intel/mda: Add MDA_OUTPUT_DIR and MDA_PREFIX environment variable support

Acked-by: Kenneth Graunke <kenneth@whitecape.org>
Acked-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/29146>

docs/envvars.rst

@@ -886,6 +886,15 @@ Intel driver environment variables
    If none of widths for particular shader stage was specified, then all
    widths are allowed.
 
+.. envvar:: MDA_OUTPUT_DIR
+
+   Directory where the mda.tar files generated when using INTEL_DEBUG=mda are
+   going to be written to.  If not set, use the current directory.
+
+.. envvar:: MDA_PREFIX
+
+   Prefix added to the mda.tar filenames generated when using INTEL_DEBUG=mda.
+
 Anvil(ANV) driver environment variables
 ---------------------------------------
 

src/intel/mda/debug_archiver.c

@@ -7,23 +7,71 @@
 
 #include "tar.h"
 #include "util/ralloc.h"
+#include "util/u_debug.h"
 
 #include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
 
 struct debug_archiver
 {
    FILE *f;
    tar_writer *tw;
    char prefix[128];
+   char *archive_path;
 };
 
+DEBUG_GET_ONCE_OPTION(mda_output_dir, "MDA_OUTPUT_DIR", ".")
+DEBUG_GET_ONCE_OPTION(mda_prefix, "MDA_PREFIX", NULL)
+
+static bool
+ensure_output_dir(const char *dir)
+{
+   if (!dir || !*dir || !strcmp(dir, "."))
+      return true;
+
+   struct stat st;
+   if (stat(dir, &st) == 0)
+      return S_ISDIR(st.st_mode);
+
+   return mkdir(dir, 0755) == 0;
+}
+
 debug_archiver *
 debug_archiver_open(void *mem_ctx, const char *name, const char *info)
 {
    debug_archiver *da = rzalloc(mem_ctx, debug_archiver);
 
    char *filename = ralloc_asprintf(mem_ctx, "%s.mda.tar", name);
-   da->f = fopen(filename, "wb+");
+
+   const char *output_dir = debug_get_option_mda_output_dir();
+   const char *prefix     = debug_get_option_mda_prefix();
+
+   if (!ensure_output_dir(output_dir)) {
+      /* Fallback to current directory on failure. */
+      output_dir = ".";
+   }
+
+   if (prefix) {
+      /* Prefix shouldn't have any `/` characters. */
+      if (strchr(prefix, '/')) {
+         char *safe_prefix = ralloc_strdup(da, prefix);
+         for (char *p = safe_prefix; *p; p++) {
+            if (*p == '/')
+               *p = '_';
+         }
+         prefix = safe_prefix;
+      }
+   }
+
+   da->archive_path = ralloc_asprintf(da, "%s/%s%s%s",
+                                      output_dir,
+                                      prefix ? prefix : "",
+                                      prefix ? "."    : "",
+                                      filename);
+
+   da->f = fopen(da->archive_path, "wb+");
 
    da->tw = rzalloc(da, tar_writer);
    tar_writer_init(da->tw, da->f);

src/intel/mda/meson.build

@@ -11,6 +11,9 @@ _libmda = static_library(
     'tar.h',
     'tar.c',
   ],
+  dependencies: [
+    idep_mesautil
+  ],
   include_directories: [inc_src],
   c_args: [c_msvc_compat_args],
   gnu_symbol_visibility: 'hidden',