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Merge "liblog: add pstore read"

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Mark Salyzyn 2015-02-26 17:23:15 +00:00 committed by Gerrit Code Review
commit ae19b63168
3 changed files with 177 additions and 1 deletions
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1
include/log/logger.h
View file

@ -159,6 +159,7 @@ int android_logger_set_prune_list(struct logger_list *logger_list,
#define ANDROID_LOG_RDWR O_RDWR
#define ANDROID_LOG_ACCMODE O_ACCMODE
#define ANDROID_LOG_NONBLOCK O_NONBLOCK
#define ANDROID_LOG_PSTORE 0x80000000
struct logger_list *android_logger_list_alloc(int mode,
unsigned int tail,

6
liblog/README
View file

@ -116,6 +116,10 @@ DESCRIPTION
code, otherwise the android_logger_list_read call will block for new
entries.
The ANDROID_LOG_PSTORE mode flag to the android_logger_open is used to
switch from the active logs to the persistent logs from before the last
reboot.
The value returned by android_logger_open can be used as a parameter to
the android_logger_clear function to empty the sub-log. It is recom‐
mended to only open log ANDROID_LOG_WRONLY in that case.
@ -132,4 +136,4 @@ SEE ALSO
17 Dec 2013 LIBLOG(3)
24 Jan 2014 LIBLOG(3)

