Re: conf: flush stdout before early exit

On Thu, May 29, 2025 at 01:08:58PM -0400, Jon Maloy wrote:

Before doing an early exit any contents of stdout is normally flushed. This doesn't happen when the output goes into a pipe and we return with _exit(). We now add an explicit flush in such cases.

Minor nitpicking on this description. AIUI * We'll *never* flush on exit with _exit(), not only when the output is a pipe * The reason we don't see the problem when stdout is a terminal is that in that case stdio flushes the buffer on each line

Fixes: d0006fa784a7 ("treewide: use _exit() over exit()")

Signed-off-by: Jon Maloy --- conf.c | 3 +++ 1 file changed, 3 insertions(+)

diff --git a/conf.c b/conf.c index a6d7e22..a1d55a3 100644 --- a/conf.c +++ b/conf.c @@ -975,6 +975,7 @@ static void usage(const char *name, FILE *f, int status) " SPEC is as described for TCP above\n" " default: none\n");

+ fflush(f); _exit(status);

pasta_opts: @@ -1029,6 +1030,7 @@ pasta_opts: " --ns-mac-addr ADDR Set MAC address on tap interface\n" " --no-splice Disable inbound socket splicing\n");

+ fflush(f); _exit(status); }

@@ -1594,6 +1596,7 @@ void conf(struct ctx *c, int argc, char **argv) FPRINTF(stdout, c->mode == MODE_PASTA ? "pasta " : "passt "); FPRINTF(stdout, VERSION_BLOB); + fflush(stdout); _exit(EXIT_SUCCESS); case 15: ret = snprintf(c->ip4.ifname_out,

-- David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson