[PATCH v2 3/7] parse-options: add precision handling for OPTION_SET_INT

["René Scharfe" <l.s.r@web.de>]

Similar to 09705696f7 (parse-options: introduce precision handling for
`OPTION_INTEGER`, 2025-04-17) support value variables of different sizes
for OPTION_SET_INT.  Do that by requiring their "precision" to be set,
casting their "value" pointer accordingly and checking whether the value
fits.

Factor out the casting code from the part of do_get_value() that handles
OPTION_INTEGER to avoid code duplication.  We're going to use it in the
next patches as well.

Signed-off-by: René Scharfe <l.s.r@web.de>
---
 builtin/update-index.c        |  6 ++++
 parse-options.c               | 56 ++++++++++++++++++++++-------------
 parse-options.h               |  2 ++
 t/helper/test-parse-options.c |  1 +
 4 files changed, 45 insertions(+), 20 deletions(-)

diff --git a/builtin/update-index.c b/builtin/update-index.c
index 538b619ba4..0c1d4ed55b 100644
--- a/builtin/update-index.c
+++ b/builtin/update-index.c
@@ -981,6 +981,7 @@ int cmd_update_index(int argc,
 			.type = OPTION_SET_INT,
 			.long_name = "assume-unchanged",
 			.value = &mark_valid_only,
+			.precision = sizeof(mark_valid_only),
 			.help = N_("mark files as \"not changing\""),
 			.flags = PARSE_OPT_NOARG | PARSE_OPT_NONEG,
 			.defval = MARK_FLAG,
@@ -989,6 +990,7 @@ int cmd_update_index(int argc,
 			.type = OPTION_SET_INT,
 			.long_name = "no-assume-unchanged",
 			.value = &mark_valid_only,
+			.precision = sizeof(mark_valid_only),
 			.help = N_("clear assumed-unchanged bit"),
 			.flags = PARSE_OPT_NOARG | PARSE_OPT_NONEG,
 			.defval = UNMARK_FLAG,
@@ -997,6 +999,7 @@ int cmd_update_index(int argc,
 			.type = OPTION_SET_INT,
 			.long_name = "skip-worktree",
 			.value = &mark_skip_worktree_only,
+			.precision = sizeof(mark_skip_worktree_only),
 			.help = N_("mark files as \"index-only\""),
 			.flags = PARSE_OPT_NOARG | PARSE_OPT_NONEG,
 			.defval = MARK_FLAG,
@@ -1005,6 +1008,7 @@ int cmd_update_index(int argc,
 			.type = OPTION_SET_INT,
 			.long_name = "no-skip-worktree",
 			.value = &mark_skip_worktree_only,
+			.precision = sizeof(mark_skip_worktree_only),
 			.help = N_("clear skip-worktree bit"),
 			.flags = PARSE_OPT_NOARG | PARSE_OPT_NONEG,
 			.defval = UNMARK_FLAG,
@@ -1079,6 +1083,7 @@ int cmd_update_index(int argc,
 			.type = OPTION_SET_INT,
 			.long_name = "fsmonitor-valid",
 			.value = &mark_fsmonitor_only,
+			.precision = sizeof(mark_fsmonitor_only),
 			.help = N_("mark files as fsmonitor valid"),
 			.flags = PARSE_OPT_NOARG | PARSE_OPT_NONEG,
 			.defval = MARK_FLAG,
@@ -1087,6 +1092,7 @@ int cmd_update_index(int argc,
 			.type = OPTION_SET_INT,
 			.long_name = "no-fsmonitor-valid",
 			.value = &mark_fsmonitor_only,
+			.precision = sizeof(mark_fsmonitor_only),
 			.help = N_("clear fsmonitor valid bit"),
 			.flags = PARSE_OPT_NOARG | PARSE_OPT_NONEG,
 			.defval = UNMARK_FLAG,
diff --git a/parse-options.c b/parse-options.c
index ddac008a5e..639f41b83b 100644
--- a/parse-options.c
+++ b/parse-options.c
@@ -88,6 +88,36 @@ static int do_get_int_value(const void *value, size_t precision, intmax_t *ret)
 	}
 }
 
