[Qemu-devel] [PATCH 18/21] VMDK: open/read/write for monolithicFlat image

[Kevin Wolf <kwolf@redhat.com>]

From: Fam Zheng <famcool@gmail.com>

Parse vmdk decriptor file and open mono flat image.
Read/write the flat extent.

Signed-off-by: Fam Zheng <famcool@gmail.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/vmdk.c |  171 +++++++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 files changed, 158 insertions(+), 13 deletions(-)

diff --git a/block/vmdk.c b/block/vmdk.c
index f637d98..e1fb962 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -65,6 +65,7 @@ typedef struct VmdkExtent {
     bool flat;
     int64_t sectors;
     int64_t end_sector;
+    int64_t flat_start_offset;
     int64_t l1_table_offset;
     int64_t l1_backup_table_offset;
     uint32_t *l1_table;
@@ -407,9 +408,10 @@ fail:
 static int vmdk_parent_open(BlockDriverState *bs)
 {
     char *p_name;
-    char desc[DESC_SIZE];
+    char desc[DESC_SIZE + 1];
     BDRVVmdkState *s = bs->opaque;
 
+    desc[DESC_SIZE] = '\0';
     if (bdrv_pread(bs->file, s->desc_offset, desc, DESC_SIZE) != DESC_SIZE) {
         return -1;
     }
@@ -584,6 +586,144 @@ static int vmdk_open_vmdk4(BlockDriverState *bs, int flags)
     return ret;
 }
 
+/* find an option value out of descriptor file */
+static int vmdk_parse_description(const char *desc, const char *opt_name,
+        char *buf, int buf_size)
+{
+    char *opt_pos, *opt_end;
+    const char *end = desc + strlen(desc);
+
+    opt_pos = strstr(desc, opt_name);
+    if (!opt_pos) {
+        return -1;
+    }
+    /* Skip "=\"" following opt_name */
+    opt_pos += strlen(opt_name) + 2;
+    if (opt_pos >= end) {
+        return -1;
+    }
+    opt_end = opt_pos;
+    while (opt_end < end && *opt_end != '"') {
+        opt_end++;
+    }
+    if (opt_end == end || buf_size < opt_end - opt_pos + 1) {
+        return -1;
+    }
+    pstrcpy(buf, opt_end - opt_pos + 1, opt_pos);
+    return 0;
+}
+
+static int vmdk_parse_extents(const char *desc, BlockDriverState *bs,
+        const char *desc_file_path)
+{
+    int ret;
+    char access[11];
+    char type[11];
+    char fname[512];
+    const char *p = desc;
+    int64_t sectors = 0;
+    int64_t flat_offset;
+
+    while (*p) {
+        /* parse extent line:
+         * RW [size in sectors] FLAT "file-name.vmdk" OFFSET
+         * or
+         * RW [size in sectors] SPARSE "file-name.vmdk"
+         */
+        flat_offset = -1;
+        ret = sscanf(p, "%10s %" SCNd64 " %10s %511s %" SCNd64,
+                access, &sectors, type, fname, &flat_offset);
+        if (ret < 4 || strcmp(access, "RW")) {
+            goto next_line;
+        } else if (!strcmp(type, "FLAT")) {
+            if (ret != 5 || flat_offset < 0) {
+                return -EINVAL;
+            }
+        } else if (ret != 4) {
+            return -EINVAL;
+        }
+
+        /* trim the quotation marks around */
+        if (fname[0] == '"') {
+            memmove(fname, fname + 1, strlen(fname));
+            if (strlen(fname) <= 1 || fname[strlen(fname) - 1] != '"') {
+                return -EINVAL;
+            }
+            fname[strlen(fname) - 1] = '\0';
+        }
+        if (sectors <= 0 ||
+            (strcmp(type, "FLAT") && strcmp(type, "SPARSE")) ||
+            (strcmp(access, "RW"))) {
+            goto next_line;
+        }
+
+        /* save to extents array */
+        if (!strcmp(type, "FLAT")) {
+            /* FLAT extent */
+            char extent_path[PATH_MAX];
+            BlockDriverState *extent_file;
+            VmdkExtent *extent;
+
+            path_combine(extent_path, sizeof(extent_path),
+                    desc_file_path, fname);
+            ret = bdrv_file_open(&extent_file, extent_path, bs->open_flags);
+            if (ret) {
+                return ret;
+            }
+            extent = vmdk_add_extent(bs, extent_file, true, sectors,
+                            0, 0, 0, 0, sectors);
+            extent->flat_start_offset = flat_offset;
+        } else {
+            /* SPARSE extent, not supported for now */
+            fprintf(stderr,
+                "VMDK: Not supported extent type \"%s\""".\n", type);
+            return -ENOTSUP;
+        }
+next_line:
+        /* move to next line */
+        while (*p && *p != '\n') {
+            p++;
+        }
+        p++;
+    }
+    return 0;
+}
+
+static int vmdk_open_desc_file(BlockDriverState *bs, int flags)
+{
+    int ret;
+    char buf[2048];
+    char ct[128];
+    BDRVVmdkState *s = bs->opaque;
+
+    ret = bdrv_pread(bs->file, 0, buf, sizeof(buf));
+    if (ret < 0) {
+        return ret;
+    }
+    buf[2047] = '\0';
+    if (vmdk_parse_description(buf, "createType", ct, sizeof(ct))) {
+        return -EINVAL;
+    }
+    if (strcmp(ct, "monolithicFlat")) {
+        fprintf(stderr,
+                "VMDK: Not supported image type \"%s\""".\n", ct);
+        return -ENOTSUP;
+    }
+    s->desc_offset = 0;
+    ret = vmdk_parse_extents(buf, bs, bs->file->filename);
+    if (ret) {
+        return ret;
+    }
+
+    /* try to open parent images, if exist */
+    if (vmdk_parent_open(bs)) {
+        qemu_free(s->extents);
+        return -EINVAL;
+    }
+    s->parent_cid = vmdk_read_cid(bs, 1);
+    return 0;
+}
+
 static int vmdk_open(BlockDriverState *bs, int flags)
 {
     uint32_t magic;
@@ -598,7 +738,7 @@ static int vmdk_open(BlockDriverState *bs, int flags)
     } else if (magic == VMDK4_MAGIC) {
         return vmdk_open_vmdk4(bs, flags);
     } else {
-        return -EINVAL;
+        return vmdk_open_desc_file(bs, flags);
     }
 }
 
