do not allow negative -l limit.

3 files changed, 12 insertions, 3 deletions

diff --git a/uxd.1 b/uxd.1
index d6868f3..d4c1cc9 100644
--- a/uxd.1
+++ b/uxd.1
@@ -109,7 +109,9 @@ bad sequences.
 .BI \-l \ length
 Stop dumping after \fIlength\fP bytes (not characters). If the limit is
 reached in the middle of a multibyte character, the entire character
-will be dumped.
+will be dumped. Can be given in decimal, hex (with \fI0x\fP prefix), or
+octal (with \fI0\fP prefix). Negative \fIlength\fP doesn\(aqt make sense, and
+is an error.
 .UNINDENT
 .\" stop dumping after <length> bytes (not characters).
 .
diff --git a/uxd.c b/uxd.c
index 95a91bd..6ea3897 100644
--- a/uxd.c
+++ b/uxd.c
@@ -230,7 +230,12 @@ void parse_args(int argc, char **argv) {
 			case 'b':
 				bold = 1; break;
 			case 'l':
-				limit = parse_number(opt, optarg); break;
+				limit = parse_number(opt, optarg);
+				if(limit < 0) {
+					fprintf(stderr, "%s: negative limit for -l not allowed.\n", self);
+					exit(1);
+				}
+				break;
 			case 'r':
 				hilite_multi = 1; break;
 			case 'm':
diff --git a/uxd.rst b/uxd.rst
index a17eb1c..a6c90fd 100644
--- a/uxd.rst
+++ b/uxd.rst
@@ -88,7 +88,9 @@ by itself.
 -l length
   Stop dumping after *length* bytes (not characters). If the limit is
   reached in the middle of a multibyte character, the entire character
-  will be dumped.
+  will be dumped. Can be given in decimal, hex (with *0x* prefix), or
+  octal (with *0* prefix). Negative *length* doesn't make sense, and
+  is an error.
 
 .. stop dumping after <length> bytes (not characters).