fix: optimize packages upload memory (#39366)

Bound the memory used when parsing uploaded packages, so instances with
low memory limits survive non-standard packages.

1. Metadata files are read through a size-limited reader, archives
themselves stay unbounded so large payloads keep working
2. zstd decoding caps the window at 128 MiB, the zstd CLI default
3. RPM headers go through a first-party reader with rpmlib's size and
array count limits that allocates only what the upload contains, until
https://github.com/sassoftware/go-rpmutils/pull/44 is released. Signing
still verifies the payload digest, and its signature header matches
rpmsign's byte for byte
4. Swift and NuGet read the zip entry they size-checked, a duplicate
name could stand in for it before
5. Terraform states check `LIMIT_SIZE_TERRAFORM_STATE` before parsing,
NuGet symbol PDBs share a 256 MiB budget
6. Oversized container configs are rejected instead of stored without
metadata, invalid Vagrant boxes answer 400 instead of 500

Signed-off-by: techknowlogick <git@tklk.dev>
Co-authored-by: techknowlogick <git@tklk.dev>
Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: techknowlogick <techknowlogick@gitea.com>

modules/packages/conda/metadata.go

@@ -11,6 +11,7 @@ import (
 	"strings"
 
 	"gitea.dev/modules/json"
+	"gitea.dev/modules/packages"
 	"gitea.dev/modules/util"
 	"gitea.dev/modules/validation"
 	"gitea.dev/modules/zstd"
@@ -147,7 +148,7 @@ func parsePackageTar(r io.Reader) (*Package, error) {
 		}
 
 		if hdr.Name == "info/index.json" {
-			if err := json.NewDecoder(tr).Decode(&i); err != nil {
+			if err := json.NewDecoder(packages.NewLimitedReader(tr, packages.MaxMetadataSize)).Decode(&i); err != nil {
 				return nil, err
 			}
 
@@ -163,7 +164,7 @@ func parsePackageTar(r io.Reader) (*Package, error) {
 				break // stop loop if both files were found
 			}
 		} else if hdr.Name == "info/about.json" {
-			if err := json.NewDecoder(tr).Decode(&a); err != nil {
+			if err := json.NewDecoder(packages.NewLimitedReader(tr, packages.MaxMetadataSize)).Decode(&a); err != nil {
 				return nil, err
 			}