@@ -679,7 +819,7 @@ static int get_cluster_offset(BlockDriverState *bs,
     if (m_data)
         m_data->valid = 0;
     if (extent->flat) {
-        *cluster_offset = 0;
+        *cluster_offset = extent->flat_start_offset;
         return 0;
     }
 
@@ -832,16 +972,20 @@ static int vmdk_read(BlockDriverState *bs, int64_t sector_num,
             /* if not allocated, try to read from parent image, if exist */
             if (bs->backing_hd) {
                 if (!vmdk_is_cid_valid(bs))
-                    return -1;
+                    return -EINVAL;
                 ret = bdrv_read(bs->backing_hd, sector_num, buf, n);
                 if (ret < 0)
-                    return -1;
+                    return ret;
             } else {
                 memset(buf, 0, 512 * n);
             }
         } else {
-            if(bdrv_pread(bs->file, cluster_offset + index_in_cluster * 512, buf, n * 512) != n * 512)
-                return -1;
+            ret = bdrv_pread(extent->file,
+                            cluster_offset + index_in_cluster * 512,
+                            buf, n * 512);
+            if (ret < 0) {
+                return ret;
+            }
         }
         nb_sectors -= n;
         sector_num += n;
@@ -865,7 +1009,7 @@ static int vmdk_write(BlockDriverState *bs, int64_t sector_num,
                 "(VMDK) Wrong offset: sector_num=0x%" PRIx64
                 " total_sectors=0x%" PRIx64 "\n",
                 sector_num, bs->total_sectors);
-        return -1;
+        return -EIO;
     }
 
     while (nb_sectors > 0) {
@@ -888,16 +1032,17 @@ static int vmdk_write(BlockDriverState *bs, int64_t sector_num,
             n = nb_sectors;
         }
 
-        if (bdrv_pwrite(bs->file,
+        ret = bdrv_pwrite(extent->file,
                         cluster_offset + index_in_cluster * 512,
-                        buf, n * 512)
-                != n * 512) {
-            return -1;
+                        buf,
+                        n * 512);
+        if (ret < 0) {
+            return ret;
         }
         if (m_data.valid) {
             /* update L2 tables */
             if (vmdk_L2update(extent, &m_data) == -1) {
-                return -1;
+                return -EIO;
             }
         }
         nb_sectors -= n;
-- 
1.7.6