git.ozlabs.org Git - ccan/blob - ccan/pipecmd/pipecmd.c

   1 /* CC0 license (public domain) - see LICENSE file for details */
   2 #include <ccan/pipecmd/pipecmd.h>
   3 #include <ccan/noerr/noerr.h>
   4 #include <stdlib.h>
   5 #include <errno.h>
   6 #include <unistd.h>
   7 #include <fcntl.h>
   8
   9 static char **gather_args(const char *arg0, va_list ap)
  10 {
  11         size_t n = 1;
  12         char **arr = calloc(sizeof(char *), n + 1);
  13
  14         if (!arr)
  15                 return NULL;
  16         arr[0] = (char *)arg0;
  17
  18         while ((arr[n++] = va_arg(ap, char *)) != NULL) {
  19                 arr = realloc(arr, sizeof(char *) * (n + 1));
  20                 if (!arr)
  21                         return NULL;
  22         }
  23         return arr;
  24 }
  25
  26 pid_t pipecmdv(int *fd_fromchild, int *fd_tochild, int *fd_errfromchild,
  27                const char *cmd, va_list ap)
  28 {
  29         char **arr = gather_args(cmd, ap);
  30         pid_t ret;
  31
  32         if (!arr) {
  33                 errno = ENOMEM;
  34                 return -1;
  35         }
  36         ret = pipecmdarr(fd_fromchild, fd_tochild, fd_errfromchild, arr);
  37         free_noerr(arr);
  38         return ret;
  39 }
  40
  41 pid_t pipecmdarr(int *fd_fromchild, int *fd_tochild, int *fd_errfromchild,
  42                  char *const *arr)
  43 {
  44         int tochild[2], fromchild[2], errfromchild[2], execfail[2];
  45         pid_t childpid;
  46         int err;
  47
  48         if (fd_tochild) {
  49                 if (pipe(tochild) != 0)
  50                         goto fail;
  51         } else {
  52                 tochild[0] = open("/dev/null", O_RDONLY);
  53                 if (tochild[0] < 0)
  54                         goto fail;
  55         }
  56         if (fd_fromchild) {
  57                 if (pipe(fromchild) != 0)
  58                         goto close_tochild_fail;
  59         } else {
  60                 fromchild[1] = open("/dev/null", O_WRONLY);
  61                 if (fromchild[1] < 0)
  62                         goto close_tochild_fail;
  63         }
  64         if (fd_errfromchild) {
  65                 if (fd_errfromchild == fd_fromchild) {
  66                         errfromchild[0] = fromchild[0];
  67                         errfromchild[1] = fromchild[1];
  68                 } else {
  69                         if (pipe(errfromchild) != 0)
  70                                 goto close_fromchild_fail;
  71                 }
  72         } else {
  73                 errfromchild[1] = open("/dev/null", O_WRONLY);
  74                 if (errfromchild[1] < 0)
  75                         goto close_fromchild_fail;
  76         }
  77
  78         if (pipe(execfail) != 0)
  79                 goto close_errfromchild_fail;
  80
  81         if (fcntl(execfail[1], F_SETFD, fcntl(execfail[1], F_GETFD)
  82                   | FD_CLOEXEC) < 0)
  83                 goto close_execfail_fail;
  84
  85         childpid = fork();
  86         if (childpid < 0)
  87                 goto close_execfail_fail;
  88
  89         if (childpid == 0) {
  90                 if (fd_tochild)
  91                         close(tochild[1]);
  92                 if (fd_fromchild)
  93                         close(fromchild[0]);
  94                 if (fd_errfromchild && fd_errfromchild != fd_fromchild)
  95                         close(errfromchild[0]);
  96
  97                 close(execfail[0]);
  98
  99                 // Child runs command.
 100                 if (tochild[0] != STDIN_FILENO) {
 101                         if (dup2(tochild[0], STDIN_FILENO) == -1)
 102                                 goto child_errno_fail;
 103                         close(tochild[0]);
 104                 }
 105                 if (fromchild[1] != STDOUT_FILENO) {
 106                         if (dup2(fromchild[1], STDOUT_FILENO) == -1)
 107                                 goto child_errno_fail;
 108                         close(fromchild[1]);
 109                 }
 110                 if (fd_errfromchild && fd_errfromchild == fd_fromchild) {
 111                         if (dup2(STDOUT_FILENO, STDERR_FILENO) == -1)
 112                                 goto child_errno_fail;
 113                 } else if (errfromchild[1] != STDERR_FILENO) {
 114                         if (dup2(errfromchild[1], STDERR_FILENO) == -1)
 115                                 goto child_errno_fail;
 116                         close(errfromchild[1]);
 117                 }
 118                 execvp(arr[0], arr);
 119
 120         child_errno_fail:
 121                 err = errno;
 122                 write(execfail[1], &err, sizeof(err));
 123                 exit(127);
 124         }
 125
 126         close(tochild[0]);
 127         close(fromchild[1]);
 128         close(errfromchild[1]);
 129         close(execfail[1]);
 130         /* Child will close this without writing on successful exec. */
 131         if (read(execfail[0], &err, sizeof(err)) == sizeof(err)) {
 132                 close(execfail[0]);
 133                 waitpid(childpid, NULL, 0);
 134                 errno = err;
 135                 return -1;
 136         }
 137         close(execfail[0]);
 138         if (fd_tochild)
 139                 *fd_tochild = tochild[1];
 140         if (fd_fromchild)
 141                 *fd_fromchild = fromchild[0];
 142         if (fd_errfromchild)
 143                 *fd_errfromchild = errfromchild[0];
 144         return childpid;
 145
 146 close_execfail_fail:
 147         close_noerr(execfail[0]);
 148         close_noerr(execfail[1]);
 149 close_errfromchild_fail:
 150         if (fd_errfromchild)
 151                 close_noerr(errfromchild[0]);
 152         close_noerr(errfromchild[1]);
 153 close_fromchild_fail:
 154         if (fd_fromchild)
 155                 close_noerr(fromchild[0]);
 156         close_noerr(fromchild[1]);
 157 close_tochild_fail:
 158         close_noerr(tochild[0]);
 159         if (fd_tochild)
 160                 close_noerr(tochild[1]);
 161 fail:
 162         return -1;
 163 }
 164
 165 pid_t pipecmd(int *fd_fromchild, int *fd_tochild, int *fd_errfromchild,
 166               const char *cmd, ...)
 167 {
 168         pid_t childpid;
 169
 170         va_list ap;
 171         va_start(ap, cmd);
 172         childpid = pipecmdv(fd_fromchild, fd_tochild, fd_errfromchild, cmd, ap);
 173         va_end(ap);
 174
 175         return childpid;
 176 }