[libgpiod][PATCH 1/5] core: provide gpiod_line_request_get_chip_path()

[Bartosz Golaszewski <brgl@xxxxxxxx>]

From: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>

While we can get the list of requested offsets from a line-request object,
this information lacks context if we don't provide any data about the GPIO
chip the request was made on. Add a helper allowing users to get the path
to the character device used to create the parent chip.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
---
 include/gpiod.h    |  9 +++++++++
 lib/chip.c         |  2 +-
 lib/internal.h     |  3 ++-
 lib/line-request.c | 20 +++++++++++++++++++-
 4 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/include/gpiod.h b/include/gpiod.h
index 3c13783..61f8ef1 100644
--- a/include/gpiod.h
+++ b/include/gpiod.h
@@ -1007,6 +1007,15 @@ gpiod_request_config_get_event_buffer_size(struct gpiod_request_config *config);
  */
 void gpiod_line_request_release(struct gpiod_line_request *request);
 
+/**
+ * @brief Get the path to the chip this request was made on.
+ * @param request Line request object.
+ * @return Path to the GPIO chip device. The returned pointer is valid for the
+ * lifetime of the request object and must not be freed by the caller.
+ */
+const char *
+gpiod_line_request_get_chip_path(struct gpiod_line_request *request);
+
 /**
  * @brief Get the number of lines in the request.
  * @param request Line request object.
diff --git a/lib/chip.c b/lib/chip.c
index 7d4d21e..e94d750 100644
--- a/lib/chip.c
+++ b/lib/chip.c
@@ -237,7 +237,7 @@ gpiod_chip_request_lines(struct gpiod_chip *chip,
 	if (ret < 0)
 		return NULL;
 
-	request = gpiod_line_request_from_uapi(&uapi_req);
+	request = gpiod_line_request_from_uapi(&uapi_req, chip->path);
 	if (!request) {
 		close(uapi_req.fd);
 		return NULL;
diff --git a/lib/internal.h b/lib/internal.h
index ef9b17e..e9ada42 100644
--- a/lib/internal.h
+++ b/lib/internal.h
@@ -26,7 +26,8 @@ void gpiod_request_config_to_uapi(struct gpiod_request_config *config,
 int gpiod_line_config_to_uapi(struct gpiod_line_config *config,
 			      struct gpio_v2_line_request *uapi_cfg);
 struct gpiod_line_request *
-gpiod_line_request_from_uapi(struct gpio_v2_line_request *uapi_req);
+gpiod_line_request_from_uapi(struct gpio_v2_line_request *uapi_req,
+			     const char *chip_path);
 int gpiod_edge_event_buffer_read_fd(int fd,
 				    struct gpiod_edge_event_buffer *buffer,
 				    size_t max_events);
diff --git a/lib/line-request.c b/lib/line-request.c
index e536355..99cbe2c 100644
--- a/lib/line-request.c
+++ b/lib/line-request.c
@@ -13,13 +13,15 @@
 #include "internal.h"
 
 struct gpiod_line_request {
+	char *chip_path;
 	unsigned int offsets[GPIO_V2_LINES_MAX];
 	size_t num_lines;
 	int fd;
 };
 
 struct gpiod_line_request *
-gpiod_line_request_from_uapi(struct gpio_v2_line_request *uapi_req)
+gpiod_line_request_from_uapi(struct gpio_v2_line_request *uapi_req,
+			     const char *chip_path)
 {
 	struct gpiod_line_request *request;
 
@@ -28,6 +30,13 @@ gpiod_line_request_from_uapi(struct gpio_v2_line_request *uapi_req)
 		return NULL;
 
 	memset(request, 0, sizeof(*request));
+
+	request->chip_path = strdup(chip_path);
+	if (!request->chip_path) {
+		free(request);
+		return NULL;
+	}
+
 	request->fd = uapi_req->fd;
 	request->num_lines = uapi_req->num_lines;
 	memcpy(request->offsets, uapi_req->offsets,
@@ -42,9 +51,18 @@ GPIOD_API void gpiod_line_request_release(struct gpiod_line_request *request)
 		return;
 
 	close(request->fd);
+	free(request->chip_path);
 	free(request);
 }
 
+GPIOD_API const char *
+gpiod_line_request_get_chip_path(struct gpiod_line_request *request)
+{
+	assert(request);
+
+	return request->chip_path;
+}
+
 GPIOD_API size_t
 gpiod_line_request_get_num_requested_lines(struct gpiod_line_request *request)
 {
-- 
2.39.2