io: better error handling when writing stuff out

also have the output stream support writing to temporary file
and do renameat/unlinkat on close depending on if all writes
succeeded or not.

src/apk_io.h

@@ -46,7 +46,7 @@ struct apk_bstream {
 
 struct apk_ostream {
 	ssize_t (*write)(void *stream, const void *buf, size_t size);
-	void (*close)(void *stream);
+	int (*close)(void *stream);
 };
 
 #define APK_MPART_DATA		1 /* data processed so far */
@@ -81,8 +81,8 @@ struct apk_bstream *apk_bstream_from_url(const char *url);
 struct apk_bstream *apk_bstream_tee(struct apk_bstream *from, int atfd, const char *to);
 
 struct apk_ostream *apk_ostream_to_fd(int fd);
-struct apk_ostream *apk_ostream_to_file(int atfd, const char *file, mode_t mode);
+struct apk_ostream *apk_ostream_to_file(int atfd, const char *file, const char *tmpfile, mode_t mode);
-struct apk_ostream *apk_ostream_to_file_gz(int atfd, const char *file, mode_t mode);
+struct apk_ostream *apk_ostream_to_file_gz(int atfd, const char *file, const char *tmpfile, mode_t mode);
 size_t apk_ostream_write_string(struct apk_ostream *ostream, const char *string);
 
 apk_blob_t apk_blob_from_istream(struct apk_istream *istream, size_t size);

src/database.c

@@ -814,7 +814,10 @@ static int apk_db_index_write_nr_cache(struct apk_database *db)
 
 	/* Write list of installed non-repository packages to
 	 * cached index file */
-	os = apk_ostream_to_file(db->cache_fd, "installed.new", 0644);
+	os = apk_ostream_to_file(db->cache_fd,
+				 "installed",
+				 "installed.new",
+				 0644);
 	if (os == NULL)
 		return -1;
 
@@ -826,11 +829,9 @@ static int apk_db_index_write_nr_cache(struct apk_database *db)
 		if (r != 0)
 			return r;
 	}
-
+	r = os->close(os);
-	os->close(os);
+	if (r < 0)
-	if (renameat(db->cache_fd, "installed.new",
+		return r;
-		     db->cache_fd, "installed") < 0)
-			return -errno;
 
 	return ctx.count;
 }
@@ -1020,6 +1021,7 @@ struct write_ctx {
 int apk_db_write_config(struct apk_database *db)
 {
 	struct apk_ostream *os;
+	int r;
 
 	if (db->root == NULL)
 		return 0;
@@ -1029,34 +1031,40 @@ int apk_db_write_config(struct apk_database *db)
 		return -1;
 	}
 
-	os = apk_ostream_to_file(db->root_fd, "var/lib/apk/world.new", 0644);
+	os = apk_ostream_to_file(db->root_fd,
+				 "var/lib/apk/world",
+				 "var/lib/apk/world.new",
+				 0644);
 	if (os == NULL)
 		return -1;
+
 	apk_deps_write(db->world, os);
 	os->write(os, "\n", 1);
-	os->close(os);
+	r = os->close(os);
-	if (renameat(db->root_fd, "var/lib/apk/world.new",
+	if (r < 0)
-	             db->root_fd, "var/lib/apk/world") < 0)
+		return r;
-		return -errno;
 
-	os = apk_ostream_to_file(db->root_fd, "var/lib/apk/installed.new", 0644);
+	os = apk_ostream_to_file(db->root_fd,
+				 "var/lib/apk/installed",
+				 "var/lib/apk/installed.new",
+				 0644);
 	if (os == NULL)
 		return -1;
 	apk_db_write_fdb(db, os);
-	os->close(os);
+	r = os->close(os);
+	if (r < 0)
+		return r;
 
