include/crypto: add a few missing #pragma once directives

Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
(Merged from https://github.com/openssl/openssl/pull/14096)

38 files changed, 133 insertions, 32 deletions

diff --git a/include/crypto/aes_platform.h b/include/crypto/aes_platform.h
index 1d8c06cb94..acd263f8de 100644
--- a/include/crypto/aes_platform.h
+++ b/include/crypto/aes_platform.h
@@ -9,6 +9,7 @@
 
 #ifndef OSSL_AES_PLATFORM_H
 # define OSSL_AES_PLATFORM_H
+# pragma once
 
 # include "openssl/aes.h"
 
diff --git a/include/crypto/aria.h b/include/crypto/aria.h
index 3bbb30ef3e..dfd07013d0 100644
--- a/include/crypto/aria.h
+++ b/include/crypto/aria.h
@@ -12,6 +12,7 @@
 
 #ifndef OSSL_CRYPTO_ARIA_H
 # define OSSL_CRYPTO_ARIA_H
+# pragma once
 
 # include <openssl/opensslconf.h>
 
diff --git a/include/crypto/asn1.h b/include/crypto/asn1.h
index 72844126ec..7d9dec10db 100644
--- a/include/crypto/asn1.h
+++ b/include/crypto/asn1.h
@@ -7,7 +7,11 @@
  * https://www.openssl.org/source/license.html
  */
 
-#include <openssl/asn1.h>
+#ifndef OSSL_CRYPTO_ASN1_H
+# define OSSL_CRYPTO_ASN1_H
+# pragma once
+
+# include <openssl/asn1.h>
 
 /* Internal ASN1 structures and functions: not for application use */
 
@@ -139,3 +143,5 @@ const EVP_MD *x509_algor_get_md(X509_ALGOR *alg);
 X509_ALGOR *x509_algor_mgf1_decode(X509_ALGOR *alg);
 int x509_algor_md_to_mgf1(X509_ALGOR **palg, const EVP_MD *mgf1md);
 int asn1_time_print_ex(BIO *bp, const ASN1_TIME *tm);
+
+#endif /* ndef OSSL_CRYPTO_ASN1_H */
diff --git a/include/crypto/asn1_dsa.h b/include/crypto/asn1_dsa.h
index df6ca0fe9c..4d2399a45f 100644
--- a/include/crypto/asn1_dsa.h
+++ b/include/crypto/asn1_dsa.h
@@ -9,6 +9,7 @@
 
 #ifndef OSSL_CRYPTO_ASN1_DSA_H
 # define OSSL_CRYPTO_ASN1_DSA_H
+# pragma once
 
 #include "internal/packet.h"
 
diff --git a/include/crypto/async.h b/include/crypto/async.h
index e9a89da314..691148858c 100644
--- a/include/crypto/async.h
+++ b/include/crypto/async.h
@@ -7,8 +7,13 @@
  * https://www.openssl.org/source/license.html
  */
 
-#include <openssl/async.h>
+#ifndef OSSL_CRYPTO_ASYNC_H
+# define OSSL_CRYPTO_ASYNC_H
+# pragma once
+
+# include <openssl/async.h>
 
 int async_init(void);
 void async_deinit(void);
 
+#endif
diff --git a/include/crypto/bn.h b/include/crypto/bn.h
index 4060541886..730854d7e1 100644
--- a/include/crypto/bn.h
+++ b/include/crypto/bn.h
@@ -9,6 +9,7 @@
 
 #ifndef OSSL_CRYPTO_BN_H
 # define OSSL_CRYPTO_BN_H
+# pragma once
 
 # include <openssl/bn.h>
 # include <limits.h>
diff --git a/include/crypto/bn_conf.h.in b/include/crypto/bn_conf.h.in
index c8fdf36cae..9d244d52a3 100644
--- a/include/crypto/bn_conf.h.in
+++ b/include/crypto/bn_conf.h.in
@@ -10,6 +10,7 @@
 
 #ifndef OSSL_CRYPTO_BN_CONF_H
 # define OSSL_CRYPTO_BN_CONF_H
+# pragma once
 
 /*
  * The contents of this file are not used in the UEFI build, as
diff --git a/include/crypto/chacha.h b/include/crypto/chacha.h
index 77cfd3b281..b789515b7e 100644
--- a/include/crypto/chacha.h
+++ b/include/crypto/chacha.h
@@ -9,6 +9,7 @@
 
