New utility program psa/psa_constant_names

Print the symbolic name corresponding to a numerical value.

Supported types: status values, algorithms, elliptic curves,
key types, key usage masks.

The program is partly generated from parsing psa/crypto.h with a few
hard-coded assumptions. This isn't ideal but it works and requires
little machinery.
diff --git a/programs/.gitignore b/programs/.gitignore
index 0241896..327dbdc 100644
--- a/programs/.gitignore
+++ b/programs/.gitignore
@@ -29,6 +29,8 @@
 pkey/rsa_sign_pss
 pkey/rsa_verify
 pkey/rsa_verify_pss
+psa/psa_constant_names
+psa/psa_constant_names_generated.c
 random/gen_entropy
 random/gen_random_ctr_drbg
 random/gen_random_havege
diff --git a/programs/Makefile b/programs/Makefile
index b6d1fa2..c65a10c 100644
--- a/programs/Makefile
+++ b/programs/Makefile
@@ -60,6 +60,7 @@
 	pkey/rsa_decrypt$(EXEXT)	pkey/rsa_encrypt$(EXEXT)	\
 	pkey/rsa_sign$(EXEXT)		pkey/rsa_verify$(EXEXT)		\
 	pkey/rsa_sign_pss$(EXEXT)	pkey/rsa_verify_pss$(EXEXT)	\
+	psa/psa_constant_names$(EXEXT)	\
 	ssl/dtls_client$(EXEXT)		ssl/dtls_server$(EXEXT)		\
 	ssl/ssl_client1$(EXEXT)		ssl/ssl_client2$(EXEXT)		\
 	ssl/ssl_server$(EXEXT)		ssl/ssl_server2$(EXEXT)		\
@@ -83,6 +84,8 @@
 APPS += test/cpp_dummy_build$(EXEXT)
 endif
 
+EXTRA_GENERATED =
+
 .SILENT:
 
 .PHONY: all clean list
@@ -92,6 +95,11 @@
 $(DEP):
 	$(MAKE) -C ../library
 
+EXTRA_GENERATED += psa/psa_constant_names_generated.c
+psa/psa_constant_names$(EXEXT): psa/psa_constant_names_generated.c
+psa/psa_constant_names_generated.c: ../scripts/generate_psa_constants.py ../include/psa/crypto.h
+	../scripts/generate_psa_constants.py
+
 aes/aescrypt2$(EXEXT): aes/aescrypt2.c $(DEP)
 	echo "  CC    aes/aescrypt2.c"
 	$(CC) $(LOCAL_CFLAGS) $(CFLAGS) aes/aescrypt2.c    $(LOCAL_LDFLAGS) $(LDFLAGS) -o $@
@@ -188,6 +196,10 @@
 	echo "  CC    pkey/rsa_encrypt.c"
 	$(CC) $(LOCAL_CFLAGS) $(CFLAGS) pkey/rsa_encrypt.c    $(LOCAL_LDFLAGS) $(LDFLAGS) -o $@
 
+psa/psa_constant_names$(EXEXT): psa/psa_constant_names.c $(DEP)
+	echo "  CC    psa/psa_constant_names.c"
+	$(CC) $(LOCAL_CFLAGS) $(CFLAGS) psa/psa_constant_names.c    $(LOCAL_LDFLAGS) $(LDFLAGS) -o $@
+
 random/gen_entropy$(EXEXT): random/gen_entropy.c $(DEP)
 	echo "  CC    random/gen_entropy.c"
 	$(CC) $(LOCAL_CFLAGS) $(CFLAGS) random/gen_entropy.c $(LOCAL_LDFLAGS) $(LDFLAGS) -o $@
@@ -294,9 +306,9 @@
 
 clean:
 ifndef WINDOWS
-	rm -f $(APPS)
+	rm -f $(APPS) $(EXTRA_GENERATED)
 else
-	del /S /Q /F *.o *.exe
+	del /S /Q /F *.o *.exe $(EXTRA_GENERATED)
 endif
 
