logger: accept untagged log entries

Add support for writing untagged log messages to /dev/log_* nodes. The
logger shall accept untagget messages after setting the tag and
the priority with appropriate ioctl() commands for particular file
descriptors.

Change-Id: I02bd7bfd843eaf316692413a48747009c42756f6
Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com>

2 files changed, 331 insertions, 35 deletions

diff --git a/drivers/staging/android/logger.c b/drivers/staging/android/logger.c
index 27b2686..8988e4b 100644
--- a/drivers/staging/android/logger.c
+++ b/drivers/staging/android/logger.c
@@ -29,9 +29,10 @@
 #include <linux/time.h>
 #include <linux/vmalloc.h>
 #include <linux/uio.h>
-#include "logger.h"
+#include <linux/fdtable.h>
+#include <linux/file.h>
 
-#include <asm/ioctls.h>
+#include "logger.h"
 
 /**
  * struct logger_log - represents a specific log, such as 'main' or 'radio'
@@ -64,6 +65,27 @@ struct logger_log {
 static LIST_HEAD(log_list);
 
 /**
+ * struct log_writer - a logging device open for writing
+ * @log:	The associated log
+ * @list:	The associated entry in @logger_log's list
+ * @b_off:	The current position in @buf
+ * @tag:	A tag to be attached to messages
+ * @prio:	Default message priority value
+ * @buff:	Temporary space to assemble messages.
+ */
+struct logger_writer {
+	struct logger_log	*log;
+	struct task_struct	*owner;
+	struct task_struct	*b_owner;
+	struct logger_entry	b_header;
+	size_t			b_off;
+	size_t			tag_len;
+	char			*tag;
+	int			prio;
+	char			*buffer;
+};
+
+/**
  * struct logger_reader - a logging device open for reading
  * @log:	The associated log
  * @list:	The associated entry in @logger_log's list
@@ -104,12 +126,15 @@ static size_t logger_offset(struct logger_log *log, size_t n)
  */
 static inline struct logger_log *file_get_log(struct file *file)
 {
+	struct logger_writer *writer = file->private_data;
+
 	if (file->f_mode & FMODE_READ) {
 		struct logger_reader *reader = file->private_data;
 
 		return reader->log;
 	}
-	return file->private_data;
+
+	return writer->log;
 }
 
 /*
@@ -409,6 +434,125 @@ static void fix_up_readers(struct logger_log *log, size_t len)
 			reader->r_off = get_next_entry(log, reader->r_off, len);
 }
 