 #ifndef OSSL_CRYPTO_CHACHA_H
 #define OSSL_CRYPTO_CHACHA_H
+# pragma once
 
 #include <stddef.h>
 
diff --git a/include/crypto/cmll_platform.h b/include/crypto/cmll_platform.h
index c82cf9f961..34fac61f07 100644
--- a/include/crypto/cmll_platform.h
+++ b/include/crypto/cmll_platform.h
@@ -9,6 +9,7 @@
 
 #ifndef OSSL_CMLL_PLATFORM_H
 # define OSSL_CMLL_PLATFORM_H
+# pragma once
 
 # if defined(CMLL_ASM) && (defined(__sparc) || defined(__sparc__))
 
diff --git a/include/crypto/cms.h b/include/crypto/cms.h
index 67263fa886..5a58407a11 100644
--- a/include/crypto/cms.h
+++ b/include/crypto/cms.h
@@ -7,7 +7,11 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef OPENSSL_NO_CMS
+#ifndef OSSL_CRYPTO_CMS_H
+# define OSSL_CRYPTO_CMS_H
+# pragma once
+
+# ifndef OPENSSL_NO_CMS
 
 /* internal CMS-ESS related stuff */
 
@@ -18,4 +22,6 @@ int cms_signerinfo_get_signing_cert_v2(CMS_SignerInfo *si,
                                        ESS_SIGNING_CERT_V2 **psc);
 int cms_signerinfo_get_signing_cert(CMS_SignerInfo *si,
                                     ESS_SIGNING_CERT **psc);
+# endif /* OPENSSL_NO_CMS */
+
 #endif
diff --git a/include/crypto/cryptlib.h b/include/crypto/cryptlib.h
index 8fd04fa16f..d70cd78415 100644
--- a/include/crypto/cryptlib.h
+++ b/include/crypto/cryptlib.h
@@ -7,8 +7,12 @@
  * https://www.openssl.org/source/license.html
  */
 
-#include <openssl/core.h>
-#include "internal/cryptlib.h"
+#ifndef OSSL_CRYPTO_CRYPTLIB_H
+# define OSSL_CRYPTO_CRYPTLIB_H
+# pragma once
+
+# include <openssl/core.h>
+# include "internal/cryptlib.h"
 
 /* This file is not scanned by mkdef.pl, whereas cryptlib.h is */
 
@@ -32,3 +36,5 @@ void ossl_malloc_setup_failures(void);
 
 int ossl_crypto_alloc_ex_data_intern(int class_index, void *obj,
                                      CRYPTO_EX_DATA *ad, int idx);
+
+#endif  /* OSSL_CRYPTO_CRYPTLIB_H */
diff --git a/include/crypto/ctype.h b/include/crypto/ctype.h
index f3ab678e14..7117281215 100644
--- a/include/crypto/ctype.h
+++ b/include/crypto/ctype.h
@@ -20,6 +20,7 @@
  */
 #ifndef OSSL_CRYPTO_CTYPE_H
 # define OSSL_CRYPTO_CTYPE_H
+# pragma once
 
 # define CTYPE_MASK_lower       0x1
 # define CTYPE_MASK_upper       0x2
diff --git a/include/crypto/decoder.h b/include/crypto/decoder.h
index f19e8bf841..5d055fecd8 100644
--- a/include/crypto/decoder.h
+++ b/include/crypto/decoder.h
@@ -9,6 +9,7 @@
 
 #ifndef OSSL_CRYPTO_DECODER_H
 # define OSSL_CRYPTO_DECODER_H
+# pragma once
 
 # include <openssl/decoder.h>
 
diff --git a/include/crypto/des_platform.h b/include/crypto/des_platform.h
index 28e319f50e..18bd2f8afd 100644
--- a/include/crypto/des_platform.h
+++ b/include/crypto/des_platform.h
@@ -9,6 +9,7 @@
 
 #ifndef OSSL_DES_PLATFORM_H
 # define OSSL_DES_PLATFORM_H
+# pragma once
 
 # if defined(DES_ASM) && (defined(__sparc) || defined(__sparc__))
 
diff --git a/include/crypto/dh.h b/include/crypto/dh.h
index 290cc7c0d2..91a2db263a 100644
--- a/include/crypto/dh.h
+++ b/include/crypto/dh.h
@@ -7,10 +7,14 @@
  * https://www.openssl.org/source/license.html
  */
 
