[libgpiod][PATCH] examples: simplify find_line_by_name

[libgpiod][PATCH] examples: simplify find_line_by_name

[Kent Gibson]

Simplify the find_line_by_name example by using
gpiod_chip_get_line_offset_from_name() rather than iterating over each
line in a chip.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
---
 examples/find_line_by_name.c | 31 +++++++++++--------------------
 1 file changed, 11 insertions(+), 20 deletions(-)

diff --git a/examples/find_line_by_name.c b/examples/find_line_by_name.c
index 16d2c4c..87b66ac 100644
--- a/examples/find_line_by_name.c
+++ b/examples/find_line_by_name.c
@@ -69,12 +69,9 @@ int main(void)
 	static const char *const line_name = "GPIO19";
 
 	struct gpiod_chip_info *cinfo;
-	struct gpiod_line_info *linfo;
-	unsigned int j, num_lines;
 	struct gpiod_chip *chip;
 	char **chip_paths;
-	const char *name;
-	int i, num_chips;
+	int i, num_chips, offset;
 
 	/*
 	 * Names are not guaranteed unique, so this finds the first line with
@@ -85,26 +82,20 @@ int main(void)
 		chip = gpiod_chip_open(chip_paths[i]);
 		if (!chip)
 			continue;
+
+		offset = gpiod_chip_get_line_offset_from_name(chip, line_name);
+		if (offset == -1)
+			goto close_chip;
+
 		cinfo = gpiod_chip_get_info(chip);
 		if (!cinfo)
-			continue;
+			goto close_chip;
 
-		num_lines = gpiod_chip_info_get_num_lines(cinfo);
-		for (j = 0; j < num_lines; j++) {
-			linfo = gpiod_chip_get_line_info(chip, j);
-			if (!linfo)
-				continue;
-			name = gpiod_line_info_get_name(linfo);
-			if (name && (strcmp(line_name, name) == 0)) {
-				printf("%s: %s %d\n", line_name,
-				       gpiod_chip_info_get_name(cinfo), j);
-				return EXIT_SUCCESS;
-			}
-
-			gpiod_line_info_free(linfo);
-		}
+		printf("%s: %s %d\n", line_name,
+				       gpiod_chip_info_get_name(cinfo), offset);
+		return EXIT_SUCCESS;
 
-		gpiod_chip_info_free(cinfo);
+close_chip:
 		gpiod_chip_close(chip);
 	}
 
-- 
2.41.0

Re: [libgpiod][PATCH] examples: simplify find_line_by_name

[Bartosz Golaszewski]

On Thu, Jul 27, 2023 at 11:11 PM Kent Gibson <warthog618@gmail.com> wrote:
>
> Simplify the find_line_by_name example by using
> gpiod_chip_get_line_offset_from_name() rather than iterating over each
> line in a chip.
>
> Signed-off-by: Kent Gibson <warthog618@gmail.com>
> ---
>  examples/find_line_by_name.c | 31 +++++++++++--------------------
>  1 file changed, 11 insertions(+), 20 deletions(-)
>
> diff --git a/examples/find_line_by_name.c b/examples/find_line_by_name.c
> index 16d2c4c..87b66ac 100644
> --- a/examples/find_line_by_name.c
> +++ b/examples/find_line_by_name.c
> @@ -69,12 +69,9 @@ int main(void)
>         static const char *const line_name = "GPIO19";
>
>         struct gpiod_chip_info *cinfo;
> -       struct gpiod_line_info *linfo;
> -       unsigned int j, num_lines;
>         struct gpiod_chip *chip;
>         char **chip_paths;
> -       const char *name;
> -       int i, num_chips;
> +       int i, num_chips, offset;
>
>         /*
>          * Names are not guaranteed unique, so this finds the first line with
> @@ -85,26 +82,20 @@ int main(void)
>                 chip = gpiod_chip_open(chip_paths[i]);
>                 if (!chip)
>                         continue;
> +
> +               offset = gpiod_chip_get_line_offset_from_name(chip, line_name);
> +               if (offset == -1)
> +                       goto close_chip;
> +
>                 cinfo = gpiod_chip_get_info(chip);
>                 if (!cinfo)
> -                       continue;
> +                       goto close_chip;
>
> -               num_lines = gpiod_chip_info_get_num_lines(cinfo);
> -               for (j = 0; j < num_lines; j++) {
> -                       linfo = gpiod_chip_get_line_info(chip, j);
> -                       if (!linfo)
> -                               continue;
> -                       name = gpiod_line_info_get_name(linfo);
> -                       if (name && (strcmp(line_name, name) == 0)) {
> -                               printf("%s: %s %d\n", line_name,
> -                                      gpiod_chip_info_get_name(cinfo), j);
> -                               return EXIT_SUCCESS;
> -                       }
> -
> -                       gpiod_line_info_free(linfo);
> -               }
> +               printf("%s: %s %d\n", line_name,
> +                                      gpiod_chip_info_get_name(cinfo), offset);
> +               return EXIT_SUCCESS;
>
> -               gpiod_chip_info_free(cinfo);
> +close_chip:
>                 gpiod_chip_close(chip);
>         }
>
> --
> 2.41.0
>

Applied, thanks!

Bart