Revert "Revert "libc: Add logcat error message for memory corruption""
This reverts commit 368ee1e4d65c555fdb0fa4b3a91d75a397936908.
diff --git a/libc/bionic/logd_write.c b/libc/bionic/logd_write.c
index 63dfd59..2bc39fa 100644
--- a/libc/bionic/logd_write.c
+++ b/libc/bionic/logd_write.c
@@ -48,6 +48,16 @@
#include <pthread.h>
+/* IMPORTANT IMPORTANT IMPORTANT: TECHNICAL NOTE
+ *
+ * Some of the functions below can be called when our malloc() implementation
+ * has detected that the heap is corrupted, or even from a signal handler.
+ *
+ * These functions should *not* use a function that allocates heap memory
+ * or is not signal-safe. Using direct system calls is acceptable, and we
+ * also assume that pthread_mutex_lock/unlock can be used too.
+ */
+
#define LOG_BUF_SIZE 1024
typedef enum {
@@ -77,9 +87,10 @@
{ __write_to_log_init, -1, "/dev/"LOGGER_LOG_RADIO }
};
+/* Important: see technical note at start of source file */
static int __write_to_log_null(log_id_t log_id, struct iovec *vec)
{
- /*
+ /*
* ALTERED behaviour from previous version
* always returns successful result
*/
@@ -97,23 +108,21 @@
* it's supposed, that log_id contains valid id always.
* this check must be performed in higher level functions
*/
+/* Important: see technical note at start of source file */
static int __write_to_log_kernel(log_id_t log_id, struct iovec *vec)
{
- ssize_t ret;
-
- do {
- ret = writev(log_channels[log_id].fd, vec, 3);
- } while ((ret < 0) && (errno == EINTR));
-
- return ret;
+ return TEMP_FAILURE_RETRY( writev(log_channels[log_id].fd, vec, 3) );
}
+/* Important: see technical note at start of source file */
static int __write_to_log_init(log_id_t log_id, struct iovec *vec)
{
if ((LOG_ID_NONE < log_id) && (log_id < LOG_ID_MAX)) {
+ int fd;
+
pthread_mutex_lock(&log_init_lock);
- int fd = open(log_channels[log_id].path, O_WRONLY);
+ fd = TEMP_FAILURE_RETRY(open(log_channels[log_id].path, O_WRONLY));
log_channels[log_id].logger =
(fd < 0) ? __write_to_log_null : __write_to_log_kernel;
@@ -130,7 +139,9 @@
return -1;
}
-static int __android_log_write(int prio, const char *tag, const char *msg)
+/* Important: see technical note at start of source file */
+__LIBC_HIDDEN__
+int __libc_android_log_write(int prio, const char *tag, const char *msg)
{
struct iovec vec[3];
log_id_t log_id = LOG_ID_MAIN;
@@ -151,7 +162,11 @@
return log_channels[log_id].logger(log_id, vec);
}
-
+/* The functions below are not designed to be called from a heap panic
+ * function or from a signal handler. As such, they are free to use complex
+ * C library functions like vsnprintf()
+ */
+__LIBC_HIDDEN__
int __libc_android_log_vprint(int prio, const char *tag, const char *fmt,
va_list ap)
{
@@ -159,9 +174,10 @@
vsnprintf(buf, LOG_BUF_SIZE, fmt, ap);
- return __android_log_write(prio, tag, buf);
+ return __libc_android_log_write(prio, tag, buf);
}
+__LIBC_HIDDEN__
int __libc_android_log_print(int prio, const char *tag, const char *fmt, ...)
{
va_list ap;
@@ -171,20 +187,21 @@
vsnprintf(buf, LOG_BUF_SIZE, fmt, ap);
va_end(ap);
- return __android_log_write(prio, tag, buf);
+ return __libc_android_log_write(prio, tag, buf);
}
+__LIBC_HIDDEN__
int __libc_android_log_assert(const char *cond, const char *tag,
const char *fmt, ...)
{
va_list ap;
- char buf[LOG_BUF_SIZE];
+ char buf[LOG_BUF_SIZE];
va_start(ap, fmt);
vsnprintf(buf, LOG_BUF_SIZE, fmt, ap);
va_end(ap);
- __android_log_write(ANDROID_LOG_FATAL, tag, buf);
+ __libc_android_log_write(ANDROID_LOG_FATAL, tag, buf);
exit(1);