From mboxrd@z Thu Jan 1 00:00:00 1970 From: john at keeping.me.uk (John Keeping) Date: Sat, 16 Jun 2018 14:11:50 +0100 Subject: [PATCH 2/2] gcc8.1: fix strcat warning In-Reply-To: <152884644738.29435.16487549202475422342.stgit@mail.warmcat.com> References: <152884643982.29435.12041657288903581464.stgit@mail.warmcat.com> <152884644738.29435.16487549202475422342.stgit@mail.warmcat.com> Message-ID: <20180616131150.GP1922@john.keeping.me.uk> On Wed, Jun 13, 2018 at 07:34:07AM +0800, Andy Green wrote: > ../ui-ssdiff.c: In function ?replace_tabs?: > ../ui-ssdiff.c:142:4: warning: ?strncat? output truncated copying between 1 and 8 bytes from a string of length 8 [-Wstringop-truncation] > strncat(result, spaces, 8 - (strlen(result) % 8)); > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > Actually the strncat that was there before intends that its > stock of spaces gets truncated, and it's not a problem. > > However gcc8.1 is also right, normally truncation is undesirable. > > Make the code do the padding explicitly. > > Signed-off-by: Andy Green Reviewed-by: John Keeping > --- > ui-ssdiff.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/ui-ssdiff.c b/ui-ssdiff.c > index 7f261ed..e520b95 100644 > --- a/ui-ssdiff.c > +++ b/ui-ssdiff.c > @@ -118,7 +118,6 @@ static char *replace_tabs(char *line) > int n_tabs = 0; > int i; > char *result; > - char *spaces = " "; > > if (linelen == 0) { > result = xmalloc(1); > @@ -138,8 +137,17 @@ static char *replace_tabs(char *line) > strcat(result, prev_buf); > break; > } else { > + char *p; > + int n; > + > strncat(result, prev_buf, cur_buf - prev_buf); > - strncat(result, spaces, 8 - (strlen(result) % 8)); > + > + n = strlen(result); > + p = result + n; > + n = 8 - (n % 8); > + while (n--) > + *p++ = ' '; > + *p = '\0'; > } > prev_buf = cur_buf + 1; > } >