Overhaul sqfs_istream_t/sqfs_ostream_t error handling

Report an error number from the implementations, change the users to
forward that error number (which also means libtar write header/link
now returns an error code) and all subsequent binaries to use
sqfs_perror() instead of relying on the function to print an error
internally.

Also, make sure to preserve errno/GetLastError() in the implementations
and print out a stringified error in sqfs_perror() if the error code
indicates an I/O error.

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

7 files changed, 209 insertions, 209 deletions

diff --git a/lib/io/src/get_line.c b/lib/io/src/get_line.c
index ad37be6..3178592 100644
--- a/lib/io/src/get_line.c
+++ b/lib/io/src/get_line.c
@@ -6,6 +6,7 @@
  */
 #include "internal.h"
 #include "sqfs/io.h"
+#include "sqfs/error.h"
 
 static void ltrim(char *buffer)
 {
@@ -44,17 +45,17 @@ int istream_get_line(sqfs_istream_t *strm, char **out,
 {
 	char *line = NULL, *new;
 	size_t line_len = 0;
+	int err;
 
 	for (;;) {
 		bool have_line = false;
 		size_t i, count, avail;
 		const sqfs_u8 *ptr;
-		int ret;
 
-		ret = strm->get_buffered_data(strm, &ptr, &avail, 0);
-		if (ret < 0)
-			goto fail_free;
-		if (ret > 0) {
+		err = strm->get_buffered_data(strm, &ptr, &avail, 0);
+		if (err < 0)
+			goto fail;
+		if (err > 0) {
 			if (line_len == 0)
 				goto out_eof;
 
@@ -78,8 +79,10 @@ int istream_get_line(sqfs_istream_t *strm, char **out,
 		}
 
 		new = realloc(line, line_len + count + 1);
-		if (new == NULL)
-			goto fail_errno;
+		if (new == NULL) {
+			err = SQFS_ERROR_ALLOC;
+			goto fail;
+		}
 
 		line = new;
 		memcpy(line + line_len, ptr, count);
@@ -108,13 +111,13 @@ int istream_get_line(sqfs_istream_t *strm, char **out,
 
 	*out = line;
 	return 0;
-fail_errno:
-	fprintf(stderr, "%s: " PRI_SZ ": %s.\n", strm->get_filename(strm),
-		*line_num, strerror(errno));
-fail_free:
+fail: {
+	int temp = errno;
 	free(line);
 	*out = NULL;
-	return -1;
+	errno = temp;
+	return err;
+}
 out_eof:
 	free(line);
 	*out = NULL;
diff --git a/lib/io/src/unix/istream.c b/lib/io/src/unix/istream.c
index ca9a183..5005a69 100644
--- a/lib/io/src/unix/istream.c
+++ b/lib/io/src/unix/istream.c
@@ -6,6 +6,7 @@
  */
 #include "../internal.h"
 #include "sqfs/io.h"
+#include "sqfs/error.h"
 
 typedef struct {
 	sqfs_istream_t base;
@@ -46,9 +47,7 @@ static int precache(sqfs_istream_t *strm)
 		if (ret < 0) {
 			if (errno == EINTR)
 				continue;
-
-			perror(file->path);
-			return -1;
+			return SQFS_ERROR_IO;
 		}
 
 		file->buffer_used += ret;
@@ -90,76 +89,72 @@ static void file_advance_buffer(sqfs_istream_t *strm, size_t count)
 
 static const char *file_get_filename(sqfs_istream_t *strm)
 {
-	file_istream_t *file = (file_istream_t *)strm;
-
-	return file->path;
+	return ((file_istream_t *)strm)->path;
 }
 
 static void file_destroy(sqfs_object_t *obj)
 {
 	file_istream_t *file = (file_istream_t *)obj;
 
-	if (file->fd != STDIN_FILENO)
-		close(file->fd);
-
+	close(file->fd);
 	free(file->path);
 	free(file);
 }
 
-sqfs_istream_t *istream_open_handle(const char *path, int fd)
+int istream_open_handle(sqfs_istream_t **out, const char *path,
+			sqfs_file_handle_t fd)
 {
 	file_istream_t *file = calloc(1, sizeof(*file));
 	sqfs_istream_t *strm = (sqfs_istream_t *)file;
 
