hostname: Fix file reading for setting node name

This isn't exactly compatible with net-tools, but it is close.
net-tools will buffer a line longer than 1024 characters (up to the next
63 characters).  This implementation will break at the 1024th character
and start a new block of 63 char names there.

I sincerely hope nobody is actually using this weird, undefined
behaviour for anything serious.

1 files changed, 13 insertions, 5 deletions

diff --git a/hostname/hostname.c b/hostname/hostname.c
index d19e4b8..b994a07 100644
--- a/hostname/hostname.c
+++ b/hostname/hostname.c
@@ -132,7 +132,7 @@ int do_set_nodename(bool file, const char *value)
 		/* This is insane.  There is no validation whatsoever.
 		 * However, strace on net-tools hostname(1) shows this to be
 		 * the exact algorithm used, so... */
-		char buf[1024];
+		char buf[1025];
 		int fildes = open(value, O_RDONLY);
 		ssize_t result = 0;
 
@@ -145,7 +145,8 @@ int do_set_nodename(bool file, const char *value)
 		while(true)
 		{
 			char *curr = buf;
-			result = read(fildes, buf, sizeof buf);
+			memset(buf, 0, sizeof buf);
+			result = read(fildes, buf, sizeof buf - 1);
 			switch(result)
 			{
 			case -1:
@@ -158,14 +159,21 @@ int do_set_nodename(bool file, const char *value)
 			}
 			do
 			{
-				len = result;
+				len = strnlen(curr, result);
 				char *pos = strchr(curr, '\n');
 				if(pos)
 				{
 					len = pos - curr;
 				}
-				sethostname(curr, (len > 63) ? 63 : len);
-			} while((curr = strchr(curr, '\n')));
+				if(len == 0 || *curr == '#') continue;
+				while(len > 63)
+				{
+					sethostname(curr, 63);
+					len -= 63;
+					curr += 63;
+				}
+				sethostname(curr, len);
+			} while(curr = strchr(curr, '\n') + 1, curr != 0x1);
 		}
 	}