diff --git a/src/libsigrok-internal.h b/src/libsigrok-internal.h
index c8940c89..275deac4 100644
--- a/src/libsigrok-internal.h
+++ b/src/libsigrok-internal.h
@@ -34,6 +34,9 @@
 #include <libserialport.h>
 #endif
 
+struct zip;
+struct zip_stat;
+
 /**
  * @file
  *
@@ -730,6 +733,11 @@ SR_PRIV int sr_packet_copy(const struct sr_datafeed_packet *packet,
 		struct sr_datafeed_packet **copy);
 SR_PRIV void sr_packet_free(struct sr_datafeed_packet *packet);
 
+/*--- session_file.c --------------------------------------------------------*/
+
+SR_PRIV GKeyFile *sr_sessionfile_read_metadata(struct zip *archive,
+			const struct zip_stat *entry);
+
 /*--- analog.c --------------------------------------------------------------*/
 
 SR_PRIV int sr_analog_init(struct sr_datafeed_analog2 *analog,
diff --git a/src/output/srzip.c b/src/output/srzip.c
index d80a7a18..c562e604 100644
--- a/src/output/srzip.c
+++ b/src/output/srzip.c
@@ -19,7 +19,6 @@
 
 #include <config.h>
 #include <stdlib.h>
-#include <unistd.h>
 #include <string.h>
 #include <errno.h>
 #include <glib.h>
@@ -42,7 +41,7 @@ static int init(struct sr_output *o, GHashTable *options)
 
 	(void)options;
 
-	if (strlen(o->filename) == 0) {
+	if (!o->filename || o->filename[0] == '\0') {
 		sr_info("srzip output module requires a file name, cannot save.");
 		return SR_ERR_ARG;
 	}
@@ -57,79 +56,84 @@ static int init(struct sr_output *o, GHashTable *options)
 static int zip_create(const struct sr_output *o)
 {
 	struct out_context *outc;
-	struct sr_channel *ch;
-	FILE *meta;
 	struct zip *zipfile;
 	struct zip_source *versrc, *metasrc;
+	struct sr_channel *ch;
 	GVariant *gvar;
+	GKeyFile *meta;
 	GSList *l;
-	int tmpfile, ret;
-	char version[1], metafile[32], *s;
+	const char *devgroup;
+	char *s, *metabuf;
+	gsize metalen;
 
 	outc = o->priv;
-	if (outc->samplerate == 0) {
-		if (sr_config_get(o->sdi->driver, o->sdi, NULL, SR_CONF_SAMPLERATE,
-				&gvar) == SR_OK) {
-			outc->samplerate = g_variant_get_uint64(gvar);
-			g_variant_unref(gvar);
-		}
+
+	if (outc->samplerate == 0 && sr_config_get(o->sdi->driver, o->sdi, NULL,
+					SR_CONF_SAMPLERATE, &gvar) == SR_OK) {
+		outc->samplerate = g_variant_get_uint64(gvar);
+		g_variant_unref(gvar);
 	}
 
 	/* Quietly delete it first, libzip wants replace ops otherwise. */
-	unlink(outc->filename);
-	if (!(zipfile = zip_open(outc->filename, ZIP_CREATE, &ret)))
+	g_unlink(outc->filename);
+	zipfile = zip_open(outc->filename, ZIP_CREATE, NULL);
+	if (!zipfile)
 		return SR_ERR;
 
 	/* "version" */
-	version[0] = '2';
-	if (!(versrc = zip_source_buffer(zipfile, version, 1, 0)))
-		return SR_ERR;
-	if (zip_add(zipfile, "version", versrc) == -1) {
-		sr_info("Error saving version into zipfile: %s.",
+	versrc = zip_source_buffer(zipfile, "2", 1, FALSE);
+	if (zip_file_add(zipfile, "version", versrc, 0) < 0) {
+		sr_err("Error saving version into zipfile: %s",
 			zip_strerror(zipfile));
+		zip_source_free(versrc);
+		zip_discard(zipfile);
 		return SR_ERR;
 	}
 
 	/* init "metadata" */
-	strcpy(metafile, "sigrok-meta-XXXXXX");
-	if ((tmpfile = g_mkstemp(metafile)) == -1)
-		return SR_ERR;
-	close(tmpfile);
-	meta = g_fopen(metafile, "wb");
-	fprintf(meta, "[global]\n");
-	fprintf(meta, "sigrok version = %s\n", SR_PACKAGE_VERSION_STRING);
-	fprintf(meta, "[device 1]\ncapturefile = logic-1\n");
-	fprintf(meta, "total probes = %d\n", g_slist_length(o->sdi->channels));
+	meta = g_key_file_new();
+
+	g_key_file_set_string(meta, "global", "sigrok version",
+			SR_PACKAGE_VERSION_STRING);
+
+	devgroup = "device 1";
+	g_key_file_set_string(meta, devgroup, "capturefile", "logic-1");
+
+	g_key_file_set_integer(meta, devgroup, "total probes",
+			g_slist_length(o->sdi->channels));
+
 	s = sr_samplerate_string(outc->samplerate);
-	fprintf(meta, "samplerate = %s\n", s);
+	g_key_file_set_string(meta, devgroup, "samplerate", s);
 	g_free(s);
 