-#include <openssl/core.h>
-#include <openssl/params.h>
-#include <openssl/dh.h>
-#include "internal/ffc.h"
+#ifndef OSSL_CRYPTO_DH_H
+# define OSSL_CRYPTO_DH_H
+# pragma once
+
+# include <openssl/core.h>
+# include <openssl/params.h>
+# include <openssl/dh.h>
+# include "internal/ffc.h"
 
 DH *dh_new_by_nid_ex(OSSL_LIB_CTX *libctx, int nid);
 DH *dh_new_ex(OSSL_LIB_CTX *libctx);
@@ -46,3 +50,5 @@ int dh_KDF_X9_42_asn1(unsigned char *out, size_t outlen,
                       const char *cek_alg,
                       const unsigned char *ukm, size_t ukmlen, const EVP_MD *md,
                       OSSL_LIB_CTX *libctx, const char *propq);
+
+#endif  /* OSSL_CRYPTO_DH_H */
diff --git a/include/crypto/dsa.h b/include/crypto/dsa.h
index 775a83c1ea..8d282ab188 100644
--- a/include/crypto/dsa.h
+++ b/include/crypto/dsa.h
@@ -7,9 +7,13 @@
  * https://www.openssl.org/source/license.html
  */
 
-#include <openssl/core.h>
-#include <openssl/dsa.h>
-#include "internal/ffc.h"
+#ifndef OSSL_CRYPTO_DSAERR_H
+# define OSSL_CRYPTO_DSAERR_H
+# pragma once
+
+# include <openssl/core.h>
+# include <openssl/dsa.h>
+# include "internal/ffc.h"
 
 #define DSA_PARAMGEN_TYPE_FIPS_186_4   0   /* Use FIPS186-4 standard */
 #define DSA_PARAMGEN_TYPE_FIPS_186_2   1   /* Use legacy FIPS186-2 standard */
@@ -34,3 +38,5 @@ int dsa_check_pub_key(const DSA *dsa, const BIGNUM *pub_key, int *ret);
 int dsa_check_pub_key_partial(const DSA *dsa, const BIGNUM *pub_key, int *ret);
 int dsa_check_priv_key(const DSA *dsa, const BIGNUM *priv_key, int *ret);
 int dsa_check_pairwise(const DSA *dsa);
+
+#endif
diff --git a/include/crypto/dso_conf.h.in b/include/crypto/dso_conf.h.in
index fd0e16b3f9..eba3deba66 100644
--- a/include/crypto/dso_conf.h.in
+++ b/include/crypto/dso_conf.h.in
@@ -10,6 +10,8 @@
 
 #ifndef OSSL_CRYPTO_DSO_CONF_H
 # define OSSL_CRYPTO_DSO_CONF_H
+# pragma once
+
 {-  # The DSO code currently always implements all functions so that no
     # applications will have to worry about that from a compilation point
     # of view. However, the "method"s may return zero unless that platform
diff --git a/include/crypto/ec.h b/include/crypto/ec.h
index 80f76d69bd..682311b26d 100644
--- a/include/crypto/ec.h
+++ b/include/crypto/ec.h
@@ -11,6 +11,8 @@
 
 #ifndef OSSL_CRYPTO_EC_H
 # define OSSL_CRYPTO_EC_H
+# pragma once
+
 # include <openssl/opensslconf.h>
 # include <openssl/evp.h>
 
diff --git a/include/crypto/ecx.h b/include/crypto/ecx.h
index df04cdb562..663cdfc566 100644
--- a/include/crypto/ecx.h
+++ b/include/crypto/ecx.h
@@ -11,6 +11,8 @@
 
 #ifndef OSSL_CRYPTO_ECX_H
 # define OSSL_CRYPTO_ECX_H
+# pragma once
+
 # include <openssl/opensslconf.h>
 
 # ifndef OPENSSL_NO_EC
diff --git a/include/crypto/err.h b/include/crypto/err.h
index b59367e8cb..9e72b5640c 100644
--- a/include/crypto/err.h
+++ b/include/crypto/err.h
@@ -9,6 +9,7 @@
 
 #ifndef OSSL_CRYPTO_ERR_H
 # define OSSL_CRYPTO_ERR_H
+# pragma once
 
 int err_load_ERR_strings_int(void);
 int err_load_crypto_strings_int(void);
diff --git a/include/crypto/ess.h b/include/crypto/ess.h
index 6ae9a8180b..74833f29a7 100644
--- a/include/crypto/ess.h
+++ b/include/crypto/ess.h
@@ -7,6 +7,10 @@
  * https://www.openssl.org/source/license.html
  */
 
