From 734846c123a8fb10e1d9df3382c3b862874e7da3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Kacper=20Michaj=C5=82ow?= <kasper93@gmail.com>
Date: Tue, 21 May 2024 22:46:00 +0200
Subject: [PATCH] test_utils: don't use subprocess for diffing test results

Helps with testing during cross-compilation and avoids external
dependency.

Output maybe is not that nice, but this output in our tests is not
useful anyway. We know if it changes it is beacuse one of the dependency
version changed.
---
 test/test_utils.c | 60 ++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 46 insertions(+), 14 deletions(-)

diff --git a/test/test_utils.c b/test/test_utils.c
index 94fd2e6bb0..22b53b5e32 100644
--- a/test/test_utils.c
+++ b/test/test_utils.c
@@ -60,23 +60,55 @@ void assert_text_files_equal_impl(const char *file, int line,
                                   const char *ref, const char *new,
                                   const char *err)
 {
-    char *path_ref = mp_tprintf(4096, "%s/%s", refdir, ref);
-    char *path_new = mp_tprintf(4096, "%s/%s", outdir, new);
+    char path_ref[4096];
+    char path_new[4096];
 
-    struct mp_subprocess_opts opts = {
-        .exe = "diff",
-        .args = (char*[]){"diff", "-u", "--", path_ref, path_new, 0},
-        .fds = { {0, .src_fd = 0}, {1, .src_fd = 1}, {2, .src_fd = 2} },
-        .num_fds = 3,
-    };
+    snprintf(path_ref, sizeof(path_ref), "%s/%s", refdir, ref);
+    snprintf(path_new, sizeof(path_new), "%s/%s", outdir, new);
 
-    struct mp_subprocess_result res;
-    mp_subprocess2(&opts, &res);
+    bool ok = false;
+    FILE *fref = fopen(path_ref, "r");
+    FILE *fnew = fopen(path_new, "r");
 
-    if (res.error || res.exit_status) {
-        if (res.error)
-            printf("Note: %s\n", mp_subprocess_err_str(res.error));
-        printf("Giving up.\n");
+    if (!fref || !fnew) {
+        printf("Error: Could not open files %s or %s\n", path_ref, path_new);
+        goto done;
+    }
+
+    char ref_line[4096];
+    char new_line[4096];
+    int line_num = 0;
+
+    while (fgets(ref_line, sizeof(ref_line), fref))
+    {
+        line_num++;
+
+        if (!fgets(new_line, sizeof(new_line), fnew)) {
+            printf("Extra line %d in reference file: %s", line_num, ref_line);
+            goto done;
+        }
+
+        if (strcmp(ref_line, new_line)) {
+            printf("Difference found at line %d:\n", line_num);
+            printf("Reference: %s", ref_line);
+            printf("New file: %s", new_line);
+            goto done;
+        }
+    }
+
+    if (fgets(new_line, sizeof(new_line), fnew)) {
+        printf("Extra line %d in new file: %s", line_num, new_line);
+        goto done;
+    }
+
+    ok = true;
+
+done:
+    if (fref)
+        fclose(fref);
+    if (fnew)
+        fclose(fnew);
+    if (!ok) {
         fflush(stdout);
         abort();
     }