Re: [PATCH v2 4/5] parse-options: introduce `OPTION_UNSIGNED`

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Hi Patrick

On 15/04/2025 13:14, Patrick Steinhardt wrote:

We have two generic ways to parse integers in the "parse-options"
subsytem:

   - `OPTION_INTEGER` parses a signed integer.

   - `OPTION_MAGNITUDE` parses an unsigned integer, but it also
     interprets suffixes like "k" or "g".

Notably missing is a middle ground that parses unsigned integers without
interpreting suffixes. Introduce a new `OPTION_UNSIGNED` option type to
plug this gap. This option type will be used in subsequent commits.
I think this is a useful addition. I wonder about the way it handles negative values though. For types narrower than uintmax_t "-1" will be rejected but large negative values that parse as small positive numbers will be accepted. Perhaps we should explicitly reject strings starting with "-" as we do in git_parse_ulong() which is used by OPTION_MAGNITUDE. This patch also needs the fix from patch 2 to detect overflows for uintmax_t. 

Best Wishes

Phillip
[1] https://lore.kernel.org/git/NYMqsJ7uttDzFT2OOEg5LLsxCSoQhTzqBs16KrMHGEKC7LzOAiYnYTEZavRQWqGH41UgjdwScwer7MssNzI7AEDHnD8GTBWvoBIqJ2e7D6g=@proton.me/ 


Signed-off-by: Patrick Steinhardt <ps@xxxxxx>
---
  parse-options.c               | 43 +++++++++++++++++++++++++++++++++++++++++++
  parse-options.h               | 12 ++++++++++++
  t/helper/test-parse-options.c |  4 +++-
  t/t0040-parse-options.sh      | 18 +++++++++++++++++-
  4 files changed, 75 insertions(+), 2 deletions(-)

