Explicitly write metadata values as integer type

r-wasm · Sep 9, 2024 · 7bc5c52 · 7bc5c52
1 parent 00dfe4e
commit 7bc5c52
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Showing 3 changed files with 5 additions and 5 deletions.
diff --git a/R/tar.R b/R/tar.R
@@ -61,8 +61,8 @@ add_tar_index <- function(file, strip = 0) {
   json <- charToRaw(jsonlite::toJSON(metadata, auto_unbox = TRUE))
   magic <- charToRaw('webR')
   reserved <- raw(4) # reserved for future use
-  block <- writeBin(as.integer(tar_end / 512), raw(), size = 4, endian = "big")
-  len <- writeBin(length(json), raw(), size = 4, endian = "big")
+  block <- writeBin(tar_end / 512, "integer", size = 4, endian = "big")
+  len <- writeBin(length(json), "integer", size = 4, endian = "big")
   length(json) <- 4 * ceiling(length(json) / 4) # pad to 4 byte boundary
   data <- c(data[1:tar_end], json, magic, reserved, block, len)
 

diff --git a/inst/pkgdown.yml b/inst/pkgdown.yml
@@ -7,7 +7,7 @@ articles:
   mount-host-dir: mount-host-dir.html
   rwasm: rwasm.html
   tar-metadata: tar-metadata.html
-last_built: 2024-09-04T08:58Z
+last_built: 2024-09-09T10:04Z
 urls:
   reference: https://r-wasm.github.io/rwasm/reference
   article: https://r-wasm.github.io/rwasm/articles
diff --git a/vignettes/tar-metadata.Rmd b/vignettes/tar-metadata.Rmd
@@ -22,6 +22,6 @@ A `.tar` archive that includes Emscripten filesystem metadata has the data layou
 | 1 | Variable | JSON metadata, UTF8 encoded, padded with `0x00` to 4 byte boundary. |
 | 2 | 4 bytes | Magic bytes: The string `"webR"`, UTF8 encoded (`0x77656252`). |
 | 3 | 4 bytes | Reserved, currently `0x00000000`. |
-| 4 | 4 bytes | Offset of JSON metadata (field 1), in units of 512-byte blocks. Signed integer, big endian. |
-| 5 | 4 bytes | Length of JSON metadata, in bytes. Signed integer, big endian. |
+| 4 | 4 bytes | Offset of JSON metadata, in units of 512-byte blocks. Signed integer, big endian. |
+| 5 | 4 bytes | Length of JSON metadata, not including trailing null characters, in bytes. Signed integer, big endian. |
 Table: Data layout for a `.tar` archive with filesystem metadata.