| 1 | /* |
| 2 | * usage: |
| 3 | * .../summon <real-summoner> <calling-nick> <calling-path> <channel> |
| 4 | */ |
| 5 | |
| 6 | #include <stdio.h> |
| 7 | #include <stdlib.h> |
| 8 | #include <unistd.h> |
| 9 | #include <ctype.h> |
| 10 | #include <errno.h> |
| 11 | #include <string.h> |
| 12 | |
| 13 | #include <utmp.h> |
| 14 | #include <sys/types.h> |
| 15 | #include <sys/stat.h> |
| 16 | #include <fcntl.h> |
| 17 | |
| 18 | static void check(const char *string, const char *what, int maxlen) { |
| 19 | int c; |
| 20 | |
| 21 | if (strlen(string) > maxlen) { fprintf(stderr,"%s too long\n",what); exit(8); } |
| 22 | while ((c= *string++)) { |
| 23 | if (isspace((unsigned char)c) || !isprint((unsigned char)c)) |
| 24 | { fprintf(stderr,"bad char in %s\n",what); exit(8); } |
| 25 | } |
| 26 | } |
| 27 | |
| 28 | static void die(const char *msg) { |
| 29 | fprintf(stderr,"%s\n",msg); exit(8); |
| 30 | } |
| 31 | |
| 32 | static void problem(const char *msg) { |
| 33 | printf("problem %s\n",msg); |
| 34 | exit(0); |
| 35 | } |
| 36 | |
| 37 | enum howbad { hb_notlogon, hb_noterminal, hb_nomessages, hb_ok }; |
| 38 | static enum howbad closest= hb_notlogon; |
| 39 | |
| 40 | static time_t best_idle; |
| 41 | static char best_line[UT_LINESIZE+1]; |
| 42 | |
| 43 | static void thisis(enum howbad hb) { |
| 44 | if (hb > closest) closest= hb; |
| 45 | } |
| 46 | |
| 47 | int main(int argc, const char *const *argv) { |
| 48 | struct utmp *ue; |
| 49 | const char *myself; |
| 50 | struct stat stab; |
| 51 | int fd; |
| 52 | char idlebuf[20]; |
| 53 | |
| 54 | if (argc != 5) die("bad usage"); |
| 55 | |
| 56 | myself= getenv("USER"); |
| 57 | if (!myself) die("USER not set"); |
| 58 | if (strlen(myself) > UT_NAMESIZE) die("own username too long"); |
| 59 | |
| 60 | check(argv[2],"nick",20); |
| 61 | check(argv[3],"path",60); |
| 62 | check(argv[4],"channel",20); |
| 63 | |
| 64 | if (chdir("/dev")) { perror("chdir /dev"); exit(8); } |
| 65 | |
| 66 | while ((errno=0, ue= getutent())) { |
| 67 | if (ue->ut_type != USER_PROCESS) continue; |
| 68 | if (strncmp(ue->ut_user,myself,UT_NAMESIZE)) continue; |
| 69 | if (!ue->ut_line[0]) { thisis(hb_noterminal); continue; } |
| 70 | ue->ut_line[UT_LINESIZE]= 0; /* overflows into next field :-/ */ |
| 71 | if (stat(ue->ut_line,&stab)) { |
| 72 | printf("warning could not stat %s: %s\n",ue->ut_line,strerror(errno)); |
| 73 | thisis(hb_noterminal); continue; |
| 74 | } |
| 75 | if (!(stab.st_mode & S_IWGRP)) { thisis(hb_nomessages); continue; } |
| 76 | closest= hb_ok; |
| 77 | if (closest == hb_ok && stab.st_atime <= best_idle) continue; |
| 78 | strcpy(best_line,ue->ut_line); |
| 79 | best_idle= stab.st_atime; |
| 80 | } |
| 81 | if (errno) { perror("getutent set errno"); exit(8); } |
| 82 | |
| 83 | switch (closest) { |
| 84 | case hb_notlogon: problem("is not logged on"); |
| 85 | case hb_noterminal: problem("does not have any terminal/shell sessions"); |
| 86 | case hb_nomessages: problem("is refusing messages"); |
| 87 | case hb_ok: break; |
| 88 | default: abort(); |
| 89 | } |
| 90 | |
| 91 | sprintf(idlebuf,"%lu",(unsigned long)best_idle); |
| 92 | |
| 93 | fd= open(best_line, O_NOCTTY|O_NONBLOCK|O_WRONLY); |
| 94 | if (fd < 0) { |
| 95 | fprintf(stderr,"unable to open terminal (%s): %s",best_line,strerror(errno)); |
| 96 | exit(8); |
| 97 | } |
| 98 | if (dup2(fd,0)) { perror("dup2"); exit(8); } |
| 99 | execlp(argv[1],argv[1], best_line,idlebuf,argv[2],argv[3],argv[4], (const char*)0); |
| 100 | perror(argv[1]); exit(8); |
| 101 | } |