cgpt: show: add some sanity checking to -i flagsstabilize-12464.B

If people use -i0, the code runs as if the flag wasn't specified.
Since valid partition numbers are [1,128], and the lower layers
already reject values outside that range (except for 0), add an
explicit check to the CLI for -i0.

Trying to display specific fields w/out -i makes no sense, and
the lower layers just ignore it.  Add an explicit check for it
so users don't try to do `cgpt show /dev/sda -s` and wonder why
the output is unchanged.

Passing more than one specific field selector like -s -b doesn't
work -- whatever flag was specified last wins.  This isn't that
obvious to users, so throw an explicit error when it happens.

BUG=None
TEST=CQ passes
BRANCH=None

Change-Id: I7c98822b79b389824b544b128ede93458b678342
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/1773964
Reviewed-by: Julius Werner <jwerner@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>

1 files changed, 14 insertions, 0 deletions

diff --git a/cgpt/cmd_show.c b/cgpt/cmd_show.c
index 22d31841..4d169f5e 100644
--- a/cgpt/cmd_show.c
+++ b/cgpt/cmd_show.c
@@ -70,6 +70,10 @@ int cmd_show(int argc, char *argv[]) {
     case 'i':
       params.partition = (uint32_t)strtoul(optarg, &e, 0);
       errorcnt += check_int_parse(c, e);
+      if (params.partition <= 0) {
+        Error("-i requires a number between 1 and 128 (inclusive)\n");
+        errorcnt++;
+      }
       break;
     case 'b':
     case 's':
@@ -82,6 +86,12 @@ int cmd_show(int argc, char *argv[]) {
     case 'R':
     case 'B':
     case 'A':
+      if (params.single_item) {
+        Error("-%c already specified; rejecting additional -%c\n",
+              params.single_item, c);
+        Error("Only a single item may be displayed at a time\n");
+        errorcnt++;
+      }
       params.single_item = c;
       break;
 
@@ -105,6 +115,10 @@ int cmd_show(int argc, char *argv[]) {
       break;
     }
   }
+  if (!params.partition && params.single_item) {
+    Error("-i required when displaying a single item\n");
+    errorcnt++;
+  }
   if (errorcnt)
   {
     Usage();