From 1be5e6f808e3908ecd13ab68b3fea0739794f02d Mon Sep 17 00:00:00 2001 From: Phil Sutter Date: Mon, 20 Nov 2017 16:54:04 +0100 Subject: libnftables: Ensure output_fp is never NULL Initialize output_fp to 'stdout' upon context creation and check output stream validity in nft_ctx_set_output(). This allows to drop checks in nft_{gmp_,}print() and do_command_export(). While doing so for the latter, simplify it a bit by using nft_print() which takes care of flushing the output stream. If applications desire to drop all output, they are supposed to open /dev/null and assign that. Signed-off-by: Phil Sutter Signed-off-by: Pablo Neira Ayuso --- src/libnftables.c | 10 ++++------ src/main.c | 1 - src/rule.c | 6 +----- 3 files changed, 5 insertions(+), 12 deletions(-) diff --git a/src/libnftables.c b/src/libnftables.c index e8fa6742..c86d8947 100644 --- a/src/libnftables.c +++ b/src/libnftables.c @@ -167,6 +167,7 @@ struct nft_ctx *nft_ctx_new(uint32_t flags) ctx->parser_max_errors = 10; init_list_head(&ctx->cache.list); ctx->flags = flags; + ctx->output.output_fp = stdout; if (flags == NFT_CTX_DEFAULT) nft_ctx_netlink_init(ctx); @@ -190,6 +191,9 @@ FILE *nft_ctx_set_output(struct nft_ctx *ctx, FILE *fp) { FILE *old = ctx->output.output_fp; + if (!fp || ferror(fp)) + return NULL; + ctx->output.output_fp = fp; return old; @@ -333,9 +337,6 @@ int nft_print(struct output_ctx *octx, const char *fmt, ...) int ret; va_list arg; - if (!octx->output_fp) - return -1; - va_start(arg, fmt); ret = vfprintf(octx->output_fp, fmt, arg); va_end(arg); @@ -349,9 +350,6 @@ int nft_gmp_print(struct output_ctx *octx, const char *fmt, ...) int ret; va_list arg; - if (!octx->output_fp) - return -1; - va_start(arg, fmt); ret = gmp_vfprintf(octx->output_fp, fmt, arg); va_end(arg); diff --git a/src/main.c b/src/main.c index ff7878c9..353b87bc 100644 --- a/src/main.c +++ b/src/main.c @@ -173,7 +173,6 @@ int main(int argc, char * const *argv) int i, val, rc; nft = nft_ctx_new(NFT_CTX_DEFAULT); - nft_ctx_set_output(nft, stdout); while (1) { val = getopt_long(argc, argv, OPTSTRING, options, NULL); diff --git a/src/rule.c b/src/rule.c index eb91be46..37d99c22 100644 --- a/src/rule.c +++ b/src/rule.c @@ -1153,9 +1153,6 @@ static int do_command_export(struct netlink_ctx *ctx, struct cmd *cmd) struct nftnl_ruleset *rs; FILE *fp = ctx->octx->output_fp; - if (!fp) - return 0; - do { rs = netlink_dump_ruleset(ctx, &cmd->handle, &cmd->location); if (rs == NULL && errno != EINTR) @@ -1163,8 +1160,7 @@ static int do_command_export(struct netlink_ctx *ctx, struct cmd *cmd) } while (rs == NULL); nftnl_ruleset_fprintf(fp, rs, cmd->export->format, 0); - fprintf(fp, "\n"); - fflush(fp); + nft_print(ctx->octx, "\n"); nftnl_ruleset_free(rs); return 0; -- cgit v1.2.3