improve error message on bad cli argument (#371)

currently the error messages have the shortopt hardcoded in them, even
when the user actually entered a longopt:

	$ ./nsxiv --framerate v
	nsxiv: Invalid argument for option -A: v

and as far as I see, there's no way to *reliably* tell weather we're
processing a longopt or a shortopt. perhaps we can do some shenanigangs
with `optind` but that seems finicky at best.

and it seems like other coreutils which support longopt has similar issues:

	$ xargs --max-procs=z
	xargs: invalid number "z" for -P option

utils like `grep` and `head` seems to work-around it by not mentioning the flag:

	$ head --lines=z
	head: invalid number of lines: ‘z’
	$ grep --max-count=l
	grep: invalid max count

this patch does the same thing as `grep/head` and omits the flag from
the error message.

Closes: https://codeberg.org/nsxiv/nsxiv/issues/368

Reviewed-on: https://codeberg.org/nsxiv/nsxiv/pulls/371
Reviewed-by: Berke Kocaoğlu <berke.kocaoglu@metu.edu.tr>

1 files changed, 7 insertions, 7 deletions

diff --git a/options.c b/options.c
index 29c7c54..ac91c63 100644
--- a/options.c
+++ b/options.c
@@ -150,7 +150,7 @@ void parse_options(int argc, char **argv)
 		case 'A':
 			n = strtol(op.optarg, &end, 0);
 			if (*end != '\0' || n <= 0 || n > INT_MAX)
-				error(EXIT_FAILURE, 0, "Invalid argument for option -A: %s", op.optarg);
+				error(EXIT_FAILURE, 0, "Invalid framerate: %s", op.optarg);
 			_options.framerate = n;
 			/* fall through */
 		case 'a':
@@ -165,7 +165,7 @@ void parse_options(int argc, char **argv)
 		case 'e':
 			n = strtol(op.optarg, &end, 0);
 			if (*end != '\0')
-				error(EXIT_FAILURE, 0, "Invalid argument for option -e: %s", op.optarg);
+				error(EXIT_FAILURE, 0, "Invalid window id: %s", op.optarg);
 			_options.embed = n;
 			break;
 		case 'f':
@@ -174,7 +174,7 @@ void parse_options(int argc, char **argv)
 		case 'G':
 			n = strtol(op.optarg, &end, 0);
 			if (*end != '\0' || n < INT_MIN || n > INT_MAX)
-				error(EXIT_FAILURE, 0, "Invalid argument for option -G: %s", op.optarg);
+				error(EXIT_FAILURE, 0, "Invalid gamma: %s", op.optarg);
 			_options.gamma = n;
 			break;
 		case 'g':
@@ -189,7 +189,7 @@ void parse_options(int argc, char **argv)
 		case 'n':
 			n = strtol(op.optarg, &end, 0);
 			if (*end != '\0' || n <= 0 || n > INT_MAX)
-				error(EXIT_FAILURE, 0, "Invalid argument for option -n: %s", op.optarg);
+				error(EXIT_FAILURE, 0, "Invalid starting number: %s", op.optarg);
 			_options.startnum = n - 1;
 			break;
 		case 'N':
@@ -210,13 +210,13 @@ void parse_options(int argc, char **argv)
 		case 'S':
 			f = strtof(op.optarg, &end) * 10.0f;
 			if (*end != '\0' || f <= 0 || f >= (float)UINT_MAX)
-				error(EXIT_FAILURE, 0, "Invalid argument for option -S: %s", op.optarg);
+				error(EXIT_FAILURE, 0, "Invalid slideshow delay: %s", op.optarg);
 			_options.slideshow = (unsigned int)f;
 			break;
 		case 's':
 			s = strchr(scalemodes, op.optarg[0]);
 			if (s == NULL || *s == '\0' || strlen(op.optarg) != 1)
-				error(EXIT_FAILURE, 0, "Invalid argument for option -s: %s", op.optarg);
+				error(EXIT_FAILURE, 0, "Invalid scale mode: %s", op.optarg);
 			_options.scalemode = s - scalemodes;
 			break;
 		case 'T':
@@ -235,7 +235,7 @@ void parse_options(int argc, char **argv)
 		case 'z':
 			n = strtol(op.optarg, &end, 0);
 			if (*end != '\0' || n <= 0)
-				error(EXIT_FAILURE, 0, "Invalid argument for option -z: %s", op.optarg);
+				error(EXIT_FAILURE, 0, "Invalid zoom level: %s", op.optarg);
 			_options.scalemode = SCALE_ZOOM;
 			_options.zoom = (float) n / 100.0f;
 			break;