From adfa8e1265f6155d1a582baa9929af198bb5d4de Mon Sep 17 00:00:00 2001
From: Mattias Andrée <m@maandree.se>
Date: Fri, 1 May 2026 17:45:39 +0200
Subject: Misc
MIME-Version: 1.0
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Content-Transfer-Encoding: 8bit

Signed-off-by: Mattias Andrée <m@maandree.se>
---
 librecrypt_settings_prefix.c | 104 ++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 93 insertions(+), 11 deletions(-)

(limited to 'librecrypt_settings_prefix.c')

diff --git a/librecrypt_settings_prefix.c b/librecrypt_settings_prefix.c
index edc7222..7568bb3 100644
--- a/librecrypt_settings_prefix.c
+++ b/librecrypt_settings_prefix.c
@@ -3,30 +3,112 @@
 #ifndef TEST
 
 
-extern inline size_t librecrypt_settings_prefix(const char *hash);
+size_t
+librecrypt_settings_prefix(const char *hash, size_t *hashsize_out)
+{
+	size_t i, len, ret = 0u;
+	size_t last_offset = 0u;
+	const struct algorithm *algo;
+	uintmax_t hashsize;
+
+	/* Find last algorithm, and beginning of result */
+	for (i = 0u; hash[i]; i++) {
+		if (hash[i] == LIBRECRYPT_HASH_COMPOSITION_DELIMITER)
+			ret = i + 1u;
+		else if (hash[i] == LIBRECRYPT_ALGORITHM_LINK_DELIMITER)
+			last_offset = ret = i + 1u;
+	}
+	/* and get `strlen(hash)` */
+	len = i;
+
+	/* TODO "_" is a prefix that is being used */
+
+	/* Return if hash size is not required */
+	if (!hashsize_out)
+		goto out;
+	/* Return 0 as hash size if default is specified */
+	if (ret == i)
+		goto zero;
+	/* Return 0 as hash size if algorithm cannot be identified or has fixed hash size */
+	algo = librecrypt_find_first_algorithm_(&hash[last_offset], len - last_offset);
+	if (!algo || !algo->flexible_hash_size)
+		goto zero;
+
+	/* Get the hash size */
+	if (!librecrypt_check_settings_(&hash[ret], len - ret, "%^b",
+	                                &hashsize, (uintmax_t)1u, (uintmax_t)SIZE_MAX,
+	                                algo->decoding_lut, algo->pad, algo->strict_pad))
+		goto zero;
+
+	*hashsize_out = (size_t)hashsize;
+	goto out;
+
+zero:
+	*hashsize_out = 0u;
+out:
+	return ret;
+}
 
 
 #else
 
 
-#define CHECK(PREFIX, SUFFIX)\
+#define CHECK_NULL(PREFIX, SUFFIX)\
+	do {\
+		EXPECT(librecrypt_settings_prefix(PREFIX SUFFIX, NULL) == sizeof(PREFIX) - 1u);\
+		EXPECT(librecrypt_settings_prefix(PREFIX, NULL) == sizeof(PREFIX) - 1u); \
+	} while (0)
+
+#if 0
+#define CHECK_ASTERISK(PREFIX, SUFFIX, HASH)\
+	do {\
+		size_t hashsize = 99999u;\
+		EXPECT(librecrypt_settings_prefix(PREFIX SUFFIX #HASH, &hashsize) == sizeof(PREFIX) - 1u);\
+		EXPECT(hashsize == HASH##u);\
+	} while (0)
+
+#define CHECK_ZERO(PREFIX, SUFFIX)\
 	do {\
-		EXPECT(librecrypt_settings_prefix(PREFIX SUFFIX) == sizeof(PREFIX) - 1u);\
-		EXPECT(librecrypt_settings_prefix(PREFIX) == sizeof(PREFIX) - 1u);\
+		size_t hashsize = 99999u;\
+		EXPECT(librecrypt_settings_prefix(PREFIX SUFFIX, &hashsize) == sizeof(PREFIX) - 1u);\
+		EXPECT(hashsize == 0u);\
 	} while (0)
 
+#define CHECK_HASHED(PREFIX, SUFFIX, HASH)\
+	do {\
+		size_t hashsize = 99999u;\
+		EXPECT(librecrypt_settings_prefix(PREFIX SUFFIX, &hashsize) == sizeof(PREFIX) - 1u);\
+		EXPECT(hashsize == HASH##u);\
+	} while (0)
+#endif
+
 
 int
 main(void)
 {
 	SET_UP_ALARM();
-	CHECK("", "result");
-	CHECK(">", "double-des result");
-	CHECK("$", "x");
-	CHECK("y$", "x");
-	CHECK("y>", "x");
-	CHECK("a$b$c>d$e$", "x");
-	CHECK("a$b$c>", "x");
+
+	/* Simple cases */
+	CHECK_NULL("", "result");
+	CHECK_NULL(">", "double-des result");
+	CHECK_NULL("$", "x");
+	CHECK_NULL("y$", "x");
+	CHECK_NULL("y>", "x");
+	CHECK_NULL("a$b$c>d$e$", "x");
+	CHECK_NULL("a$b$c>", "x");
+
+	/* Discard asterisk-notation */
+	CHECK_NULL("", "*10");
+	CHECK_NULL(">", "*11");
+	CHECK_NULL("$", "*12");
+	CHECK_NULL("y$", "*13");
+	CHECK_NULL("y>", "*012");
+	CHECK_NULL("a$b$c>d$e$", "*1");
+	CHECK_NULL("a$b$c>", "*2");
+	CHECK_NULL("a$b$c>*10$", "*2");
+
+	/* TODO test hash size output (requires algorithms) */
+
 	return 0;
 }
 
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