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commit 9e9941a182d046afe3c7ce7ae459981dc757ca40
parent 77f5a41ff26371cfc77644ba49c760e7778c142b
Author: Christian Grothoff <christian@grothoff.org>
Date:   Sat, 10 Oct 2026 22:37:13 +0200

mmap() instead of sendfile(), avoids holding extra FDs

Diffstat:
M
src/mhd/mhd_spa.c
 | 
69
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++------

1 file changed, 63 insertions(+), 6 deletions(-)
diff --git a/src/mhd/mhd_spa.c b/src/mhd/mhd_spa.c
@@ -50,6 +50,17 @@ struct WebuiFile
    */
   struct MHD_Response *responses[TALER_MHD_CT_MAX];
 
+  /**
+   * mmap()'ed file contents served by the respective @e responses,
+   * NULL for empty files.  Use munmap() to release.
+   */
+  void *maps[TALER_MHD_CT_MAX];
+
+  /**
+   * Sizes of the respective @e maps.
+   */
+  size_t map_sizes[TALER_MHD_CT_MAX];
+
 };
 
 
@@ -162,6 +173,8 @@ build_webui (void *cls,
   struct TALER_MHD_Spa *spa = cls;
   int fd;
   struct stat sb;
+  size_t size;
+  void *buf;
   struct MHD_Response *response;
   char *ext;
   const char *mime;
@@ -195,6 +208,36 @@ build_webui (void *cls,
     GNUNET_break (0 == close (fd));
     return GNUNET_SYSERR;
   }
+  if (SIZE_MAX < ((unsigned long long) sb.st_size))
+  {
+    GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_ERROR,
+                              "fstat-size",
+                              dn);
+    GNUNET_break (0 == close (fd));
+    return GNUNET_SYSERR;
+  }
+  size = (size_t) sb.st_size;
+  buf = NULL;
+  if (0 != size)
+  {
+    buf = mmap (NULL,
+                size,
+                PROT_READ,
+                MAP_SHARED,
+                fd,
+                0);
+    if (MAP_FAILED == buf)
+    {
+      GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_ERROR,
+                                "mmap",
+                                dn);
+      GNUNET_break (0 == close (fd));
+      return GNUNET_SYSERR;
+    }
+  }
+  /* The mapping stays valid after the descriptor is closed; do not
+     hold one descriptor per file for the lifetime of the process. */
+  GNUNET_break (0 == close (fd));
 
   fn = GNUNET_strdup (slash + 1);
   ext = strrchr (fn,
@@ -232,13 +275,14 @@ build_webui (void *cls,
       break;
     }
 
-  response = MHD_create_response_from_fd (
-    sb.st_size,
-    fd /* FD now owned by MHD! */);
+  response = MHD_create_response_from_buffer_static (size,
+                                                     buf);
   if (NULL == response)
   {
-    /* MHD did not take ownership of the FD after all */
-    GNUNET_break (0 == close (fd));
+    GNUNET_break (0);
+    if (NULL != buf)
+      GNUNET_break (0 == munmap (buf,
+                                 size));
     GNUNET_free (fn);
     return GNUNET_SYSERR;
   }
@@ -250,6 +294,9 @@ build_webui (void *cls,
   {
     GNUNET_break (0);
     MHD_destroy_response (response);
+    if (NULL != buf)
+      GNUNET_break (0 == munmap (buf,
+                                 size));
     GNUNET_free (fn);
     return GNUNET_SYSERR;
   }
@@ -293,10 +340,14 @@ build_webui (void *cls,
     }
     GNUNET_assert (NULL == w->responses[ct]);
     w->responses[ct] = response;
+    w->maps[ct] = buf;
+    w->map_sizes[ct] = size;
   }
   return GNUNET_OK;
 skip:
-  GNUNET_break (0 == close (fd));
+  if (NULL != buf)
+    GNUNET_break (0 == munmap (buf,
+                               size));
   GNUNET_free (fn);
   return GNUNET_OK;
 }
@@ -368,6 +419,12 @@ TALER_MHD_spa_free (struct TALER_MHD_Spa *spa)
         MHD_destroy_response (w->responses[ct]);
         w->responses[ct] = NULL;
       }
+      if (NULL != w->maps[ct])
+      {
+        GNUNET_break (0 == munmap (w->maps[ct],
+                                   w->map_sizes[ct]));
+        w->maps[ct] = NULL;
+      }
     }
     GNUNET_free (w->path);
     GNUNET_free (w);