Fix a few warnings pointed out via clang scan-build

Some of these are legit (the backup hash NULL checks), while others are
either extemely unlikely or just impossible for the static code
analysis to prove, but are worth adding anyway because they have little
overhead.

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

lib/libalpm/add.c

@@ -257,6 +257,8 @@ static int extract_single_file(alpm_handle_t *handle, struct archive *archive,
 				/* check newpkg first, so that adding backup files is retroactive */
 				backup = _alpm_needbackup(entryname, alpm_pkg_get_backup(newpkg));
 				if(backup) {
+					/* if we force hash_orig to be non-NULL retroactive backup works */
+					hash_orig = "";
 					needbackup = 1;
 				}
 
@@ -268,11 +270,6 @@ static int extract_single_file(alpm_handle_t *handle, struct archive *archive,
 						needbackup = 1;
 					}
 				}
-
-				/* if we force hash_orig to be non-NULL retroactive backup works */
-				if(needbackup && !hash_orig) {
-					hash_orig = "";
-				}
 			}
 		}
 		/* else if(S_ISLNK(entrymode)) */
@@ -319,7 +316,7 @@ static int extract_single_file(alpm_handle_t *handle, struct archive *archive,
 		_alpm_log(handle, PM_LOG_DEBUG, "original: %s\n", hash_orig);
 
 		if(!oldpkg) {
-			if(strcmp(hash_local, hash_pkg) != 0) {
+			if(hash_local && hash_pkg && strcmp(hash_local, hash_pkg) != 0) {
 				/* looks like we have a local file that has a different hash as the
 				 * file in the package, move it to a .pacorig */
 				char newpath[PATH_MAX];
@@ -352,9 +349,9 @@ static int extract_single_file(alpm_handle_t *handle, struct archive *archive,
 		} else if(hash_orig) {
 			/* the fun part */
 
-			if(strcmp(hash_orig, hash_local) == 0) {
+			if(hash_local && strcmp(hash_orig, hash_local) == 0) {
 				/* installed file has NOT been changed by user */
-				if(strcmp(hash_orig, hash_pkg) != 0) {
+				if(hash_pkg && strcmp(hash_orig, hash_pkg) != 0) {
 					_alpm_log(handle, PM_LOG_DEBUG, "action: installing new file: %s\n",
 							entryname_orig);
 
@@ -366,18 +363,18 @@ static int extract_single_file(alpm_handle_t *handle, struct archive *archive,
 						errors++;
 					}
 				} else {
-					/* there's no sense in installing the same file twice, install
+					/* no sense in installing the same file twice, install
-					 * ONLY is the original and package hashes differ */
+					 * ONLY if the original and package hashes differ */
 					_alpm_log(handle, PM_LOG_DEBUG, "action: leaving existing file in place\n");
 					unlink(checkfile);
 				}
-			} else if(strcmp(hash_orig, hash_pkg) == 0) {
+			} else if(hash_pkg && strcmp(hash_orig, hash_pkg) == 0) {
 				/* originally installed file and new file are the same - this
 				 * implies the case above failed - i.e. the file was changed by a
 				 * user */
 				_alpm_log(handle, PM_LOG_DEBUG, "action: leaving existing file in place\n");
 				unlink(checkfile);
-			} else if(strcmp(hash_local, hash_pkg) == 0) {
+			} else if(hash_local && hash_pkg && strcmp(hash_local, hash_pkg) == 0) {
 				/* this would be magical.  The above two cases failed, but the
 				 * user changes just so happened to make the new file exactly the
 				 * same as the one in the package... skip it */
@@ -460,6 +457,8 @@ static int commit_single_pkg(alpm_handle_t *handle, alpm_pkg_t *newpkg,
 	alpm_db_t *db = handle->db_local;
 	alpm_trans_t *trans = handle->trans;
 
+	ASSERT(trans != NULL, return -1);
+
 	snprintf(scriptlet, PATH_MAX, "%s%s-%s/install",
 			_alpm_db_path(db), alpm_pkg_get_name(newpkg),
 			alpm_pkg_get_version(newpkg));

lib/libalpm/backup.c

@@ -40,7 +40,7 @@ int _alpm_split_backup(const char *string, alpm_backup_t **backup)
 	STRDUP(str, string, return -1);
 
 	/* tab delimiter */
-	ptr = strchr(str, '\t');
+	ptr = str ? strchr(str, '\t') : NULL;
 	if(ptr == NULL) {
 		(*backup)->name = str;
 		(*backup)->hash = NULL;

lib/libalpm/conflict.c

@@ -65,7 +65,7 @@ void _alpm_conflict_free(alpm_conflict_t *conflict)
 alpm_conflict_t *_alpm_conflict_dup(const alpm_conflict_t *conflict)
 {
 	alpm_conflict_t *newconflict;
-	CALLOC(newconflict, 1, sizeof(alpm_conflict_t), );
+	CALLOC(newconflict, 1, sizeof(alpm_conflict_t), return NULL);
 
 	STRDUP(newconflict->package1, conflict->package1, return NULL);
 	STRDUP(newconflict->package2, conflict->package2, return NULL);

lib/libalpm/dload.c

@@ -162,7 +162,7 @@ static int curl_download_internal(alpm_handle_t *handle,
 	char hostname[256];
 	char error_buffer[CURL_ERROR_SIZE];
 	struct stat st;
-	long timecond, remote_time;
+	long timecond, remote_time = -1;
 	double remote_size, bytes_dl;
 	struct sigaction sig_pipe[2], sig_int[2];
 	struct fileinfo dlfile;

src/pacman/pacman.c

@@ -721,15 +721,18 @@ static void cl_to_log(int argc, char* argv[])
 {
 	size_t size = 0;
 	int i;
-	for(i = 0; i<argc; i++) {
+	for(i = 0; i < argc; i++) {
 		size += strlen(argv[i]) + 1;
 	}
+	if(!size) {
+		return;
+	}
 	char *cl_text = malloc(size);
 	if(!cl_text) {
 		return;
 	}
 	char *p = cl_text;
-	for(i = 0; i<argc-1; i++) {
+	for(i = 0; i < argc - 1; i++) {
 		strcpy(p, argv[i]);
 		p += strlen(argv[i]);
 		*p++ = ' ';