Allow disabling of internal (libdownload) code

Add a new --disable-internal-download flag to configure allowing the
internal download code to be skipped. This will be helpful on platforms that
currently don't support either libdownload or libfetch (such as Cygwin) and
for just compiling a lighter weight pacman binary.

This was made really easy by our recent refactoring of the download code
into separate internal and external functions, as well as some error code
cleanup.

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

configure.ac

@@ -98,6 +98,11 @@ AC_ARG_WITH(db-ext,
 	AC_HELP_STRING([--with-db-ext=ext], [set the file extension used by the database]),
 	[DBEXT=$withval], [DBEXT=.db.tar.gz])
 
+# Help line for libdownload/libfetch
+AC_ARG_ENABLE(internal-download,
+	AC_HELP_STRING([--disable-internal-download], [do not build with libdownload/libfetch support]),
+	[internaldownload=$enableval], [internaldownload=yes])
+
 # Help line for documentation
 AC_ARG_ENABLE(doc,
 	AC_HELP_STRING([--disable-doc], [prevent make from looking at doc/ dir]),
@@ -137,10 +142,21 @@ AM_GNU_GETTEXT([external])
 AM_GNU_GETTEXT_VERSION(0.13.1)
 
 # Check for libarchive
-AC_CHECK_LIB([archive], [archive_read_data], , AC_MSG_ERROR([libarchive is needed to compile pacman!]))
+AC_CHECK_LIB([archive], [archive_read_data], ,
+	AC_MSG_ERROR([libarchive is needed to compile pacman!]))
 
-# Check for libdownload
+# Enable or disable usage of libdownload/libfetch
-AC_CHECK_LIB([download], [downloadParseURL], , AC_MSG_ERROR([libdownload is needed to compile pacman!]))
+AC_MSG_CHECKING(whether to link with download library)
+if test "x$internaldownload" = "xyes" ; then
+	AC_MSG_RESULT(yes)
+	AC_DEFINE([INTERNAL_DOWNLOAD], , [Use internal download library])
+	# Check for libdownload if it was actually requested
+	AC_CHECK_LIB([download], [downloadParseURL], ,
+		AC_MSG_ERROR([libdownload is needed to compile pacman!]))
+else
+	AC_MSG_RESULT(no)
+fi
+AM_CONDITIONAL(INTERNAL_DOWNLOAD, test "x$internaldownload" = "xyes")
 
 # Checks for header files.
 AC_CHECK_HEADERS([fcntl.h libintl.h limits.h locale.h string.h strings.h sys/ioctl.h sys/statvfs.h sys/time.h syslog.h wchar.h])
@@ -352,6 +368,7 @@ pacman_display_version:
 
   Compilation options:
     Run make in doc/ dir   : ${wantdoc}
+    Use download library   : ${internaldownload}
     Doxygen support        : ${usedoxygen}
     Asciidoc support       : ${useasciidoc}
     debug support          : ${debug}

lib/libalpm/alpm.h

@@ -468,12 +468,10 @@ enum _pmerrno_t {
 	PM_ERR_RETRIEVE,
 	PM_ERR_PKG_HOLD,
 	PM_ERR_INVALID_REGEX,
-  /* Downloading */
-	PM_ERR_CONNECT_FAILED,
-	PM_ERR_FORK_FAILED,
 	/* External library errors */
 	PM_ERR_LIBARCHIVE,
-	PM_ERR_LIBDOWNLOAD
+	PM_ERR_LIBDOWNLOAD,
+	PM_ERR_EXTERNAL_DOWNLOAD
 };
 
 extern enum _pmerrno_t pm_errno;

lib/libalpm/dload.c

@@ -24,7 +24,9 @@
 #include <errno.h>
 #include <string.h>
 #include <unistd.h>
+#if defined(INTERNAL_DOWNLOAD)
 #include <download.h> /* libdownload */
+#endif
 
 /* libalpm */
 #include "dload.h"
@@ -34,30 +36,6 @@
 #include "util.h"
 #include "handle.h"
 
-/* Build a 'struct url' from an url. */
-static struct url *url_for_string(const char *url)
-{
-	struct url *ret = NULL;
-	ret = downloadParseURL(url);
-	if(!ret) {
-		_alpm_log(PM_LOG_ERROR, _("url '%s' is invalid\n"), url);
-		RET_ERR(PM_ERR_SERVER_BAD_URL, NULL);
-	}
-
-	/* if no URL scheme specified, assume HTTP */
-	if(strlen(ret->scheme) == 0) {
-		_alpm_log(PM_LOG_WARNING, _("url scheme not specified, assuming HTTP\n"));
-		strcpy(ret->scheme, SCHEME_HTTP);
-	}
-	/* add a user & password for anonymous FTP */
-	if(strcmp(ret->scheme,SCHEME_FTP) == 0 && strlen(ret->user) == 0) {
-		strcpy(ret->user, "anonymous");
-		strcpy(ret->pwd, "libalpm@guest");
-	}
-
-	return(ret);
-}
-
 static char *get_filename(const char *url) {
 	char *filename = strrchr(url, '/');
 	if(filename != NULL) {
@@ -86,6 +64,31 @@ static char *get_tempfile(const char *path, const char *filename) {
 	return(tempfile);
 }
 