+static char *strnrchr(const char *s, size_t count, int c)
+{
+	const char *last = NULL;
+	if (!count)
+		return NULL;
+	do {
+		if (*s == (char)c)
+			last = s;
+	} while (--count && *s++);
+	return (char *)last;
+}
+
+static struct file *replace_file(struct files_struct *files,
+				 struct file *oldf,
+				 struct file *newf)
+{
+	struct file *file = NULL;
+	struct fdtable *fdt;
+	unsigned int i;
+
+	spin_lock(&files->file_lock);
+	fdt = files_fdtable(files);
+	for (i = 0; i < fdt->max_fds && file != oldf; i++) {
+		if (fdt->fd[i] == oldf) {
+			file = xchg(&fdt->fd[i], newf);
+		}
+	}
+	spin_unlock(&files->file_lock);
+
+	if (file)
+		filp_close(file, files);
+
+	return file;
+}
+
+static struct file *make_new_file(struct file *file)
+{
+	struct logger_writer *writer = file->private_data;
+	struct logger_writer *nwriter;
+	struct file *nfile;
+	char *pbuf, *p;
+
+	pbuf = kzalloc(PATH_MAX, GFP_KERNEL);
+	if (!pbuf) {
+		return ERR_PTR(-ENOMEM);
+	}
+
+	p = file_path(file, pbuf, PATH_MAX);
+	if (!p) {
+		kfree(pbuf);
+		return ERR_PTR(-EFAULT);
+	}
+
+	nfile = filp_open(p, O_WRONLY, 0);
+	kfree(pbuf);
+	if (!nfile) {
+		return ERR_PTR(-EFAULT);
+	}
+
+	nwriter = nfile->private_data;
+	nwriter->prio = writer->prio;
+	nwriter->tag = kstrdup(writer->tag, GFP_KERNEL);
+	nwriter->tag_len = writer->tag_len;
+
+	if (!replace_file(current->files, file, nfile)) {
+		filp_close(nfile, current->files);
+		return ERR_PTR(-EFAULT);
+	}
+
+	return nfile;
+}
+
+static void write_log_data(struct logger_log *log,
+			   struct logger_entry *header,
+			   struct logger_writer *writer,
+			   size_t chunk_len)
+{
+	size_t len, w_off;
+
+	/* header */
+	len = min(sizeof(struct logger_entry), log->size - log->w_off);
+	memcpy(log->buffer + log->w_off, header, len);
+	memcpy(log->buffer, (char *)header + len, sizeof(struct logger_entry) - len);
+	w_off =  logger_offset(log, log->w_off + sizeof(struct logger_entry));
+
+	/* priority */
+	log->buffer[w_off] = (unsigned char)writer->prio;
+	w_off = logger_offset(log, w_off + 1);
+
+	/* tag */
+	len = min_t(size_t, writer->tag_len + 1, log->size - w_off);
+	memcpy(log->buffer + w_off, writer->tag, len);
+	memcpy(log->buffer, writer->tag + len, writer->tag_len + 1 - len);
+	w_off = logger_offset(log, w_off + writer->tag_len + 1);
+
+	/* message */
+	len = min(chunk_len, log->size - w_off);
+	memcpy(log->buffer + w_off, writer->buffer, chunk_len);
+	memcpy(log->buffer, writer->buffer + len, chunk_len - len);
+	log->w_off = logger_offset(log, w_off + chunk_len);
+}
+
+static void flush_thread_data(struct file* file)
+{
+	struct logger_writer *writer = file->private_data;
+	struct logger_log *log = file_get_log(file);
+	size_t chunk_len = 0;
+
+	chunk_len = writer->b_off + 1;
+	writer->b_header.len = chunk_len + writer->tag_len + 2;
+
+	fix_up_readers(log, sizeof(struct logger_entry) + writer->b_header.len);
+
+	write_log_data(log, &writer->b_header, writer, chunk_len);
+
+	writer->b_off = 0;
+	writer->buffer[0] = '\0';
+}
+
 /*
  * logger_write_iter - our write method, implementing support for write(),
  * writev(), and aio_write(). Writes are our fast path, and we try to optimize
@@ -416,10 +560,16 @@ static void fix_up_readers(struct logger_log *log, size_t len)
  */
 static ssize_t logger_write_iter(struct kiocb *iocb, struct iov_iter *from)
 {
-	struct logger_log *log = file_get_log(iocb->ki_filp);
+	struct file *file = iocb->ki_filp;
+	struct logger_writer *writer = file->private_data;
+	struct logger_log *log = file_get_log(file);
 	struct logger_entry header;
 	struct timespec now;
 	size_t len, count, w_off;
+	bool from_stdio = false;
+
+	if (writer->tag && writer->prio >= 2)
+		from_stdio = true;
 
 	count = min_t(size_t, iov_iter_count(from), LOGGER_ENTRY_MAX_PAYLOAD);
 
@@ -439,46 +589,120 @@ static ssize_t logger_write_iter(struct kiocb *iocb, struct iov_iter *from)
 
 	mutex_lock(&log->mutex);
 
-	/*
-	 * Fix up any readers, pulling them forward to the first readable
-	 * entry after (what will be) the new write offset. We do this now
-	 * because if we partially fail, we can end up with clobbered log
-	 * entries that encroach on readable buffer.
-	 */
-	fix_up_readers(log, sizeof(struct logger_entry) + header.len);
+	/* Prepend messages from STDOUT and STDERR with a tag and prio */
+	if (from_stdio) {
+		char *p;
+		size_t chunk_len = 0;
+		size_t max_payload = LOGGER_ENTRY_MAX_PAYLOAD - writer->tag_len - 2;
 
-	len = min(sizeof(header), log->size - log->w_off);
-	memcpy(log->buffer + log->w_off, &header, len);
-	memcpy(log->buffer, (char *)&header + len, sizeof(header) - len);
+		if (writer->owner != current->group_leader) {
+			struct file *nfile;
 