-	if (file == NULL) {
-		perror(path);
-		return NULL;
-	}
+	if (file == NULL)
+		return SQFS_ERROR_ALLOC;
 
 	sqfs_object_init(file, file_destroy, NULL);
 
 	file->path = strdup(path);
 	if (file->path == NULL) {
-		perror(path);
-		goto fail_free;
+		int temp = errno;
+		free(file);
+		errno = temp;
+		return SQFS_ERROR_ALLOC;
 	}
 
 	file->fd = dup(fd);
 	if (file->fd < 0) {
-		perror(path);
-		goto fail_path;
+		int temp = errno;
+		free(file->path);
+		free(file);
+		errno = temp;
+		return SQFS_ERROR_IO;
 	}
 	close(fd);
 
 	strm->get_buffered_data = file_get_buffered_data;
 	strm->advance_buffer = file_advance_buffer;
 	strm->get_filename = file_get_filename;
-	return strm;
-fail_path:
-	free(file->path);
-fail_free:
-	free(file);
-	return NULL;
+
+	*out = strm;
+	return 0;
 }
 
-sqfs_istream_t *istream_open_file(const char *path)
+int istream_open_file(sqfs_istream_t **out, const char *path)
 {
 	sqfs_file_handle_t fd;
-	sqfs_istream_t *out;
+	int ret;
 
-	if (sqfs_open_native_file(&fd, path, SQFS_FILE_OPEN_READ_ONLY)) {
-		perror(path);
-		return NULL;
-	}
+	ret = sqfs_open_native_file(&fd, path, SQFS_FILE_OPEN_READ_ONLY);
+	if (ret)
+		return ret;
 
-	out = istream_open_handle(path, fd);
-	if (out == NULL)
+	ret = istream_open_handle(out, path, fd);
+	if (ret != 0)
 		close(fd);
 
-	return out;
+	return ret;
 }
 
-sqfs_istream_t *istream_open_stdin(void)
+int istream_open_stdin(sqfs_istream_t **out)
 {
-	return istream_open_handle("stdin", STDIN_FILENO);
+	return istream_open_handle(out, "stdin", STDIN_FILENO);
 }
diff --git a/lib/io/src/unix/ostream.c b/lib/io/src/unix/ostream.c
index 52a566a..a97d8f3 100644
--- a/lib/io/src/unix/ostream.c
+++ b/lib/io/src/unix/ostream.c
@@ -6,6 +6,7 @@
  */
 #include "../internal.h"
 #include "sqfs/io.h"
+#include "sqfs/error.h"
 
 typedef struct {
 	sqfs_ostream_t base;
@@ -23,15 +24,14 @@ static int write_all(file_ostream_t *file, const sqfs_u8 *data, size_t size)
 		ssize_t ret = write(file->fd, data, size);
 
 		if (ret == 0) {
-			fprintf(stderr, "%s: truncated write.\n", file->path);
-			return -1;
+			errno = EPIPE;
+			return SQFS_ERROR_IO;
 		}
 
 		if (ret < 0) {
 			if (errno == EINTR)
 				continue;
-			perror(file->path);
-			return -1;
+			return SQFS_ERROR_IO;
 		}
 
 		file->size += ret;
@@ -46,6 +46,7 @@ static int realize_sparse(file_ostream_t *file)
 {
 	unsigned char *buffer;
 	size_t diff, bufsz;
+	int ret;
 
 	if (file->sparse_count == 0)
 		return 0;
@@ -54,15 +55,18 @@ static int realize_sparse(file_ostream_t *file)
 		bufsz = file->sparse_count > 1024 ? 1024 : file->sparse_count;
 		buffer = calloc(1, bufsz);
 		if (buffer == NULL)
-			goto fail;
+			return SQFS_ERROR_ALLOC;
 
 		while (file->sparse_count > 0) {
 			diff = file->sparse_count > (off_t)bufsz ?
 				bufsz : (size_t)file->sparse_count;
 
