/* cookie.c - print a cookie at random from cookie-dough * * First version by Jim Blandy - Tue May 8 1990 - Oberlin College, OH * Modified by Karl Fogel - Thu 29 Feb 1996 - Oberlin College, OH, USA. * * This program selects and prints a cookie from cookie-dough. * The cookie-dough file should be a text file containing the cookies, * separated by \ characters. If you want to include a \ in the text, * you can double it. */ #define _POSIX_SOURCE #include #include #include #include #include #include #include #define BOF EOF #define SEPARATOR ('\\') /* This just gets argv[0] in main; it's for error messages. */ char *progname; /* Where the goodies are. */ char *cookie_jar; /* If no cookie jar specified on command line, then use this one: */ #ifndef DEFAULT_COOKIE_JAR #define DEFAULT_COOKIE_JAR "/usr/local/lib/cookie/cookie-dough" #endif size_t file_size (char *file) { size_t file_size; struct stat stat_buf; stat (file, &stat_buf); file_size = (long) stat_buf.st_size; return file_size; } /* `fp' should be stdin or stderr. */ void usage (FILE *fp) { char *msg = "Usage: \"%s [COOKIEFILE]\"\n" "Prints out a fortune cookie message.\n" "\n" "If no COOKIEFILE given, it checks environment variable COOKIE_JAR.\n" "Failing that, it tries " DEFAULT_COOKIE_JAR ".\n" "\n" "To read a cookiefile whose name starts with a hyphen, use the\n" "empty option (\"-\"), as in:\n" "\n" "\"%s - [COOKIEFILE-WHOSE-NAME-STARTS-WITH-A-DASH]\"\n" "\n" "Run \"%s -help\" for this message.\n" ; fprintf (fp, msg, progname, progname, progname); exit ((fp == stderr)? 1 : 0); } FILE * fopen_cookie_jar (int argc, char **argv) { FILE *fp; if (argc < 2) { if ((cookie_jar = (char *) getenv ("COOKIE_JAR")) == NULL) cookie_jar = DEFAULT_COOKIE_JAR; } else /* argc >= 2 */ { if (argv[1][0] == '-') { if ((strcmp (argv[1], "-h") == 0) || (strcmp (argv[1], "-u") == 0) || (strcmp (argv[1], "-help") == 0) || (strcmp (argv[1], "--help") == 0) || (strcmp (argv[1], "-usage") == 0) || (strcmp (argv[1], "--usage") == 0) || (strcmp (argv[1], "-?") == 0) ) { usage (stdout); } else if ((strcmp (argv[1], "-") == 0) || (strcmp (argv[1], "--") == 0)) { /* The end of option parsing, next arg is a file no matter what. */ if (argc < 3) usage (stderr); if (argc > 3) usage (stderr); else /* argc == 3 */ cookie_jar = argv[2]; } else usage (stderr); } else if (argc > 2) usage (stderr); else cookie_jar = argv[1]; } /* We now have a cookie_jar from whatever source. Open it. */ if ((fp = fopen (cookie_jar, "r")) == NULL) { fprintf (stderr, "%s: error: fopen %s failed\n", progname, cookie_jar); exit (1); } return fp; } void reach_into_cookie_jar (FILE *fp) { size_t size; long int pos; int rc; pid_t pid; pid = getpid (); srand (time (NULL) + (int) pid); size = file_size (cookie_jar); /* What the heck, it's not an error. */ if (size == 0) exit (0); pos = (long) (rand () % size); /* Subtract 1 to avoid landing on the last char. The reasoning behind this is arcane but secure. */ if ((pos == size) && (pos > 0)) pos--; rc = fseek (fp, pos, SEEK_SET); if (rc != 0) { fprintf (stderr, "%s: error: fseek %s[%ld] failed\n", progname, cookie_jar, pos); fclose (fp); exit (1); } } /* Get the character CH before "point", or BOF. * Assuming not BOF, Decrement file position so next call gets * character before CH. */ int getc_backward (FILE *fp) { int ch, rc; rc = fseek (fp, -1, SEEK_CUR); if (rc != 0) { if (ftell (fp) != 0) { fprintf (stderr, "%s: error: fseek failed\n", progname); exit (1); } else ch = BOF; } else { ch = getc (fp); rc = fseek (fp, -1, SEEK_CUR); if (rc != 0) { /* We just read a char thus can't be at pos 0, so error unconditionally. */ fprintf (stderr, "%s: error: fseek failed\n", progname); exit (1); } if (rc != 0) { /* If not at pos 0, then something went wrong. */ if (ftell (fp) != 0) { fprintf (stderr, "%s: error: fseek failed\n", progname); exit (1); } } } return ch; } void grab_a_cookie (FILE *fp) { int ch; int rc; int bs_count = 0; long int pos; /* We've landed somewhere in the file, probably smack in the middle of a cookie. Find the start of this cookie. */ /* Special-case the start of the file. */ if (ftell (fp) == 0) return; /* If landed on a backslash, rewind until before backslashes or until start of file. */ while ((ch = getc_backward (fp)) != BOF) { while (ch == SEPARATOR) { bs_count++; /* Maybe save the current position; if we read an odd number of backslashes, then we'll want to jump back here because it's the start of the cookie: */ if (bs_count == 1) pos = ftell (fp) + 1; ch = getc_backward (fp); /* The start of the file is automatically the start of the first cookie. */ if (ch == BOF) { /* We must have worked our way back here, because above we special-cased the start of the file. */ if ((bs_count == 1) || ((bs_count % 2) == 0)) { rc = fseek (fp, pos, SEEK_SET); if (rc != 0) { fprintf (stderr, "%s: error: fseek failed\n", progname); fclose (fp); exit (1); } } else /* (bs_count % 2) != 0 */ { rc = fseek (fp, pos, SEEK_SET); if (rc != 0) { fprintf (stderr, "%s: error: fseek failed\n", progname); fclose (fp); exit (1); } } return; } } if ((bs_count % 2) != 0) { rc = fseek (fp, pos, SEEK_SET); if (rc != 0) { fprintf (stderr, "%s: error: fseek failed\n", progname); fclose (fp); exit (1); } break; } else bs_count = 0; } } void eat_the_cookie (FILE *fp) { int ch; /* Now print out the cookie. */ while ((ch = getc (fp)) != EOF) { if (ch == SEPARATOR) { int ch2; ch2 = getc (fp); if ((ch2 != SEPARATOR) || (ch2 == EOF)) break; } printf ("%c", ch); } } void main (int argc, char **argv) { FILE *fp; /* Set up the program's name. */ if (argc < 1) /* huh? */ progname = "cookie"; else progname = argv[0]; fp = fopen_cookie_jar (argc, argv); reach_into_cookie_jar (fp); grab_a_cookie (fp); eat_the_cookie (fp); fclose (fp); }