-	if (renameat(db->root_fd, "var/lib/apk/installed.new",
+	os = apk_ostream_to_file(db->root_fd,
-		     db->root_fd, "var/lib/apk/installed") < 0)
+				 "var/lib/apk/scripts.tar",
-		return -errno;
+				 "var/lib/apk/scripts.tar.new",
-
+				 0644);
-	os = apk_ostream_to_file(db->root_fd, "var/lib/apk/scripts.tar.new", 0644);
 	if (os == NULL)
 		return -1;
 	apk_db_scriptdb_write(db, os);
-	os->close(os);
+	r = os->close(os);
-	if (renameat(db->root_fd, "var/lib/apk/scripts.tar.new",
+	if (r < 0)
-		     db->root_fd, "var/lib/apk/scripts.tar") < 0)
+		return r;
-		return -errno;
 
 	unlinkat(db->root_fd, "var/lib/apk/scripts", 0);
 	apk_db_index_write_nr_cache(db);
@@ -1796,6 +1804,13 @@ static int apk_db_unpack_pkg(struct apk_database *db,
 	if (ctx.replaces)
 		free(ctx.replaces);
 
+	if (need_copy) {
+		if (r == 0)
+			renameat(db->cachetmp_fd, file, db->cache_fd, file);
+		else
+			unlinkat(db->cachetmp_fd, file, 0);
+	}
+
 	if (r != 0) {
 		apk_error("%s-%s: %s",
 			  newpkg->name->name, newpkg->version,
@@ -1808,9 +1823,6 @@ static int apk_db_unpack_pkg(struct apk_database *db,
 
 	apk_db_migrate_files(db, newpkg);
 
-	if (need_copy)
-		renameat(db->cachetmp_fd, file, db->cache_fd, file);
-
 	return 0;
 err:
 	if (!reinstall)

src/gunzip.c

@@ -190,24 +190,29 @@ static ssize_t gzo_write(void *stream, const void *ptr, size_t size)
 	return size;
 }
 
-static void gzo_close(void *stream)
+static int gzo_close(void *stream)
 {
 	struct apk_gzip_ostream *gos = (struct apk_gzip_ostream *) stream;
 	unsigned char buffer[1024];
 	size_t have;
-	int r;
+	int r, rc = 0;
 
 	do {
 		gos->zs.avail_out = sizeof(buffer);
 		gos->zs.next_out = buffer;
 		r = deflate(&gos->zs, Z_FINISH);
 		have = sizeof(buffer) - gos->zs.avail_out;
-		gos->output->write(gos->output, buffer, have);
+		if (gos->output->write(gos->output, buffer, have) != have)
+			rc = -EIO;
 	} while (r == Z_OK);
-	gos->output->close(gos->output);
+	r = gos->output->close(gos->output);
+	if (r != 0)
+		rc = r;
 
 	deflateEnd(&gos->zs);
 	free(stream);
+
+	return rc;
 }
 
 struct apk_ostream *apk_ostream_gzip(struct apk_ostream *output)

src/index.c

@@ -169,7 +169,7 @@ static int index_main(void *ctx, struct apk_database *db, int argc, char **argv)
 	}
 
 	if (ictx->output != NULL)
-		os = apk_ostream_to_file(AT_FDCWD, ictx->output, 0644);
+		os = apk_ostream_to_file(AT_FDCWD, ictx->output, NULL, 0644);
 	else
 		os = apk_ostream_to_fd(STDOUT_FILENO);
 	if (ictx->method == APK_SIGN_GENERATE) {

src/io.c

@@ -65,8 +65,10 @@ struct apk_istream *apk_istream_from_fd(int fd)
 		return NULL;
 
 	fis = malloc(sizeof(struct apk_fd_istream));
-	if (fis == NULL)
+	if (fis == NULL) {
+		close(fd);
 		return NULL;
+	}
 
 	*fis = (struct apk_fd_istream) {
 		.is.read = fdi_read,
@@ -527,7 +529,11 @@ struct apk_istream *apk_istream_from_file_gz(int atfd, const char *file)
 
 struct apk_fd_ostream {
 	struct apk_ostream os;
-	int fd;
+	int fd, rc;
+
+	const char *file, *tmpfile;
+	int atfd;
+
 	size_t bytes;
 	char buffer[1024];
 };
@@ -555,8 +561,10 @@ static ssize_t fdo_flush(struct apk_fd_ostream *fos)
 	if (fos->bytes == 0)
 		return 0;
 
