libalpm: add new errno for download initialization

The error string "failed to retrieve some files" implies that the
download may have begun and some files may have been partially
downloaded.

If we know no download actually took place we can be more clear about
this.

lib/libalpm/alpm.h

@@ -308,6 +308,8 @@ typedef enum _alpm_errno_t {
 	/** Files conflict */
 	ALPM_ERR_FILE_CONFLICTS,
 	/* Misc */
+	/** Download setup failed */
+	ALPM_ERR_RETRIEVE_PREPARE,
 	/** Download failed */
 	ALPM_ERR_RETRIEVE,
 	/** Invalid Regex */

lib/libalpm/be_sync.c

@@ -153,7 +153,7 @@ int SYMEXPORT alpm_db_update(alpm_handle_t *handle, alpm_list_t *dbs, int force)
 
 	syncpath = get_sync_dir(handle);
 	ASSERT(syncpath != NULL, return -1);
-	temporary_syncpath = _alpm_temporary_download_dir_setup(syncpath, handle->sandboxuser);
+	temporary_syncpath = _alpm_temporary_download_dir_setup(handle, syncpath);
 	ASSERT(temporary_syncpath != NULL, FREE(syncpath); return -1);
 
 	/* make sure we have a sane umask */

lib/libalpm/dload.c

@@ -1304,7 +1304,7 @@ int SYMEXPORT alpm_fetch_pkgurl(alpm_handle_t *handle, const alpm_list_t *urls,
 
 	/* find a valid cache dir to download to */
 	cachedir = _alpm_filecache_setup(handle);
-	temporary_cachedir = _alpm_temporary_download_dir_setup(cachedir, handle->sandboxuser);
+	temporary_cachedir = _alpm_temporary_download_dir_setup(handle, cachedir);
 	ASSERT(temporary_cachedir != NULL, return -1);
 
 	for(i = urls; i; i = i->next) {

lib/libalpm/error.c

@@ -138,6 +138,8 @@ const char SYMEXPORT *alpm_strerror(alpm_errno_t err)
 		case ALPM_ERR_FILE_CONFLICTS:
 			return _("conflicting files");
 		/* Miscellaneous */
+		case ALPM_ERR_RETRIEVE_PREPARE:
+			return _("failed to initialize download");
 		case ALPM_ERR_RETRIEVE:
 			return _("failed to retrieve some files");
 		case ALPM_ERR_INVALID_REGEX:

lib/libalpm/sync.c

@@ -780,7 +780,7 @@ static int download_files(alpm_handle_t *handle)
 	alpm_list_t *payloads = NULL;
 
 	cachedir = _alpm_filecache_setup(handle);
-	temporary_cachedir = _alpm_temporary_download_dir_setup(cachedir, handle->sandboxuser);
+	temporary_cachedir = _alpm_temporary_download_dir_setup(handle, cachedir);
 	if(temporary_cachedir == NULL) {
 		ret = -1;
 		goto finish;

lib/libalpm/util.c

@@ -23,6 +23,7 @@
  */
 
 #include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
 #include <ctype.h>
 #include <dirent.h>
@@ -949,32 +950,53 @@ const char *_alpm_filecache_setup(alpm_handle_t *handle)
 /** Create a temporary directory under the supplied directory.
  * The new directory is writable by the download user, and will be
  * removed after the download operation has completed.
+ * @param handle an alpm handle
  * @param dir existing sync or cache directory
- * @param user download user name
  * @return pointer to a sub-directory writable by the download user inside the existing directory.
  */
-char *_alpm_temporary_download_dir_setup(const char *dir, const char *user)
+char *_alpm_temporary_download_dir_setup(alpm_handle_t *handle, const char *dir)
 {
+	const char *user = handle->sandboxuser;
+	uid_t myuid = getuid();
 	struct passwd const *pw = NULL;
 
-	ASSERT(dir != NULL, return NULL);
-	if(user != NULL) {
-		ASSERT((pw = getpwnam(user)) != NULL, return NULL);
+	ASSERT(dir != NULL, RET_ERR(handle, ALPM_ERR_WRONG_ARGS, NULL));
+	if(myuid == 0 && user != NULL) {
+		errno = 0;
+		pw = getpwnam(user);
+
+		if(pw == NULL) {
+			if(errno == 0) {
+				_alpm_log(handle, ALPM_LOG_ERROR,
+						_("download user '%s' does not exist\n"), user);
+			} else {
+				_alpm_log(handle, ALPM_LOG_ERROR,
+						_("failed to get download user '%s': %s\n"),
+						user, strerror(errno));
+			}
+			RET_ERR(handle, ALPM_ERR_RETRIEVE_PREPARE, NULL);
+		}
 	}
 
 	const char template[] = "download-XXXXXX";
 	size_t newdirlen = strlen(dir) + sizeof(template) + 1;
 	char *newdir = NULL;
-	MALLOC(newdir, newdirlen, return NULL);
+	MALLOC(newdir, newdirlen, RET_ERR(handle, ALPM_ERR_MEMORY, NULL));
 	snprintf(newdir, newdirlen - 1, "%s%s", dir, template);
 	if(mkdtemp(newdir) == NULL) {
+		_alpm_log(handle, ALPM_LOG_ERROR,
+				_("failed to create temporary download directory %s: %s\n"),
+				newdir, strerror(errno));
 		free(newdir);
-		return NULL;
+		RET_ERR(handle, ALPM_ERR_RETRIEVE_PREPARE, NULL);
 	}
 	if(pw != NULL) {
 		if(chown(newdir, pw->pw_uid, pw->pw_gid) == -1) {
+			_alpm_log(handle, ALPM_LOG_ERROR,
+					_("failed to chown temporary download directory %s: %s\n"),
+					newdir, strerror(errno));
 			free(newdir);
-			return NULL;
+			RET_ERR(handle, ALPM_ERR_RETRIEVE_PREPARE, NULL);
 		}
 	}
 	newdir[newdirlen-2] = '/';

lib/libalpm/util.h

@@ -139,7 +139,7 @@ char *_alpm_filecache_find(alpm_handle_t *handle, const char *filename);
 /* Checks whether a file exists in cache */
 int _alpm_filecache_exists(alpm_handle_t *handle, const char *filename);
 const char *_alpm_filecache_setup(alpm_handle_t *handle);
-char *_alpm_temporary_download_dir_setup(const char *dir, const char *user);
+char *_alpm_temporary_download_dir_setup(alpm_handle_t *handle, const char *dir);
 void _alpm_remove_temporary_download_dir(const char *dir);
 
 /* Unlike many uses of alpm_pkgvalidation_t, _alpm_test_checksum expects