diff options
Diffstat (limited to 'qemu-img.c')
| -rw-r--r-- | qemu-img.c | 50 |
1 files changed, 45 insertions, 5 deletions
diff --git a/qemu-img.c b/qemu-img.c index 5bdac8ddb7..ceffefeacb 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -173,7 +173,8 @@ static void QEMU_NORETURN help(void) "(default: 512)\n" " 'count=N' copy only N input blocks\n" " 'if=FILE' read from FILE\n" - " 'of=FILE' write to FILE\n"; + " 'of=FILE' write to FILE\n" + " 'skip=N' skip N bs-sized blocks at the start of input\n"; printf("%s\nSupported formats:", help_msg); bdrv_iterate_format(format_print, NULL); @@ -3807,6 +3808,7 @@ out: #define C_COUNT 02 #define C_IF 04 #define C_OF 010 +#define C_SKIP 020 struct DdInfo { unsigned int flags; @@ -3817,6 +3819,7 @@ struct DdIo { int bsz; /* Block size */ char *filename; uint8_t *buf; + int64_t offset; }; struct DdOpts { @@ -3877,6 +3880,22 @@ static int img_dd_of(const char *arg, return 0; } +static int img_dd_skip(const char *arg, + struct DdIo *in, struct DdIo *out, + struct DdInfo *dd) +{ + char *end; + + in->offset = qemu_strtosz_suffix(arg, &end, QEMU_STRTOSZ_DEFSUFFIX_B); + + if (in->offset < 0 || *end) { + error_report("invalid number: '%s'", arg); + return 1; + } + + return 0; +} + static int img_dd(int argc, char **argv) { int ret = 0; @@ -3900,12 +3919,14 @@ static int img_dd(int argc, char **argv) struct DdIo in = { .bsz = 512, /* Block size is by default 512 bytes */ .filename = NULL, - .buf = NULL + .buf = NULL, + .offset = 0 }; struct DdIo out = { .bsz = 512, .filename = NULL, - .buf = NULL + .buf = NULL, + .offset = 0 }; const struct DdOpts options[] = { @@ -3913,6 +3934,7 @@ static int img_dd(int argc, char **argv) { "count", img_dd_count, C_COUNT }, { "if", img_dd_if, C_IF }, { "of", img_dd_of, C_OF }, + { "skip", img_dd_skip, C_SKIP }, { NULL, NULL, 0 } }; const struct option long_options[] = { @@ -4032,7 +4054,14 @@ static int img_dd(int argc, char **argv) size = dd.count * in.bsz; } - qemu_opt_set_number(opts, BLOCK_OPT_SIZE, size, &error_abort); + /* Overflow means the specified offset is beyond input image's size */ + if (dd.flags & C_SKIP && (in.offset > INT64_MAX / in.bsz || + size < in.bsz * in.offset)) { + qemu_opt_set_number(opts, BLOCK_OPT_SIZE, 0, &error_abort); + } else { + qemu_opt_set_number(opts, BLOCK_OPT_SIZE, + size - in.bsz * in.offset, &error_abort); + } ret = bdrv_create(drv, out.filename, opts, &local_err); if (ret < 0) { @@ -4051,9 +4080,20 @@ static int img_dd(int argc, char **argv) goto out; } + if (dd.flags & C_SKIP && (in.offset > INT64_MAX / in.bsz || + size < in.offset * in.bsz)) { + /* We give a warning if the skip option is bigger than the input + * size and create an empty output disk image (i.e. like dd(1)). + */ + error_report("%s: cannot skip to specified offset", in.filename); + in_pos = size; + } else { + in_pos = in.offset * in.bsz; + } + in.buf = g_new(uint8_t, in.bsz); - for (in_pos = 0, out_pos = 0; in_pos < size; block_count++) { + for (out_pos = 0; in_pos < size; block_count++) { int in_ret, out_ret; if (in_pos + in.bsz > size) { |