+#ifndef OSSL_CRYPTO_ESS_H
+# define OSSL_CRYPTO_ESS_H
+# pragma once
+
 /* internal ESS related stuff */
 
 ESS_SIGNING_CERT *ESS_SIGNING_CERT_get(PKCS7_SIGNER_INFO *si);
@@ -89,3 +93,5 @@ struct ESS_signing_cert_v2_st {
     STACK_OF(ESS_CERT_ID_V2) *cert_ids;
     STACK_OF(POLICYINFO) *policy_info;
 };
+
+#endif /* OSSL_CRYPTO_ESS_H */
diff --git a/include/crypto/evp.h b/include/crypto/evp.h
index 60f07c7cf7..b78535aed0 100644
--- a/include/crypto/evp.h
+++ b/include/crypto/evp.h
@@ -7,10 +7,14 @@
  * https://www.openssl.org/source/license.html
  */
 
-#include <openssl/evp.h>
-#include <openssl/core_dispatch.h>
-#include "internal/refcount.h"
-#include "crypto/ecx.h"
+#ifndef OSSL_CRYPTO_EVP_H
+# define OSSL_CRYPTO_EVP_H
+# pragma once
+
+# include <openssl/evp.h>
+# include <openssl/core_dispatch.h>
+# include "internal/refcount.h"
+# include "crypto/ecx.h"
 
 /*
  * Don't free up md_ctx->pctx in EVP_MD_CTX_reset, use the reserved flag
@@ -793,10 +797,10 @@ int evp_keymgmt_copy(const EVP_KEYMGMT *keymgmt,
 
 /* Pulling defines out of C source files */
 
-#define EVP_RC4_KEY_SIZE 16
-#ifndef TLS1_1_VERSION
-# define TLS1_1_VERSION   0x0302
-#endif
+# define EVP_RC4_KEY_SIZE 16
+# ifndef TLS1_1_VERSION
+#  define TLS1_1_VERSION   0x0302
+# endif
 
 void evp_encode_ctx_set_flags(EVP_ENCODE_CTX *ctx, unsigned int flags);
 
@@ -816,7 +820,7 @@ int pkcs5_pbkdf2_hmac_ex(const char *pass, int passlen,
                          const EVP_MD *digest, int keylen, unsigned char *out,
                          OSSL_LIB_CTX *libctx, const char *propq);
 
-#ifndef FIPS_MODULE
+# ifndef FIPS_MODULE
 /*
  * Internal helpers for stricter EVP_PKEY_CTX_{set,get}_params().
  *
@@ -842,9 +846,12 @@ int evp_pkey_ctx_get1_id_prov(EVP_PKEY_CTX *ctx, void *id);
 int evp_pkey_ctx_get1_id_len_prov(EVP_PKEY_CTX *ctx, size_t *id_len);
 
 int evp_pkey_ctx_use_cached_data(EVP_PKEY_CTX *ctx);
-#endif /* !defined(FIPS_MODULE) */
+# endif /* !defined(FIPS_MODULE) */
+
 void evp_method_store_flush(OSSL_LIB_CTX *libctx);
 int evp_set_default_properties_int(OSSL_LIB_CTX *libctx, const char *propq,
                                    int loadconfig);
 
 void evp_md_ctx_clear_digest(EVP_MD_CTX *ctx, int force);
+
+#endif /* OSSL_CRYPTO_EVP_H */
diff --git a/include/crypto/lhash.h b/include/crypto/lhash.h
index 9629936262..d7bd2c137f 100644
--- a/include/crypto/lhash.h
+++ b/include/crypto/lhash.h
@@ -9,7 +9,8 @@
 
 #ifndef OSSL_CRYPTO_LHASH_H
 # define OSSL_CRYPTO_LHASH_H
+# pragma once
 
 unsigned long openssl_lh_strcasehash(const char *);
 
-#endif
+#endif  /* OSSL_CRYPTO_LHASH_H */
diff --git a/include/crypto/pem.h b/include/crypto/pem.h
index e3ec8b24cb..24e4787acc 100644
--- a/include/crypto/pem.h
+++ b/include/crypto/pem.h
@@ -9,6 +9,7 @@
 