-	/* Work with a copy until we are ready to commit the whole entry */
-	w_off =  logger_offset(log, log->w_off + sizeof(struct logger_entry));
+			nfile = make_new_file(file);
+			if (IS_ERR(nfile)) {
+				mutex_unlock(&log->mutex);
+				return PTR_ERR(nfile);
+			}
+
+			file = nfile;
+			writer = file->private_data;
+		}
+
+		/* Allocate STDIO line buffer */
+		if (!writer->buffer) {
+			writer->buffer = kzalloc(LOGGER_ENTRY_MAX_PAYLOAD, GFP_KERNEL);
+			writer->b_off = 0;
+
+			if (!writer->buffer) {
+				mutex_unlock(&log->mutex);
+				return -ENOMEM;
+			}
+		}
+
+		/* flush message from a different thread */
+		if (writer->b_owner != current && writer->b_off)
+			flush_thread_data(file);
+
+		count = min_t(size_t, iov_iter_count(from), max_payload - 1);
+
+		do {
+
+			if (copy_from_iter(writer->buffer + writer->b_off, count, from) != count) {
+				mutex_unlock(&log->mutex);
+				return -EFAULT;
+			}
 
-	len = min(count, log->size - w_off);
+			/* TODO: replace NULL characters with new lines */
+			p = strnrchr(writer->buffer + writer->b_off, count, '\n');
+			if (p) {
+				*p++ = '\0';
+				chunk_len = p - writer->buffer;
+			} else {
+				writer->buffer[count++] = '\0';
+				chunk_len = count;
+			}
+
+			header.len = chunk_len + writer->tag_len + 2;
+			fix_up_readers(log, sizeof(struct logger_entry) + header.len);
+
+			write_log_data(log, &header, writer, chunk_len);
+
+			/* move the remaining part of the message */
+			memmove(writer->buffer, p, writer->b_off + count - chunk_len);
+
+			/* new b_off points where the rimainder of the string ends */
+			writer->b_off = writer->b_off + count - chunk_len;
+			writer->buffer[writer->b_off] = '\0';
+
+		} while ((count = min_t(size_t, iov_iter_count(from), max_payload - 1)));
+
+		/* save for remaining unfinished line */
+		writer->b_header = header;
+		writer->b_owner = current;
+	} else {
 
-	if (copy_from_iter(log->buffer + w_off, len, from) != len) {
 		/*
-		 * Note that by not updating log->w_off, this abandons the
-		 * portion of the new entry that *was* successfully
-		 * copied, just above.  This is intentional to avoid
-		 * message corruption from missing fragments.
+		 * Fix up any readers, pulling them forward to the first readable
+		 * entry after (what will be) the new write offset. We do this now
+		 * because if we partially fail, we can end up with clobbered log
+		 * entries that encroach on readable buffer.
 		 */
-		mutex_unlock(&log->mutex);
-		return -EFAULT;
-	}
+		fix_up_readers(log, sizeof(struct logger_entry) + header.len);
 
-	if (copy_from_iter(log->buffer, count - len, from) != count - len) {
-		mutex_unlock(&log->mutex);
-		return -EFAULT;
+		len = min(sizeof(header), log->size - log->w_off);
+		memcpy(log->buffer + log->w_off, &header, len);
+		memcpy(log->buffer, (char *)&header + len, sizeof(header) - len);
+
+		/* Work with a copy until we are ready to commit the whole entry */
+		w_off =  logger_offset(log, log->w_off + sizeof(struct logger_entry));
+
+		len = min(count, log->size - w_off);
+
+		if (copy_from_iter(log->buffer + w_off, len, from) != len) {
+			/*
+			 * Note that by not updating log->w_off, this abandons the
+			 * portion of the new entry that *was* successfully
+			 * copied, just above.  This is intentional to avoid
+			 * message corruption from missing fragments.
+			 */
+			mutex_unlock(&log->mutex);
+			return -EFAULT;
+		}
+
+		if (copy_from_iter(log->buffer, count - len, from) != count - len) {
+			mutex_unlock(&log->mutex);
+			return -EFAULT;
+		}
+
+		log->w_off = logger_offset(log, w_off + count);
 	}
 
