63 lines
1.7 KiB
C
63 lines
1.7 KiB
C
/*
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* This file is part of the Fun programming language.
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* https://fun-lang.xyz/
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*
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* Copyright 2025 Johannes Findeisen
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* Licensed under the terms of the Apache-2.0 license.
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* https://opensource.org/license/apache-2-0
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*/
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/**
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* @file proc_system.c
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* @brief Implements OP_PROC_SYSTEM to execute a shell command and return exit code.
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*
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* Behavior:
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* - Pops command (string); executes it using system(3); pushes the process exit code (int) or -1 on failure.
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*
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* Errors:
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* - If command is not a string or cannot be executed, returns -1.
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*/
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case OP_PROC_SYSTEM: {
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/* Pops command string; pushes exit code number */
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Value cmdv = pop_value(vm);
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char *cmd = value_to_string_alloc(&cmdv);
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free_value(cmdv);
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if (!cmd) {
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push_value(vm, make_int(-1));
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break;
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}
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/* Security hardening: reject commands containing shell metacharacters or control chars
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to reduce risk of command injection when using system(3). This preserves simple
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command execution like "ls -l" but blocks dangerous constructs like pipes, redirects,
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command substitution, etc. */
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const char *bad = "&;|$<>`\\\"'()*?[]{}~";
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int unsafe = 0;
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for (const unsigned char *p = (const unsigned char *)cmd; *p; ++p) {
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if (*p < 0x20 || strchr(bad, (int)*p)) { /* control or meta */
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unsafe = 1;
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break;
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}
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}
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if (unsafe) {
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/* refuse to execute potentially unsafe shell command */
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push_value(vm, make_int(-1));
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free(cmd);
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break;
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}
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int status = system(cmd);
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int code = -1;
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#ifdef __unix__
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if (status == -1)
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code = -1;
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else if (WIFEXITED(status))
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code = WEXITSTATUS(status);
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else
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code = -1;
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#else
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code = status;
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#endif
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push_value(vm, make_int(code));
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free(cmd);
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break;
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}
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