logger: Add the update kernel struct to userspace

Android's kernel logger can optionally return UID information
in addition to the previously returned information. This
information is available by telling the kernel to use the
updated structure via the newly introduced LOGGER_SET_VERSION
ioctl.

int fd = open("/dev/log/main", O_RDONLY);
int version = 2;
ioctl(fd, LOGGER_SET_VERSION, &version);

Change-Id: I3914be41de55342c2918f8978fcd4d2b96a09288

1 files changed, 38 insertions, 3 deletions

diff --git a/include/cutils/logger.h b/include/cutils/logger.h
index b60f7ad..ccb0cac 100644
--- a/include/cutils/logger.h
+++ b/include/cutils/logger.h
@@ -11,7 +11,13 @@
 #define _UTILS_LOGGER_H
 
 #include <stdint.h>
+#include <sys/types.h>
 
+/*
+ * The userspace structure for version 1 of the logger_entry ABI.
+ * This structure is returned to userspace by the kernel logger
+ * driver unless an upgrade to a newer ABI version is requested.
+ */
 struct logger_entry {
     uint16_t    len;    /* length of the payload */
     uint16_t    __pad;  /* no matter what, we get 2 bytes of padding */
@@ -22,14 +28,41 @@ struct logger_entry {
     char        msg[0]; /* the entry's payload */
 };
 
+/*
+ * The userspace structure for version 2 of the logger_entry ABI.
+ * This structure is returned to userspace if ioctl(LOGGER_SET_VERSION)
+ * is called with version==2
+ */
+struct logger_entry_v2 {
+    uint16_t    len;       /* length of the payload */
+    uint16_t    hdr_size;  /* sizeof(struct logger_entry_v2) */
+    int32_t     pid;       /* generating process's pid */
+    int32_t     tid;       /* generating process's tid */
+    int32_t     sec;       /* seconds since Epoch */
+    int32_t     nsec;      /* nanoseconds */
+    uid_t       euid;      /* effective UID of logger */
+    char        msg[0];    /* the entry's payload */
+};
+
 #define LOGGER_LOG_MAIN		"log/main"
 #define LOGGER_LOG_RADIO	"log/radio"
 #define LOGGER_LOG_EVENTS	"log/events"
 #define LOGGER_LOG_SYSTEM	"log/system"
 
-#define LOGGER_ENTRY_MAX_LEN		(4*1024)
-#define LOGGER_ENTRY_MAX_PAYLOAD	\
-	(LOGGER_ENTRY_MAX_LEN - sizeof(struct logger_entry))
+/*
+ * The maximum size of the log entry payload that can be
+ * written to the kernel logger driver. An attempt to write
+ * more than this amount to /dev/log/* will result in a
+ * truncated log entry.
+ */
+#define LOGGER_ENTRY_MAX_PAYLOAD	4076
+
+/*
+ * The maximum size of a log entry which can be read from the
+ * kernel logger driver. An attempt to read less than this amount
+ * may result in read() returning EINVAL.
+ */
+#define LOGGER_ENTRY_MAX_LEN		(5*1024)
 
 #ifdef HAVE_IOCTL
 
@@ -41,6 +74,8 @@ struct logger_entry {
 #define LOGGER_GET_LOG_LEN		_IO(__LOGGERIO, 2) /* used log len */
 #define LOGGER_GET_NEXT_ENTRY_LEN	_IO(__LOGGERIO, 3) /* next entry len */
 #define LOGGER_FLUSH_LOG		_IO(__LOGGERIO, 4) /* flush log */
+#define LOGGER_GET_VERSION		_IO(__LOGGERIO, 5) /* abi version */
+#define LOGGER_SET_VERSION		_IO(__LOGGERIO, 6) /* abi version */
 
 #endif // HAVE_IOCTL