 	for (l = o->sdi->channels; l; l = l->next) {
 		ch = l->data;
-		if (ch->type != SR_CHANNEL_LOGIC)
-			continue;
-		if (!ch->enabled)
-			continue;
-		fprintf(meta, "probe%d = %s\n", ch->index + 1, ch->name);
+		if (ch->enabled && ch->type == SR_CHANNEL_LOGIC) {
+			s = g_strdup_printf("probe%d", ch->index + 1);
+			g_key_file_set_string(meta, devgroup, s, ch->name);
+			g_free(s);
+		}
 	}
-	fclose(meta);
+	metabuf = g_key_file_to_data(meta, &metalen, NULL);
+	g_key_file_free(meta);
 
-	if (!(metasrc = zip_source_file(zipfile, metafile, 0, -1))) {
-		unlink(metafile);
-		return SR_ERR;
-	}
-	if (zip_add(zipfile, "metadata", metasrc) == -1) {
-		unlink(metafile);
+	metasrc = zip_source_buffer(zipfile, metabuf, metalen, FALSE);
+	if (zip_file_add(zipfile, "metadata", metasrc, 0) < 0) {
+		sr_err("Error saving metadata into zipfile: %s",
+			zip_strerror(zipfile));
+		zip_source_free(metasrc);
+		zip_discard(zipfile);
+		g_free(metabuf);
 		return SR_ERR;
 	}
 
-	if ((ret = zip_close(zipfile)) == -1) {
-		sr_info("Error saving zipfile: %s.", zip_strerror(zipfile));
-		unlink(metafile);
+	if (zip_close(zipfile) < 0) {
+		sr_err("Error saving zipfile: %s", zip_strerror(zipfile));
+		zip_discard(zipfile);
+		g_free(metabuf);
 		return SR_ERR;
 	}
-
-	unlink(metafile);
+	g_free(metabuf);
 
 	return SR_OK;
 }
@@ -140,72 +144,62 @@ static int zip_append(const struct sr_output *o, unsigned char *buf,
 	struct out_context *outc;
 	struct zip *archive;
 	struct zip_source *logicsrc;
-	zip_int64_t num_files;
-	struct zip_file *zf;
+	int64_t i, num_files;
 	struct zip_stat zs;
 	struct zip_source *metasrc;
 	GKeyFile *kf;
 	GError *error;
-	gsize len;
-	int chunk_num, next_chunk_num, tmpfile, ret, i;
+	uint64_t chunk_num;
 	const char *entry_name;
-	char *metafile, tmpname[32], chunkname[16];
+	char *metabuf;
+	gsize metalen;
+	char *chunkname;
+	unsigned int next_chunk_num;
 
 	outc = o->priv;
-	if (!(archive = zip_open(outc->filename, 0, &ret)))
+	if (!(archive = zip_open(outc->filename, 0, NULL)))
 		return SR_ERR;
 
