tests: fw_cfg: add a function to get the fw_cfg file

This is useful to write qtest about fw_cfg file entry.

Signed-off-by: Li Qiang <liq3ea@163.com>
Acked-by: Thomas Huth <thuth@redhat.com>
Tested-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20190424140643.62457-3-liq3ea@163.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>

2 files changed, 47 insertions, 0 deletions

diff --git a/tests/libqos/fw_cfg.c b/tests/libqos/fw_cfg.c
index c6839c5..1f46258 100644
--- a/tests/libqos/fw_cfg.c
+++ b/tests/libqos/fw_cfg.c
@@ -16,6 +16,7 @@
 #include "libqos/fw_cfg.h"
 #include "libqtest.h"
 #include "qemu/bswap.h"
+#include "hw/nvram/fw_cfg.h"
 
 void qfw_cfg_select(QFWCFG *fw_cfg, uint16_t key)
 {
@@ -59,6 +60,50 @@ static void mm_fw_cfg_select(QFWCFG *fw_cfg, uint16_t key)
     qtest_writew(fw_cfg->qts, fw_cfg->base, key);
 }
 
+/*
+ * The caller need check the return value. When the return value is
+ * nonzero, it means that some bytes have been transferred.
+ *
+ * If the fw_cfg file in question is smaller than the allocated & passed-in
+ * buffer, then the buffer has been populated only in part.
+ *
+ * If the fw_cfg file in question is larger than the passed-in
+ * buffer, then the return value explains how much room would have been
+ * necessary in total. And, while the caller's buffer has been fully
+ * populated, it has received only a starting slice of the fw_cfg file.
+ */
+size_t qfw_cfg_get_file(QFWCFG *fw_cfg, const char *filename,
+                      void *data, size_t buflen)
+{
+    uint32_t count;
+    uint32_t i;
+    unsigned char *filesbuf = NULL;
+    size_t dsize;
+    FWCfgFile *pdir_entry;
+    size_t filesize = 0;
+
+    qfw_cfg_get(fw_cfg, FW_CFG_FILE_DIR, &count, sizeof(count));
+    count = be32_to_cpu(count);
+    dsize = sizeof(uint32_t) + count * sizeof(struct fw_cfg_file);
+    filesbuf = g_malloc(dsize);
+    qfw_cfg_get(fw_cfg, FW_CFG_FILE_DIR, filesbuf, dsize);
+    pdir_entry = (FWCfgFile *)(filesbuf + sizeof(uint32_t));
+    for (i = 0; i < count; ++i, ++pdir_entry) {
+        if (!strcmp(pdir_entry->name, filename)) {
+            uint32_t len = be32_to_cpu(pdir_entry->size);
+            uint16_t sel = be16_to_cpu(pdir_entry->select);
+            filesize = len;
+            if (len > buflen) {
+                len = buflen;
+            }
+            qfw_cfg_get(fw_cfg, sel, data, len);
+            break;
+        }
+    }
+    g_free(filesbuf);
+    return filesize;
+}
+
 static void mm_fw_cfg_read(QFWCFG *fw_cfg, void *data, size_t len)
 {
     uint8_t *ptr = data;
diff --git a/tests/libqos/fw_cfg.h b/tests/libqos/fw_cfg.h
index 60de81e..13325cc 100644
--- a/tests/libqos/fw_cfg.h
+++ b/tests/libqos/fw_cfg.h
@@ -31,6 +31,8 @@ void qfw_cfg_get(QFWCFG *fw_cfg, uint16_t key, void *data, size_t len);
 uint16_t qfw_cfg_get_u16(QFWCFG *fw_cfg, uint16_t key);
 uint32_t qfw_cfg_get_u32(QFWCFG *fw_cfg, uint16_t key);
 uint64_t qfw_cfg_get_u64(QFWCFG *fw_cfg, uint16_t key);
+size_t qfw_cfg_get_file(QFWCFG *fw_cfg, const char *filename,
+                        void *data, size_t buflen);
 
 QFWCFG *mm_fw_cfg_init(QTestState *qts, uint64_t base);
 void mm_fw_cfg_uninit(QFWCFG *fw_cfg);