Move the file digest code out of match.c and into filedigest.c.

Inspired by RedHat changes that used libgcrypt.
Also add digest_type_to_name() to map a sudo digest type (int)
to a name (string) and use it.

plugins/sudoers/filedigest.c

@@ -0,0 +1,142 @@
+/*
+ * Copyright (c) 2017 Todd C. Miller <Todd.Miller@courtesan.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <config.h>
+
+#include <sys/types.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#ifdef HAVE_STRING_H
+# include <string.h>
+#endif /* HAVE_STRING_H */
+#ifdef HAVE_STRINGS_H
+# include <strings.h>
+#endif /* HAVE_STRINGS_H */
+#if defined(HAVE_STDINT_H)
+# include <stdint.h>
+#elif defined(HAVE_INTTYPES_H)
+# include <inttypes.h>
+#endif
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+
+#include "sudoers.h"
+#include "parse.h"
+
+#ifdef HAVE_SHA224UPDATE
+# include <sha2.h>
+#else
+# include "compat/sha2.h"
+#endif
+
+static struct digest_function {
+    const unsigned int digest_len;
+    void (*init)(SHA2_CTX *);
+#ifdef SHA2_VOID_PTR
+    void (*update)(SHA2_CTX *, const void *, size_t);
+    void (*final)(void *, SHA2_CTX *);
+#else
+    void (*update)(SHA2_CTX *, const unsigned char *, size_t);
+    void (*final)(unsigned char *, SHA2_CTX *);
+#endif
+} digest_functions[] = {
+    {
+	SHA224_DIGEST_LENGTH,
+	SHA224Init,
+	SHA224Update,
+	SHA224Final
+    }, {
+	SHA256_DIGEST_LENGTH,
+	SHA256Init,
+	SHA256Update,
+	SHA256Final
+    }, {
+	SHA384_DIGEST_LENGTH,
+	SHA384Init,
+	SHA384Update,
+	SHA384Final
+    }, {
+	SHA512_DIGEST_LENGTH,
+	SHA512Init,
+	SHA512Update,
+	SHA512Final
+    }, {
+	0
+    }
+};
+
+unsigned char *
+sudo_filedigest(int fd, const char *file, int digest_type, size_t *digest_len)
+{
+    struct digest_function *func = NULL;
+    unsigned char *file_digest = NULL;
+    unsigned char buf[32 * 1024];
+    size_t nread;
+    SHA2_CTX ctx;
+    int i, fd2;
+    FILE *fp = NULL;
+    debug_decl(sudo_filedigest, SUDOERS_DEBUG_UTIL)
+
+    for (i = 0; digest_functions[i].digest_len != 0; i++) {
+	if (digest_type == i) {
+	    func = &digest_functions[i];
+	    break;
+	}
+    }
+    if (func == NULL) {
+	sudo_warnx(U_("unsupported digest type %d for %s"), digest_type, file);
+	goto bad;
+    }
+
+    if ((fd2 = dup(fd)) == -1) {
+	sudo_debug_printf(SUDO_DEBUG_INFO, "unable to dup %s: %s",
+	    file, strerror(errno));
+	goto bad;
+    }
+    if ((fp = fdopen(fd2, "r")) == NULL) {
+	sudo_debug_printf(SUDO_DEBUG_INFO, "unable to fdopen %s: %s",
+	    file, strerror(errno));
+	close(fd2);
+	goto bad;
+    }
+    if ((file_digest = malloc(func->digest_len)) == NULL) {
+	sudo_warnx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+	goto bad;
+    }
+
+    func->init(&ctx);
+    while ((nread = fread(buf, 1, sizeof(buf), fp)) != 0) {
+	func->update(&ctx, buf, nread);
+    }
+    if (ferror(fp)) {
+	sudo_warnx(U_("%s: read error"), file);
+	goto bad;
+    }
+    func->final(file_digest, &ctx);
+    fclose(fp);
+
+    *digest_len = func->digest_len;
+    debug_return_ptr(file_digest);
+bad:
+    free(file_digest);
+    if (fp != NULL)
+	fclose(fp);
+    debug_return_ptr(NULL);
+}