-	if ((r = safe_write(fos->fd, fos->buffer, fos->bytes)) != fos->bytes)
+	if ((r = safe_write(fos->fd, fos->buffer, fos->bytes)) != fos->bytes) {
+		fos->rc = r < 0 ? r : -EIO;
 		return r;
+	}
 
 	fos->bytes = 0;
 	return 0;
@@ -572,8 +580,12 @@ static ssize_t fdo_write(void *stream, const void *ptr, size_t size)
 		r = fdo_flush(fos);
 		if (r != 0)
 			return r;
-		if (size >= sizeof(fos->buffer) / 2)
+		if (size >= sizeof(fos->buffer) / 2) {
-			return safe_write(fos->fd, ptr, size);
+			r = safe_write(fos->fd, ptr, size);
+			if (r != size)
+				fos->rc = r < 0 ? r : -EIO;
+			return r;
+		}
 	}
 
 	memcpy(&fos->buffer[fos->bytes], ptr, size);
@@ -582,14 +594,28 @@ static ssize_t fdo_write(void *stream, const void *ptr, size_t size)
 	return size;
 }
 
-static void fdo_close(void *stream)
+static int fdo_close(void *stream)
 {
 	struct apk_fd_ostream *fos =
 		container_of(stream, struct apk_fd_ostream, os);
+	int rc = fos->rc;
 
 	fdo_flush(fos);
-	close(fos->fd);
+	if (fos->fd > STDERR_FILENO &&
+	    close(fos->fd) < 0)
+		rc = -errno;
+
+	if (fos->tmpfile != NULL) {
+		if (rc == 0)
+			renameat(fos->atfd, fos->tmpfile,
+				 fos->atfd, fos->file);
+		else
+			unlinkat(fos->atfd, fos->tmpfile, 0);
+	}
+
 	free(fos);
+
+	return rc;
 }
 
 struct apk_ostream *apk_ostream_to_fd(int fd)
@@ -600,8 +626,10 @@ struct apk_ostream *apk_ostream_to_fd(int fd)
 		return NULL;
 
 	fos = malloc(sizeof(struct apk_fd_ostream));
-	if (fos == NULL)
+	if (fos == NULL) {
+		close(fd);
 		return NULL;
+	}
 
 	*fos = (struct apk_fd_ostream) {
 		.os.write = fdo_write,
@@ -612,17 +640,32 @@ struct apk_ostream *apk_ostream_to_fd(int fd)
 	return &fos->os;
 }
 
-struct apk_ostream *apk_ostream_to_file(int atfd, const char *file, mode_t mode)
+struct apk_ostream *apk_ostream_to_file(int atfd,
+					const char *file,
+					const char *tmpfile,
+					mode_t mode)
 {
+	struct apk_ostream *os;
 	int fd;
 
-	fd = openat(atfd, file, O_CREAT | O_RDWR | O_TRUNC, mode);
+	fd = openat(atfd, tmpfile ?: file, O_CREAT | O_RDWR | O_TRUNC, mode);
 	if (fd < 0)
 		return NULL;
 
 	fcntl(fd, F_SETFD, FD_CLOEXEC);
 
-	return apk_ostream_to_fd(fd);
+	os = apk_ostream_to_fd(fd);
+	if (os == NULL)
+		return NULL;
+
+	if (tmpfile != NULL) {
+		struct apk_fd_ostream *fos =
+			container_of(os, struct apk_fd_ostream, os);
+		fos->file = file;
+		fos->tmpfile = tmpfile;
+		fos->atfd = atfd;
+	}
+	return os;
 }
 
 struct apk_counter_ostream {
@@ -639,12 +682,13 @@ static ssize_t co_write(void *stream, const void *ptr, size_t size)
 	return size;
 }
 
-static void co_close(void *stream)
+static int co_close(void *stream)
 {
 	struct apk_counter_ostream *cos =
 		container_of(stream, struct apk_counter_ostream, os);
 
 	free(cos);
+	return 0;
 }
 
 struct apk_ostream *apk_ostream_counter(off_t *counter)