samsung-ipc/utils: add data_read and data_write

These wrappers are meant to handle the case where read or writes
handles a smaller number of bytes than requested.

This way that handling doesn't need to be duplicated everywhere
in libsamsung-ipc.

Having access to the ipc_client struct could enable future
logging of read and writes without having to change any of the
code already using data_read and data_write.

Signed-off-by: Denis 'GNUtoo' Carikli <GNUtoo@cyberdimension.org>

1 files changed, 43 insertions, 0 deletions

diff --git a/samsung-ipc/utils.c b/samsung-ipc/utils.c
index c0734ac..44cbe2d 100644
--- a/samsung-ipc/utils.c
+++ b/samsung-ipc/utils.c
@@ -38,6 +38,49 @@
 
 #include <samsung-ipc.h>
 
+ssize_t data_read(__attribute__((unused)) struct ipc_client *client, int fd,
+		  void *buf, size_t count)
+{
+	/* From read(2): "According  to POSIX.1, if count is greater than
+	 * SSIZE_MAX, the result is implementation-defined"
+	 */
+	ssize_t remaining = (ssize_t)count;
+
+	while (remaining > 0) {
+		ssize_t rc;
+
+		rc = read(fd, buf, count);
+		if (rc == -1)
+			/* errno is passed to the caller */
+			return rc;
+		remaining -= rc;
+	}
+
+	return count;
+}
+
+ssize_t data_write(__attribute__((unused)) struct ipc_client *client, int fd,
+		   const void *buf, size_t count)
+{
+	/* From write(2): "According  to POSIX.1, if count is greater than
+	 * SSIZE_MAX, the result is implementation-defined"
+	 */
+	ssize_t remaining = (ssize_t)count;
+
+	while (remaining > 0) {
+		ssize_t rc;
+
+		rc = write(fd, buf, count);
+		if (rc == -1)
+			/* errno is passed to the caller */
+			return rc;
+		remaining -= rc;
+	}
+
+	return count;
+
+}
+
 void *file_data_read(struct ipc_client *client, const char *path, size_t size,
 		     size_t chunk_size, unsigned int offset)
 {