[Qemu-devel] [PATCH v2 03/43] Add qemu_get_counted_string to read a string prefixed by a count byte

["Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

and use it in loadvm_state.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 include/migration/qemu-file.h |  2 ++
 qemu-file.c                   | 15 +++++++++++++++
 savevm.c                      | 18 ++++++++++--------
 3 files changed, 27 insertions(+), 8 deletions(-)

diff --git a/include/migration/qemu-file.h b/include/migration/qemu-file.h
index 80af3ff..e50d696 100644
--- a/include/migration/qemu-file.h
+++ b/include/migration/qemu-file.h
@@ -300,4 +300,6 @@ static inline void qemu_get_sbe64s(QEMUFile *f, int64_t *pv)
 {
     qemu_get_be64s(f, (uint64_t *)pv);
 }
+
+int qemu_get_counted_string(QEMUFile *f, uint8_t *buf);
 #endif
diff --git a/qemu-file.c b/qemu-file.c
index d64bee2..f6d64ce 100644
--- a/qemu-file.c
+++ b/qemu-file.c
@@ -879,6 +879,21 @@ uint64_t qemu_get_be64(QEMUFile *f)
     return v;
 }
 
+/*
+ * Get a string whose length is determined by a single preceding byte
+ * A preallocated 256 byte buffer must be passed in.
+ * Returns: 0 on success and a 0 terminated string in the buffer
+ */
+int qemu_get_counted_string(QEMUFile *f, uint8_t *buf)
+{
+    unsigned int len = qemu_get_byte(f);
+    int res = qemu_get_buffer(f, buf, len);
+
+    buf[len] = 0;
+
+    return res != len;
+}
+
 #define QSB_CHUNK_SIZE      (1 << 10)
 #define QSB_MAX_CHUNK_SIZE  (10 * QSB_CHUNK_SIZE)
 
diff --git a/savevm.c b/savevm.c
index c3a1f68..cb6f0de 100644
--- a/savevm.c
+++ b/savevm.c
@@ -908,7 +908,7 @@ int qemu_loadvm_state(QEMUFile *f)
 
     v = qemu_get_be32(f);
     if (v == QEMU_VM_FILE_VERSION_COMPAT) {
-        fprintf(stderr, "SaveVM v2 format is obsolete and don't work anymore\n");
+        error_report("SaveVM v2 format is obsolete and don't work anymore");
         return -ENOTSUP;
     }
     if (v != QEMU_VM_FILE_VERSION) {
@@ -918,31 +918,33 @@ int qemu_loadvm_state(QEMUFile *f)
     while ((section_type = qemu_get_byte(f)) != QEMU_VM_EOF) {
         uint32_t instance_id, version_id, section_id;
         SaveStateEntry *se;
-        char idstr[257];
-        int len;
+        char idstr[256];
 
         switch (section_type) {
         case QEMU_VM_SECTION_START:
         case QEMU_VM_SECTION_FULL:
             /* Read section start */
             section_id = qemu_get_be32(f);
-            len = qemu_get_byte(f);
-            qemu_get_buffer(f, (uint8_t *)idstr, len);
-            idstr[len] = 0;
+            if (qemu_get_counted_string(f, (uint8_t *)idstr)) {
+                error_report("Unable to read ID string for section %u",
+                            section_id);
+                return -EINVAL;
+            }
             instance_id = qemu_get_be32(f);
             version_id = qemu_get_be32(f);
 
             /* Find savevm section */
             se = find_se(idstr, instance_id);
             if (se == NULL) {
-                fprintf(stderr, "Unknown savevm section or instance '%s' %d\n", idstr, instance_id);
+                error_report("Unknown savevm section or instance '%s' %d",
+                             idstr, instance_id);
                 ret = -EINVAL;
                 goto out;
             }
 
             /* Validate version */
             if (version_id > se->version_id) {
-                fprintf(stderr, "savevm: unsupported version %d for '%s' v%d\n",
+                error_report("savevm: unsupported version %d for '%s' v%d",
                         version_id, idstr, se->version_id);
                 ret = -EINVAL;
                 goto out;
-- 
1.9.3