Fix reading of gz file size for endian issue. Fixes #39

DESCRIPTION

@@ -1,7 +1,7 @@
 Package: yyjsonr
 Type: Package
 Title: Fast 'JSON', 'NDJSON' and 'GeoJSON' Parser and Generator 
-Version: 0.1.20
+Version: 0.1.20.9000
 Authors@R: c(
     person("Mike", "Cheng", role = c("aut", "cre", 'cph'), 
     email = "[email protected]"),

NEWS.md

@@ -1,4 +1,7 @@
 
+# yyjsonr 0.1.20.9000 2024-04-12
+
+* Get size of gzipped file in an endian-neutral way. Issue #39
 
 # yyjsonr 0.1.20 2024-04-10
 

src/R-yyjson-parse.c

@@ -1953,19 +1953,21 @@ SEXP parse_from_gzfile_(SEXP filename_, SEXP parse_opts_) {
   // Read tail end of .gz file to get length.
   // If uncompressed length > 4GB this method will fail as there are 
   // only 4-bytes reserved for the field!
+  // Stored as a little-endian 32bit int.  Reading this byte-by-byte
+  // to avoid an endianness issue on 32bit powerpc (Issue #39)
   //~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   FILE *fp = fopen(filename, "rb");
   if (fp == NULL) {
     error("couldn't open file: %s", filename);
   }
 
   fseek(fp, -4, SEEK_END);
-  int32_t uncompressed_len;
-  size_t nbytes = fread(&uncompressed_len, 1, 4, fp);
+  int32_t uncompressed_len = 0;
+  uncompressed_len += fgetc(fp);
+  uncompressed_len += fgetc(fp) <<  8;
+  uncompressed_len += fgetc(fp) << 16;
+  uncompressed_len += fgetc(fp) << 24;
   fclose(fp);
-  if (nbytes != 4) {
-    error("Couldn't read size from end of file: %s", filename);
-  }
 
   //~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   // Allocate a buffer to hold the uncompressed file.