allow specifying errors by symbolic name

1 files changed, 24 insertions, 2 deletions

diff --git a/strerror.c b/strerror.c
index 0e0359b..820d78c 100644
--- a/strerror.c
+++ b/strerror.c
@@ -1,6 +1,8 @@
 #define _XOPEN_SOURCE 700
+#include <ctype.h>
 #include <string.h>
 #include <stdio.h>
+#include <strings.h>
 #include <stdlib.h>
 
 #include "strerror.h"
@@ -13,6 +15,16 @@ const char *errname(int err)
 	return "-";
 }
 
+int errnum(const char *name)
+{
+	for (int i = 0; i < sizeof(errlist) / sizeof(errlist[0]); i++) {
+		if (errlist[i] && !strcasecmp(name, errlist[i])) {
+			return i;
+		}
+	}
+	return -1;
+}
+
 int main(int argc, char *argv[])
 {
 	int n = 1;
@@ -23,8 +35,18 @@ int main(int argc, char *argv[])
 	}
 
 	do {
-		int err = atoi(argv[n]);
-		printf("%d: %s [%s]\n", err, strerror(err), errname(err));
+		int err = -1;
+		if (toupper(argv[n][0]) == 'E') {
+			err = errnum(argv[n]);
+		} else {
+			err = atoi(argv[n]);
+		}
+
+		if (err == -1) {
+			fprintf(stderr, "%s: %s: unknown error code\n", argv[0], argv[n]);
+		} else {
+			printf("%d: %s [%s]\n", err, strerror(err), errname(err));
+		}
 	} while (argv[++n]);
 
 	return 0;