-			if (write_all(file, buffer, diff)) {
+			ret = write_all(file, buffer, diff);
+			if (ret) {
+				int temp = errno;
 				free(buffer);
-				return -1;
+				errno = temp;
+				return ret;
 			}
 
 			file->sparse_count -= diff;
@@ -71,35 +75,31 @@ static int realize_sparse(file_ostream_t *file)
 		free(buffer);
 	} else {
 		if (lseek(file->fd, file->sparse_count, SEEK_CUR) == (off_t)-1)
-			goto fail;
+			return SQFS_ERROR_IO;
 
 		if (ftruncate(file->fd, file->size) != 0)
-			goto fail;
+			return SQFS_ERROR_IO;
 
 		file->sparse_count = 0;
 	}
 
 	return 0;
-fail:
-	perror(file->path);
-	return -1;
 }
 
 static int file_append(sqfs_ostream_t *strm, const void *data, size_t size)
 {
 	file_ostream_t *file = (file_ostream_t *)strm;
+	int ret;
 
-	if (size == 0)
-		return 0;
-
-	if (data == NULL) {
+	if (size == 0 || data == NULL) {
 		file->sparse_count += size;
 		file->size += size;
 		return 0;
 	}
 
-	if (realize_sparse(file))
-		return -1;
+	ret = realize_sparse(file);
+	if (ret)
+		return ret;
 
 	return write_all(file, data, size);
 }
@@ -107,15 +107,15 @@ static int file_append(sqfs_ostream_t *strm, const void *data, size_t size)
 static int file_flush(sqfs_ostream_t *strm)
 {
 	file_ostream_t *file = (file_ostream_t *)strm;
+	int ret;
 
-	if (realize_sparse(file))
-		return -1;
+	ret = realize_sparse(file);
+	if (ret)
+		return ret;
 
 	if (fsync(file->fd) != 0) {
-		if (errno == EINVAL)
-			return 0;
-		perror(file->path);
-		return -1;
+		if (errno != EINVAL)
+			return SQFS_ERROR_IO;
 	}
 
 	return 0;
@@ -132,33 +132,36 @@ static void file_destroy(sqfs_object_t *obj)
 
 static const char *file_get_filename(sqfs_ostream_t *strm)
 {
-	file_ostream_t *file = (file_ostream_t *)strm;
-
-	return file->path;
+	return ((file_ostream_t *)strm)->path;
 }
 
-sqfs_ostream_t *ostream_open_handle(const char *path, int fd, int flags)
+int ostream_open_handle(sqfs_ostream_t **out, const char *path,
+			sqfs_file_handle_t fd, int flags)
 {
 	file_ostream_t *file = calloc(1, sizeof(*file));
 	sqfs_ostream_t *strm = (sqfs_ostream_t *)file;
 
-	if (file == NULL) {
-		perror(path);
-		return NULL;
-	}
+	*out = NULL;
+	if (file == NULL)
+		return SQFS_ERROR_ALLOC;
 
 	sqfs_object_init(file, file_destroy, NULL);
 
 	file->path = strdup(path);
 	if (file->path == NULL) {
-		perror(path);
-		goto fail_free;
+		int temp = errno;
+		free(file);
+		errno = temp;
+		return SQFS_ERROR_ALLOC;
 	}
 
 	file->fd = dup(fd);
 	if (file->fd < 0) {
-		perror(path);
-		goto fail_path;
+		int temp = errno;
+		free(file->path);
+		free(file);
+		errno = temp;
+		return SQFS_ERROR_IO;
 	}
 
 	close(fd);
@@ -167,33 +170,34 @@ sqfs_ostream_t *ostream_open_handle(const char *path, int fd, int flags)
 	strm->append = file_append;
 	strm->flush = file_flush;
 	strm->get_filename = file_get_filename;
-	return strm;
-fail_path:
-	free(file->path);
-fail_free:
-	free(file);
-	return NULL;
+
+	*out = strm;
+	return 0;
 }
 
-sqfs_ostream_t *ostream_open_file(const char *path, int flags)
+int ostream_open_file(sqfs_ostream_t **out, const char *path, int flags)
 {
 	sqfs_file_handle_t fd;
-	sqfs_ostream_t *out;
+	int ret;
 
