From 5c3cd59af6550d6f8d74487c1e46cdb0b171ff7d Mon Sep 17 00:00:00 2001 From: "C. McEnroe" Date: Mon, 7 Jun 2021 00:08:59 -0400 Subject: [PATCH] Add seprintf Based on seprint(2) from Plan 9. I'm not sure if my return value exactly matches Plan 9's in the case of truncation. seprint(2) is described only as returning a pointer to the terminating '\0', but if it does so even in the case of truncation, it is awkward for the caller to detect. This implementation returns end in the truncation case, so that (ptr == end) indicates truncation. --- chat.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/chat.h b/chat.h index e48799c..e9bee8b 100644 --- a/chat.h +++ b/chat.h @@ -44,6 +44,18 @@ typedef unsigned uint; typedef unsigned char byte; +static inline char *seprintf(char *ptr, char *end, const char *fmt, ...) + __attribute__((format(printf, 3, 4))); +static inline char *seprintf(char *ptr, char *end, const char *fmt, ...) { + va_list ap; + va_start(ap, fmt); + int n = vsnprintf(ptr, end - ptr, fmt, ap); + va_end(ap); + if (n < 0) return NULL; + ptr += n; + return (ptr > end ? end : ptr); +} + struct Cat { char *buf; size_t cap;