init: file_reopen, keep stdin/stdout on their standard fds

3 files changed, 40 insertions, 15 deletions

diff --git a/src/init/main.c b/src/init/main.c
index 1674f8c..88553e9 100644
--- a/src/init/main.c
+++ b/src/init/main.c
@@ -19,7 +19,7 @@ int main(void) {
 	// allocate bss
 	_syscall_memflag(&_bss_start, &_bss_end - &_bss_start, MEMFLAG_PRESENT);
 
-	stdout = file_open("/com1", 0);
+	file_reopen(stdout, "/com1", 0);
 	printf("preinit\n");
 
 	/* move everything provided by the kernel to /kdev */
@@ -55,12 +55,14 @@ int main(void) {
 	}
 
 	if (!_syscall_fork(0, NULL)) {
-		libc_file *new = file_open("/kdev/com1", 0);
-		if (!new) {
+		if (!file_reopen(stdout, "/kdev/com1", 0)) {
+			printf("couldn't open /kdev/com1\n"); // TODO borked
+			_syscall_exit(1);
+		}
+		if (!file_reopen(stdin, "/kdev/com1", 0)) {
 			printf("couldn't open /kdev/com1\n");
 			_syscall_exit(1);
 		}
-		stdout = stdin = new; // TODO file_clone, this is bad
 
 		shell_loop();
 		_syscall_exit(1);
@@ -68,17 +70,11 @@ int main(void) {
 
 
 	if (!_syscall_fork(0, NULL)) {
-		libc_file *new;
-		new = file_open("/vga_tty", 0);
-		if (!new) {
-			printf("couldn't open /vga_tty\n");
+		if (!file_reopen(stdout, "/vga_tty", 0)) {
+			printf("couldn't open /vga_tty\n"); // TODO borked
 			_syscall_exit(1);
 		}
-		file_close(stdout);
-		stdout = new;
-
-		stdin = file_open("/keyboard", 0);
-		if (!stdin) {
+		if (!file_reopen(stdin, "/keyboard", 0)) {
 			printf("couldn't open /keyboard\n");
 			_syscall_exit(1);
 		}
diff --git a/src/init/stdlib.c b/src/init/stdlib.c
index a02eb7c..4d26c2e 100644
--- a/src/init/stdlib.c
+++ b/src/init/stdlib.c
@@ -2,7 +2,11 @@
 #include <shared/printf.h>
 #include <shared/syscalls.h>
 
-libc_file *stdin, *stdout;
+// TODO oh god this garbage - malloc, actually open, [...]
+static libc_file _stdin_null  = { .fd = 0 };
+static libc_file _stdout_null = { .fd = 1 };
+
+libc_file *stdin = &_stdin_null, *stdout = &_stdout_null;
 
 static void backend_file(void *arg, const char *buf, size_t len) {
 	file_write((libc_file*)arg, buf, len);
@@ -67,6 +71,29 @@ libc_file *file_open(const char *path, int flags) {
 	return f;
 }
 
+libc_file *file_reopen(libc_file *f, const char *path, int flags) {
+	/* partially based on the musl implementation of freopen */
+	libc_file *f2;
+	if (!path) goto fail;
+	f2 = file_open(path, flags);
+	if (!f2) goto fail;
+
+	/* shouldn't happen, but if it happens, let's roll with it. */
+	if (f->fd == f2->fd) f2->fd = -1;
+
+	if (_syscall_dup(f2->fd, f->fd, 0) < 0) goto fail2;
+	f->pos = f2->pos;
+	f->eof = f2->eof;
+	file_close(f2);
+	return f;
+
+fail2:
+	file_close(f2);
+fail:
+	file_close(f);
+	return NULL;
+}
+
 int file_read(libc_file *f, char *buf, size_t len) {
 	if (f->fd < 0) return -1;
 
@@ -88,5 +115,6 @@ int file_write(libc_file *f, const char *buf, size_t len) {
 
 void file_close(libc_file *f) {
 	if (f->fd > 0) _syscall_close(f->fd);
-	free(f);
+	if (f != &_stdin_null && f != &_stdout_null)
+		free(f);
 }
diff --git a/src/init/stdlib.h b/src/init/stdlib.h
index f7917da..e1e753d 100644
--- a/src/init/stdlib.h
+++ b/src/init/stdlib.h
@@ -15,6 +15,7 @@ typedef struct {
 	bool eof;
 } libc_file;
 libc_file *file_open(const char *path, int flags);
+libc_file *file_reopen(libc_file*, const char *path, int flags);
 int file_read(libc_file*, char *buf, size_t len);
 int file_write(libc_file*, const char *buf, size_t len);
 void file_close(libc_file*);