lib/cmdline/closefrom_except.c

   1 /*
   2  *  This program is free software; you can redistribute it and/or modify
   3  *  it under the terms of the GNU General Public License as published by
   4  *  the Free Software Foundation; either version 3 of the License, or
   5  *  (at your option) any later version.
   6  *
   7  *  This program is distributed in the hope that it will be useful,
   8  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
   9  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  10  *  GNU General Public License for more details.
  11  *
  12  *  You should have received a copy of the GNU General Public License
  13  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
  14  */
  15
  16 #include "replace.h"
  17 #include "closefrom_except.h"
  18 #include <popt.h>
  19
  20 int closefrom_except(int lower, int *fds, size_t num_fds)
  21 {
  22         size_t i;
  23         int max_keep = -1;
  24         int fd, ret;
  25
  26         for (i=0; i<num_fds; i++) {
  27                 max_keep = MAX(max_keep, fds[i]);
  28         }
  29         if (max_keep == -1) {
  30                 return 0;
  31         }
  32
  33         for (fd = lower; fd < max_keep; fd++) {
  34                 bool keep = false;
  35
  36                 /*
  37                  * O(num_fds*max_keep), but we expect the number of
  38                  * fds to keep to be very small, typically 0,1,2 and
  39                  * very few more.
  40                  */
  41                 for (i=0; i<num_fds; i++) {
  42                         if (fd == fds[i]) {
  43                                 keep = true;
  44                                 break;
  45                         }
  46                 }
  47                 if (keep) {
  48                         continue;
  49                 }
  50                 ret = close(fd);
  51                 if ((ret == -1) && (errno != EBADF)) {
  52                         return errno;
  53                 }
  54         }
  55
  56         closefrom(MAX(lower, max_keep+1));
  57         return 0;
  58 }
  59
  60 int closefrom_except_fd_params(
  61         int lower,
  62         size_t num_fd_params,
  63         const char *fd_params[],
  64         int argc,
  65         const char *argv[])
  66 {
  67         int fds[num_fd_params];
  68         size_t i;
  69         struct poptOption long_options[num_fd_params + 1];
  70         poptContext pc;
  71         int ret;
  72
  73         for (i=0; i<num_fd_params; i++) {
  74                 fds[i] = -1;
  75                 long_options[i] = (struct poptOption) {
  76                         .longName = fd_params[i],
  77                         .argInfo = POPT_ARG_INT,
  78                         .arg = &fds[i],
  79                 };
  80         }
  81         long_options[num_fd_params] = (struct poptOption) { .longName=NULL, };
  82
  83         pc = poptGetContext(argv[0], argc, argv, long_options, 0);
  84
  85         while ((ret = poptGetNextOpt(pc)) != -1) {
  86                 /* do nothing */
  87         }
  88
  89         poptFreeContext(pc);
  90
  91         ret = closefrom_except(lower, fds, ARRAY_SIZE(fds));
  92         return ret;
  93 }