tools/lib/subcmd/run-command.c

   1 #include <unistd.h>
   2 #include <sys/types.h>
   3 #include <sys/stat.h>
   4 #include <fcntl.h>
   5 #include <string.h>
   6 #include <errno.h>
   7 #include <sys/wait.h>
   8 #include "subcmd-util.h"
   9 #include "run-command.h"
  10 #include "exec-cmd.h"
  11
  12 #define STRERR_BUFSIZE 128
  13
  14 static inline void close_pair(int fd[2])
  15 {
  16         close(fd[0]);
  17         close(fd[1]);
  18 }
  19
  20 static inline void dup_devnull(int to)
  21 {
  22         int fd = open("/dev/null", O_RDWR);
  23         dup2(fd, to);
  24         close(fd);
  25 }
  26
  27 int start_command(struct child_process *cmd)
  28 {
  29         int need_in, need_out, need_err;
  30         int fdin[2], fdout[2], fderr[2];
  31         char sbuf[STRERR_BUFSIZE];
  32
  33         /*
  34          * In case of errors we must keep the promise to close FDs
  35          * that have been passed in via ->in and ->out.
  36          */
  37
  38         need_in = !cmd->no_stdin && cmd->in < 0;
  39         if (need_in) {
  40                 if (pipe(fdin) < 0) {
  41                         if (cmd->out > 0)
  42                                 close(cmd->out);
  43                         return -ERR_RUN_COMMAND_PIPE;
  44                 }
  45                 cmd->in = fdin[1];
  46         }
  47
  48         need_out = !cmd->no_stdout
  49                 && !cmd->stdout_to_stderr
  50                 && cmd->out < 0;
  51         if (need_out) {
  52                 if (pipe(fdout) < 0) {
  53                         if (need_in)
  54                                 close_pair(fdin);
  55                         else if (cmd->in)
  56                                 close(cmd->in);
  57                         return -ERR_RUN_COMMAND_PIPE;
  58                 }
  59                 cmd->out = fdout[0];
  60         }
  61
  62         need_err = !cmd->no_stderr && cmd->err < 0;
  63         if (need_err) {
  64                 if (pipe(fderr) < 0) {
  65                         if (need_in)
  66                                 close_pair(fdin);
  67                         else if (cmd->in)
  68                                 close(cmd->in);
  69                         if (need_out)
  70                                 close_pair(fdout);
  71                         else if (cmd->out)
  72                                 close(cmd->out);
  73                         return -ERR_RUN_COMMAND_PIPE;
  74                 }
  75                 cmd->err = fderr[0];
  76         }
  77
  78         fflush(NULL);
  79         cmd->pid = fork();
  80         if (!cmd->pid) {
  81                 if (cmd->no_stdin)
  82                         dup_devnull(0);
  83                 else if (need_in) {
  84                         dup2(fdin[0], 0);
  85                         close_pair(fdin);
  86                 } else if (cmd->in) {
  87                         dup2(cmd->in, 0);
  88                         close(cmd->in);
  89                 }
  90
  91                 if (cmd->no_stderr)
  92                         dup_devnull(2);
  93                 else if (need_err) {
  94                         dup2(fderr[1], 2);
  95                         close_pair(fderr);
  96                 }
  97
  98                 if (cmd->no_stdout)
  99                         dup_devnull(1);
 100                 else if (cmd->stdout_to_stderr)
 101                         dup2(2, 1);
 102                 else if (need_out) {
 103                         dup2(fdout[1], 1);
 104                         close_pair(fdout);
 105                 } else if (cmd->out > 1) {
 106                         dup2(cmd->out, 1);
 107                         close(cmd->out);
 108                 }
 109
 110                 if (cmd->dir && chdir(cmd->dir))
 111                         die("exec %s: cd to %s failed (%s)", cmd->argv[0],
 112                             cmd->dir, strerror_r(errno, sbuf, sizeof(sbuf)));
 113                 if (cmd->env) {
 114                         for (; *cmd->env; cmd->env++) {
 115                                 if (strchr(*cmd->env, '='))
 116                                         putenv((char*)*cmd->env);
 117                                 else
 118                                         unsetenv(*cmd->env);
 119                         }
 120                 }
 121                 if (cmd->preexec_cb)
 122                         cmd->preexec_cb();
 123                 if (cmd->exec_cmd) {
 124                         execv_cmd(cmd->argv);
 125                 } else {
 126                         execvp(cmd->argv[0], (char *const*) cmd->argv);
 127                 }
 128                 exit(127);
 129         }
 130
 131         if (cmd->pid < 0) {
 132                 int err = errno;
 133                 if (need_in)
 134                         close_pair(fdin);
 135                 else if (cmd->in)
 136                         close(cmd->in);
 137                 if (need_out)
 138                         close_pair(fdout);
 139                 else if (cmd->out)
 140                         close(cmd->out);
 141                 if (need_err)
 142                         close_pair(fderr);
 143                 return err == ENOENT ?
 144                         -ERR_RUN_COMMAND_EXEC :
 145                         -ERR_RUN_COMMAND_FORK;
 146         }
 147
 148         if (need_in)
 149                 close(fdin[0]);
 150         else if (cmd->in)
 151                 close(cmd->in);
 152
 153         if (need_out)
 154                 close(fdout[1]);
 155         else if (cmd->out)
 156                 close(cmd->out);
 157
 158         if (need_err)
 159                 close(fderr[1]);
 160
 161         return 0;
 162 }
 163
 164 static int wait_or_whine(pid_t pid)
 165 {
 166         char sbuf[STRERR_BUFSIZE];
 167
 168         for (;;) {
 169                 int status, code;
 170                 pid_t waiting = waitpid(pid, &status, 0);
 171
 172                 if (waiting < 0) {
 173                         if (errno == EINTR)
 174                                 continue;
 175                         fprintf(stderr, " Error: waitpid failed (%s)",
 176                                 strerror_r(errno, sbuf, sizeof(sbuf)));
 177                         return -ERR_RUN_COMMAND_WAITPID;
 178                 }
 179                 if (waiting != pid)
 180                         return -ERR_RUN_COMMAND_WAITPID_WRONG_PID;
 181                 if (WIFSIGNALED(status))
 182                         return -ERR_RUN_COMMAND_WAITPID_SIGNAL;
 183
 184                 if (!WIFEXITED(status))
 185                         return -ERR_RUN_COMMAND_WAITPID_NOEXIT;
 186                 code = WEXITSTATUS(status);
 187                 switch (code) {
 188                 case 127:
 189                         return -ERR_RUN_COMMAND_EXEC;
 190                 case 0:
 191                         return 0;
 192                 default:
 193                         return -code;
 194                 }
 195         }
 196 }
 197
 198 int finish_command(struct child_process *cmd)
 199 {
 200         return wait_or_whine(cmd->pid);
 201 }
 202
 203 int run_command(struct child_process *cmd)
 204 {
 205         int code = start_command(cmd);
 206         if (code)
 207                 return code;
 208         return finish_command(cmd);
 209 }
 210
 211 static void prepare_run_command_v_opt(struct child_process *cmd,
 212                                       const char **argv,
 213                                       int opt)
 214 {
 215         memset(cmd, 0, sizeof(*cmd));
 216         cmd->argv = argv;
 217         cmd->no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0;
 218         cmd->exec_cmd = opt & RUN_EXEC_CMD ? 1 : 0;
 219         cmd->stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
 220 }
 221
 222 int run_command_v_opt(const char **argv, int opt)
 223 {
 224         struct child_process cmd;
 225         prepare_run_command_v_opt(&cmd, argv, opt);
 226         return run_command(&cmd);
 227 }