 list:
diff --git a/programs/psa/psa_constant_names.c b/programs/psa/psa_constant_names.c
new file mode 100644
index 0000000..d422e14
--- /dev/null
+++ b/programs/psa/psa_constant_names.c
@@ -0,0 +1,157 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "psa/crypto.h"
+
+/* There are different GET_HASH macros for different kinds of algorithms
+ * built from hashes, but the values are all constructed on the
+ * same model. */
+#define PSA_ALG_GET_HASH(alg)                                   \
+    (((alg) & PSA_ALG_HASH_MASK) | PSA_ALG_CATEGORY_HASH)
+
+static void append(char **buffer, size_t buffer_size,
+                   size_t *required_size,
+                   const char *string, size_t length)
+{
+    *required_size += length;
+    if (*required_size < buffer_size) {
+        memcpy(*buffer, string, length);
+        *buffer += length;
+    }
+}
+
+/* The code of these function is automatically generated and included below. */
+static const char *psa_ecc_curve_name(psa_ecc_curve_t curve);
+static const char *psa_hash_algorithm_name(psa_algorithm_t hash_alg);
+
+static void append_with_curve(char **buffer, size_t buffer_size,
+                              size_t *required_size,
+                              const char *string, size_t length,
+                              psa_ecc_curve_t curve)
+{
+    const char *curve_name = psa_ecc_curve_name(curve);
+    append(buffer, buffer_size, required_size, string, length);
+    append(buffer, buffer_size, required_size, "(", 1);
+    if (curve_name != NULL) {
+        append(buffer, buffer_size, required_size,
+               curve_name, strlen(curve_name));
+    } else {
+        size_t n = snprintf(*buffer, buffer_size - *required_size,
+                            "0x%04x", (unsigned) curve);
+        if (n < buffer_size - *required_size) *buffer += n;
+        *required_size += n;
+    }
+    append(buffer, buffer_size, required_size, ")", 1);
+}
+
+static void append_with_hash(char **buffer, size_t buffer_size,
+                             size_t *required_size,
+                             const char *string, size_t length,
+                             psa_algorithm_t hash_alg)
+{
+    const char *hash_name = psa_hash_algorithm_name(hash_alg);
+    append(buffer, buffer_size, required_size, string, length);
+    append(buffer, buffer_size, required_size, "(", 1);
+    if (hash_name != NULL) {
+        append(buffer, buffer_size, required_size,
+               hash_name, strlen(hash_name));
+    } else {
+        size_t n = snprintf(*buffer, buffer_size - *required_size,
+                            "0x%08lx", (unsigned long) hash_alg);
+        if (n < buffer_size - *required_size) *buffer += n;
+        *required_size += n;
+    }
+    append(buffer, buffer_size, required_size, ")", 1);
+}
+
+#include "psa_constant_names_generated.c"
+
+static int psa_snprint_status(char *buffer, size_t buffer_size,
+                              psa_status_t status)
+{
+    const char *name = psa_strerror(status);
+    if (name == NULL) {
+        return snprintf(buffer, buffer_size, "%ld", (long) status);
+    } else {
+        size_t length = strlen(name);
+        if (length < buffer_size) {
+            memcpy(buffer, name, length + 1);
+            return length;
+        } else {
+            return buffer_size;
+        }
+    }
+}
+
+static int psa_snprint_ecc_curve(char *buffer, size_t buffer_size,
+                                 psa_ecc_curve_t curve)
+{
+    const char *name = psa_ecc_curve_name(curve);
+    if (name == NULL) {
+        return snprintf(buffer, buffer_size, "0x%04x", (unsigned) curve);
+    } else {
+        size_t length = strlen(name);
+        if (length < buffer_size) {
+            memcpy(buffer, name, length + 1);
+            return length;
+        } else {
+            return buffer_size;
+        }
+    }
+}
+
+static void usage(const char *program_name)
+{
+    printf("Usage: %s TYPE VALUE\n",
+           program_name == NULL ? "psa_constant_names" : program_name);
+    printf("Print the symbolic name whose numerical value is VALUE in TYPE.\n");
+    printf("Supported types (with = between aliases):\n");
+    printf("  alg=algorithm         Status code (psa_algorithm_t)\n");
+    printf("  curve=ecc_curve       Elliptic curve identifier (psa_ecc_curve_t)\n");
