Add pipes to shell, add wc

src/user/app/wc/wc.c

@@ -0,0 +1,59 @@
+#include "src/lib/string.h"
+#include "src/lib/syscall.h"
+#include "src/lib/util.h"
+#include "src/user/syscall.h"
+
+#define BLOCK_SIZE 65536
+
+#define PRINT_S(s) write(1, s, sizeof(s) - 1);
+#define PRINT_D(s) write(1, s, string_length(s));
+
+exit_code_t pass(uint64_t fd) {
+  static char buffer[BLOCK_SIZE];
+  uint64_t bytes;
+  uint64_t total = 0;
+  while ((bytes = read(fd, BLOCK_SIZE, buffer))) {
+    if (bytes == (uint64_t)-1) {
+      PRINT_S("wc: could not read file\n");
+      return EXIT_CODE_GENERAL_FAILURE;
+    } else {
+      total += bytes;
+    }
+  }
+
+  uint64_t l = string_format("%d\n", BLOCK_SIZE, buffer, total);
+  write(1, buffer, l);
+
+  return EXIT_CODE_OK;
+}
+
+exit_code_t wc(const char *path) {
+  uint64_t fd = open(path, OPEN_FILE);
+
+  if (fd == (uint64_t)-1) {
+    PRINT_S("wc: path does not exist\n");
+    return EXIT_CODE_GENERAL_FAILURE;
+  }
+
+  exit_code_t code = pass(fd);
+
+  close(fd);
+
+  return code;
+}
+
+exit_code_t main(uint64_t argc, const char **argv) {
+  if (argc == 1) {
+    return pass(0);
+  }
+
+  uint64_t code = EXIT_CODE_OK;
+  for (uint64_t i = 1; i < argc; i++) {
+    exit_code_t c = wc(argv[i]);
+    if (c != EXIT_CODE_OK) {
+      code = c;
+    }
+  }
+
+  return code;
+}