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80a4a65 3c7b4e4 80a4a65 3c7b4e4 80a4a65 3c7b4e4 80a4a65 4871da9 3c7b4e4 4871da9 3c7b4e4 4871da9 80a4a65 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 | """Built-in Unix tools reimplemented in Python so they work on Windows.
These are what the OS simulator uses for cat / ls / sha256sum / base64 /
xxd / tr / … . External tools (python, openssl, …) are executed via
subprocess from :mod:`app.sandbox.terminal`.
"""
import base64
import binascii
import hashlib
import os
from typing import Optional
from app.core.constants import HELP_TEXT
def _safe_path(workdir: str, filename: str) -> Optional[str]:
"""Resolve filename safely within workdir, preventing path traversal.
Returns the resolved path if safe, None if traversal detected.
"""
# Strip leading slashes and replace ..
cleaned = filename.lstrip("/\\").replace("..", "_")
target = os.path.normpath(os.path.join(workdir, cleaned))
# Verify the resolved path is within workdir
real_workdir = os.path.realpath(workdir)
real_target = os.path.realpath(target)
if not real_target.startswith(real_workdir + os.sep) and real_target != real_workdir:
return None
return target
def shell_builtins(args: list[str], workdir: str) -> Optional[dict]:
"""Run a built-in command. Returns a ``{stdout, stderr, exitCode}``
result dict, or ``None`` if the tool is not a built-in (caller should
fall through to subprocess)."""
tool = args[0] if args else ""
rest = args[1:]
try:
if tool == "cat":
if not rest:
return {"stdout": "", "stderr": "cat: missing filename", "exitCode": 1}
out, err = [], ""
for fname in rest:
p = _safe_path(workdir, fname)
if p is None:
err += f"cat: {fname}: Path traversal blocked\n"
continue
if not os.path.isfile(p):
err += f"cat: {fname}: No such file\n"
continue
with open(p, "r", encoding="utf-8", errors="replace") as f:
out.append(f.read())
return {"stdout": "\n".join(out), "stderr": err, "exitCode": 0 if not err else 1}
if tool == "ls":
entries = sorted(os.listdir(workdir))
lines = []
for n in entries:
if n.startswith("."):
continue
p = os.path.join(workdir, n)
if os.path.isdir(p):
lines.append(f"<DIR> {n}")
else:
lines.append(f" {n}")
return {"stdout": "\n".join(lines), "stderr": "", "exitCode": 0}
if tool == "pwd":
return {"stdout": workdir, "stderr": "", "exitCode": 0}
if tool == "echo":
return {"stdout": " ".join(rest), "stderr": "", "exitCode": 0}
if tool == "whoami":
return {"stdout": os.environ.get("USERNAME") or os.environ.get("USER") or "student", "stderr": "", "exitCode": 0}
if tool == "clear":
return {"stdout": "\x1b[2J\x1b[H", "stderr": "", "exitCode": 0, "clear": True}
if tool == "help":
return {"stdout": HELP_TEXT, "stderr": "", "exitCode": 0}
if tool in ("sha256sum", "md5sum", "sha1sum"):
algo = {"sha256sum": "sha256", "md5sum": "md5", "sha1sum": "sha1"}[tool]
if not rest:
return {"stdout": "", "stderr": f"{tool}: missing filename", "exitCode": 1}
out, err = [], ""
for fname in rest:
p = _safe_path(workdir, fname)
if p is None:
err += f"{tool}: {fname}: Path traversal blocked\n"
continue
if not os.path.isfile(p):
err += f"{tool}: {fname}: No such file\n"
continue
with open(p, "rb") as f:
h = hashlib.new(algo, f.read()).hexdigest()
out.append(f"{h} {fname}")
return {"stdout": "\n".join(out), "stderr": err, "exitCode": 0 if not err else 1}
if tool == "base64":
decode = "-d" in rest
args2 = [a for a in rest if a != "-d"]
if not args2:
import sys
data = sys.stdin.read() if not sys.stdin.isatty() else b""
if decode:
return {"stdout": base64.b64decode(data).decode("utf-8", "replace"), "stderr": "", "exitCode": 0}
return {"stdout": base64.b64encode(data).decode(), "stderr": "", "exitCode": 0}
out, err = [], ""
for fname in args2:
p = os.path.join(workdir, fname.lstrip("/\\").replace("..", "_"))
if not os.path.isfile(p):
err += f"base64: {fname}: No such file\n"
continue
with open(p, "rb") as f:
data = f.read()
if decode:
out.append(base64.b64decode(data).decode("utf-8", "replace"))
else:
out.append(base64.b64encode(data).decode())
return {"stdout": "\n".join(out), "stderr": err, "exitCode": 0 if not err else 1}