+    printf("  type=key_type         Status code (psa_key_type_t)\n");
+    printf("  usage=key_usage       Key usage (psa_key_usage_t)\n");
+    printf("  error=status          Status code (psa_status_t)\n");
+}
+
+int main(int argc, char *argv[])
+{
+    char buffer[200];
+    unsigned long value;
+    char *end;
+
+    if (argc <= 1 ||
+        !strcmp(argv[1], "help") ||
+        !strcmp(argv[1], "--help"))
+    {
+        usage(argv[0]);
+        return EXIT_FAILURE;
+    }
+    if (argc != 3) {
+        usage(argv[0]);
+        return EXIT_FAILURE;
+    }
+    value = strtoul(argv[2], &end, 0);
+    if (*end) {
+        printf("Non-numeric value: %s\n", argv[2]);
+        return EXIT_FAILURE;
+    }
+
+    if (!strcmp(argv[1], "error") || !strcmp(argv[1], "status"))
+        psa_snprint_status(buffer, sizeof(buffer), value);
+    else if (!strcmp(argv[1], "alg") || !strcmp(argv[1], "algorithm"))
+        psa_snprint_algorithm(buffer, sizeof(buffer), value);
+    else if (!strcmp(argv[1], "curve") || !strcmp(argv[1], "ecc_curve"))
+        psa_snprint_ecc_curve(buffer, sizeof(buffer), value);
+    else if (!strcmp(argv[1], "type") || !strcmp(argv[1], "key_type"))
+        psa_snprint_key_type(buffer, sizeof(buffer), value);
+    else if (!strcmp(argv[1], "usage") || !strcmp(argv[1], "key_usage"))
+        psa_snprint_key_usage(buffer, sizeof(buffer), value);
+    else {
+        printf("Unknown type: %s\n", argv[1]);
+        return EXIT_FAILURE;
+    }
+
+    puts(buffer);
+    return EXIT_SUCCESS;
+}
diff --git a/scripts/generate_psa_constants.py b/scripts/generate_psa_constants.py
new file mode 100755
index 0000000..e4cb45b
--- /dev/null
+++ b/scripts/generate_psa_constants.py
@@ -0,0 +1,301 @@
+#!/usr/bin/env python
+import os
+import re
+import sys
+
+output_template = '''\
+/* Automatically generated by generate_psa_constant.py. DO NOT EDIT. */
+
+static const char *psa_strerror(psa_status_t status)
+{
+    switch (status) {
+    %(status_cases)s
+    default: return NULL;
+    }
+}
+
+static const char *psa_ecc_curve_name(psa_ecc_curve_t curve)
+{
+    switch (curve) {
+    %(ecc_curve_cases)s
+    default: return NULL;
+    }
+}
+
+static const char *psa_hash_algorithm_name(psa_algorithm_t hash_alg)
+{
+    switch (hash_alg) {
+    %(hash_algorithm_cases)s
+    default: return NULL;
+    }
+}
+
+static int psa_snprint_key_type(char *buffer, size_t buffer_size,
+                                psa_key_type_t type)
+{
+    size_t required_size = 0;
+    switch (type) {
+    %(key_type_cases)s
+    default:
+        %(key_type_code)s{
+            return snprintf(buffer, buffer_size,
+                            "0x%%08lx", (unsigned long) type);
+        }
+        break;
+    }
+    buffer[0] = 0;
+    return required_size;
+}
+
+static void append_padding_mode(char **buffer, size_t buffer_size,
+                                size_t *required_size,
+                                psa_algorithm_t padding_mode)
+{
+    size_t n;
+    append(buffer, buffer_size, required_size, " | ", 3);
+    switch (padding_mode) {
+    %(padding_mode_cases)s
+    default:
+        n = snprintf(*buffer, buffer_size - *required_size,
+                     "0x%%08lx", (unsigned long) padding_mode);
+        if (n < buffer_size - *required_size) *buffer += n;
+        *required_size += n;
+        break;
+    }
+}
+
+static int psa_snprint_algorithm(char *buffer, size_t buffer_size,
+                                 psa_algorithm_t alg)
+{
+    size_t required_size = 0;
+    psa_algorithm_t padding_mode = -1;
+    psa_algorithm_t alg_without_padding = alg;
+    if (PSA_ALG_IS_CIPHER(alg) && PSA_ALG_IS_BLOCK_CIPHER(alg)) {
+            padding_mode = alg & PSA_ALG_BLOCK_CIPHER_PADDING_MASK;
+            alg_without_padding = alg & ~PSA_ALG_BLOCK_CIPHER_PADDING_MASK;
+    }
+    switch (alg_without_padding) {
+    %(algorithm_cases)s
+    default:
+        %(algorithm_code)s{
+            return snprintf(buffer, buffer_size,
+                            "0x%%08lx", (unsigned long) alg);
+        }
+        break;
+    }
+    if (padding_mode != (psa_algorithm_t) -1) {
+        append_padding_mode(&buffer, buffer_size, &required_size, padding_mode);
+    }
+    buffer[0] = 0;
+    return required_size;
+}
+
+static int psa_snprint_key_usage(char *buffer, size_t buffer_size,
