expand.c

   1 /*  Copyright 1986-1992 Emmet P. Gray.
   2  *  Copyright 1996-2002,2007,2009 Alain Knaff.
   3  *  This file is part of mtools.
   4  *
   5  *  Mtools is free software: you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation, either version 3 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  Mtools is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with Mtools.  If not, see <http://www.gnu.org/licenses/>.
  17  *
  18  * Do filename expansion with the shell.
  19  */
  20
  21 #define EXPAND_BUF      2048
  22
  23 #include "sysincludes.h"
  24 #include "mtools.h"
  25
  26 #ifndef OS_mingw32msvc
  27 int safePopenOut(const char **command, char *output, int len)
  28 {
  29         int pipefd[2];
  30         pid_t pid;
  31         int status;
  32         int last;
  33
  34         if(pipe(pipefd)) {
  35                 return -2;
  36         }
  37         switch((pid=fork())){
  38                 case -1:
  39                         return -2;
  40                 case 0: /* the son */
  41                         close(pipefd[0]);
  42                         destroy_privs();
  43                         close(1);
  44                         close(2); /* avoid nasty error messages on stderr */
  45                         if(dup(pipefd[1]) < 0) {
  46                                 perror("Dup error");
  47                                 exit(1);
  48                         }
  49                         close(pipefd[1]);
  50                         execvp(command[0], (char**)(command+1));
  51                         exit(1);
  52                 default:
  53                         close(pipefd[1]);
  54                         break;
  55         }
  56         last=read(pipefd[0], output, len);
  57         kill(pid,9);
  58         wait(&status);
  59         if(last<0) {
  60                 return -1;
  61         }
  62         return last;
  63 }
  64 #endif
  65
  66
  67 const char *expand(const char *input, char *ans)
  68 {
  69 #ifndef OS_mingw32msvc
  70         int last;
  71         char buf[256];
  72         const char *command[] = { "/bin/sh", "sh", "-c", 0, 0 };
  73
  74         ans[EXPAND_BUF-1]='\0';
  75
  76         if (input == NULL)
  77                 return(NULL);
  78         if (*input == '\0')
  79                 return("");
  80                                         /* any thing to expand? */
  81         if (!strpbrk(input, "$*(){}[]\\?`~")) {
  82                 strncpy(ans, input, EXPAND_BUF-1);
  83                 return(ans);
  84         }
  85                                         /* popen an echo */
  86 #ifdef HAVE_SNPRINTF
  87         snprintf(buf, 255, "echo %s", input);
  88 #else
  89         sprintf(buf, "echo %s", input);
  90 #endif
  91
  92         command[3]=buf;
  93         last=safePopenOut(command, ans, EXPAND_BUF-1);
  94         if(last<0) {
  95                 perror("Pipe read error");
  96                 exit(1);
  97         }
  98         if(last)
  99                 ans[last-1] = '\0';
 100         else
 101                 strncpy(ans, input, EXPAND_BUF-1);
 102         return ans;
 103 #else
 104         strncpy(ans, input, EXPAND_BUF-1);
 105         ans[EXPAND_BUF-1]='\0';
 106         return ans;
 107 #endif
 108 }