-	if (sqfs_open_native_file(&fd, path, flags)) {
-		perror(path);
-		return NULL;
-	}
+	*out = NULL;
+	ret = sqfs_open_native_file(&fd, path, flags);
+	if (ret)
+		return ret;
 
-	out = ostream_open_handle(path, fd, flags);
-	if (out == NULL)
+	ret = ostream_open_handle(out, path, fd, flags);
+	if (ret) {
+		int temp = errno;
 		close(fd);
+		errno = temp;
+		return ret;
+	}
 
-	return out;
+	return 0;
 }
 
-sqfs_ostream_t *ostream_open_stdout(void)
+int ostream_open_stdout(sqfs_ostream_t **out)
 {
-	return ostream_open_handle("stdout", STDOUT_FILENO,
+	return ostream_open_handle(out, "stdout", STDOUT_FILENO,
 				   SQFS_FILE_OPEN_NO_SPARSE);
 }
diff --git a/lib/io/src/win32/istream.c b/lib/io/src/win32/istream.c
index 7cc7144..1a4f4db 100644
--- a/lib/io/src/win32/istream.c
+++ b/lib/io/src/win32/istream.c
@@ -6,6 +6,7 @@
  */
 #include "../internal.h"
 #include "sqfs/io.h"
+#include "sqfs/error.h"
 
 #define WIN32_LEAN_AND_MEAN
 #include <windows.h>
@@ -52,8 +53,7 @@ static int precache(sqfs_istream_t *strm)
 			}
 
 			SetLastError(error);
-			w32_perror(file->path);
-			return -1;
+			return SQFS_ERROR_IO;
 		}
 
 		if (actual == 0) {
@@ -112,31 +112,34 @@ static void file_destroy(sqfs_object_t *obj)
 	free(file);
 }
 
-sqfs_istream_t *istream_open_handle(const char *path, HANDLE hnd)
+int istream_open_handle(sqfs_istream_t **out, const char *path, HANDLE hnd)
 {
 	file_istream_t *file = calloc(1, sizeof(*file));
 	sqfs_istream_t *strm = (sqfs_istream_t *)file;
 	BOOL ret;
 
-	if (file == NULL) {
-		perror(path);
-		return NULL;
-	}
+	if (file == NULL)
+		return SQFS_ERROR_ALLOC;
 
 	sqfs_object_init(file, file_destroy, NULL);
 
 	file->path = strdup(path);
 	if (file->path == NULL) {
-		perror(path);
-		goto fail_free;
+		DWORD temp = GetLastError();
+		free(file);
+		SetLastError(temp);
+		return SQFS_ERROR_ALLOC;
 	}
 
 	ret = DuplicateHandle(GetCurrentProcess(), hnd,
 			      GetCurrentProcess(), &file->hnd,
 			      0, FALSE, DUPLICATE_SAME_ACCESS);
 	if (!ret) {
-		w32_perror(path);
-		goto fail_path;
+		DWORD temp = GetLastError();
+		free(file->path);
+		free(file);
+		SetLastError(temp);
+		return SQFS_ERROR_IO;
 	}
 
 	CloseHandle(hnd);
@@ -144,34 +147,34 @@ sqfs_istream_t *istream_open_handle(const char *path, HANDLE hnd)
 	strm->get_buffered_data = file_get_buffered_data;
 	strm->advance_buffer = file_advance_buffer;
 	strm->get_filename = file_get_filename;
-	return strm;
-fail_path:
-	free(file->path);
-fail_free:
-	free(file);
-	return NULL;
+
+	*out = strm;
+	return 0;
 }
 
-sqfs_istream_t *istream_open_file(const char *path)
+int istream_open_file(sqfs_istream_t **out, const char *path)
 {
 	sqfs_file_handle_t hnd;
-	sqfs_istream_t *out;
+	int ret;
 
-	if (sqfs_open_native_file(&hnd, path, SQFS_FILE_OPEN_READ_ONLY)) {
-		w32_perror(path);
-		return NULL;
-	}
+	ret = sqfs_open_native_file(&hnd, path, SQFS_FILE_OPEN_READ_ONLY);
+	if (ret)
+		return ret;
 