+#if defined(INTERNAL_DOWNLOAD)
+/* Build a 'struct url' from an url. */
+static struct url *url_for_string(const char *url)
+{
+	struct url *ret = NULL;
+	ret = downloadParseURL(url);
+	if(!ret) {
+		_alpm_log(PM_LOG_ERROR, _("url '%s' is invalid\n"), url);
+		RET_ERR(PM_ERR_SERVER_BAD_URL, NULL);
+	}
+
+	/* if no URL scheme specified, assume HTTP */
+	if(strlen(ret->scheme) == 0) {
+		_alpm_log(PM_LOG_WARNING, _("url scheme not specified, assuming HTTP\n"));
+		strcpy(ret->scheme, SCHEME_HTTP);
+	}
+	/* add a user & password for anonymous FTP */
+	if(strcmp(ret->scheme,SCHEME_FTP) == 0 && strlen(ret->user) == 0) {
+		strcpy(ret->user, "anonymous");
+		strcpy(ret->pwd, "libalpm@guest");
+	}
+
+	return(ret);
+}
+
 static int download_internal(const char *url, const char *localpath,
 		time_t mtimeold, time_t *mtimenew) {
 	FILE *dlf, *localf = NULL;
@@ -230,6 +233,7 @@ cleanup:
 	downloadFreeURL(fileurl);
 	return(ret);
 }
+#endif
 
 static int download_external(const char *url, const char *localpath,
 		time_t mtimeold, time_t *mtimenew) {
@@ -242,9 +246,13 @@ static int download_external(const char *url, const char *localpath,
 	char cwd[PATH_MAX];
 	char *destfile, *tempfile, *filename;
 
+	if(!handle->xfercommand) {
+		RET_ERR(PM_ERR_EXTERNAL_DOWNLOAD, -1);
+	}
+
 	filename = get_filename(url);
 	if(!filename) {
-		return(-1);
+		RET_ERR(PM_ERR_EXTERNAL_DOWNLOAD, -1);
 	}
 	destfile = get_destfile(localpath, filename);
 	tempfile = get_tempfile(localpath, filename);
@@ -275,7 +283,7 @@ static int download_external(const char *url, const char *localpath,
 	getcwd(cwd, PATH_MAX);
 	if(chdir(localpath)) {
 		_alpm_log(PM_LOG_WARNING, _("could not chdir to %s\n"), localpath);
-		pm_errno = PM_ERR_CONNECT_FAILED;
+		pm_errno = PM_ERR_EXTERNAL_DOWNLOAD;
 		ret = -1;
 		goto cleanup;
 	}
@@ -285,7 +293,7 @@ static int download_external(const char *url, const char *localpath,
 
 	if(retval == -1) {
 		_alpm_log(PM_LOG_WARNING, _("running XferCommand: fork failed!\n"));
-		pm_errno = PM_ERR_FORK_FAILED;
+		pm_errno = PM_ERR_EXTERNAL_DOWNLOAD;
 		ret = -1;
 	} else if(retval != 0) {
 		/* download failed */
@@ -331,8 +339,18 @@ static int download(const char *url, const char *localpath,
 		return(ret ? -1 : 0);
 	}
 
+	/* We have a few things to take into account here.
+	 * 1. If we have both internal/external available, choose based on
+	 * whether xfercommand is populated.
+	 * 2. If we only have external available, we should first check
+	 * if a command was provided before we drop into download_external.
+	 */
 	if(handle->xfercommand == NULL) {
+#if defined(INTERNAL_DOWNLOAD)
 		ret = download_internal(url, localpath, mtimeold, mtimenew);
+#else
+		RET_ERR(PM_ERR_EXTERNAL_DOWNLOAD, -1);
+#endif
 	} else {
 		ret = download_external(url, localpath, mtimeold, mtimenew);
 	}

lib/libalpm/error.c

@@ -19,7 +19,9 @@
 
 #include "config.h"
 
+#if defined(INTERNAL_DOWNLOAD)
 #include <download.h> /* downloadLastErrString */
+#endif
 
 /* libalpm */
 #include "util.h"
@@ -132,9 +134,6 @@ const char SYMEXPORT *alpm_strerror(int err)
 			return _("not confirmed");
 		case PM_ERR_INVALID_REGEX:
 			return _("invalid regular expression");
-		/* Downloading */
-		case PM_ERR_CONNECT_FAILED:
-			return _("connection to remote host failed");
 		/* Errors from external libraries- our own wrapper error */
 		case PM_ERR_LIBARCHIVE:
 			/* it would be nice to use archive_error_string() here, but that
@@ -142,7 +141,14 @@ const char SYMEXPORT *alpm_strerror(int err)
 			 * error string instead. */
 			return _("libarchive error");
 		case PM_ERR_LIBDOWNLOAD:
+#if defined(INTERNAL_DOWNLOAD)
 			return downloadLastErrString;
+#else
+			/* obviously shouldn't get here... */
+			return _("libdownload error");
+#endif
+		case PM_ERR_EXTERNAL_DOWNLOAD:
+			return _("error invoking external downloader");
 		/* Unknown error! */
 		default:
 			return _("unexpected error");