script: Write variables to a FILE

Each variable is NULL terminated inside the file just like the
control stream which saves us from having to flatten it when
writing to the control stream.
Once written, create env pointers to the start of each string
just after the NULL terminator.

This also means that we just need to free two buffers when
dhcpcd exits (FILE buffer and env buffer) rather than each variable
individually.

If open_memstream(3) is not supported by libc then dhcpcd will
write to a file in /tmp instead.

1 files changed, 28 insertions, 42 deletions

diff --git a/src/ipv6nd.c b/src/ipv6nd.c
index 5ece711e..b879c171 100644
--- a/src/ipv6nd.c
+++ b/src/ipv6nd.c
@@ -1384,11 +1384,11 @@ ipv6nd_getoption(struct dhcpcd_ctx *ctx,
 }
 
 ssize_t
-ipv6nd_env(char **env, const char *prefix, const struct interface *ifp)
+ipv6nd_env(FILE *fp, const struct interface *ifp)
 {
 	size_t i, j, n, len, olen;
 	struct ra *rap;
-	char ndprefix[32], abuf[24];
+	char ndprefix[32];
 	struct dhcp_opt *opt;
 	uint8_t *p;
 	struct nd_opt_hdr ndo;
@@ -1401,34 +1401,24 @@ ipv6nd_env(char **env, const char *prefix, const struct interface *ifp)
 		if (rap->iface != ifp)
 			continue;
 		i++;
-		if (prefix != NULL)
-			snprintf(ndprefix, sizeof(ndprefix),
-			    "%s_nd%zu", prefix, i);
-		else
-			snprintf(ndprefix, sizeof(ndprefix),
-			    "nd%zu", i);
-		if (env)
-			setvar(&env[n], ndprefix, "from", rap->sfrom);
-		n++;
-		if (env)
-			setvard(&env[n], ndprefix, "acquired",
-			    (size_t)rap->acquired.tv_sec);
-		n++;
-		if (env)
-			setvard(&env[n], ndprefix, "now", (size_t)now.tv_sec);
-		n++;
+		snprintf(ndprefix, sizeof(ndprefix), "nd%zu", i);
+		if (efprintf(fp, "%s_from=%s", ndprefix, rap->sfrom) == -1)
+			return -1;
+		if (efprintf(fp, "%s_acquired=%ld", ndprefix,
+		    rap->acquired.tv_sec) == -1)
+			return -1;
+		if (efprintf(fp, "%s_now=%ld", ndprefix, now.tv_sec) == -1)
+			return -1;
 
 		/* Zero our indexes */
-		if (env) {
-			for (j = 0, opt = rap->iface->ctx->nd_opts;
-			    j < rap->iface->ctx->nd_opts_len;
-			    j++, opt++)
-				dhcp_zero_index(opt);
-			for (j = 0, opt = rap->iface->options->nd_override;
-			    j < rap->iface->options->nd_override_len;
-			    j++, opt++)
-				dhcp_zero_index(opt);
-		}
+		for (j = 0, opt = rap->iface->ctx->nd_opts;
+		    j < rap->iface->ctx->nd_opts_len;
+		    j++, opt++)
+			dhcp_zero_index(opt);
+		for (j = 0, opt = rap->iface->options->nd_override;
+		    j < rap->iface->options->nd_override_len;
+		    j++, opt++)
+			dhcp_zero_index(opt);
 
 		/* Unlike DHCP, ND6 options *may* occur more than once.
 		 * There is also no provision for option concatenation
@@ -1461,13 +1451,12 @@ ipv6nd_env(char **env, const char *prefix, const struct interface *ifp)
 				if (j == rap->iface->ctx->nd_opts_len)
 					opt = NULL;
 			}
-			if (opt) {
-				n += dhcp_envoption(rap->iface->ctx,
-				    env == NULL ? NULL : &env[n],
-				    ndprefix, rap->iface->name,
-				    opt, ipv6nd_getoption,
-				    p + sizeof(ndo), olen - sizeof(ndo));
-			}
+			if (opt == NULL)
+				continue;
+			dhcp_envoption(rap->iface->ctx, fp,
+			    ndprefix, rap->iface->name,
+			    opt, ipv6nd_getoption,
+			    p + sizeof(ndo), olen - sizeof(ndo));
 		}
 
 		/* We need to output the addresses we actually made
@@ -1481,15 +1470,12 @@ ipv6nd_env(char **env, const char *prefix, const struct interface *ifp)
 			    !(ia->flags & IPV6_AF_ADDED) ||
 			    ia->prefix_vltime == 0)
 				continue;
-			j++;
-			if (env) {
-				snprintf(abuf, sizeof(abuf), "addr%zu", j);
-				setvar(&env[n], ndprefix, abuf, ia->saddr);
-			}
-			n++;
+			if (efprintf(fp, "%s_addr%zu=%s",
+			    ndprefix, j++, ia->saddr) == -1)
+				return -1;
 		}
 	}
-	return (ssize_t)n;
+	return 1;
 }
 
 void