From 799d930c2540933c23a1b6ba28e8e5e4f3bccb64 Mon Sep 17 00:00:00 2001
From: Nathan Reiner <nathan@nathanreiner.xyz>
Date: Thu, 9 Feb 2023 18:05:28 +0100
Subject: add variable system via env

---
 smash/Makefile |  2 +-
 smash/env.c    | 85 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 smash/env.h    |  9 +++++++
 smash/main.c   | 16 ++++++++---
 4 files changed, 107 insertions(+), 5 deletions(-)
 create mode 100644 smash/env.c
 create mode 100644 smash/env.h

diff --git a/smash/Makefile b/smash/Makefile
index 1d8e228..b8fb606 100644
--- a/smash/Makefile
+++ b/smash/Makefile
@@ -17,4 +17,4 @@ unit_test_exec:
 	./test
 
 all:
-	gcc main.c comment.c exec.c parser.c builtin.c ../lib/slib.a -static -nostdlib -fno-stack-protector -Wno-implicit-function-declaration -fno-builtin -o smash -DVARIABLES_UNIT_TEST -g
+	gcc main.c env.c comment.c exec.c parser.c builtin.c ../lib/slib.a -static -nostdlib -fno-stack-protector -Wno-implicit-function-declaration -fno-builtin -o smash -DVARIABLES_UNIT_TEST -g
diff --git a/smash/env.c b/smash/env.c
new file mode 100644
index 0000000..1bf7e21
--- /dev/null
+++ b/smash/env.c
@@ -0,0 +1,85 @@
+#include "../lib/env/env.h"
+#include "../lib/cstr/cstr.h"
+#include "../lib/malloc/malloc.h"
+
+#include "../lib/io/io.h"
+
+#include "env.h"
+
+void clear_buf(char *buf, u64 size)
+{
+	for (int i = 0; i < size; ++i) buf[i] = 0;
+}
+
+void init_arg_env(int argc, const char **argv)
+{
+	char buf[32];
+	u64_to_cstr(argc - 1, buf, 32);
+	setenv("@", buf);
+	for (int i = 1; i < argc; ++i) {
+		clear_buf(buf, 32);
+		u64_to_cstr(i - 1, buf, 32);
+		setenv(buf, argv[i]);
+	}
+}
+
+
+char* new_line_and_replace_vars(const char *line, u64 n)
+{
+	char var[64];
+	int size;
+	char *replaced;
+
+	for (int i = 0; i < n && line[i]; ++i) {
+		if (line[i] == '$') {
+			clear_buf(var, 64);
+			++i;
+			for (int j = 0; line[i] && line[i] != ' ';) {
+				var[j] = line[i];
+				++j;
+				++i;
+			}
+
+			if (cstr_length(var) == 0) {
+				size++;
+			} else {
+				const char *e = getenv(var);
+				if (e) size += cstr_length(e);
+			}
+		} else {
+			size++;
+		}
+	}
+
+	replaced = malloc(size + 1);
+	int line_pos = 0;
+
+	for (int i = 0; i < size && line[line_pos]; ++i) {
+
+		if (line[line_pos] == '$') {
+			clear_buf(var, 64);
+			++line_pos;
+
+			for (int j = 0; line[line_pos] && line[line_pos] != ' ';) {
+				var[j] = line[line_pos];
+				++j;
+				++line_pos;
+			}
+
+			if (cstr_length(var)) {
+				const char *e = getenv(var);
+				while (*e) {
+					replaced[i++] = *(e++);
+				}
+			}
+
+		} else {
+			replaced[i] = line[line_pos++];
+		}
+	}
+	
+
+	replaced[size] = 0;
+
+	return replaced;
+}
diff --git a/smash/env.h b/smash/env.h
new file mode 100644
index 0000000..0c233e9
--- /dev/null
+++ b/smash/env.h
@@ -0,0 +1,9 @@
+#ifndef SMASH_ENV_H
+#define SMASH_ENV_H
+
+#include "../lib/sys/sizes.h"
+
+void init_arg_env(int argc, const char **argv);
+char *new_line_and_replace_vars(const char *line, u64 n);
+
+#endif
diff --git a/smash/main.c b/smash/main.c
index 48aaed6..645f4eb 100644
--- a/smash/main.c
+++ b/smash/main.c
@@ -1,10 +1,12 @@
 #include "exec.h"
 #include "comment.h"
+#include "env.h"
 
 #include "../lib/sys/io.h"
 #include "../lib/cstr/cstr.h"
 #include "../lib/sys/dup2.h"
 #include "../lib/sys/exit.h"
+#include "../lib/malloc/malloc.h"
 
 #include "../lib/io/io.h"
 #include "../lib/sys/errno.h"
@@ -53,14 +55,17 @@ int io_getline(int fd, char *linebuf)
 	return size;
 }
 
-int main(int argc, char *argv[], char *envp[])
+int main(int argc, char *argv[])
 {
 	char prompt[] = "$ ";
 	i64 line_length;
 	int fd = STDIN_FD;
 	char linebuf[BUFSIZ];
+	char *line;
 
-	if (argc == 2) {
+	init_arg_env(argc, (const char**)argv);
+
+	if (argc > 1) {
 		fd = open(argv[1], OPEN_READ_ONLY, 0);
 
 		if (fd < 0) {
@@ -80,11 +85,14 @@ int main(int argc, char *argv[], char *envp[])
 		}
 
 		remove_comment(linebuf);
-		line_length = cstr_length(linebuf);
+		line = new_line_and_replace_vars(linebuf, BUFSIZ);
+		line_length = cstr_length(line);
 
 		if (line_length > 0) {
-			exec(linebuf);
+			exec(line);
 		}
+
+		free(line);
 	}
 
 	if (fd != STDOUT_FD)
-- 
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