-	out = istream_open_handle(path, hnd);
-	if (out == NULL)
+	ret = istream_open_handle(out, path, hnd);
+	if (ret) {
+		DWORD temp = GetLastError();
 		CloseHandle(hnd);
+		SetLastError(temp);
+		return ret;
+	}
 
-	return out;
+	return 0;
 }
 
-sqfs_istream_t *istream_open_stdin(void)
+int istream_open_stdin(sqfs_istream_t **out)
 {
 	HANDLE hnd = GetStdHandle(STD_INPUT_HANDLE);
 
-	return istream_open_handle("stdin", hnd);
+	return istream_open_handle(out, "stdin", hnd);
 }
diff --git a/lib/io/src/win32/ostream.c b/lib/io/src/win32/ostream.c
index 5b584e5..b2ba599 100644
--- a/lib/io/src/win32/ostream.c
+++ b/lib/io/src/win32/ostream.c
@@ -6,6 +6,7 @@
  */
 #include "../internal.h"
 #include "sqfs/io.h"
+#include "sqfs/error.h"
 
 #define WIN32_LEAN_AND_MEAN
 #include <windows.h>
@@ -23,10 +24,8 @@ static int write_data(file_ostream_t *file, const void *data, size_t size)
 	DWORD diff;
 
 	while (size > 0) {
-		if (!WriteFile(file->hnd, data, size, &diff, NULL)) {
-			w32_perror(file->path);
-			return -1;
-		}
+		if (!WriteFile(file->hnd, data, size, &diff, NULL))
+			return SQFS_ERROR_IO;
 
 		size -= diff;
 		data = (const char *)data + diff;
@@ -40,6 +39,7 @@ static int realize_sparse(file_ostream_t *file)
 	size_t bufsz, diff;
 	LARGE_INTEGER pos;
 	void *buffer;
+	int ret;
 
 	if (file->sparse_count == 0)
 		return 0;
@@ -48,18 +48,19 @@ static int realize_sparse(file_ostream_t *file)
 		bufsz = file->sparse_count > 1024 ? 1024 : file->sparse_count;
 		buffer = calloc(1, bufsz);
 
-		if (buffer == NULL) {
-			fputs("out-of-memory\n", stderr);
-			return -1;
-		}
+		if (buffer == NULL)
+			return SQFS_ERROR_ALLOC;
 
 		while (file->sparse_count > 0) {
 			diff = file->sparse_count > bufsz ?
 				bufsz : file->sparse_count;
 
-			if (write_data(file, buffer, diff)) {
+			ret = write_data(file, buffer, diff);
+			if (ret) {
+				DWORD temp = GetLastError();
 				free(buffer);
-				return -1;
+				SetLastError(temp);
+				return ret;
 			}
 
 			file->sparse_count -= diff;
@@ -70,34 +71,30 @@ static int realize_sparse(file_ostream_t *file)
 		pos.QuadPart = file->sparse_count;
 
 		if (!SetFilePointerEx(file->hnd, pos, NULL, FILE_CURRENT))
-			goto fail;
+			return SQFS_ERROR_IO;
 
 		if (!SetEndOfFile(file->hnd))
-			goto fail;
+			return SQFS_ERROR_IO;
 
 		file->sparse_count = 0;
 	}
 
 	return 0;
-fail:
-	w32_perror(file->path);
-	return -1;
 }
 
 static int file_append(sqfs_ostream_t *strm, const void *data, size_t size)
 {
 	file_ostream_t *file = (file_ostream_t *)strm;
+	int ret;
 
-	if (size == 0)
-		return 0;
-
-	if (data == NULL) {
+	if (size == 0 || data == NULL) {
 		file->sparse_count += size;
 		return 0;
 	}
 
-	if (realize_sparse(file))
-		return -1;
+	ret = realize_sparse(file);
+	if (ret)
+		return ret;
 
 	return write_data(file, data, size);
 }
@@ -105,14 +102,14 @@ static int file_append(sqfs_ostream_t *strm, const void *data, size_t size)
 static int file_flush(sqfs_ostream_t *strm)
 {
 	file_ostream_t *file = (file_ostream_t *)strm;
+	int ret;
 
-	if (realize_sparse(file))
-		return -1;
+	ret = realize_sparse(file);
+	if (ret)
+		return ret;
 
