ubiupdatevol: add a --skip option

This already has a --size option for controlling how many bytes to read
from the input.  Add a --skip option to control the offset into the input
too.  This way people don't have to do `dd | ubiupdatevol`.

While we're here, I've fixed the types used with args.size and the read
loop so that they can hold the right sizes (like setting a 32bit+ size).

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

diff --git a/ubi-utils/ubiupdatevol.c b/ubi-utils/ubiupdatevol.c
index 7fedb3c402c63526c035bb953844298c10b3e278..509679194343f8f330d7e83831825a36a49e6df9 100644 (file)
--- a/ubi-utils/ubiupdatevol.c
+++ b/ubi-utils/ubiupdatevol.c
@@ -45,7 +45,8 @@ struct args {
        const char *img;
        /* For deprecated -d and -B options handling */
        char dev_name[256];
-       int size;
+       long long size;
+       long long skip;
        int use_stdin;
 };
 
@@ -56,7 +57,8 @@ static const char doc[] = PROGRAM_NAME " version " VERSION
 
 static const char optionsstr[] =
 "-t, --truncate             truncate volume (wipe it out)\n"
-"-s, --size=<bytes>         bytes in input, if not reading from file\n"
+"-s, --size=<bytes>         bytes to read from input\n"
+"    --skip=<bytes>         leading bytes to skip from input\n"
 "-h, --help                 print help message\n"
 "-V, --version              print program version";
 
@@ -67,6 +69,8 @@ static const char usage[] =
 "Example 2: " PROGRAM_NAME " /dev/ubi0_1 -t - wipe out UBI volume /dev/ubi0_1";
 
 static const struct option long_options[] = {
+       /* Order matters for opts w/val=0; see option_index below. */
+       { .name = "skip",     .has_arg = 1, .flag = NULL, .val = 0 },
        { .name = "truncate", .has_arg = 0, .flag = NULL, .val = 't' },
        { .name = "help",     .has_arg = 0, .flag = NULL, .val = 'h' },
        { .name = "version",  .has_arg = 0, .flag = NULL, .val = 'V' },
@@ -77,19 +81,29 @@ static const struct option long_options[] = {
 static int parse_opt(int argc, char * const argv[])
 {
        while (1) {
-               int key, error = 0;
+               int option_index, key, error = 0;
 
-               key = getopt_long(argc, argv, "ts:h?V", long_options, NULL);
+               key = getopt_long(argc, argv, "ts:h?V", long_options, &option_index);
                if (key == -1)
                        break;
 
                switch (key) {
+               case 0:
+                       switch (option_index) {
+                       case 0: /* --skip */
+                               args.skip = simple_strtoull(optarg, &error);
+                               if (error || args.skip < 0)
+                                       return errmsg("bad skip: " "\"%s\"", optarg);
+                               break;
+                       }
+                       break;
+
                case 't':
                        args.truncate = 1;
                        break;
 
                case 's':
-                       args.size = simple_strtoul(optarg, &error);
+                       args.size = simple_strtoull(optarg, &error);
                        if (error || args.size < 0)
                                return errmsg("bad size: " "\"%s\"", optarg);
                        break;
@@ -198,7 +212,7 @@ static int update_volume(libubi_t libubi, struct ubi_vol_info *vol_info)
                        goto out_free;
                }
 
-               bytes = st.st_size;
+               bytes = st.st_size - args.skip;
        } else
                bytes = args.size;
 
@@ -214,14 +228,23 @@ static int update_volume(libubi_t libubi, struct ubi_vol_info *vol_info)
                goto out_free;
        }
 
-       if (args.use_stdin)
+       if (args.use_stdin) {
                ifd = STDIN_FILENO;
-       else {
+               if (args.skip) {
+                       errmsg("seeking stdin not supported");
+                       goto out_close1;
+               }
+       } else {
                ifd = open(args.img, O_RDONLY);
                if (ifd == -1) {
                        sys_errmsg("cannot open \"%s\"", args.img);
                        goto out_close1;
                }
+
+               if (args.skip && lseek(ifd, args.skip, SEEK_CUR) == -1) {
+                       sys_errmsg("lseek input by %lld failed", args.skip);
+                       goto out_close;
+               }
        }
 
        err = ubi_update_start(libubi, fd, bytes);
@@ -231,10 +254,8 @@ static int update_volume(libubi_t libubi, struct ubi_vol_info *vol_info)
        }
 
        while (bytes) {
-               int ret, to_copy = vol_info->leb_size;
-
-               if (to_copy > bytes)
-                       to_copy = bytes;
+               ssize_t ret;
+               int to_copy = min(vol_info->leb_size, bytes);
 
                ret = read(ifd, buf, to_copy);
                if (ret <= 0) {