[syslinux] [PATCH 5/8] extlinux/main.c: implement write_to_device()

[Robert Yang]

* Create the file for writting.
* Construct the bmap.
* Patch the boot sector.
* Patch ldlinux.sys.

Signed-off-by: Robert Yang <liezhi.yang at windriver.com>
---
 extlinux/main.c | 127 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 127 insertions(+)

diff --git a/extlinux/main.c b/extlinux/main.c
index 3acf5b5..99a078c 100644
--- a/extlinux/main.c
+++ b/extlinux/main.c
@@ -222,6 +222,11 @@ ok:
     return rv;
 }
 
+/* Patch syslinux_bootsect */
+static void patch_syslinux_bootsect(int devfd)
+{
+}
+
 /*
  * Query the device geometry and put it into the boot sector.
  * Map the file and put the map in the boot sector and file.
@@ -1056,10 +1061,132 @@ static int ext_write_to_fs(ext2_file_t e2_file, const void *buf, size_t count,
     return done;
 }
 
+/* Construct the boot file map */
+static int ext_construct_sectmap_fs(ext2_filsys fs, ext2_ino_t newino,
+                                sector_t *sectors, int nsect)
+{
+}
+
 static int write_to_device(ext2_filsys fs, const char *filename,
                                   const char *str, int length, int i_flags,
                                   int devfd)
 {
+    ext2_ino_t          newino;
+    ext2_ino_t          root = EXT2_ROOT_INO;
+    struct ext2_inode   inode;
+    int                 retval, i, modbytes, nsect;
+    ext2_file_t         e2_file;
+    sector_t            *sectors;
+
+
+    /* Remove it if it is already exists */
+    retval = ext2fs_namei(fs, root, root, filename, &newino);
+    if (retval == 0) {
+        dprintf("%s: the file already exists: %s, removing it\n",
+                program, filename);
+        retval = ext2fs_unlink(fs, root, filename, newino, 0);
+        if (retval) {
+            fprintf(stderr, "%s: failed to unlink: %s\n", program, filename);
+            return retval;
+        }
+    }
+
+    /* Create new inode */
+    retval = ext2fs_new_inode(fs, root, 010755, 0, &newino);
+    if (retval) {
+        fprintf(stderr, "%s: ERROR: failed to create inode for: %s\n",
+                program, filename);
+        return retval;
+    }
+
+    /* Link the inode and the filename */
+    retval = ext2fs_link(fs, root, filename, newino, EXT2_FT_REG_FILE);
+    if (retval) {
+        fprintf(stderr, "%s: ERROR: failed to link inode for: %s.\n",
+                program, filename);
+        return retval;
+    }
+
+    if (ext2fs_test_inode_bitmap2(fs->inode_map, newino))
+       fprintf(stderr, "%s: warning: inode already set %s.\n",
+            program, filename);
+
+        ext2fs_inode_alloc_stats2(fs, newino, +1, 0);
+        memset(&inode, 0, sizeof(inode));
+	inode.i_mode = LINUX_S_IFREG | LINUX_S_IRUSR | LINUX_S_IRGRP
+                        | LINUX_S_IROTH;
+	inode.i_flags |= i_flags;
+        inode.i_atime = inode.i_ctime = inode.i_mtime =
+            fs->now ? fs->now : time(0);
+        inode.i_links_count = 1;
+        if (fs->super->s_feature_incompat &
+            EXT3_FEATURE_INCOMPAT_EXTENTS) {
+            struct ext3_extent_header *eh;
+
+            eh = (struct ext3_extent_header *) &inode.i_block[0];
+            eh->eh_depth = 0;
+            eh->eh_entries = 0;
+            eh->eh_magic = ext2fs_cpu_to_le16(EXT3_EXT_MAGIC);
+            i = (sizeof(inode.i_block) - sizeof(*eh)) /
+                sizeof(struct ext3_extent);
+            eh->eh_max = ext2fs_cpu_to_le16(i);
+            inode.i_flags |= EXT4_EXTENTS_FL;
+    }
+
+    retval = ext2fs_write_new_inode(fs, newino, &inode);
+    if (retval) {
+        fprintf(stderr, "%s: ERROR: while writting inode %d.\n",
+                program, newino);
+        return 1;
+    }
+
+    retval = ext2fs_file_open(fs, newino, EXT2_FILE_WRITE, &e2_file);
+    if (retval) {
+        fprintf(stderr, "%s: ERROR: failed to open %s.\n",
+                program, filename);
+        return 1;
+    }
+
+    /* Write to file */
+    if (ext_write_to_fs(e2_file, str, length, 0, filename) == -1)
+        goto fail;
+
+    if (strcmp(filename, "ldlinux.sys") == 0) {
+        /* Write ADV */
+        if (ext_write_to_fs(e2_file, syslinux_adv, 2 * ADV_SIZE,
+                boot_image_len, "ADV") == -1)
+            goto fail;
+
+        /* Patch syslinux_bootsect */
+        patch_syslinux_bootsect(devfd);
+
+        /* Patch ldlinux.sys */
+        dprintf("%s: patching ldlinux.sys\n", program);
+        nsect = (boot_image_len + SECTOR_SIZE - 1) >> SECTOR_SHIFT;
+        nsect += 2;                        /* Two sectors for the ADV */
+        sectors = alloca(sizeof(sector_t) * nsect);
+        memset(sectors, 0, nsect * sizeof *sectors);
+        /* The sectors will be modified and used by syslinux_patch() */
+        retval = ext_construct_sectmap_fs(fs, newino, sectors, nsect);
+        if (retval)
+            goto fail;
+
+        /* Create the modified image in memory */
+        modbytes = syslinux_patch(sectors, nsect, opt.stupid_mode,
+                            opt.raid_mode, NULL, subvol);
+
+        /* Rewrite the first modbytes of ldlinux.sys */
+        if (ext_write_to_fs(e2_file, str, modbytes, 0, "modified ldlinux.sys")
+                 == -1) {
+            fprintf(stderr, "%s: ERROR: failed to patch %s.\n", program,
+                    filename);
+            goto fail;
+        }
+    }
+
+fail:
+    (void) ext2fs_file_close(e2_file);
+    return retval;
 }
 
 static int handle_adv_on_device(ext2_filsys fs, int update_only)
-- 
1.9.1