-	if (!FlushFileBuffers(file->hnd)) {
-		w32_perror(file->path);
-		return -1;
-	}
+	if (!FlushFileBuffers(file->hnd))
+		return SQFS_ERROR_IO;
 
 	return 0;
 }
@@ -128,36 +125,36 @@ static void file_destroy(sqfs_object_t *obj)
 
 static const char *file_get_filename(sqfs_ostream_t *strm)
 {
-	file_ostream_t *file = (file_ostream_t *)strm;
-
-	return file->path;
+	return ((file_ostream_t *)strm)->path;
 }
 
-sqfs_ostream_t *ostream_open_handle(const char *path, HANDLE hnd, int flags)
+int ostream_open_handle(sqfs_ostream_t **out, const char *path,
+			sqfs_file_handle_t hnd, int flags)
 {
 	file_ostream_t *file = calloc(1, sizeof(*file));
 	sqfs_ostream_t *strm = (sqfs_ostream_t *)file;
 	BOOL ret;
 
-	if (file == NULL) {
-		perror(path);
-		return NULL;
-	}
+	if (file == NULL)
+		return SQFS_ERROR_ALLOC;
 
 	sqfs_object_init(file, file_destroy, NULL);
 
 	file->path = strdup(path);
 	if (file->path == NULL) {
-		perror(path);
-		goto fail_free;
+		free(file);
+		return SQFS_ERROR_ALLOC;
 	}
 
 	ret = DuplicateHandle(GetCurrentProcess(), hnd,
 			      GetCurrentProcess(), &file->hnd,
 			      0, FALSE, DUPLICATE_SAME_ACCESS);
 	if (!ret) {
-		w32_perror(path);
-		goto fail_path;
+		DWORD temp = GetLastError();
+		free(file->path);
+		free(file);
+		SetLastError(temp);
+		return SQFS_ERROR_IO;
 	}
 
 	CloseHandle(hnd);
@@ -166,39 +163,36 @@ sqfs_ostream_t *ostream_open_handle(const char *path, HANDLE hnd, int flags)
 	strm->append = file_append;
 	strm->flush = file_flush;
 	strm->get_filename = file_get_filename;
-	return strm;
-fail_path:
-	free(file->path);
-fail_free:
-	free(file);
-	return NULL;
+
+	*out = strm;
+	return 0;
 }
 
-sqfs_ostream_t *ostream_open_file(const char *path, int flags)
+int ostream_open_file(sqfs_ostream_t **out, const char *path, int flags)
 {
 	sqfs_file_handle_t hnd;
-	sqfs_ostream_t *out;
-
-	if (sqfs_open_native_file(&hnd, path, flags)) {
-		w32_perror(path);
-		return NULL;
-	}
+	int ret;
 
-	if (hnd == INVALID_HANDLE_VALUE) {
-		w32_perror(path);
-		return NULL;
-	}
+	*out = NULL;
+	ret = sqfs_open_native_file(&hnd, path, flags);
+	if (ret)
+		return ret;
 
-	out = ostream_open_handle(path, hnd, flags);
-	if (out == NULL)
+	ret = ostream_open_handle(out, path, hnd, flags);
+	if (ret) {
+		DWORD temp = GetLastError();
 		CloseHandle(hnd);
+		SetLastError(temp);
+		return SQFS_ERROR_IO;
+	}
 
-	return out;
+	return 0;
 }
 
-sqfs_ostream_t *ostream_open_stdout(void)
+int ostream_open_stdout(sqfs_ostream_t **out)
 {
 	HANDLE hnd = GetStdHandle(STD_OUTPUT_HANDLE);
 
-	return ostream_open_handle("stdout", hnd, SQFS_FILE_OPEN_NO_SPARSE);
+	return ostream_open_handle(out, "stdout", hnd,
+				   SQFS_FILE_OPEN_NO_SPARSE);
 }
diff --git a/lib/io/src/xfrm/istream.c b/lib/io/src/xfrm/istream.c
index c499f6c..ee4b5bd 100644
--- a/lib/io/src/xfrm/istream.c
+++ b/lib/io/src/xfrm/istream.c
@@ -6,6 +6,7 @@
  */
 #include "../internal.h"
 #include "sqfs/io.h"
+#include "sqfs/error.h"
 
 typedef struct istream_xfrm_t {
 	sqfs_istream_t base;
@@ -52,11 +53,8 @@ static int precache(sqfs_istream_t *base)
 					       BUFSZ - out_off,
 					       &in_off, &out_off, mode);
 