+                                 psa_key_usage_t usage)
+{
+    size_t required_size = 0;
+    if (usage == 0) {
+        if (buffer_size > 1) {
+            buffer[0] = '0';
+            buffer[1] = 0;
+        } else if (buffer_size == 1) {
+            buffer[0] = 0;
+        }
+        return 1;
+    }
+%(key_usage_code)s
+    if (usage != 0) {
+        if (required_size != 0) {
+            append(&buffer, buffer_size, &required_size, " | ", 3);
+        }
+        required_size += snprintf(buffer, buffer_size - required_size,
+                                  "0x%%08x", usage);
+    } else {
+        buffer[0] = 0;
+    }
+    return required_size;
+}
+
+/* End of automatically generated file. */
+'''
+
+key_type_from_curve_template = '''if (%(tester)s(type)) {
+        append_with_curve(&buffer, buffer_size, &required_size,
+                          "%(builder)s", %(builder_length)s,
+                          PSA_KEY_TYPE_GET_CURVE(type));
+    } else '''
+
+algorithm_from_hash_template = '''if (%(tester)s(alg_without_padding)) {
+        append_with_hash(&buffer, buffer_size, &required_size,
+                         "%(builder)s", %(builder_length)s,
+                         PSA_ALG_GET_HASH(alg_without_padding));
+    } else '''
+
+bit_test_template = '''\
+    if (%(var)s & %(flag)s) {
+        if (required_size != 0) {
+            append(&buffer, buffer_size, &required_size, " | ", 3);
+        }
+        append(&buffer, buffer_size, &required_size, "%(flag)s", %(length)d);
+        %(var)s ^= %(flag)s;
+    }\
+'''
+
+class MacroCollector:
+    def __init__(self):
+        self.statuses = set()
+        self.key_types = set()
+        self.key_types_from_curve = {}
+        self.ecc_curves = set()
+        self.algorithms = set()
+        self.hash_algorithms = set()
+        self.block_cipher_padding_modes = set()
+        self.algorithms_from_hash = {}
+        self.key_usages = set()
+
+    # "#define" followed by a macro name with either no parameters
+    # or a single parameter. Grab the macro name in group 1, the
+    # parameter name if any in group 2 and the definition in group 3.
+    definition_re = re.compile(r'\s*#\s*define\s+(\w+)(?:\s+|\((\w+)\)\s*)(.+)(?:/[*/])?')
+
+    def read_line(self, line):
+        m = re.match(self.definition_re, line)
+        if not m:
+            return
+        name, parameter, definition = m.groups()
+        if name.endswith('_FLAG') or name.endswith('MASK'):
+            # Macro only to build actual values
+            return
+        elif (name.startswith('PSA_ERROR_') or name == 'PSA_SUCCESS') \
+           and not parameter:
+            self.statuses.add(name)
+        elif name.startswith('PSA_KEY_TYPE_') and not parameter:
+            self.key_types.add(name)
+        elif name.startswith('PSA_KEY_TYPE_') and parameter == 'curve':
+            self.key_types_from_curve[name] = name[:13] + 'IS_' + name[13:]
+        elif name.startswith('PSA_ECC_CURVE_') and not parameter:
+            self.ecc_curves.add(name)
+        elif name.startswith('PSA_ALG_BLOCK_CIPHER_PAD_') and not parameter:
+            self.block_cipher_padding_modes.add(name)
+        elif name.startswith('PSA_ALG_') and not parameter:
+            if name in ['PSA_ALG_BLOCK_CIPHER_BASE',
+                        'PSA_ALG_ECDSA_BASE',
+                        'PSA_ALG_RSA_PKCS1V15_SIGN_BASE']:
+                # Ad hoc skipping of duplicate names for some numerical values
+                return
+            self.algorithms.add(name)
+            # Ad hoc detection of hash algorithms
+            if re.search(r'0x010000[0-9A-Fa-f]{2}', definition):
+                self.hash_algorithms.add(name)
+        elif name.startswith('PSA_ALG_') and parameter == 'hash_alg':
+            if name in ['PSA_ALG_DSA', 'PSA_ALG_ECDSA']:
+                # A naming irregularity
+                tester = name[:8] + 'IS_RANDOMIZED_' + name[8:]
+            else:
+                tester = name[:8] + 'IS_' + name[8:]
+            self.algorithms_from_hash[name] = tester
+        elif name.startswith('PSA_KEY_USAGE_') and not parameter:
+            self.key_usages.add(name)
+        else:
+            # Other macro without parameter
+            return
+
+    def read_file(self, header_file):
