Userland: Use getline instead of Core::File::standard_input in grep

Core::IODevice (which Core::File inherits from) does not have a
reasonable way to block for a line. grep was spinning on
IODevice::read_line, passing endless empty strings to the matcher
lambda. Use getline instead, which will at least block in the Kernel for
characters to be available on stdin and only return full lines (or eof)

1 files changed, 10 insertions, 5 deletions

diff --git a/Userland/Utilities/grep.cpp b/Userland/Utilities/grep.cpp
index 25ab2e900c..8022fc487c 100644
--- a/Userland/Utilities/grep.cpp
+++ b/Userland/Utilities/grep.cpp
@@ -25,6 +25,7 @@
  */
 
 #include <AK/ByteBuffer.h>
+#include <AK/ScopeGuard.h>
 #include <AK/String.h>
 #include <AK/Utf8View.h>
 #include <AK/Vector.h>
@@ -186,15 +187,19 @@ int main(int argc, char** argv)
     };
 
     if (!files.size() && !recursive) {
-        auto stdin_file = Core::File::standard_input();
-        while (!stdin_file->eof()) {
-            auto line = stdin_file->read_line();
-            bool is_binary = line.bytes().contains_slow(0);
+        char* line = nullptr;
+        size_t line_len = 0;
+        ssize_t nread = 0;
+        ScopeGuard free_line = [line] { free(line); };
+        while ((nread = getline(&line, &line_len, stdin)) != -1) {
+            ASSERT(nread > 0);
+            StringView line_view(line, nread - 1);
+            bool is_binary = line_view.contains(0);
 
             if (is_binary && binary_mode == BinaryFileMode::Skip)
                 return 1;
 
-            if (matches(line, "stdin", false, is_binary) && is_binary && binary_mode == BinaryFileMode::Binary)
+            if (matches(line_view, "stdin", false, is_binary) && is_binary && binary_mode == BinaryFileMode::Binary)
                 return 0;
         }
     } else {