-		if (ret == XFRM_STREAM_ERROR) {
-			fprintf(stderr, "%s: internal error in decompressor.\n",
-				base->get_filename(base));
-			return -1;
-		}
+		if (ret == XFRM_STREAM_ERROR)
+			return SQFS_ERROR_COMPRESSOR;
 
 		xfrm->buffer_used = out_off;
 		xfrm->wrapped->advance_buffer(xfrm->wrapped, in_off);
diff --git a/lib/io/src/xfrm/ostream.c b/lib/io/src/xfrm/ostream.c
index 4c77f42..c035f2a 100644
--- a/lib/io/src/xfrm/ostream.c
+++ b/lib/io/src/xfrm/ostream.c
@@ -6,6 +6,7 @@
  */
 #include "../internal.h"
 #include "sqfs/io.h"
+#include "sqfs/error.h"
 
 typedef struct ostream_xfrm_t {
 	sqfs_ostream_t base;
@@ -26,7 +27,7 @@ static int flush_inbuf(ostream_xfrm_t *xfrm, bool finish)
 	const int mode = finish ? XFRM_STREAM_FLUSH_FULL :
 		XFRM_STREAM_FLUSH_NONE;
 	sqfs_u32 off_in = 0, off_out = 0;
-	int ret;
+	int ret, ioret;
 
 	while (finish || off_in < avail_in) {
 		ret = xfrm->xfrm->process_data(xfrm->xfrm,
@@ -36,15 +37,13 @@ static int flush_inbuf(ostream_xfrm_t *xfrm, bool finish)
 					       avail_out - off_out,
 					       &off_in, &off_out, mode);
 
-		if (ret == XFRM_STREAM_ERROR) {
-			fprintf(stderr,
-				"%s: internal error in compressor.\n",
-				xfrm->wrapped->get_filename(xfrm->wrapped));
-			return -1;
-		}
+		if (ret == XFRM_STREAM_ERROR)
+			return SQFS_ERROR_COMPRESSOR;
 
-		if (xfrm->wrapped->append(xfrm->wrapped, xfrm->outbuf, off_out))
-			return -1;
+		ioret = xfrm->wrapped->append(xfrm->wrapped,
+					      xfrm->outbuf, off_out);
+		if (ioret)
+			return ioret;
 
 		off_out = 0;
 
@@ -53,8 +52,10 @@ static int flush_inbuf(ostream_xfrm_t *xfrm, bool finish)
 	}
 
 	if (off_out > 0) {
-		if (xfrm->wrapped->append(xfrm->wrapped, xfrm->outbuf, off_out))
-			return -1;
+		ret = xfrm->wrapped->append(xfrm->wrapped,
+					    xfrm->outbuf, off_out);
+		if (ret)
+			return ret;
 	}
 
 	if (off_in < avail_in) {
@@ -74,8 +75,9 @@ static int xfrm_append(sqfs_ostream_t *strm, const void *data, size_t size)
 
 	while (size > 0) {
 		if (xfrm->inbuf_used >= BUFSZ) {
-			if (flush_inbuf(xfrm, false))
-				return -1;
+			int ret = flush_inbuf(xfrm, false);
+			if (ret)
+				return ret;
 		}
 
 		diff = BUFSZ - xfrm->inbuf_used;
@@ -102,8 +104,9 @@ static int xfrm_flush(sqfs_ostream_t *strm)
 	ostream_xfrm_t *xfrm = (ostream_xfrm_t *)strm;
 
 	if (xfrm->inbuf_used > 0) {
-		if (flush_inbuf(xfrm, true))
-			return -1;
+		int ret = flush_inbuf(xfrm, true);
+		if (ret)
+			return ret;
 	}
 
 	return xfrm->wrapped->flush(xfrm->wrapped);