171
liblog/log_read.c
View file

@ -19,6 +19,7 @@
#include <inttypes.h>
#include <poll.h>
#include <signal.h>
#include <stdbool.h>
#include <stddef.h>
#define NOMINMAX /* for windows to suppress definition of min in stdlib.h */
#include <stdlib.h>
@ -30,6 +31,8 @@
#include <cutils/sockets.h>
#include <log/log.h>
#include <log/logger.h>
#include <private/android_filesystem_config.h>
#include <private/android_logger.h>
/* branchless on many architectures. */
#define min(x,y) ((y) ^ (((x) ^ (y)) & -((x) < (y))))
@ -357,10 +360,64 @@ static int check_log_success(char *buf, ssize_t ret)
return 0;
}
/* Determine the credentials of the caller */
static bool uid_has_log_permission(uid_t uid)
{
return (uid == AID_SYSTEM) || (uid == AID_LOG) || (uid == AID_ROOT);
}
static uid_t get_best_effective_uid()
{
uid_t euid;
uid_t uid;
gid_t gid;
ssize_t i;
static uid_t last_uid = (uid_t) -1;
if (last_uid != (uid_t) -1) {
return last_uid;
}
uid = getuid();
if (uid_has_log_permission(uid)) {
return last_uid = uid;
}
euid = geteuid();
if (uid_has_log_permission(euid)) {
return last_uid = euid;
}
gid = getgid();
if (uid_has_log_permission(gid)) {
return last_uid = gid;
}
gid = getegid();
if (uid_has_log_permission(gid)) {
return last_uid = gid;
}
i = getgroups((size_t) 0, NULL);
if (i > 0) {
gid_t list[i];
getgroups(i, list);
while (--i >= 0) {
if (uid_has_log_permission(list[i])) {
return last_uid = list[i];
}
}
}
return last_uid = uid;
}
int android_logger_clear(struct logger *logger)
{
char buf[512];
if (logger->top->mode & ANDROID_LOG_PSTORE) {
if (uid_has_log_permission(get_best_effective_uid())) {
return unlink("/sys/fs/pstore/pmsg-ramoops-0");
}
errno = EPERM;
return -1;
}
return check_log_success(buf,
send_log_msg(logger, "clear %d", buf, sizeof(buf)));
}
@ -564,6 +621,116 @@ struct logger_list *android_logger_list_open(log_id_t id,
return logger_list;
}
static int android_logger_list_read_pstore(struct logger_list *logger_list,
struct log_msg *log_msg)
{
ssize_t ret;
off_t current, next;
uid_t uid;
struct logger *logger;
struct __attribute__((__packed__)) {
android_pmsg_log_header_t p;
android_log_header_t l;
} buf;
static uint8_t preread_count;
memset(log_msg, 0, sizeof(*log_msg));
if (logger_list->sock < 0) {
int fd = open("/sys/fs/pstore/pmsg-ramoops-0", O_RDONLY);
if (fd < 0) {
return -errno;
}
logger_list->sock = fd;
preread_count = 0;
}
ret = 0;
while(1) {
if (preread_count < sizeof(buf)) {
ret = TEMP_FAILURE_RETRY(read(logger_list->sock,
&buf.p.magic + preread_count,
sizeof(buf) - preread_count));
if (ret < 0) {
return -errno;
}
preread_count += ret;
}
if (preread_count != sizeof(buf)) {
return preread_count ? -EIO : -EAGAIN;
}
if ((buf.p.magic != LOGGER_MAGIC)
|| (buf.p.len <= sizeof(buf))
|| (buf.p.len > (sizeof(buf) + LOGGER_ENTRY_MAX_PAYLOAD))
|| (buf.l.id >= LOG_ID_MAX)
|| (buf.l.realtime.tv_nsec >= NS_PER_SEC)) {
do {
memmove(&buf.p.magic, &buf.p.magic + 1, --preread_count);
} while (preread_count && (buf.p.magic != LOGGER_MAGIC));
continue;
}
preread_count = 0;
logger_for_each(logger, logger_list) {
if (buf.l.id != logger->id) {
continue;
}
if ((logger_list->start.tv_sec || logger_list->start.tv_nsec)
&& ((logger_list->start.tv_sec > buf.l.realtime.tv_sec)
|| ((logger_list->start.tv_sec == buf.l.realtime.tv_sec)
&& (logger_list->start.tv_nsec > buf.l.realtime.tv_nsec)))) {
break;
}
if (logger_list->pid && (logger_list->pid != buf.p.pid)) {
break;
}
uid = get_best_effective_uid();
if (!uid_has_log_permission(uid) && (uid != buf.p.uid)) {
break;
}
ret = TEMP_FAILURE_RETRY(read(logger_list->sock,
log_msg->entry_v3.msg,
buf.p.len - sizeof(buf)));
if (ret < 0) {
return -errno;
}
if (ret != (ssize_t)(buf.p.len - sizeof(buf))) {
return -EIO;
}
log_msg->entry_v3.len = buf.p.len - sizeof(buf);
log_msg->entry_v3.hdr_size = sizeof(log_msg->entry_v3);
log_msg->entry_v3.pid = buf.p.pid;
log_msg->entry_v3.tid = buf.l.tid;
log_msg->entry_v3.sec = buf.l.realtime.tv_sec;
log_msg->entry_v3.nsec = buf.l.realtime.tv_nsec;
log_msg->entry_v3.lid = buf.l.id;
return ret;
}
current = TEMP_FAILURE_RETRY(lseek(logger_list->sock,
(off_t)0, SEEK_CUR));
if (current < 0) {
return -errno;
}
next = TEMP_FAILURE_RETRY(lseek(logger_list->sock,
(off_t)(buf.p.len - sizeof(buf)),
SEEK_CUR));
if (next < 0) {
return -errno;
}
if ((next - current) != (ssize_t)(buf.p.len - sizeof(buf))) {
return -EIO;
}
}
}
static void caught_signal(int signum __unused)
{
}
@ -582,6 +749,10 @@ int android_logger_list_read(struct logger_list *logger_list,
return -EINVAL;
}
if (logger_list->mode & ANDROID_LOG_PSTORE) {
return android_logger_list_read_pstore(logger_list, log_msg);
}
if (logger_list->mode & ANDROID_LOG_NONBLOCK) {
memset(&ignore, 0, sizeof(ignore));
ignore.sa_handler = caught_signal;