lib/crypt.h: provide list of supported hash algorithms

Makefile.am

@@ -384,6 +384,7 @@ check_PROGRAMS = \
 	test/checksalt \
 	test/compile-strong-alias \
 	test/crypt-badargs \
+	test/crypt-get-supported-hash-methods \
 	test/crypt-gost-yescrypt \
 	test/crypt-nested-call \
 	test/crypt-sm3-yescrypt \
@@ -509,6 +510,7 @@ test_checksalt_LDADD = $(COMMON_TEST_OBJECTS)
 test_des_obsolete_LDADD = $(COMMON_TEST_OBJECTS)
 test_des_obsolete_r_LDADD = $(COMMON_TEST_OBJECTS)
 test_crypt_badargs_LDADD = $(COMMON_TEST_OBJECTS)
+test_crypt_get_supported_hash_methods_LDADD = $(COMMON_TEST_OBJECTS)
 test_crypt_nested_call_LDADD = $(COMMON_TEST_OBJECTS)
 test_crypt_too_long_phrase_LDADD = $(COMMON_TEST_OBJECTS)
 test_preferred_method_LDADD = $(COMMON_TEST_OBJECTS)

build-aux/scripts/gen-crypt-hashes-h

@@ -110,6 +110,16 @@ EOT
 
 #define HASH_ALGORITHM_DEFAULT "$default_prefix"
 EOT
+
+    # List of supported hash methods
+    my @provided_hashes = ();
+    while (my ($e, $v) = each %{$hconf->hashes}){
+        if ($enabled{$e}) {
+            push @provided_hashes, "$e:@{[$v->prefix]}";
+        }
+    }
+    print "\n#define SUPPORTED_HASH_METHODS \\\n";
+    print '  "' . (join ";\" \\\n  \"", sort @provided_hashes) . '"';
     print <<'EOT';
 
 #endif /* crypt-hashes.h */

lib/crypt.c

@@ -419,3 +419,9 @@ crypt_preferred_method (void)
 }
 SYMVER_crypt_preferred_method;
 #endif
+
+const char *crypt_get_supported_hash_methods(void)
+{
+    return SUPPORTED_HASH_METHODS;
+}
+SYMVER_crypt_get_supported_hash_methods;

lib/crypt.h.in

@@ -244,6 +244,11 @@ extern const char *crypt_preferred_method (void);
 /* Version number as a string constant.  */
 #define XCRYPT_VERSION_STR "@XCRYPT_VERSION_STR@"
 
+/* List of provided by the current build hash algorithms*/
+
+#define CRYPT_GET_SUPPORTED_HASH_METHODS_AVAILABLE 1
+extern const char *crypt_get_supported_hash_methods(void);
+
 @END_DECLS@
 
 #endif /* crypt.h */

lib/libcrypt.map.in

@@ -19,6 +19,7 @@ crypt_gensalt_ra	XCRYPT_2.0	GLIBC_2.0:owl:suse	GLIBC_2.2.2:alt     OW_CRYPT_1.0:
 # Actively supported interfaces from libxcrypt.
 crypt_checksalt		XCRYPT_4.3
 crypt_preferred_method	XCRYPT_4.4
+crypt_get_supported_hash_methods XCRYPT_4.5
 
 # Interfaces for code compatibility with libxcrypt v3.1.1 and earlier.
 # No longer available to new binaries.  Include in version-script, only
@@ -45,4 +46,4 @@ fcrypt			-		GLIBC_2.0
 %chain GLIBC_2.3 GLIBC_2.4 GLIBC_2.12 GLIBC_2.16 GLIBC_2.17 GLIBC_2.18
 %chain GLIBC_2.21 GLIBC_2.27 GLIBC_2.29 GLIBC_2.32 GLIBC_2.33 GLIBC_2.35
 %chain GLIBC_2.36 GLIBC_2.38
-%chain OW_CRYPT_1.0 XCRYPT_2.0 XCRYPT_4.3 XCRYPT_4.4
+%chain OW_CRYPT_1.0 XCRYPT_2.0 XCRYPT_4.3 XCRYPT_4.4 XCRYPT_4.5

test/crypt-get-supported-hash-methods.c

@@ -0,0 +1,76 @@
+#include <stdio.h>
+#include <string.h>
+
+#include "crypt-port.h"
+
+const char defined_hash_methods[] =
+#if INCLUDE_bcrypt
+  "bcrypt:$2b$;"
+#endif
+#if INCLUDE_bcrypt_a
+  "bcrypt_a:$2a$;"
+#endif
+#if INCLUDE_bcrypt_x
+  "bcrypt_x:$2x$;"
+#endif
+#if INCLUDE_bcrypt_y
+  "bcrypt_y:$2y$;"
+#endif
+#if INCLUDE_bigcrypt
+  "bigcrypt:;"
+#endif
+#if INCLUDE_bsdicrypt
+  "bsdicrypt:_;"
+#endif
+#if INCLUDE_descrypt
+  "descrypt:;"
+#endif
+#if INCLUDE_gost_yescrypt
+  "gost_yescrypt:$gy$;"
+#endif
+#if INCLUDE_md5crypt
+  "md5crypt:$1$;"
+#endif
+#if INCLUDE_nt
+  "nt:$3$;"
+#endif
+#if INCLUDE_scrypt
+  "scrypt:$7$;"
+#endif
+#if INCLUDE_sha1crypt
+  "sha1crypt:$sha1;"
+#endif
+#if INCLUDE_sha256crypt
+  "sha256crypt:$5$;"
+#endif
+#if INCLUDE_sha512crypt
+  "sha512crypt:$6$;"
+#endif
+#if INCLUDE_sm3_yescrypt
+  "sm3_yescrypt:$sm3y$;"
+#endif
+#if INCLUDE_sm3crypt
+  "sm3crypt:$sm3$;"
+#endif
+#if INCLUDE_sunmd5
+  "sunmd5:$md5;"
+#endif
+#if INCLUDE_yescrypt
+  "yescrypt:$y$;"
+#endif
+"";
+
+int main(void)
+{
+    const char *expected = defined_hash_methods;
+    const char *reported = crypt_get_supported_hash_methods();
+    size_t len1 = strlen(expected) - 1, len2 = strlen(reported);
+    int res = (len1 != len2 || strncmp(expected, reported, len2));
+
+    // Assume there is ";" in the end of defined_hash_methods
+    fprintf(stderr, "Compiled and reported by"
+            " crypt_get_supported_hash_methods() lists of supported"
+            " hash methods are %sequal:\n\"%s\" %s=\n\"%s;\"\n",
+            (res ? "NOT " : ""), expected, (res ? "!" : "="), reported);
+    return res;
+}