apio
8eb986df63
This is a GNU extension, but I'm fine with adding it to libc. It's guarded by the _GNU_SOURCE feature test macro anyways.
67 lines
1.6 KiB
C++
67 lines
1.6 KiB
C++
#include <errno.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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static void terminate_libc()
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{
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fclose(stdout);
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fclose(stderr);
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fclose(stdin);
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}
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static void initialize_random()
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{
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unsigned int seed = 3735928559U;
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FILE* fp = fopen("/dev/random", "rw");
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if (!fp)
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{
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errno = 0;
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goto failed_to_read_dev_random;
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}
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fread(&seed, sizeof(seed), 1, fp);
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if (ferror(fp))
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{
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errno = 0;
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fclose(fp);
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goto failed_to_read_dev_random;
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}
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fclose(fp);
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failed_to_read_dev_random:
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srand(seed); // If we failed, this will be seeded with a known value. Else, it will be seeded with a random value
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// from the kernel.
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return;
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}
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static void check_for_file(int fd, FILE** target_stream, const char* path, const char* mode)
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{
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if (lseek(fd, 0, SEEK_CUR) < 0)
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{
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if (errno == EBADF) *target_stream = fopen(path, mode);
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else
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exit(-127);
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if (!*target_stream) exit(-127);
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errno = 0;
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}
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else { *target_stream = fdopen(fd, mode); }
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}
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extern char* program_invocation_name;
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extern "C" void initialize_libc(int argc, char** argv)
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{
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check_for_file(STDIN_FILENO, &stdin, "/dev/kbd", "r");
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check_for_file(STDOUT_FILENO, &stdout, "/dev/console", "rw");
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check_for_file(STDERR_FILENO, &stderr, "/dev/console", "rw");
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program_invocation_name =
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argv[0]; // argv[0] should only be nullptr when being init, which shouldn't use program_invocation_name anyways.
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initialize_random();
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atexit(terminate_libc);
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} |