libnftables: Simplify nft_run_cmd_from_buffer footprint

With libnftables documentation being upstream and one confirmed external
user (nftlb), time to break the API!

First of all, the command buffer passed to nft_run_cmd_from_buffer may
(and should) be const. One should consider it a bug if that function
ever changed it's content.

On the other hand, there is no point in passing the buffer's length as
separate argument: NULL bytes are not expected to occur in the input, so
it is safe to rely upon strlen(). Also, the actual parsers don't require
a buffer length passed to them, either. The only use-case for it is when
reallocating the buffer to append a final newline character, there
strlen() is perfectly sufficient.

Suggested-by: Harald Welte <laforge@gnumonks.org>
Cc: Laura Garcia Liebana <nevola@gmail.com>
Cc: Eric Leblond <eric@regit.org>
Cc: Arturo Borrero Gonzalez <arturo@netfilter.org>
Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 4 insertions, 5 deletions

diff --git a/doc/libnftables.adoc b/doc/libnftables.adoc
index c947ef37..adfc9420 100644
--- a/doc/libnftables.adoc
+++ b/doc/libnftables.adoc
@@ -53,8 +53,7 @@ const char *nft_ctx_get_error_buffer(struct nft_ctx* '\*ctx'*);
 int nft_ctx_add_include_path(struct nft_ctx* '\*ctx'*, const char* '\*path'*);
 void nft_ctx_clear_include_paths(struct nft_ctx* '\*ctx'*);
 
-int nft_run_cmd_from_buffer(struct nft_ctx* '\*nft'*,
-			    char* '\*buf'*, size_t* 'buflen'*);
+int nft_run_cmd_from_buffer(struct nft_ctx* '\*nft'*, const char* '\*buf'*);
 int nft_run_cmd_from_filename(struct nft_ctx* '\*nft'*,
 			      const char* '\*filename'*);*
 
@@ -244,7 +243,7 @@ The *nft_ctx_clear_include_paths*() function removes all include paths, even the
 === nft_run_cmd_from_buffer() and nft_run_cmd_from_filename()
 These functions perform the actual work of parsing user input into nftables commands and executing them.
 
-The *nft_run_cmd_from_buffer*() function passes the command(s) contained in 'buf' with size 'buflen' to the library, respecting settings and state in 'nft'.
+The *nft_run_cmd_from_buffer*() function passes the command(s) contained in 'buf' (which must be null-terminated) to the library, respecting settings and state in 'nft'.
 
 The *nft_run_cmd_from_filename*() function passes the content of 'filename' to the library, respecting settings and state in 'nft'.
 
@@ -272,7 +271,7 @@ int main(void)
 
 	while (1) {
 		if (nft_ctx_buffer_output(nft) ||
-		    nft_run_cmd_from_buffer(nft, list_cmd, strlen(list_cmd))) {
+		    nft_run_cmd_from_buffer(nft, list_cmd)) {
 			rc = 1;
 			break;
 		}
@@ -300,7 +299,7 @@ int main(void)
 		if (buf[0] == 'q' && buf[1] == '\0')
 			break;
 
-		if (nft_run_cmd_from_buffer(nft, buf, strlen(buf))) {
+		if (nft_run_cmd_from_buffer(nft, buf)) {
 			rc = 1;
 			break;
 		}