libc/progname: saner implementation

what the fuck was I thinking when I originally implemented that?

1 files changed, 23 insertions, 9 deletions

diff --git a/src/libc/stdlib/progname.c b/src/libc/stdlib/progname.c
index 4cc0fb2..bd90063 100644
--- a/src/libc/stdlib/progname.c
+++ b/src/libc/stdlib/progname.c
@@ -12,17 +12,31 @@ void setprogname(const char *pg) {
 	setproctitle(NULL);
 }
 
+#define DESCLEN (sizeof(_psdata_loc->desc))
+
 void setproctitle(const char *fmt, ...) {
-	// TODO bounds checking
-	if (!fmt) {
-		strcpy(_psdata_loc->desc, progname);
-		return;
+	char *title = NULL;
+
+	if (fmt) {
+		va_list ap;
+		va_start(ap, fmt);
+		int ret = vasprintf(&title, fmt, ap);
+		va_end(ap);
+		if (ret < 0) {
+			/* strictly speaking this is unnecessary (my vasprintf already
+			 * behaves like this), but I want it to be clear that if title
+			 * isn't NULL, it's a valid string */
+			title = NULL;
+		}
 	}
-	sprintf(_psdata_loc->desc, "%s: ", progname);
 
-	va_list argp;
-	va_start(argp, fmt);
-	vsnprintf(_psdata_loc->desc + strlen(_psdata_loc->desc), 128, fmt, argp);
-	va_end(argp);
+	if (title) {
+		snprintf(_psdata_loc->desc, DESCLEN, "%s: %s", progname, title);
+		free(title);
+	} else {
+		/* poor man's strlcpy. i do like the symmetry between the two branches
+		 * though */
+		snprintf(_psdata_loc->desc, DESCLEN, "%s", progname);
+	}
 }