Routix/tareas/ush/shell.c

   1 /*
   2    This partial code is a modified version of Marc Rochkind's A Real Shell,
   3    published in "Advanced UNIX Programming", Prentice Hall, 1985.
   4 */
   5
   6 #include "shell.h"
   7
   8 #define MAXARG 20
   9 #define MAXFNAME 500
  10 #define MAXWORD  100
  11 #define BADFD -2
  12
  13 main()  /* real shell */
  14 {
  15    char *prompt;
  16    int pid, fd;
  17    TOKEN  term;
  18    static TOKEN command();
  19    static void waitfor();
  20
  21    ignoresig();
  22    if(!EVinit())
  23         fatal ("can't initialize environment");
  24    if( (prompt = EVget("PS2")) == NULL)
  25         prompt = ">";
  26    printf("%s", prompt);
  27
  28    while(1){
  29         term = command(&pid, FALSE, NULL);
  30         if ( term != T_AMP && pid != 0)
  31              waitfor(pid);
  32         if ( term == T_NL)
  33              printf("%s", prompt);
  34         for(fd = 3; fd< 20; fd++)
  35              (void)close(fd);  /*ignore error */
  36       }
  37 }
  38
  39 static TOKEN
  40 command(int *waitpid, BOOLEAN  makepipe, int *pipefdp) /* do simple cmd */
  41 {
  42
  43      TOKEN token, term ;
  44      int argc, srcfd, dstfd, pid, pfd[2];
  45      char *argv[MAXARG + 1], srcfile[MAXFNAME],dstfile[MAXFNAME];
  46      char word[MAXWORD], *malloc();
  47      BOOLEAN append;
  48      static int invoke( );
  49
  50      argc = 0;
  51      srcfd = 0;
  52      dstfd = 1;
  53      while (1) {
  54          switch ( token = gettoken(word)) {
  55          case T_WORD:
  56               if (argc == MAXARG){
  57                   fprintf(stderr, "Too many args\n");
  58                   break;
  59                 }
  60               if (( argv[argc] = malloc(strlen(word) +1)) == NULL) {
  61                    fprintf(stderr, "Out of argmemory\n");
  62                    break;
  63                  }
  64               strcpy(argv[argc], word);
  65               argc ++;
  66               continue;
  67          case T_LT:
  68                if(makepipe){
  69                   fprintf(stderr, "Extra<\n");
  70                   break;
  71                 }
  72                if (gettoken(srcfile) != T_WORD){
  73                    fprintf(stderr, "Illegal <\n");
  74                    break;
  75                  }
  76                srcfd = BADFD;
  77                continue;
  78          case T_GT:
  79                if (dstfd !=1) {
  80                    fprintf(stderr, "Extra > or >> \n");
  81                    break;
  82                  }
  83                if (gettoken(dstfile) != T_WORD) {
  84                    fprintf(stderr, "Illegal > or >> \n");
  85                    break;
  86                  }
  87                dstfd = BADFD;
  88                append = FALSE;
  89                continue;
  90          case T_GTGT:
  91                if (dstfd != 1) {
  92                    fprintf(stderr, "Extra > or >>\n");
  93                    break;
  94                 }
  95                if (gettoken(dstfile) != T_WORD){
  96                    fprintf(stderr, "Illegal >or >>\n");
  97                    break;
  98                  }
  99                dstfd = BADFD;
 100                append = TRUE;
 101                continue;
 102          case T_BAR:
 103          case T_AMP:
 104          case T_SEMI:
 105          case T_NL:
 106                argv[argc] = NULL;
 107                if ( token == T_BAR) {
 108                     if ( dstfd !=1) {
 109                          fprintf(stderr, "> or >> conflicts with |\n");
 110                          break;
 111                        }
 112                     term = command ( waitpid, TRUE, &dstfd);
 113                   }
 114                else
 115                     term = token;
 116
 117                if ( makepipe ){
 118                      if ( pipe(pfd) == -1)
 119                           syserr("pipe");
 120                           *pipefdp = pfd[1];
 121                           srcfd = pfd[0];
 122                  }
 123                if(term == T_AMP)pid = invoke(argc, argv, srcfd,
 124                             srcfile, dstfd, dstfile, append, TRUE);
 125                else pid=invoke(argc,argv,srcfd, srcfile,dstfd, dstfile,
 126                            append, FALSE);
