Userspace: Write a dynamic loader
This allows running executing dynamically linked executables!
This commit is contained in:
174
userspace/programs/DynamicLoader/utils.cpp
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174
userspace/programs/DynamicLoader/utils.cpp
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#include "utils.h"
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#include <errno.h>
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#include <fcntl.h>
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#include <unistd.h>
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void print(int fd, const char* buffer)
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{
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size_t len = 0;
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while (buffer[len])
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len++;
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syscall(SYS_WRITE, fd, buffer, len);
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}
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static const char* errno_to_string(int error);
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[[noreturn]] void print_error_and_exit(const char* message, int error)
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{
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print(STDERR_FILENO, message);
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if (error < 0)
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{
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print(STDERR_FILENO, ": ");
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print(STDERR_FILENO, errno_to_string(-error));
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}
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print(STDERR_FILENO, "\n");
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syscall(SYS_EXIT, 1);
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__builtin_unreachable();
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}
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int strcmp(const char* s1, const char* s2)
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{
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const unsigned char* u1 = reinterpret_cast<const unsigned char*>(s1);
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const unsigned char* u2 = reinterpret_cast<const unsigned char*>(s2);
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for (; *u1 && *u2; u1++, u2++)
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if (*u1 != *u2)
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break;
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return *u1 - *u2;
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}
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char* strcpy(char* __restrict s1, const char* __restrict s2)
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{
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size_t i = 0;
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for (; s2[i]; i++)
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s1[i] = s2[i];
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s1[i] = '\0';
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return s1;
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}
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void* memcpy(void* __restrict dstp, const void* __restrict srcp, size_t n)
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{
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unsigned char* dst = static_cast<unsigned char*>(dstp);
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const unsigned char* src = static_cast<const unsigned char*>(srcp);
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for (size_t i = 0; i < n; i++)
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dst[i] = src[i];
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return dstp;
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}
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static int s_random_fd;
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void init_random()
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{
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s_random_fd = syscall(SYS_OPEN, "/dev/random", O_RDONLY);
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if (s_random_fd < 0)
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print_error_and_exit("could not open /dev/random", s_random_fd);
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}
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void fini_random()
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{
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auto ret = syscall(SYS_CLOSE, s_random_fd);
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if (ret < 0)
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print_error_and_exit("could not close /dev/random", ret);
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}
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uintptr_t get_random_uptr()
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{
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uintptr_t result;
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if (auto ret = syscall(SYS_READ, s_random_fd, &result, sizeof(result)); ret != sizeof(result))
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print_error_and_exit("could not read from /dev/random", ret);
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return result;
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}
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static const char* errno_to_string(int error)
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{
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switch (error)
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{
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case 0: return "Success";
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case E2BIG: return "Argument list too long.";
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case EACCES: return "Permission denied.";
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case EADDRINUSE: return "Address in use.";
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case EADDRNOTAVAIL: return "Address not available.";
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case EAFNOSUPPORT: return "Address family not supported.";
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case EAGAIN: return "Resource unavailable, try again.";
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case EALREADY: return "Connection already in progress.";
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case EBADF: return "Bad file descriptor.";
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case EBADMSG: return "Bad message.";
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case EBUSY: return "Device or resource busy.";
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case ECANCELED: return "Operation canceled.";
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case ECHILD: return "No child processes.";
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case ECONNABORTED: return "Connection aborted.";
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case ECONNREFUSED: return "Connection refused.";
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case ECONNRESET: return "Connection reset.";
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case EDEADLK: return "Resource deadlock would occur.";
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case EDESTADDRREQ: return "Destination address required.";
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case EDOM: return "Mathematics argument out of domain of function.";
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case EDQUOT: return "Reserved.";
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case EEXIST: return "File exists.";
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case EFAULT: return "Bad address.";
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case EFBIG: return "File too large.";
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case EHOSTUNREACH: return "Host is unreachable.";
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case EIDRM: return "Identifier removed.";
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case EILSEQ: return "Illegal byte sequence.";
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case EINPROGRESS: return "Operation in progress.";
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case EINTR: return "Interrupted function.";
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case EINVAL: return "Invalid argument.";
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case EIO: return "I/O error.";
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case EISCONN: return "Socket is connected.";
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case EISDIR: return "Is a directory.";
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case ELOOP: return "Too many levels of symbolic links.";
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case EMFILE: return "File descriptor value too large.";
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case EMLINK: return "Too many links.";
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case EMSGSIZE: return "Message too large.";
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case EMULTIHOP: return "Reserved.";
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case ENAMETOOLONG: return "Filename too long.";
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case ENETDOWN: return "Network is down.";
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case ENETRESET: return "Connection aborted by network.";
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case ENETUNREACH: return "Network unreachable.";
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case ENFILE: return "Too many files open in system.";
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case ENOBUFS: return "No buffer space available.";
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case ENODATA: return "No message is available on the STREAM head read queue.";
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case ENODEV: return "No such device.";
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case ENOENT: return "No such file or directory.";
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case ENOEXEC: return "Executable file format error.";
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case ENOLCK: return "No locks available.";
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case ENOLINK: return "Reserved.";
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case ENOMEM: return "Not enough space.";
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case ENOMSG: return "No message of the desired type.";
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case ENOPROTOOPT: return "Protocol not available.";
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case ENOSPC: return "No space left on device.";
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case ENOSR: return "No STREAM resources.";
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case ENOSTR: return "Not a STREAM.";
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case ENOSYS: return "Functionality not supported.";
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case ENOTCONN: return "The socket is not connected.";
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case ENOTDIR: return "Not a directory or a symbolic link to a directory.";
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case ENOTEMPTY: return "Directory not empty.";
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case ENOTRECOVERABLE: return "State not recoverable.";
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case ENOTSOCK: return "Not a socket.";
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case ENOTSUP: return "Not supported.";
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case ENOTTY: return "Inappropriate I/O control operation.";
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case ENXIO: return "No such device or address.";
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case EOPNOTSUPP: return "Operation not supported on socket .";
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case EOVERFLOW: return "Value too large to be stored in data type.";
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case EOWNERDEAD: return "Previous owner died.";
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case EPERM: return "Operation not permitted.";
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case EPIPE: return "Broken pipe.";
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case EPROTO: return "Protocol error.";
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case EPROTONOSUPPORT: return "Protocol not supported.";
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case EPROTOTYPE: return "Protocol wrong type for socket.";
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case ERANGE: return "Result too large.";
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case EROFS: return "Read-only file system.";
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case ESPIPE: return "Invalid seek.";
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case ESRCH: return "No such process.";
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case ESTALE: return "Reserved.";
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case ETIME: return "Stream ioctl() timeout.";
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case ETIMEDOUT: return "Connection timed out.";
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case ETXTBSY: return "Text file busy.";
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case EWOULDBLOCK: return "Operation would block.";
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case EXDEV: return "Cross-device link.";
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case EEXISTS: return "File exists";
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case ENOTBLK: return "Block device required";
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case EUNKNOWN: return "Unknown error";
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}
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return nullptr;
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}
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