sh: Add support for running commands in the background

5 files changed, 22 insertions, 2 deletions

diff --git a/userland/minibox/utilities/sh/ast.c b/userland/minibox/utilities/sh/ast.c
index 64dd725..98f4818 100644
--- a/userland/minibox/utilities/sh/ast.c
+++ b/userland/minibox/utilities/sh/ast.c
@@ -61,6 +61,11 @@ int parse_command(struct TOKEN **token_ptr, struct AST *cur) {
     cur->file_out = token->string_rep;
     token = token->next;
   }
+  // Parse '&'
+  if (token && TOKEN_BACKGROUND == token->type) {
+    cur->should_background = 1;
+    token = token->next;
+  }
   // Parse pipe '|'
   if (token && TOKEN_PIPE == token->type) {
     cur->pipe_rhs = allocate_ast();
diff --git a/userland/minibox/utilities/sh/ast.h b/userland/minibox/utilities/sh/ast.h
index ae43f67..0c5768f 100644
--- a/userland/minibox/utilities/sh/ast.h
+++ b/userland/minibox/utilities/sh/ast.h
@@ -27,6 +27,7 @@ struct AST {
   struct AST *pipe_rhs; // in "func1 | func2" func2 is the piped rhs
   int file_out_fd_to_use;
   int file_out_append;
+  int should_background;
   struct sv file_out; // in "func1 > file.txt" file.txt is the file_out
   struct AST *next;
 };
diff --git a/userland/minibox/utilities/sh/lexer.c b/userland/minibox/utilities/sh/lexer.c
index 0df796f..40e7211 100644
--- a/userland/minibox/utilities/sh/lexer.c
+++ b/userland/minibox/utilities/sh/lexer.c
@@ -49,7 +49,7 @@ int parse_operand(struct sv *code_ptr, struct TOKEN *cur) {
   TRY_PARSE_STRING(">>", TOKEN_STREAM_APPEND);
   TRY_PARSE_STRING(">", TOKEN_STREAM);
   TRY_PARSE_STRING("|", TOKEN_PIPE);
-  // TODO: &
+  TRY_PARSE_STRING("&", TOKEN_BACKGROUND);
 
   // Failed to parse
   return 0;
diff --git a/userland/minibox/utilities/sh/lexer.h b/userland/minibox/utilities/sh/lexer.h
index b8ca95c..887c923 100644
--- a/userland/minibox/utilities/sh/lexer.h
+++ b/userland/minibox/utilities/sh/lexer.h
@@ -11,6 +11,7 @@ typedef enum {
   TOKEN_PIPE,
   TOKEN_STREAM,
   TOKEN_STREAM_APPEND,
+  TOKEN_BACKGROUND,
 } token_type_t;
 
 struct TOKEN {
diff --git a/userland/minibox/utilities/sh/sh.c b/userland/minibox/utilities/sh/sh.c
index 1505de3..e129044 100644
--- a/userland/minibox/utilities/sh/sh.c
+++ b/userland/minibox/utilities/sh/sh.c
@@ -7,6 +7,8 @@
 #include <sys/wait.h>
 #include <unistd.h>
 
+int active_processes = 0;
+
 int execute_command(struct AST *ast, int input_fd);
 
 int execute_binary(struct AST *ast, int input_fd) {
@@ -69,9 +71,20 @@ int execute_binary(struct AST *ast, int input_fd) {
       close(out);
     return execute_command(ast->pipe_rhs, slave_input);
   }
+
+  active_processes++;
+  if (ast->should_background) {
+    return pid;
+  }
+
   int rc;
   // FIXME: Should use waitpid ... when my OS supports that
-  wait(&rc);
+  for (; active_processes > 0;) {
+    if (-1 == wait(&rc)) {
+      continue;
+    }
+    active_processes--;
+  }
   return rc;
 }