Only check necessary signatures and checksums

The precedence goes as follows: signature > sha256sum > md5sum

Add some logic and helper methods to check what we have available when
loading a package, and then only check what is necessary to verify the
package. This should speed up sync database verifies as we no longer
will be doing both a checksum and a signature validation.

Signed-off-by: Dan McGee <dan@archlinux.org>

lib/libalpm/be_package.c

@@ -288,8 +288,7 @@ alpm_pkg_t *_alpm_pkg_load_internal(alpm_handle_t *handle, const char *pkgfile,
 		int full, const char *md5sum, const char *sha256sum, const char *base64_sig,
 		alpm_siglevel_t level)
 {
-	int ret;
-	int config = 0;
+	int ret, skip_checksums, config = 0;
 	struct archive *archive;
 	struct archive_entry *entry;
 	alpm_pkg_t *newpkg = NULL;
@@ -314,9 +313,22 @@ alpm_pkg_t *_alpm_pkg_load_internal(alpm_handle_t *handle, const char *pkgfile,
 		RET_ERR(handle, ALPM_ERR_PKG_OPEN, NULL);
 	}
 
-	/* first steps- validate the package file */
+	/* can we get away with skipping checksums? */
+	skip_checksums = 0;
+	if(level & ALPM_SIG_PACKAGE) {
+		if(base64_sig) {
+			skip_checksums = 1;
+		} else {
+			char *sigpath = _alpm_sigpath(handle, pkgfile);
+			if(sigpath && !_alpm_access(handle, NULL, sigpath, R_OK)) {
+				skip_checksums = 1;
+			}
+			free(sigpath);
+		}
+	}
+
 	_alpm_log(handle, ALPM_LOG_DEBUG, "md5sum: %s\n", md5sum);
-	if(md5sum) {
+	if(!skip_checksums && md5sum && !sha256sum) {
 		_alpm_log(handle, ALPM_LOG_DEBUG, "checking md5sum for %s\n", pkgfile);
 		if(_alpm_test_checksum(pkgfile, md5sum, ALPM_CSUM_MD5) != 0) {
 			alpm_pkg_free(newpkg);
@@ -325,7 +337,7 @@ alpm_pkg_t *_alpm_pkg_load_internal(alpm_handle_t *handle, const char *pkgfile,
 	}
 
 	_alpm_log(handle, ALPM_LOG_DEBUG, "sha256sum: %s\n", sha256sum);
-	if(sha256sum) {
+	if(!skip_checksums && sha256sum) {
 		_alpm_log(handle, ALPM_LOG_DEBUG, "checking sha256sum for %s\n", pkgfile);
 		if(_alpm_test_checksum(pkgfile, sha256sum, ALPM_CSUM_SHA256) != 0) {
 			alpm_pkg_free(newpkg);

lib/libalpm/be_sync.c

@@ -192,7 +192,7 @@ int SYMEXPORT alpm_db_update(int force, alpm_db_t *db)
 
 		if(ret == 0 && (level & ALPM_SIG_DATABASE)) {
 			/* an existing sig file is no good at this point */
-			char *sigpath = _alpm_db_sig_path(db);
+			char *sigpath = _alpm_sigpath(handle, _alpm_db_path(db));
 			if(!sigpath) {
 				ret = -1;
 				break;

lib/libalpm/db.c

@@ -375,20 +375,6 @@ const char *_alpm_db_path(alpm_db_t *db)
 	return db->_path;
 }
 
-char *_alpm_db_sig_path(alpm_db_t *db)
-{
-	char *sigpath;
-	size_t len;
-	const char *dbfile = _alpm_db_path(db);
-	if(!db || !dbfile) {
-		return NULL;
-	}
-	len = strlen(dbfile) + strlen(".sig") + 1;
-	CALLOC(sigpath, len, sizeof(char), RET_ERR(db->handle, ALPM_ERR_MEMORY, NULL));
-	sprintf(sigpath, "%s.sig", dbfile);
-	return sigpath;
-}
-
 int _alpm_db_cmp(const void *d1, const void *d2)
 {
 	alpm_db_t *db1 = (alpm_db_t *)d1;

lib/libalpm/db.h

@@ -80,7 +80,6 @@ struct __alpm_db_t {
 alpm_db_t *_alpm_db_new(const char *treename, int is_local);
 void _alpm_db_free(alpm_db_t *db);
 const char *_alpm_db_path(alpm_db_t *db);
-char *_alpm_db_sig_path(alpm_db_t *db);
 int _alpm_db_cmp(const void *d1, const void *d2);
 alpm_list_t *_alpm_db_search(alpm_db_t *db, const alpm_list_t *needles);
 alpm_db_t *_alpm_db_register_local(alpm_handle_t *handle);

lib/libalpm/signing.c

@@ -186,6 +186,28 @@ error:
 	return 1;
 }
 
+
+/**
+ * Form a signature path given a file path.
+ * Caller must free the result.
+ * @param handle the context handle
+ * @param path the full path to a file
+ * @return the path with '.sig' appended, NULL on errors
+ */
+char *_alpm_sigpath(alpm_handle_t *handle, const char *path)
+{
+	char *sigpath;
+	size_t len;
+
+	if(!path) {
+		return NULL;
+	}
+	len = strlen(path) + 5;
+	CALLOC(sigpath, len, sizeof(char), RET_ERR(handle, ALPM_ERR_MEMORY, NULL));
+	sprintf(sigpath, "%s.sig", path);
+	return sigpath;
+}
+
 /**
  * Check the PGP signature for the given file path.
  * If base64_sig is provided, it will be used as the signature data after
@@ -226,13 +248,9 @@ int _alpm_gpgme_checksig(alpm_handle_t *handle, const char *path,
 	result->count = 0;
 
 	if(!base64_sig) {
-		size_t len = strlen(path) + 5;
-		CALLOC(sigpath, len, sizeof(char), RET_ERR(handle, ALPM_ERR_MEMORY, -1));
-		snprintf(sigpath, len, "%s.sig", path);
-
-		if(!_alpm_access(handle, NULL, sigpath, R_OK) == 0) {
-			/* sigcount is 0 */
-		}
+		sigpath = _alpm_sigpath(handle, path);
+		/* this will just help debugging */
+		_alpm_access(handle, NULL, sigpath, R_OK);
 	}
 
 	if(init_gpgme(handle)) {
@@ -274,6 +292,8 @@ int _alpm_gpgme_checksig(alpm_handle_t *handle, const char *path,
 		/* file-based, it is on disk */
 		sigfile = fopen(sigpath, "rb");
 		if(sigfile == NULL) {
+			_alpm_log(handle, ALPM_LOG_DEBUG, "sig path %s could not be opened\n",
+					sigpath);
 			handle->pm_errno = ALPM_ERR_SIG_MISSING;
 			goto error;
 		}

lib/libalpm/signing.h

@@ -21,6 +21,7 @@
 
 #include "alpm.h"
 
+char *_alpm_sigpath(alpm_handle_t *handle, const char *path);
 int _alpm_gpgme_checksig(alpm_handle_t *handle, const char *path,
 		const char *base64_sig, alpm_sigresult_t *result);
 int _alpm_check_pgp_helper(alpm_handle_t *handle, const char *path,