things

2 files changed, 93 insertions, 6 deletions

diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..5a20cd6
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,2 @@
+run.so: run.c
+	cc -std=c99 -Wall -fPIC -I/usr/include/lua5.3 run.c -o run.so -shared
diff --git a/run.c b/run.c
index ff2565c..27ea514 100644
--- a/run.c
+++ b/run.c
@@ -5,6 +5,7 @@
 #include <fcntl.h>
 #include <string.h>
 #include <lua.h>
+#include <lauxlib.h>
 
 #define CKE(val, name) do { if (val == -1) { perror(name); exit(1); } } while (0)
 
@@ -63,14 +64,14 @@ void empipe(int pipefd[2]) {
 	fcntl(pipefd[1], F_SETFD, FD_CLOEXEC);
 }
 
-void run(int count, char **progs[], char *inputstr, size_t inputlen) {
+char *run(int count, char **progs[], size_t inputlen, char *inputstr, size_t *outlen) {
 	if (inputstr) count++;
-	int (*pipefds)[2] = malloc((count-1) * sizeof(int[2]));
+	int (*pipefds)[2] = malloc(count * sizeof(int[2]));
 	pid_t *pids = malloc(count * sizeof(pid_t));
-	for (int i = 0; i < count-1; i++) empipe(pipefds[i]);
+	for (int i = 0; i < count; i++) empipe(pipefds[i]);
 	for (int i = 0; i < count; i++) {
-		int input =        (i == 0) ? -1 : pipefds[i-1][0];
-		int output = (i == count-1) ? -1 : pipefds[i  ][1];
+		int input  = (i == 0) ? -1 : pipefds[i-1][0];
+		int output = pipefds[i][1];
 		if (!inputstr) pids[i] = filefork(progs[i  ], input, output);
 		else if (i==0) pids[i] = echofork(inputstr, inputlen, output);
 		     else      pids[i] = filefork(progs[i-1], input, output);
@@ -84,6 +85,25 @@ void run(int count, char **progs[], char *inputstr, size_t inputlen) {
 		CKE(close(pipefds[i][0]), "close");
 		CKE(close(pipefds[i][1]), "close");
 	}
+	CKE(close(pipefds[count-1][1]), "close");
+
+	// if the program produces too much data, you will be killed
+	size_t readed = 0;
+	size_t cap = 1024*1024;
+	char *buf = malloc(cap*sizeof(char));
+	size_t remaining = cap;
+	size_t amt = 0;
+	do {
+		amt = read(pipefds[count-1][0], buf+readed, remaining);
+		readed += amt;
+		remaining -= amt;
+		if (remaining == 0) {
+			buf = realloc(buf, cap + cap);
+			remaining += cap;
+			cap += cap;
+		}
+	} while (amt != 0);
+	CKE(close(pipefds[count-1][0]), "close");
 
 	for (int i = 0; i < count; i++) {
 		int status;
@@ -93,9 +113,74 @@ void run(int count, char **progs[], char *inputstr, size_t inputlen) {
 
 	free(pipefds);
 	free(pids);
+
+	*outlen = readed;
+	return buf;
+}
+
+#define FAIL(msg) do { luaL_where(L, 1); lua_pushliteral(L, msg); lua_concat(L, 2); fail = 1; goto finish; } while (0)
+int do_the_thing(lua_State *L) {
+	int fail = 0;
+	char ***argvs = NULL;
+	char *outbuf = NULL;
+	size_t nprogs = 0;
+	if (lua_gettop(L) != 1) FAIL("run wants exactly one argument");
+	if (lua_type(L, 1) != LUA_TTABLE) FAIL("run needs table argumnt");
+	nprogs = lua_rawlen(L, 1);
+	if (nprogs == 0) FAIL("need at least one program to run");
+	argvs = calloc(nprogs, sizeof(char**));
+	for (int i = 0; i < nprogs; i++) {
+		int ty = lua_rawgeti(L, 1, i + 1);
+		if (ty != LUA_TTABLE) FAIL("program arglist must be table");
+		size_t argc = lua_rawlen(L, 2);
+		if (argc == 0) FAIL("need at least one argument to program");
+		argvs[i] = calloc(argc + 1, sizeof(char*));
+		for (int j = 0; j < argc; j++) {
+			int ty = lua_rawgeti(L, 2, j + 1);
+			if (ty != LUA_TSTRING) FAIL("program argument must be string");
+			size_t slen = 0; char *str = lua_tolstring(L, 3, &slen);
+			argvs[i][j] = calloc(slen + 1, sizeof(char));
+			memcpy(argvs[i][j], str, slen);
+			argvs[i][j][slen] = '\0'; // just to make sure
+			lua_pop(L, 1);
+		}
+		argvs[i][argc] = NULL; // just to make sure
+		lua_pop(L, 1);
+	}
+
+	char *inputstr = NULL; size_t inputlen = 0;
+	lua_pushliteral(L, "input");
+	int ty = lua_rawget(L, 1);
+	switch (ty) {
+	case LUA_TNIL: break;
+	case LUA_TSTRING:
+		inputstr = lua_tolstring(L, 2, &inputlen);
+		break;
+	default: FAIL("input field must be string if present");
+	}
+
+	size_t outlen;
+	outbuf = run(nprogs, argvs, inputlen, inputstr, &outlen);
+	lua_pushlstring(L, outbuf, outlen);
+
+finish:
+	if (argvs != NULL) {
+		for (int i = 0; i < nprogs; i++) {
+			if (argvs[i] != NULL) {
+				for (int j = 0; argvs[i][j] != NULL; j++) {
+					free(argvs[i][j]);
+				}
+				free(argvs[i]);
+			}
+		}
+		free(argvs);
+	}
+	free(outbuf);
+	if (fail) return lua_error(L);
+	return 1;
 }
 
 int luaopen_run(lua_State *L) {
-	lua_pushliteral(L, "fuck");
+	lua_pushcfunction(L, &do_the_thing);
 	return 1;
 }