/libc_logging.h"
size_t __fbufsize(FILE* fp) {
return fp->_bf._size;
@@ -76,11 +73,19 @@
fflush(NULL);
}
-int __fsetlocking(FILE*, int) {
- // We don't currently have an implementation that would obey this,
- // so make setting the state a no-op and always return "we handle locking for you".
- // http://b/17154740 suggests ways we could fix this.
- return FSETLOCKING_INTERNAL;
+int __fsetlocking(FILE* fp, int type) {
+ int old_state = _EXT(fp)->_stdio_handles_locking ? FSETLOCKING_INTERNAL : FSETLOCKING_BYCALLER;
+ if (type == FSETLOCKING_QUERY) {
+ return old_state;
+ }
+
+ if (type != FSETLOCKING_INTERNAL && type != FSETLOCKING_BYCALLER) {
+ // The API doesn't let us report an error, so blow up.
+ __libc_fatal("Bad type (%d) passed to __fsetlocking", type);
+ }
+
+ _EXT(fp)->_stdio_handles_locking = (type == FSETLOCKING_INTERNAL);
+ return old_state;
}
void clearerr_unlocked(FILE* fp) {