 #ifndef OSSL_INTERNAL_PEM_H
 # define OSSL_INTERNAL_PEM_H
+# pragma once
 
 # include <openssl/pem.h>
 
diff --git a/include/crypto/pkcs7.h b/include/crypto/pkcs7.h
index 60e01e5c39..17bb3cd72c 100644
--- a/include/crypto/pkcs7.h
+++ b/include/crypto/pkcs7.h
@@ -7,4 +7,10 @@
  * https://www.openssl.org/source/license.html
  */
 
+#ifndef OSSL_CRYPTO_PKCS7_H
+# define OSSL_CRYPTO_PKCS7_H
+# pragma once
+
 void pkcs7_resolve_libctx(PKCS7 *p7);
+
+#endif
diff --git a/include/crypto/poly1305.h b/include/crypto/poly1305.h
index a73c2311d4..86317bcf8a 100644
--- a/include/crypto/poly1305.h
+++ b/include/crypto/poly1305.h
@@ -7,6 +7,10 @@
  * https://www.openssl.org/source/license.html
  */
 
+#ifndef OSSL_CRYPTO_POLY1305_H
+# define OSSL_CRYPTO_POLY1305_H
+# pragma once
+
 #include <stddef.h>
 
 #define POLY1305_BLOCK_SIZE  16
@@ -38,3 +42,5 @@ size_t Poly1305_ctx_size(void);
 void Poly1305_Init(POLY1305 *ctx, const unsigned char key[32]);
 void Poly1305_Update(POLY1305 *ctx, const unsigned char *inp, size_t len);
 void Poly1305_Final(POLY1305 *ctx, unsigned char mac[16]);
+
+#endif /* OSSL_CRYPTO_POLY1305_H */
diff --git a/include/crypto/punycode.h b/include/crypto/punycode.h
index ab31494060..5b3074a348 100644
--- a/include/crypto/punycode.h
+++ b/include/crypto/punycode.h
@@ -9,7 +9,7 @@
 
 #ifndef OSSL_CRYPTO_PUNYCODE_H
 # define OSSL_CRYPTO_PUNYCODE_H
-
+# pragma once
 
 int ossl_punycode_decode (
 	const char *pEncoded,
diff --git a/include/crypto/rand.h b/include/crypto/rand.h
index c870245521..89505aa0ed 100644
--- a/include/crypto/rand.h
+++ b/include/crypto/rand.h
@@ -17,6 +17,7 @@
 
 #ifndef OSSL_CRYPTO_RAND_H
 # define OSSL_CRYPTO_RAND_H
+# pragma once
 
 # include <openssl/rand.h>
 # include "crypto/rand_pool.h"
diff --git a/include/crypto/rand_pool.h b/include/crypto/rand_pool.h
index 9c5c92e365..26e65c0436 100644
--- a/include/crypto/rand_pool.h
+++ b/include/crypto/rand_pool.h
@@ -9,6 +9,7 @@
 
 #ifndef OSSL_PROVIDER_RAND_POOL_H
 # define OSSL_PROVIDER_RAND_POOL_H
+# pragma once
 
 # include <stdio.h>
 # include <openssl/rand.h>
diff --git a/include/crypto/rsa.h b/include/crypto/rsa.h
index 599978dc3b..62087b347e 100644
--- a/include/crypto/rsa.h
+++ b/include/crypto/rsa.h
@@ -9,6 +9,7 @@
 
 #ifndef OSSL_INTERNAL_RSA_H
 # define OSSL_INTERNAL_RSA_H
+# pragma once
 
 # include <openssl/core.h>
 # include <openssl/rsa.h>
diff --git a/include/crypto/security_bits.h b/include/crypto/security_bits.h
index c62d89bcb8..90cb7d625f 100644
--- a/include/crypto/security_bits.h
+++ b/include/crypto/security_bits.h
@@ -9,6 +9,7 @@
 
 #ifndef OSSL_SECURITY_BITS_H
 # define OSSL_SECURITY_BITS_H
+# pragma once
 
 uint16_t ifc_ffc_compute_security_bits(int n);
 
diff --git a/include/crypto/sha.h b/include/crypto/sha.h
index 9a86599984..7c0276a23a 100644
--- a/include/crypto/sha.h
+++ b/include/crypto/sha.h
@@ -10,6 +10,7 @@
 