+        for line in header_file:
+            self.read_line(line)
+
+    def make_return_case(self, name):
+        return 'case %(name)s: return "%(name)s";' % {'name': name}
+
+    def make_append_case(self, name):
+        template = ('case %(name)s: '
+                    'append(&buffer, buffer_size, &required_size, "%(name)s", %(length)d); '
+                    'break;')
+        return template % {'name': name, 'length': len(name)}
+
+    def make_inner_append_case(self, name):
+        template = ('case %(name)s: '
+                    'append(buffer, buffer_size, required_size, "%(name)s", %(length)d); '
+                    'break;')
+        return template % {'name': name, 'length': len(name)}
+
+    def make_bit_test(self, var, flag):
+        return bit_test_template % {'var': var,
+                                    'flag': flag,
+                                    'length': len(flag)}
+
+    def make_status_cases(self):
+        return '\n    '.join(map(self.make_return_case,
+                                 sorted(self.statuses)))
+
+    def make_ecc_curve_cases(self):
+        return '\n    '.join(map(self.make_return_case,
+                                 sorted(self.ecc_curves)))
+
+    def make_key_type_cases(self):
+        return '\n    '.join(map(self.make_append_case,
+                                 sorted(self.key_types)))
+
+    def make_key_type_from_curve_code(self, builder, tester):
+        return key_type_from_curve_template % {'builder': builder,
+                                               'builder_length': len(builder),
+                                               'tester': tester}
+
+    def make_key_type_code(self):
+        d = self.key_types_from_curve
+        make = self.make_key_type_from_curve_code
+        return '\n        '.join([make(k, d[k]) for k in sorted(d.keys())])
+
+    def make_hash_algorithm_cases(self):
+        return '\n    '.join(map(self.make_return_case,
+                                 sorted(self.hash_algorithms)))
+
+    def make_padding_mode_cases(self):
+        return '\n    '.join(map(self.make_inner_append_case,
+                                 sorted(self.block_cipher_padding_modes)))
+
+    def make_algorithm_cases(self):
+        return '\n    '.join(map(self.make_append_case,
+                                 sorted(self.algorithms)))
+
+    def make_algorithm_from_hash_code(self, builder, tester):
+        return algorithm_from_hash_template % {'builder': builder,
+                                               'builder_length': len(builder),
+                                               'tester': tester}
+
+    def make_algorithm_code(self):
+        d = self.algorithms_from_hash
+        make = self.make_algorithm_from_hash_code
+        return '\n        '.join([make(k, d[k]) for k in sorted(d.keys())])
+
+    def make_key_usage_code(self):
+        return '\n'.join([self.make_bit_test('usage', bit)
+                          for bit in sorted(self.key_usages)])
+
+    def write_file(self, output_file):
+        data = {}
+        data['status_cases'] = self.make_status_cases()
+        data['ecc_curve_cases'] = self.make_ecc_curve_cases()
+        data['key_type_cases'] = self.make_key_type_cases()
+        data['key_type_code'] = self.make_key_type_code()
+        data['hash_algorithm_cases'] = self.make_hash_algorithm_cases()
+        data['padding_mode_cases'] = self.make_padding_mode_cases()
+        data['algorithm_cases'] = self.make_algorithm_cases()
+        data['algorithm_code'] = self.make_algorithm_code()
+        data['key_usage_code'] = self.make_key_usage_code()
+        output_file.write(output_template % data)
+
+def generate_psa_constants(header_file_name, output_file_name):
+    collector = MacroCollector()
+    with open(header_file_name) as header_file:
+        collector.read_file(header_file)
+    temp_file_name = output_file_name + '.tmp'
+    with open(temp_file_name, 'w') as output_file:
+        collector.write_file(output_file)
+    os.rename(temp_file_name, output_file_name)
+
+if __name__ == '__main__':
+    if not os.path.isdir('programs') and os.path.isdir('../programs'):
+        os.chdir('..')
+    generate_psa_constants('include/psa/crypto.h',
+                           'programs/psa/psa_constant_names_generated.c')