[Qemu-devel] [PATCH v5 2/9] dump: Add API to write header of flatten format

[Qiao Nuohan <qiaonuohan@cn.fujitsu.com>]

flatten format may be used when writing kdump-compressed format. To get more
detailed information about flatten format of kdump-compressed format, please
refer to the following URL:
http://sourceforge.net/projects/makedumpfile/

The two functions here are used to write start flat header and end flat header
to vmcore, and they will be called later if flatten format is used.

struct MakedumpfileHeader stored at the head of vmcore is used to indicate the
vmcore is in flatten format.

struct MakedumpfileHeader {
    char signature[16];     /* = "makedumpfile" */
    int64_t type;           /* = 1 */
    int64_t version;        /* = 1 */
};

And struct MakedumpfileDataHeader, with offset and buf_size set to -1, is used
to indicate the end of vmcore in flatten format.

struct MakedumpfileDataHeader {
    int64_t offset;         /* = -1 */
    int64_t buf_size;       /* = -1 */
};

Signed-off-by: Qiao Nuohan <qiaonuohan@cn.fujitsu.com>
Reviewed-by: Zhang Xiaohe <zhangxh@cn.fujitsu.com>
---
 dump.c                |   40 ++++++++++++++++++++++++++++++++++++++++
 include/sysemu/dump.h |   17 +++++++++++++++++
 2 files changed, 57 insertions(+), 0 deletions(-)

diff --git a/dump.c b/dump.c
index 4e478b1..f04d4fc 100644
--- a/dump.c
+++ b/dump.c
@@ -674,6 +674,46 @@ static int create_vmcore(DumpState *s)
     return 0;
 }
 
+static int write_start_flat_header(int fd)
+{
+    char buf[MAX_SIZE_MDF_HEADER];
+    MakedumpfileHeader mh;
+
+    memset(&mh, 0, sizeof(mh));
+    strncpy(mh.signature, MAKEDUMPFILE_SIGNATURE,
+            strlen(MAKEDUMPFILE_SIGNATURE));
+
+    mh.type = cpu_to_be64(TYPE_FLAT_HEADER);
+    mh.version = cpu_to_be64(VERSION_FLAT_HEADER);
+
+    memset(buf, 0, sizeof(buf));
+    memcpy(buf, &mh, sizeof(mh));
+
+    size_t written_size;
+    written_size = qemu_write_full(fd, buf, sizeof(buf));
+    if (written_size != sizeof(buf)) {
+        return -1;
+    }
+
+    return 0;
+}
+
+static int write_end_flat_header(int fd)
+{
+    MakedumpfileDataHeader mdh;
+
+    mdh.offset = END_FLAG_FLAT_HEADER;
+    mdh.buf_size = END_FLAG_FLAT_HEADER;
+
+    size_t written_size;
+    written_size = qemu_write_full(fd, &mdh, sizeof(mdh));
+    if (written_size != sizeof(mdh)) {
+        return -1;
+    }
+
+    return 0;
+}
+
 static ram_addr_t get_start_block(DumpState *s)
 {
     RAMBlock *block;
diff --git a/include/sysemu/dump.h b/include/sysemu/dump.h
index b8c770f..81cbaa8 100644
--- a/include/sysemu/dump.h
+++ b/include/sysemu/dump.h
@@ -14,12 +14,29 @@
 #ifndef DUMP_H
 #define DUMP_H
 
+#define MAKEDUMPFILE_SIGNATURE      "makedumpfile"
+#define MAX_SIZE_MDF_HEADER         (4096) /* max size of makedumpfile_header */
+#define TYPE_FLAT_HEADER            (1)    /* type of flattened format */
+#define VERSION_FLAT_HEADER         (1)    /* version of flattened format */
+#define END_FLAG_FLAT_HEADER        (-1)
+
 typedef struct ArchDumpInfo {
     int d_machine;  /* Architecture */
     int d_endian;   /* ELFDATA2LSB or ELFDATA2MSB */
     int d_class;    /* ELFCLASS32 or ELFCLASS64 */
 } ArchDumpInfo;
 
+typedef struct QEMU_PACKED MakedumpfileHeader {
+    char signature[16];     /* = "makedumpfile" */
+    int64_t type;
+    int64_t version;
+} MakedumpfileHeader;
+
+typedef struct QEMU_PACKED MakedumpfileDataHeader {
+    int64_t offset;
+    int64_t buf_size;
+} MakedumpfileDataHeader;
+
 int cpu_get_dump_info(ArchDumpInfo *info);
 ssize_t cpu_get_note_size(int class, int machine, int nr_cpus);
 
-- 
1.7.1