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/cran/metadata.go

@@ -13,6 +13,7 @@ import (
 	"regexp"
 	"strings"
 
+	"gitea.dev/modules/packages"
 	"gitea.dev/modules/util"
 )
 
@@ -151,7 +152,7 @@ func ParseDescription(r io.Reader) (*Package, error) {
 		Metadata: &Metadata{},
 	}
 
-	scanner := bufio.NewScanner(r)
+	scanner := bufio.NewScanner(packages.NewLimitedReader(r, packages.MaxMetadataSize))
 
 	var b strings.Builder
 	for scanner.Scan() {
@@ -173,11 +174,11 @@ func ParseDescription(r io.Reader) (*Package, error) {
 		b.WriteString(line)
 	}
 
-	if err := setField(p, b.String()); err != nil {
+	if err := scanner.Err(); err != nil {
 		return nil, err
 	}
 
-	if err := scanner.Err(); err != nil {
+	if err := setField(p, b.String()); err != nil {
 		return nil, err
 	}