+static enum parse_opt_result set_int_value(const struct option *opt,
+					   enum opt_parsed flags,
+					   intmax_t value)
+{
+	switch (opt->precision) {
+	case sizeof(int8_t):
+		*(int8_t *)opt->value = value;
+		return 0;
+	case sizeof(int16_t):
+		*(int16_t *)opt->value = value;
+		return 0;
+	case sizeof(int32_t):
+		*(int32_t *)opt->value = value;
+		return 0;
+	case sizeof(int64_t):
+		*(int64_t *)opt->value = value;
+		return 0;
+	default:
+		BUG("invalid precision for option %s", optname(opt, flags));
+	}
+}
+
+static int signed_int_fits(intmax_t value, size_t precision)
+{
+	size_t bits = precision * CHAR_BIT;
+	intmax_t upper_bound = INTMAX_MAX >> (bitsizeof(intmax_t) - bits);
+	intmax_t lower_bound = -upper_bound - 1;
+	return lower_bound <= value && value <= upper_bound;
+}
+
 static enum parse_opt_result do_get_value(struct parse_opt_ctx_t *p,
 					  const struct option *opt,
 					  enum opt_parsed flags,
@@ -136,8 +166,7 @@ static enum parse_opt_result do_get_value(struct parse_opt_ctx_t *p,
 		return 0;
 
 	case OPTION_SET_INT:
-		*(int *)opt->value = unset ? 0 : opt->defval;
-		return 0;
+		return set_int_value(opt, flags, unset ? 0 : opt->defval);
 
 	case OPTION_STRING:
 		if (unset)
@@ -219,23 +248,7 @@ static enum parse_opt_result do_get_value(struct parse_opt_ctx_t *p,
 			return error(_("value %s for %s not in range [%"PRIdMAX",%"PRIdMAX"]"),
 				     arg, optname(opt, flags), (intmax_t)lower_bound, (intmax_t)upper_bound);
 
-		switch (opt->precision) {
-		case 1:
-			*(int8_t *)opt->value = value;
-			return 0;
-		case 2:
-			*(int16_t *)opt->value = value;
-			return 0;
-		case 4:
-			*(int32_t *)opt->value = value;
-			return 0;
-		case 8:
-			*(int64_t *)opt->value = value;
-			return 0;
-		default:
-			BUG("invalid precision for option %s",
-			    optname(opt, flags));
-		}
+		return set_int_value(opt, flags, value);
 	}
 	case OPTION_UNSIGNED:
 	{
@@ -617,10 +630,13 @@ static void parse_options_check(const struct option *opts)
 		    opts->long_name && !(opts->flags & PARSE_OPT_NONEG))
 			optbug(opts, "OPTION_SET_INT 0 should not be negatable");
 		switch (opts->type) {
+		case OPTION_SET_INT:
+			if (!signed_int_fits(opts->defval, opts->precision))
+				optbug(opts, "has invalid defval");
+			/* fallthru */
 		case OPTION_COUNTUP:
 		case OPTION_BIT:
 		case OPTION_NEGBIT:
-		case OPTION_SET_INT:
 		case OPTION_NUMBER:
 		case OPTION_BITOP:
 			if ((opts->flags & PARSE_OPT_OPTARG) ||
diff --git a/parse-options.h b/parse-options.h
index c75a473c9e..71516e4b5b 100644
--- a/parse-options.h
+++ b/parse-options.h
@@ -190,6 +190,7 @@ struct option {
 	.short_name = (s), \
 	.long_name = (l), \
 	.value = (v), \
+	.precision = sizeof(*v), \
 	.help = (h), \
 	.flags = PARSE_OPT_NOARG | (f), \
 	.defval = (i), \
@@ -260,6 +261,7 @@ struct option {
 	.short_name = (s), \
 	.long_name = (l), \
 	.value = (v), \
+	.precision = sizeof(*v), \
 	.help = (h), \
 	.flags = PARSE_OPT_NOARG | PARSE_OPT_HIDDEN, \
 	.defval = 1, \
diff --git a/t/helper/test-parse-options.c b/t/helper/test-parse-options.c
index 1e03ff88f6..2ba2546d70 100644
--- a/t/helper/test-parse-options.c
+++ b/t/helper/test-parse-options.c
@@ -131,6 +131,7 @@ int cmd__parse_options(int argc, const char **argv)
 			.short_name = 'B',
 			.long_name = "no-fear",
 			.value = &boolean,
+			.precision = sizeof(boolean),
 			.help = "be brave",
 			.flags = PARSE_OPT_NOARG | PARSE_OPT_NONEG,
 			.defval = 1,
-- 
2.50.0