if tool == "xxd":
if not rest:
return {"stdout": "", "stderr": "xxd: missing filename", "exitCode": 1}
p = os.path.join(workdir, rest[0].lstrip("/\\").replace("..", "_"))
if not os.path.isfile(p):
return {"stdout": "", "stderr": f"xxd: {rest[0]}: No such file", "exitCode": 1}
with open(p, "rb") as f:
data = f.read()
return {"stdout": binascii.hexlify(data).decode(), "stderr": "", "exitCode": 0}
if tool == "tr":
if len(rest) < 2:
return {"stdout": "", "stderr": "tr: usage: tr SET1 SET2", "exitCode": 1}
set1, set2 = rest[0], rest[1]
if len(rest) > 2:
src = " ".join(rest[2:])
for a, b in zip(set1, set2):
src = src.replace(a, b)
return {"stdout": src, "stderr": "", "exitCode": 0}
return {"stdout": "", "stderr": "tr: no input", "exitCode": 1}
if tool == "file":
if not rest:
return {"stdout": "", "stderr": "file: missing filename", "exitCode": 1}
fname = rest[0]
p = os.path.join(workdir, fname.lstrip("/\\").replace("..", "_"))
if not os.path.isfile(p):
return {"stdout": "", "stderr": f"file: {fname}: No such file", "exitCode": 1}
with open(p, "rb") as f:
header = f.read(8)
if header.startswith(b"\xff\xd8\xff"):
return {"stdout": f"{fname}: JPEG image data, JFIF standard 1.01", "stderr": "", "exitCode": 0}
if header.startswith(b"\x89PNG\r\n\x1a\n"):
return {"stdout": f"{fname}: PNG image data, 8-bit/color RGBA, non-interlaced", "stderr": "", "exitCode": 0}
if header.startswith(b"PK\x03\x04"):
return {"stdout": f"{fname}: Zip archive data, at least v2.0 to extract", "stderr": "", "exitCode": 0}
with open(p, "rb") as f:
content = f.read()
if b"PK\x03\x04" in content:
if content.startswith(b"\xff\xd8\xff"):
return {"stdout": f"{fname}: JPEG image data (with appended Zip archive data)", "stderr": "", "exitCode": 0}
return {"stdout": f"{fname}: Zip archive data (appended)", "stderr": "", "exitCode": 0}
try:
content.decode("utf-8")
return {"stdout": f"{fname}: ASCII text", "stderr": "", "exitCode": 0}
except UnicodeDecodeError:
return {"stdout": f"{fname}: data", "stderr": "", "exitCode": 0}
if tool == "strings":
if not rest:
return {"stdout": "", "stderr": "strings: missing filename", "exitCode": 1}
fname = rest[0]
p = os.path.join(workdir, fname.lstrip("/\\").replace("..", "_"))
if not os.path.isfile(p):
return {"stdout": "", "stderr": f"strings: {fname}: No such file", "exitCode": 1}
with open(p, "rb") as f:
data = f.read()
out = []
curr = []
for b in data:
if 32 <= b <= 126 or b == 10 or b == 13:
curr.append(chr(b))
else:
if len(curr) >= 4:
out.append("".join(curr).strip())
curr = []
if len(curr) >= 4:
out.append("".join(curr).strip())
out = [line for line in out if line]
return {"stdout": "\n".join(out[:1000]), "stderr": "", "exitCode": 0}
if tool in ("unzip", "unzip-file"):
if not rest:
return {"stdout": "", "stderr": "unzip: missing filename", "exitCode": 1}
fname = rest[0]
args_clean = [a for a in rest if not a.startswith("-")]
if not args_clean:
return {"stdout": "", "stderr": "unzip: missing filename", "exitCode": 1}
fname = args_clean[0]
p = os.path.join(workdir, fname.lstrip("/\\").replace("..", "_"))
if not os.path.isfile(p):
return {"stdout": "", "stderr": f"unzip: {fname}: No such file", "exitCode": 1}
import zipfile
try:
out_lines = [f"Archive: {fname}"]
with zipfile.ZipFile(p, 'r') as zip_ref:
# Validate all paths before extraction (Zip Slip prevention)
for info in zip_ref.infolist():
target = os.path.realpath(os.path.join(workdir, info.filename))
if not target.startswith(os.path.realpath(workdir) + os.sep) and target != os.path.realpath(workdir):
return {
"stdout": "",
"stderr": f"unzip: blocked path traversal: {info.filename}",
"exitCode": 1,
}
# Safe to extract
zip_ref.extractall(workdir)
for info in zip_ref.infolist():
out_lines.append(f" extracting: {info.filename}")
return {"stdout": "\n".join(out_lines), "stderr": "", "exitCode": 0}
except Exception as e:
return {"stdout": "", "stderr": "unzip: error occurred", "exitCode": 1}
except Exception as e:
return {"stdout": "", "stderr": f"{tool}: {e}", "exitCode": 1}
return None # not a builtin
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