#!/usr/bin/env bash
# Shared helpers for building MCP resource content payloads.
set -euo pipefail
mcp_resource_detect_mime() {
local path="$1"
local fallback="${2:-text/plain}"
if command -v file >/dev/null 2>&1; then
local detected
# --brief keeps output compact; --mime returns mime + charset where available.
if detected="$(file --mime --brief -- "${path}" 2>/dev/null || true)"; then
detected="${detected%%;*}"
detected="$(printf '%s' "${detected}" | tr '[:upper:]' '[:lower:]' | awk '{$1=$1};1')"
if [ -n "${detected}" ]; then
printf '%s' "${detected}"
return 0
fi
fi
fi
printf '%s' "${fallback}"
}
mcp_resource_is_binary_mime() {
local mime="$1"
local lower
lower="$(printf '%s' "${mime}" | tr '[:upper:]' '[:lower:]')"
case "${lower}" in
*charset=binary*) return 0 ;;
application/octet-stream | application/x-executable | application/pdf) return 0 ;;
application/zip | application/x-gzip | application/x-bzip2 | application/x-xz) return 0 ;;
image/* | audio/* | video/*) return 0 ;;
esac
# Treat common textual mime types as non-binary.
case "${lower}" in
text/*) return 1 ;;
*json* | *xml* | *yaml* | *csv* | *javascript* | *x-shellscript* | *x-sh*) return 1 ;;
*markdown* | *html* | *css*) return 1 ;;
esac
# Default: consider mime binary-safe to avoid emitting raw bytes into JSON.
return 0
}
mcp_resource_should_base64() {
local path="$1"
local mime="$2"
if mcp_resource_is_binary_mime "${mime}"; then
return 0
fi
if command -v od >/dev/null 2>&1 && command -v grep >/dev/null 2>&1; then
if LC_ALL=C od -An -t x1 -N 1024 -- "${path}" 2>/dev/null | LC_ALL=C grep -Eq '(^|[[:space:]])00([[:space:]]|$)'; then
return 0
fi
fi
return 1
}
mcp_resource_content_object_from_file() {
local path="$1"
local mime_hint="${2:-text/plain}"
local uri="${3:-}"
if [ ! -r "${path}" ]; then
return 1
fi
local mime
mime="$(mcp_resource_detect_mime "${path}" "${mime_hint}")"
local base64_mode=1
if mcp_resource_should_base64 "${path}" "${mime}"; then
base64_mode=0
fi
local payload
if [ "${base64_mode}" -eq 0 ]; then
if ! command -v base64 >/dev/null 2>&1; then
return 1
fi
local blob
blob="$(LC_ALL=C base64 <"${path}" | tr -d '\r\n')"
payload="$("${MCPBASH_JSON_TOOL_BIN}" -n -c \
--arg uri "${uri}" \
--arg mime "${mime}" \
--arg blob "${blob}" \
'{
uri: $uri,
mimeType: $mime,
blob: $blob
} | del(.uri | select(.==""))' 2>/dev/null || true)"
else
local text_content
text_content="$(cat -- "${path}")"
payload="$("${MCPBASH_JSON_TOOL_BIN}" -n -c \
--arg uri "${uri}" \
--arg mime "${mime}" \
--arg text "${text_content}" \
'{
uri: $uri,
mimeType: $mime,
text: $text
} | del(.uri | select(.==""))' 2>/dev/null || true)"
fi
if [ -z "${payload}" ]; then
return 1
fi
printf '%s' "${payload}"
}