diff --git a/parse-options.c b/parse-options.c
index ae836c384c7..9670e46a679 100644
--- a/parse-options.c
+++ b/parse-options.c
@@ -216,6 +216,49 @@ static enum parse_opt_result do_get_value(struct parse_opt_ctx_t *p,
  			    optname(opt, flags));
  		}
  	}
+	case OPTION_UNSIGNED:
+	{
+		uintmax_t upper_bound = UINTMAX_MAX >> (bitsizeof(uintmax_t) - CHAR_BIT * opt->precision);
+		uintmax_t value;
+
+		if (unset) {
+			value = 0;
+		} else if (opt->flags & PARSE_OPT_OPTARG && !p->opt) {
+			value = opt->defval;
+		} else if (get_arg(p, opt, flags, &arg)) {
+			return -1;
+		} else if (!*arg) {
+			return error(_("%s expects a numerical value"),
+				     optname(opt, flags));
+		} else {
+			value = strtoumax(arg, (char **)&s, 10);
+			if (*s)
+				return error(_("%s expects a numerical value"),
+					     optname(opt, flags));
+		}
+
+		if (value > upper_bound)
+			return error(_("value %"PRIuMAX" for %s exceeds %"PRIuMAX),
+				     value, optname(opt, flags), 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));
+		}
+	}
  	case OPTION_MAGNITUDE:
  	{
  		uintmax_t upper_bound = UINTMAX_MAX >> (bitsizeof(uintmax_t) - CHAR_BIT * opt->precision);
diff --git a/parse-options.h b/parse-options.h
index 4b561679581..20ea7d2ab13 100644
--- a/parse-options.h
+++ b/parse-options.h
@@ -25,6 +25,7 @@ enum parse_opt_type {
  	/* options with arguments (usually) */
  	OPTION_STRING,
  	OPTION_INTEGER,
+	OPTION_UNSIGNED,
  	OPTION_MAGNITUDE,
  	OPTION_CALLBACK,
  	OPTION_LOWLEVEL_CALLBACK,
@@ -224,6 +225,16 @@ struct option {
  	.help = (h), \
  	.flags = (f), \
  }
+#define OPT_UNSIGNED_F(s, l, v, h, f) { \
+	.type = OPTION_UNSIGNED, \
+	.short_name = (s), \
+	.long_name = (l), \
+	.value = (v), \
+	.precision = sizeof(*v), \
+	.argh = N_("n"), \
+	.help = (h), \
+	.flags = (f), \
+}
#define OPT_END() { \ 
  	.type = OPTION_END, \
@@ -276,6 +287,7 @@ struct option {
  #define OPT_CMDMODE(s, l, v, h, i)  OPT_CMDMODE_F(s, l, v, h, i, 0)
#define OPT_INTEGER(s, l, v, h) OPT_INTEGER_F(s, l, v, h, 0) 
+#define OPT_UNSIGNED(s, l, v, h)    OPT_UNSIGNED_F(s, l, v, h, 0)
  #define OPT_MAGNITUDE(s, l, v, h) { \
  	.type = OPTION_MAGNITUDE, \
  	.short_name = (s), \
diff --git a/t/helper/test-parse-options.c b/t/helper/test-parse-options.c
index 46deb4317ef..0d559288d9c 100644
--- a/t/helper/test-parse-options.c
+++ b/t/helper/test-parse-options.c
@@ -120,7 +120,7 @@ int cmd__parse_options(int argc, const char **argv)
  	};
  	struct string_list expect = STRING_LIST_INIT_NODUP;
  	struct string_list list = STRING_LIST_INIT_NODUP;
-	uint16_t m16 = 0;
+	uint16_t m16 = 0, u16 = 0;
  	int16_t i16 = 0;
struct option options[] = { 
@@ -142,6 +142,7 @@ int cmd__parse_options(int argc, const char **argv)
  		OPT_GROUP(""),
  		OPT_INTEGER('i', "integer", &integer, "get a integer"),
  		OPT_INTEGER(0, "i16", &i16, "get a 16 bit integer"),
+		OPT_UNSIGNED(0, "u16", &u16, "get a 16 bit unsigned integer"),
  		OPT_INTEGER('j', NULL, &integer, "get a integer, too"),
  		OPT_MAGNITUDE('m', "magnitude", &magnitude, "get a magnitude"),
  		OPT_MAGNITUDE(0, "m16", &m16, "get a 16 bit magnitude"),
@@ -215,6 +216,7 @@ int cmd__parse_options(int argc, const char **argv)
  	show(&expect, &ret, "boolean: %d", boolean);
  	show(&expect, &ret, "integer: %d", integer);
  	show(&expect, &ret, "i16: %"PRIdMAX, (intmax_t) i16);
+	show(&expect, &ret, "u16: %"PRIuMAX, (uintmax_t) u16);
  	show(&expect, &ret, "magnitude: %lu", magnitude);
  	show(&expect, &ret, "m16: %"PRIuMAX, (uintmax_t) m16);
  	show(&expect, &ret, "timestamp: %"PRItime, timestamp);
diff --git a/t/t0040-parse-options.sh b/t/t0040-parse-options.sh
index 5f503b26cc8..9946e69f586 100755
--- a/t/t0040-parse-options.sh
+++ b/t/t0040-parse-options.sh
@@ -23,6 +23,7 @@ usage: test-tool parse-options <options>
      -i, --[no-]integer <n>
                            get a integer
      --[no-]i16 <n>        get a 16 bit integer
+    --[no-]u16 <n>        get a 16 bit unsigned integer
      -j <n>                get a integer, too
      -m, --magnitude <n>   get a magnitude
      --m16 <n>             get a 16 bit magnitude
@@ -139,6 +140,7 @@ cat >expect <<\EOF
  boolean: 2
  integer: 1729
  i16: 0
+u16: 0
  magnitude: 16384
  m16: 0
  timestamp: 0
@@ -161,6 +163,7 @@ cat >expect <<\EOF
  boolean: 2
  integer: 1729
  i16: 9000
+u16: 5432
  magnitude: 16384
  m16: 32768
  timestamp: 0
@@ -173,7 +176,7 @@ file: prefix/fi.le
  EOF
test_expect_success 'long options' ' 
-	test-tool parse-options --boolean --integer 1729 --i16 9000 --magnitude 16k \
+	test-tool parse-options --boolean --integer 1729 --i16 9000 --u16 5432 --magnitude 16k \
  		--m16 32k --boolean --string2=321 --verbose --verbose --no-dry-run \
  		--abbrev=10 --file fi.le --obsolete \
  		>output 2>output.err &&
@@ -186,6 +189,7 @@ test_expect_success 'abbreviate to something longer than SHA1 length' '
  	boolean: 0
  	integer: 0
  	i16: 0
+	u16: 0
  	magnitude: 0
  	m16: 0
  	timestamp: 0
@@ -262,6 +266,7 @@ cat >expect <<\EOF
  boolean: 1
  integer: 13
  i16: 0
+u16: 0
  magnitude: 0
  m16: 0
  timestamp: 0
@@ -287,6 +292,7 @@ cat >expect <<\EOF
  boolean: 0
  integer: 2
  i16: 0
+u16: 0
  magnitude: 0
  m16: 0
  timestamp: 0
@@ -356,6 +362,7 @@ Callback: "four", 0
  boolean: 5
  integer: 4
  i16: 0
+u16: 0
  magnitude: 0
  m16: 0
  timestamp: 0
@@ -383,6 +390,7 @@ cat >expect <<\EOF
  boolean: 1
  integer: 23
  i16: 0
+u16: 0
  magnitude: 0
  m16: 0
  timestamp: 0
@@ -464,6 +472,7 @@ cat >expect <<\EOF
  boolean: 0
  integer: 0
  i16: 0
+u16: 0
  magnitude: 0
  m16: 0
  timestamp: 0
@@ -820,4 +829,11 @@ test_expect_success 'm16 limits range' '
  	test_grep "value 65536 for option .m16. exceeds 65535" err
  '
+test_expect_success 'u16 limits range' ' 
+	test-tool parse-options --u16 65535 >out &&
+	test_grep "u16: 65535" out &&
+	test_must_fail test-tool parse-options --u16 65536 2>err &&
+	test_grep "value 65536 for option .u16. exceeds 65535" err
+'
+
  test_done
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