 127
 128                if (token != T_BAR)
 129                     *waitpid = pid;
 130                if (argc == 0 && (token != T_NL || srcfd >1))
 131                     fprintf(stderr, "Missing command\n");
 132                while (--argc >= 0)
 133                       free(argv[argc]);
 134                return(term);
 135              case T_EOF:
 136                   exit(0);
 137              }
 138        }
 139 }
 140
 141 static int invoke(int argc,char *argv[],int srcfd, char *srcfile,
 142           int dstfd,char *dstfile,BOOLEAN append, BOOLEAN bckgrnd)
 143                               /* invoke simple command */
 144 {
 145
 146     static void redirect();
 147     int pid;
 148     static BOOLEAN builtin();
 149
 150     if (argc == 0  || builtin(argc, argv, srcfd, dstfd))
 151         return(0);
 152     switch (pid = fork()) {
 153     case -1:
 154          fprintf(stderr, "Can't create new process\n");
 155          return(0);
 156     case 0:
 157          if (!bckgrnd)
 158              entrysig();
 159          if (!EVupdate())
 160              fatal("can't update environment");
 161          redirect(srcfd, srcfile, dstfd, dstfile, append, bckgrnd);
 162          execvp(argv[0], argv);
 163          fprintf(stderr, "Can't execute %s\n", argv[0]);
 164          exit(0);
 165     default:
 166          if (srcfd > 0 && close(srcfd) == -1)
 167              syserr("close src");
 168          if (dstfd > 1 && close(dstfd) == -1)
 169              syserr("close dst");
 170          if (bckgrnd)
 171              printf("%d\n", pid);
 172          return(pid);
 173     }
 174 }
 175 /*     REDIRECCION ANULADA MOMENTANEAMENTE
 176 static void redirect(int srcfd, char *srcfile, int dstfd,char *dstfile,
 177              BOOLEAN append, BOOLEAN bckgrnd)  /* I/O redirection */
 178 {
 179    int flags, fd;
 180    long lseek();
 181
 182    if (srcfd == 0 && bckgrnd) {
 183        strcpy(srcfile, "/dev/null");
 184        srcfd = BADFD;
 185     }
 186
 187    if (srcfd !=0 ) {
 188        if ( close(0) == -1)
 189             syserr("close");
 190        if (srcfd > 0) {
 191             if ( dup(srcfd) !=0)
 192                  fatal("dup");
 193              }
 194        else if (open (srcfile, O_RDONLY, 0) == -1){
 195              fprintf(stderr, "Can't open %s\n", srcfile);
 196              exit(0);
 197        }
 198    }
 199
 200    if (dstfd !=1) {
 201        if (close(1) == -1)
 202            syserr("close");
 203        if (dstfd > 1){
 204            if (dup(dstfd) != 1)
 205                fatal("dup");
 206             }
 207        else {
 208             flags = O_WRONLY | O_CREAT;
 209             if(!append)
 210                 flags |= O_TRUNC;
 211             if (open(dstfile, flags, 0666) == -1) {
 212                fprintf(stderr, "Can't create %s\n", dstfile);
 213                exit(0);
 214              }
 215             if(append)
 216                if(lseek(1, 0L,2) == -1)
 217                  syserr("lseek");
 218           }
 219      }
 220    for (fd =3; fd<20; fd++)
 221        (void)close(fd);  // ignore error
 222 }
 223 */
 224 static void waitfor(int pid)  /* wait for child */
 225 {
 226
 227     int wpid, status;
 228
 229     while( (wpid = wait(&status)) != pid && wpid !=-1 )
 230          statusprt(wpid, status);
 231     if (wpid == pid )
 232          statusprt(0, status);
 233 }
 234
 235 static BOOLEAN builtin(int argc, char *argv[], int srcfd, int  dstfd)
 236                               /* do built-in */
 237 {
 238      char *path;
 239
 240      if (strchr(argv[0], '=') !=NULL)
 241          asg(argc, argv);
 242      else if (strcmp(argv[0], "export") == 0 )
 243           export(argc, argv);
 244      else if (strcmp(argv[0], "set") == 0 )
 245           set(argc, argv);
 246      else if (strcmp(argv[0], "cd") == 0 ){
 247           if ( argc >1)
 248               path = argv[1];
 249           else
 250               if (( path = EVget("HOME")) ==NULL)
 251                     path = ".";
 252           if (chdir(path) ==-1)
 253               fprintf(stderr, "%s: bad directory\n", path);
 254         }
 255      else
 256           return( FALSE);
 257      if (srcfd !=0 || dstfd !=1)
 258           fprintf(stderr, "Illegal redirection or pipeline\n");
 259 }