[Qemu-devel] [PATCH] [RfC] fw_cfg file sort

[Gerd Hoffmann <kraxel@redhat.com>]

This is what it takes to have a sorted fw_cfg file directory.
Entries are inserted at the correct place instead of being
appended to the end in case sorting is enabled.

Compatibility fluff (enable sorting for new machine types only)
isn't there yet.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 hw/nvram/fw_cfg.c | 30 ++++++++++++++++++++++++------
 1 file changed, 24 insertions(+), 6 deletions(-)

diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c
index 0f35931..83205e0 100644
--- a/hw/nvram/fw_cfg.c
+++ b/hw/nvram/fw_cfg.c
@@ -639,7 +639,7 @@ void fw_cfg_add_file_callback(FWCfgState *s,  const char *filename,
                               FWCfgReadCallback callback, void *callback_opaque,
                               void *data, size_t len)
 {
-    int i, index;
+    int i, index, count;
     size_t dsize;
 
     if (!s->files) {
@@ -648,13 +648,31 @@ void fw_cfg_add_file_callback(FWCfgState *s,  const char *filename,
         fw_cfg_add_bytes(s, FW_CFG_FILE_DIR, s->files, dsize);
     }
 
-    index = be32_to_cpu(s->files->count);
-    assert(index < FW_CFG_FILE_SLOTS);
+    count = be32_to_cpu(s->files->count);
+    assert(count < FW_CFG_FILE_SLOTS);
+
+    index = count;
+    if (1 /* sort entries */) {
+        while (index > 0 && strcmp(filename, s->files->f[index-1].name) < 0) {
+            s->files->f[index] =
+                s->files->f[index - 1];
+            s->files->f[index].select =
+                cpu_to_be16(FW_CFG_FILE_FIRST + index);
+            s->entries[0][FW_CFG_FILE_FIRST + index] =
+                s->entries[0][FW_CFG_FILE_FIRST + index - 1];
+            index--;
+        }
+        memset(&s->files->f[index],
+               0, sizeof(FWCfgFile));
+        memset(&s->entries[0][FW_CFG_FILE_FIRST + index],
+               0, sizeof(FWCfgEntry));
+    }
 
     pstrcpy(s->files->f[index].name, sizeof(s->files->f[index].name),
             filename);
-    for (i = 0; i < index; i++) {
-        if (strcmp(s->files->f[index].name, s->files->f[i].name) == 0) {
+    for (i = 0; i <= count; i++) {
+        if (i != index &&
+            strcmp(s->files->f[index].name, s->files->f[i].name) == 0) {
             error_report("duplicate fw_cfg file name: %s",
                          s->files->f[index].name);
             exit(1);
@@ -668,7 +686,7 @@ void fw_cfg_add_file_callback(FWCfgState *s,  const char *filename,
     s->files->f[index].select = cpu_to_be16(FW_CFG_FILE_FIRST + index);
     trace_fw_cfg_add_file(s, index, s->files->f[index].name, len);
 
-    s->files->count = cpu_to_be32(index+1);
+    s->files->count = cpu_to_be32(count+1);
 }
 
 void fw_cfg_add_file(FWCfgState *s,  const char *filename,
-- 
1.8.3.1