[PATCH] wg: include filename in error messages

[PATCH] wg: include filename in error messages

[Tony Finch]

When wg(8) is invoked from a script, it can be hard to tell what
caused an error message if the message does not contain enough
context.

Signed-off-by: Tony Finch <dot@dotat.at>
---
 src/config.c  |  8 ++++----
 src/setconf.c | 11 +++++++----
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git src/config.c src/config.c
index 81ccb47..9f15477 100644
--- src/config.c
+++ src/config.c
@@ -123,7 +123,7 @@ static bool parse_keyfile(uint8_t key[static WG_KEY_LEN], const char *path)

 	f = fopen(path, "r");
 	if (!f) {
-		perror("fopen");
+		fprintf(stderr, "open %s: %s", path, strerror(errno));
 		return false;
 	}

@@ -135,19 +135,19 @@ static bool parse_keyfile(uint8_t key[static WG_KEY_LEN], const char *path)
 			goto out;
 		}

-		fprintf(stderr, "Invalid length key in key file\n");
+		fprintf(stderr, "Invalid length key in %s\n", path);
 		goto out;
 	}
 	dst[WG_KEY_LEN_BASE64 - 1] = '\0';

 	while ((c = getc(f)) != EOF) {
 		if (!char_is_space(c)) {
-			fprintf(stderr, "Found trailing character in key file: `%c'\n", c);
+			fprintf(stderr, "Found trailing character `%c' in %s\n", c, path);
 			goto out;
 		}
 	}
 	if (ferror(f) && errno) {
-		perror("getc");
+		fprintf(stderr, "read %s: %s", path, strerror(errno));
 		goto out;
 	}
 	ret = parse_key(key, dst);
diff --git src/setconf.c src/setconf.c
index 1c5b138..414785d 100644
--- src/setconf.c
+++ src/setconf.c
@@ -3,6 +3,7 @@
  * Copyright (C) 2015-2020 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
  */

+#include <errno.h>
 #include <stddef.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -102,6 +103,7 @@ int setconf_main(int argc, const char *argv[])
 {
 	struct wgdevice *device = NULL;
 	struct config_ctx ctx;
+	const char *path = NULL;
 	FILE *config_input = NULL;
 	char *config_buffer = NULL;
 	size_t config_buffer_len = 0;
@@ -112,9 +114,10 @@ int setconf_main(int argc, const char *argv[])
 		return 1;
 	}

-	config_input = fopen(argv[2], "r");
+	path = argv[2];
+	config_input = fopen(path, "r");
 	if (!config_input) {
-		perror("fopen");
+		fprintf(stderr, "open %s: %s", path, strerror(errno));
 		return 1;
 	}
 	if (!config_read_init(&ctx, !strcmp(argv[0], "addconf"))) {
@@ -123,13 +126,13 @@ int setconf_main(int argc, const char *argv[])
 	}
 	while (getline(&config_buffer, &config_buffer_len, config_input) >= 0) {
 		if (!config_read_line(&ctx, config_buffer)) {
-			fprintf(stderr, "Configuration parsing error\n");
+			fprintf(stderr, "Configuration parsing error in %s\n", path);
 			goto cleanup;
 		}
 	}
 	device = config_read_finish(&ctx);
 	if (!device) {
-		fprintf(stderr, "Invalid configuration\n");
+		fprintf(stderr, "Invalid configuration in %s\n", path);
 		goto cleanup;
 	}
 	strncpy(device->name, argv[1], IFNAMSIZ - 1);
-- 
2.39.2

Re: [PATCH] wg: include filename in error messages

[Tony Finch]

Yesterday when I was setting up wireguard using ifupdown, I got a "file
not found" error which mentioned neither the program nor the filename, so
I was at a loss. After making ifupdown more verbose the problem turned out
to be wireguard.

When I was preparing this patch I really wanted to change all the error
reporting to use err(3) because in my experience it's reasonably nice for
the programmer and the user. Dunno if err(3) counts as part of a sane libc
or if it's worth spending time on such a patch?

-- 
Tony Finch  <dot@dotat.at>  https://dotat.at/
Fair Isle, Faeroes: Variable 2 to 4 in west Faeroes at first,
otherwise southeasterly 4 to 6. Moderate, occasionally rough at first
in east Fair Isle. Showers, fog patches later. Good, occasionally very
poor later.