-	if (zip_stat(archive, "metadata", 0, &zs) == -1)
+	if (zip_stat(archive, "metadata", 0, &zs) < 0) {
+		sr_err("Failed to open metadata: %s", zip_strerror(archive));
+		zip_discard(archive);
 		return SR_ERR;
-
-	metafile = g_malloc(zs.size);
-	zf = zip_fopen_index(archive, zs.index, 0);
-	zip_fread(zf, metafile, zs.size);
-	zip_fclose(zf);
-
+	}
+	kf = sr_sessionfile_read_metadata(archive, &zs);
+	if (!kf) {
+		zip_discard(archive);
+		return SR_ERR_DATA;
+	}
 	/*
 	 * If the file was only initialized but doesn't yet have any
 	 * data it in, it won't have a unitsize field in metadata yet.
 	 */
 	error = NULL;
-	kf = g_key_file_new();
-	if (!g_key_file_load_from_data(kf, metafile, zs.size, 0, &error)) {
-		sr_err("Failed to parse metadata: %s.", error->message);
-		return SR_ERR;
-	}
-	g_free(metafile);
-	tmpname[0] = '\0';
+	metabuf = NULL;
 	if (!g_key_file_has_key(kf, "device 1", "unitsize", &error)) {
 		if (error && error->code != G_KEY_FILE_ERROR_KEY_NOT_FOUND) {
-			sr_err("Failed to check unitsize key: %s", error ? error->message : "?");
+			sr_err("Failed to check unitsize key: %s", error->message);
+			g_error_free(error);
+			g_key_file_free(kf);
+			zip_discard(archive);
 			return SR_ERR;
 		}
+		g_clear_error(&error);
+
 		/* Add unitsize field. */
 		g_key_file_set_integer(kf, "device 1", "unitsize", unitsize);
-		metafile = g_key_file_to_data(kf, &len, &error);
-		strcpy(tmpname, "sigrok-meta-XXXXXX");
-		if ((tmpfile = g_mkstemp(tmpname)) == -1)
-			return SR_ERR;
-		if (write(tmpfile, metafile, len) < 0) {
-			sr_dbg("Failed to create new metadata: %s", g_strerror(errno));
-			g_free(metafile);
-			unlink(tmpname);
+		metabuf = g_key_file_to_data(kf, &metalen, NULL);
+		metasrc = zip_source_buffer(archive, metabuf, metalen, FALSE);
+
+		if (zip_replace(archive, zs.index, metasrc) < 0) {
+			sr_err("Failed to replace metadata: %s",
+				zip_strerror(archive));
+			g_key_file_free(kf);
+			zip_source_free(metasrc);
+			zip_discard(archive);
+			g_free(metabuf);
 			return SR_ERR;
 		}
-		close(tmpfile);
-		if (!(metasrc = zip_source_file(archive, tmpname, 0, -1))) {
-			sr_err("Failed to create zip source for metadata.");
-			g_free(metafile);
-			unlink(tmpname);
-			return SR_ERR;
-		}
-		if (zip_replace(archive, zs.index, metasrc) == -1) {
-			sr_err("Failed to replace metadata file.");
-			g_free(metafile);
-			unlink(tmpname);
-			return SR_ERR;
-		}
-		g_free(metafile);
 	}
 	g_key_file_free(kf);
 
@@ -213,39 +207,50 @@ static int zip_append(const struct sr_output *o, unsigned char *buf,
 	num_files = zip_get_num_entries(archive, 0);
 	for (i = 0; i < num_files; i++) {
 		entry_name = zip_get_name(archive, i, 0);
-		if (strncmp(entry_name, "logic-1", 7))
+		if (!entry_name || strncmp(entry_name, "logic-1", 7) != 0)
 			continue;
-		if (strlen(entry_name) == 7) {
+		if (entry_name[7] == '\0') {
 			/* This file has no extra chunks, just a single "logic-1".
 			 * Rename it to "logic-1-1" * and continue with chunk 2. */
-			if (zip_rename(archive, i, "logic-1-1") == -1) {
-				sr_err("Failed to rename 'logic-1' to 'logic-1-1'.");
-				unlink(tmpname);
+			if (zip_rename(archive, i, "logic-1-1") < 0) {
+				sr_err("Failed to rename 'logic-1' to 'logic-1-1': %s",
+					zip_strerror(archive));
+				zip_discard(archive);
+				g_free(metabuf);
 				return SR_ERR;
 			}
 			next_chunk_num = 2;
 			break;
-		} else if (strlen(entry_name) > 8 && entry_name[7] == '-') {
-			chunk_num = strtoull(entry_name + 8, NULL, 10);
-			if (chunk_num >= next_chunk_num)
+		} else if (entry_name[7] == '-') {
+			chunk_num = g_ascii_strtoull(entry_name + 8, NULL, 10);
+			if (chunk_num < G_MAXINT && chunk_num >= next_chunk_num)
 				next_chunk_num = chunk_num + 1;
 		}
 	}
-	snprintf(chunkname, 15, "logic-1-%d", next_chunk_num);
-	if (!(logicsrc = zip_source_buffer(archive, buf, length, FALSE))) {
-		unlink(tmpname);
+
+	if (length % unitsize != 0) {
+		sr_warn("Chunk size %d not a multiple of the"
+			" unit size %d.", length, unitsize);
+	}
+	logicsrc = zip_source_buffer(archive, buf, length, FALSE);
+	chunkname = g_strdup_printf("logic-1-%u", next_chunk_num);
+	i = zip_add(archive, chunkname, logicsrc);
+	g_free(chunkname);
+	if (i < 0) {
+		sr_err("Failed to add chunk 'logic-1-%u': %s",
+			next_chunk_num, zip_strerror(archive));
+		zip_source_free(logicsrc);
+		zip_discard(archive);
+		g_free(metabuf);
 		return SR_ERR;
 	}
-	if (zip_add(archive, chunkname, logicsrc) == -1) {
-		unlink(tmpname);
+	if (zip_close(archive) < 0) {
+		sr_err("Error saving session file: %s", zip_strerror(archive));
+		zip_discard(archive);
+		g_free(metabuf);
 		return SR_ERR;
 	}
-	if ((ret = zip_close(archive)) == -1) {
-		sr_info("error saving session file: %s", zip_strerror(archive));
-		unlink(tmpname);
-		return SR_ERR;
-	}
-	unlink(tmpname);
+	g_free(metabuf);
 
 	return SR_OK;
 }