 #ifndef OSSL_CRYPTO_SHA_H
 # define OSSL_CRYPTO_SHA_H
+# pragma once
 
 # include <openssl/opensslconf.h>
 
diff --git a/include/crypto/siphash.h b/include/crypto/siphash.h
index 1575141c40..bb4d614998 100644
--- a/include/crypto/siphash.h
+++ b/include/crypto/siphash.h
@@ -7,12 +7,16 @@
  * https://www.openssl.org/source/license.html
  */
 
-#include <stddef.h>
+#ifndef OSSL_CRYPTO_SIPHASH_H
+# define OSSL_CRYPTO_SIPHASH_H
+# pragma once
 
-#define SIPHASH_BLOCK_SIZE        8
-#define SIPHASH_KEY_SIZE         16
-#define SIPHASH_MIN_DIGEST_SIZE   8
-#define SIPHASH_MAX_DIGEST_SIZE  16
+# include <stddef.h>
+
+# define SIPHASH_BLOCK_SIZE        8
+# define SIPHASH_KEY_SIZE         16
+# define SIPHASH_MIN_DIGEST_SIZE   8
+# define SIPHASH_MAX_DIGEST_SIZE  16
 
 typedef struct siphash_st SIPHASH;
 
@@ -23,3 +27,5 @@ int SipHash_Init(SIPHASH *ctx, const unsigned char *k,
                  int crounds, int drounds);
 void SipHash_Update(SIPHASH *ctx, const unsigned char *in, size_t inlen);
 int SipHash_Final(SIPHASH *ctx, unsigned char *out, size_t outlen);
+
+#endif
diff --git a/include/crypto/sm2.h b/include/crypto/sm2.h
index 78fd4dbc13..2bd0af03d6 100644
--- a/include/crypto/sm2.h
+++ b/include/crypto/sm2.h
@@ -11,6 +11,8 @@
 
 #ifndef OSSL_CRYPTO_SM2_H
 # define OSSL_CRYPTO_SM2_H
+# pragma once
+
 # include <openssl/opensslconf.h>
 
 # ifndef OPENSSL_NO_SM2
diff --git a/include/crypto/sm4.h b/include/crypto/sm4.h
index fb5253d857..87be6daa91 100644
--- a/include/crypto/sm4.h
+++ b/include/crypto/sm4.h
@@ -10,6 +10,7 @@
 
 #ifndef OSSL_CRYPTO_SM4_H
 # define OSSL_CRYPTO_SM4_H
+# pragma once
 
 # include <openssl/opensslconf.h>
 # include <openssl/e_os2.h>
diff --git a/include/crypto/sparse_array.h b/include/crypto/sparse_array.h
index a8031cd3f1..ee49105167 100644
--- a/include/crypto/sparse_array.h
+++ b/include/crypto/sparse_array.h
@@ -10,6 +10,7 @@
 
 #ifndef OSSL_CRYPTO_SPARSE_ARRAY_H
 # define OSSL_CRYPTO_SPARSE_ARRAY_H
+# pragma once
 
 # include <openssl/e_os2.h>
 
diff --git a/include/crypto/store.h b/include/crypto/store.h
index 8bd2bc022f..72d5a01a96 100644
--- a/include/crypto/store.h
+++ b/include/crypto/store.h
@@ -9,6 +9,7 @@
 
 #ifndef OSSL_CRYPTO_STORE_H
 # define OSSL_CRYPTO_STORE_H
+# pragma once
 
 # include <openssl/bio.h>
 # include <openssl/store.h>
diff --git a/include/crypto/x509.h b/include/crypto/x509.h
index 542a3d6e60..93cb814017 100644
--- a/include/crypto/x509.h
+++ b/include/crypto/x509.h
@@ -7,9 +7,13 @@
  * https://www.openssl.org/source/license.html
  */
 
-#include "internal/refcount.h"
-#include <openssl/asn1.h>
-#include <openssl/x509.h>
+#ifndef OSSL_CRYPTO_X509_H
+# define OSSL_CRYPTO_X509_H
+# pragma once
+
+# include "internal/refcount.h"
+# include <openssl/asn1.h>
+# include <openssl/x509.h>
 
 /* Internal X509 structures and functions: not for application use */
 
@@ -320,3 +324,5 @@ int X509_PUBKEY_get0_libctx(OSSL_LIB_CTX **plibctx, const char **ppropq,
                             const X509_PUBKEY *key);
 /* Calculate default key identifier according to RFC 5280 section 4.2.1.2 (1) */
 ASN1_OCTET_STRING *x509_pubkey_hash(X509_PUBKEY *pubkey);
+
+#endif