Fix for lack of basic error checking in writing compressed .blend files

(which is enabled by default). If there was a problem reading or writing
in the compression process, the original .blend file could get lost. Now
errors are checked, and writing is done as follows:

write .blend@ -> compress .blend@ to .blend@.gz ->
rename .blend@.gz to .blend -> remove .blend@

We've had blender crash here, lose the original .blend and leave an
empty .blend@. It is not clear to me where this would happen in practice 
if there is enough disk space and permissions are correct, so the actual
crash is likely not fixed by this commit.

1 files changed, 23 insertions, 13 deletions

diff --git a/source/blender/blenlib/intern/fileops.c b/source/blender/blenlib/intern/fileops.c
index ae20eda5a59..52ebab9b1ff 100644
--- a/source/blender/blenlib/intern/fileops.c
+++ b/source/blender/blenlib/intern/fileops.c
@@ -153,29 +153,39 @@ int BLI_gzip(char *from, char *to) {
 	char buffer[10240];
 	int file;
 	int readsize = 0;
+	int rval= 0, err;
+	gzFile gzfile;
 	
-	gzFile gzfile = gzopen(to,"wb"); 
-	if (NULL == gzfile) return -1;
+	gzfile = gzopen(to, "wb"); 
+	if(gzfile == NULL)
+		return -1;
 	
-	file = open(from,O_BINARY|O_RDONLY);
-	
-	if (file < 0)	return -2;
+	file = open(from, O_BINARY|O_RDONLY);
+	if(file < 0)
+		return -2;
 
-	while ( 1 )
-	{
+	while(1) {
 		readsize = read(file, buffer, 10240);
+
+		if(readsize < 0) {
+			rval= -2; /* error happened in reading */
+			fprintf(stderr, "Error reading file %s: %s.\n", from, strerror(errno));
+			break;
+		}
+		else if(readsize == 0)
+			break; /* done reading */
 		
-		if (readsize <= 0) break;
-		
-		gzwrite(gzfile,buffer,readsize);
+		if(gzwrite(gzfile, buffer, readsize) <= 0) {
+			rval= -1; /* error happened in writing */
+			fprintf(stderr, "Error writing gz file %s: %s.\n", to, gzerror(gzfile, &err));
+			break;
+		}
 	}
 	
 	gzclose(gzfile);
 	close(file);
-	
-	remove(from);
 
-	return 0;
+	return rval;
 }
 
 /* return 1 when file can be written */