-	log->w_off = logger_offset(log, w_off + count);
 	mutex_unlock(&log->mutex);
 
 	/* wake up any blocked readers */
 	wake_up_interruptible(&log->wq);
 
-	return len;
+	return count;
 }
 
 static struct logger_log *get_log_from_minor(int minor)
@@ -530,7 +754,16 @@ static int logger_open(struct inode *inode, struct file *file)
 
 		file->private_data = reader;
 	} else {
-		file->private_data = log;
+		struct logger_writer *writer;
+
+		writer = kzalloc(sizeof(struct logger_writer), GFP_KERNEL);
+		if (!writer)
+			return -ENOMEM;
+
+		writer->log = log;
+		writer->owner = current->group_leader;
+
+		file->private_data = writer;
 	}
 
 	return 0;
@@ -552,6 +785,12 @@ static int logger_release(struct inode *ignored, struct file *file)
 		mutex_unlock(&log->mutex);
 
 		kfree(reader);
+	} else {
+		struct logger_writer *writer = file->private_data;
+
+		kfree(writer->tag);
+		kfree(writer->buffer);
+		kfree(writer);
 	}
 
 	return 0;
@@ -606,10 +845,53 @@ static long logger_set_version(struct logger_reader *reader, void __user *arg)
 	return 0;
 }
 
+static long logger_set_prio(struct logger_writer *writer, void __user *arg)
+{
+	int prio;
+
+	prio = (int)(uintptr_t)arg;
+
+	if ((prio < 2) || (prio > 7))
+		return -EINVAL;
+
+	writer->prio = prio;
+	return 0;
+}
+
+static long logger_set_tag(struct logger_writer *writer, void __user *arg)
+{
+	int len;
+	char *p, *q;
+
+	if (copy_from_user(&len, arg, sizeof(int)))
+		return -EFAULT;
+
+	arg += sizeof(int);
+
+
+	p = kzalloc(len, GFP_KERNEL);
+	if (!p)
+		return -ENOMEM;
+
+	if (copy_from_user(p, arg, len)) {
+		kfree(p);
+		return -EFAULT;
+	}
+	p[len-1] = '\0';
+
+	q = writer->tag;
+	writer->tag = p;
+	writer->tag_len = len - 1; /* without NULL */
+	kfree(q);
+
+	return 0;
+}
+
 static long logger_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 {
 	struct logger_log *log = file_get_log(file);
 	struct logger_reader *reader;
+	struct logger_writer *writer;
 	long ret = -EINVAL;
 	void __user *argp = (void __user *)arg;
 
@@ -648,10 +930,6 @@ static long logger_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 			ret = 0;
 		break;
 	case LOGGER_FLUSH_LOG:
-		if (!(file->f_mode & FMODE_WRITE)) {
-			ret = -EBADF;
-			break;
-		}
 		if (!(in_egroup_p(file_inode(file)->i_gid) ||
 		      capable(CAP_SYSLOG))) {
 			ret = -EPERM;
@@ -678,6 +956,22 @@ static long logger_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 		reader = file->private_data;
 		ret = logger_set_version(reader, argp);
 		break;
+	case LOGGER_SET_PRIO: 	/* 44552 */
+		if (file->f_mode & FMODE_READ) {
+			ret = -EBADF;
+			break;
+		}
+		writer = file->private_data;
+		ret = logger_set_prio(writer, argp);
+		break;
+	case LOGGER_SET_TAG:	/* 44551 */
+		if (file->f_mode & FMODE_READ) {
+			ret = -EBADF;
+			break;
+		}
+		writer = file->private_data;
+		ret = logger_set_tag(writer, argp);
+		break;
 	}
 
 	mutex_unlock(&log->mutex);
diff --git a/drivers/staging/android/logger.h b/drivers/staging/android/logger.h
index 70af7d8..b11e48c 100644
--- a/drivers/staging/android/logger.h
+++ b/drivers/staging/android/logger.h
@@ -85,5 +85,7 @@ struct logger_entry {
 #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 */
+#define LOGGER_SET_TAG			_IO(__LOGGERIO, 7) /* stdio tag */
+#define LOGGER_SET_PRIO			_IO(__LOGGERIO, 8) /* stdio priority */
 
 #endif /* _LINUX_LOGGER_H */