libcompat: Add a helper to get/set OS error state

On Unix like OSes, this saves/restores errno, on Windows both errno
and GetLastError state are saved/restored.

This should make it simpler to preserve that across function calls.

Additionally, while tracking down uses of GetLastError, some places
where the error code was printed out directly where replaced with
instances of w32_perror.

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

1 files changed, 28 insertions, 0 deletions

diff --git a/include/compat.h b/include/compat.h
index 7c9f937..f376665 100644
--- a/include/compat.h
+++ b/include/compat.h
@@ -265,4 +265,32 @@ int sqfs_tools_fprintf(FILE *strm, const char *fmt, ...) PRINTF_ATTRIB(2, 3);
 #define putc sqfs_tools_fputc
 #endif
 
+/****************************** error handling ******************************/
+
+#if defined(_WIN32) || defined(__WINDOWS__)
+typedef struct {
+	int unix_errno;
+	DWORD w32_errno;
+} os_error_t;
+
+static SQFS_INLINE os_error_t get_os_error_state(void)
+{
+	os_error_t out = { errno, GetLastError() };
+	return out;
+}
+
+static SQFS_INLINE void set_os_error_state(os_error_t err)
+{
+	SetLastError(err.w32_errno);
+	errno = err.unix_errno;
+}
+#else
+#include <errno.h>
+
+typedef int os_error_t;
+
+#define get_os_error_state() errno
+#define set_os_error_state(err) errno = (err)
+#endif
+
 #endif /* COMPAT_H */