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 <linux/string.h>
   7 #include <errno.h>
   8 #include <sys/wait.h>
   9 #include "subcmd-util.h"
  10 #include "run-command.h"
  11 #include "exec-cmd.h"
  12
  13 #define STRERR_BUFSIZE 128
  14
  15 static inline void close_pair(int fd[2])
  16 {
  17         close(fd[0]);
  18         close(fd[1]);
  19 }
  20
  21 static inline void dup_devnull(int to)
  22 {
  23         int fd = open("/dev/null", O_RDWR);
  24         dup2(fd, to);
  25         close(fd);
  26 }
  27
  28 int start_command(struct child_process *cmd)
  29 {
  30         int need_in, need_out, need_err;
  31         int fdin[2], fdout[2], fderr[2];
  32         char sbuf[STRERR_BUFSIZE];
  33
  34         /*
  35          * In case of errors we must keep the promise to close FDs
  36          * that have been passed in via ->in and ->out.
  37          */
  38
  39         need_in = !cmd->no_stdin && cmd->in < 0;
  40         if (need_in) {
  41                 if (pipe(fdin) < 0) {
  42                         if (cmd->out > 0)
  43                                 close(cmd->out);
  44                         return -ERR_RUN_COMMAND_PIPE;
  45                 }
  46                 cmd->in = fdin[1];
  47         }
  48
  49         need_out = !cmd->no_stdout
  50                 && !cmd->stdout_to_stderr
  51                 && cmd->out < 0;
  52         if (need_out) {
  53                 if (pipe(fdout) < 0) {
  54                         if (need_in)
  55                                 close_pair(fdin);
  56                         else if (cmd->in)
  57                                 close(cmd->in);
  58                         return -ERR_RUN_COMMAND_PIPE;
  59                 }
  60                 cmd->out = fdout[0];
  61         }
  62
  63         need_err = !cmd->no_stderr && cmd->err < 0;
  64         if (need_err) {
  65                 if (pipe(fderr) < 0) {
  66                         if (need_in)
  67                                 close_pair(fdin);
  68                         else if (cmd->in)
  69                                 close(cmd->in);
  70                         if (need_out)
  71                                 close_pair(fdout);
  72                         else if (cmd->out)
  73                                 close(cmd->out);
  74                         return -ERR_RUN_COMMAND_PIPE;
  75                 }
  76                 cmd->err = fderr[0];
  77         }
  78
  79         fflush(NULL);
  80         cmd->pid = fork();
  81         if (!cmd->pid) {
  82                 if (cmd->no_stdin)
  83                         dup_devnull(0);
  84                 else if (need_in) {
  85                         dup2(fdin[0], 0);
  86                         close_pair(fdin);
  87                 } else if (cmd->in) {
  88                         dup2(cmd->in, 0);
  89                         close(cmd->in);
  90                 }
  91
  92                 if (cmd->no_stderr)
  93                         dup_devnull(2);
  94                 else if (need_err) {
  95                         dup2(fderr[1], 2);
  96                         close_pair(fderr);
  97                 }
  98
  99                 if (cmd->no_stdout)
 100                         dup_devnull(1);
 101                 else if (cmd->stdout_to_stderr)
 102                         dup2(2, 1);
 103                 else if (need_out) {
 104                         dup2(fdout[1], 1);
 105                         close_pair(fdout);
 106                 } else if (cmd->out > 1) {
 107                         dup2(cmd->out, 1);
 108                         close(cmd->out);
 109                 }
 110
 111                 if (cmd->dir && chdir(cmd->dir))
 112                         die("exec %s: cd to %s failed (%s)", cmd->argv[0],
 113                             cmd->dir, str_error_r(errno, sbuf, sizeof(sbuf)));
 114                 if (cmd->env) {
 115                         for (; *cmd->env; cmd->env++) {
 116                                 if (strchr(*cmd->env, '='))
 117                                         putenv((char*)*cmd->env);
 118                                 else
 119                                         unsetenv(*cmd->env);
 120                         }
 121                 }
 122                 if (cmd->preexec_cb)
 123                         cmd->preexec_cb();
 124                 if (cmd->exec_cmd) {
 125                         execv_cmd(cmd->argv);
 126                 } else {
 127                         execvp(cmd->argv[0], (char *const*) cmd->argv);
 128                 }
 129                 exit(127);
 130         }
 131
 132         if (cmd->pid < 0) {
 133                 int err = errno;
 134                 if (need_in)
 135                         close_pair(fdin);
 136                 else if (cmd->in)
 137                         close(cmd->in);
 138                 if (need_out)
 139                         close_pair(fdout);
 140                 else if (cmd->out)
 141                         close(cmd->out);
 142                 if (need_err)
 143                         close_pair(fderr);
 144                 return err == ENOENT ?
 145                         -ERR_RUN_COMMAND_EXEC :
 146                         -ERR_RUN_COMMAND_FORK;
 147         }
 148
 149         if (need_in)
 150                 close(fdin[0]);
 151         else if (cmd->in)
 152                 close(cmd->in);
 153
 154         if (need_out)
 155                 close(fdout[1]);
 156         else if (cmd->out)
 157                 close(cmd->out);
 158
 159         if (need_err)
 160                 close(fderr[1]);
 161
 162         return 0;
 163 }
 164
 165 static int wait_or_whine(pid_t pid)
 166 {
 167         char sbuf[STRERR_BUFSIZE];
 168
 169         for (;;) {
 170                 int status, code;
 171                 pid_t waiting = waitpid(pid, &status, 0);
 172
 173                 if (waiting < 0) {
 174                         if (errno == EINTR)
 175                                 continue;
 176                         fprintf(stderr, " Error: waitpid failed (%s)",
 177                                 str_error_r(errno, sbuf, sizeof(sbuf)));
 178                         return -ERR_RUN_COMMAND_WAITPID;
 179                 }
 180                 if (waiting != pid)
 181                         return -ERR_RUN_COMMAND_WAITPID_WRONG_PID;
 182                 if (WIFSIGNALED(status))
 183                         return -ERR_RUN_COMMAND_WAITPID_SIGNAL;
 184
 185                 if (!WIFEXITED(status))
 186                         return -ERR_RUN_COMMAND_WAITPID_NOEXIT;
 187                 code = WEXITSTATUS(status);
 188                 switch (code) {
 189                 case 127:
 190                         return -ERR_RUN_COMMAND_EXEC;
 191                 case 0:
 192                         return 0;
 193                 default:
 194                         return -code;
 195                 }
 196         }
 197 }
 198
 199 int finish_command(struct child_process *cmd)
 200 {
 201         return wait_or_whine(cmd->pid);
 202 }
 203
 204 int run_command(struct child_process *cmd)
 205 {
 206         int code = start_command(cmd);
 207         if (code)
 208                 return code;
 209         return finish_command(cmd);
 210 }
 211
 212 static void prepare_run_command_v_opt(struct child_process *cmd,
 213                                       const char **argv,
 214                                       int opt)
 215 {
 216         memset(cmd, 0, sizeof(*cmd));
 217         cmd->argv = argv;
 218         cmd->no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0;
 219         cmd->exec_cmd = opt & RUN_EXEC_CMD ? 1 : 0;
 220         cmd->stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
 221 }
 222
 223 int run_command_v_opt(const char **argv, int opt)
 224 {
 225         struct child_process cmd;
 226         prepare_run_command_v_opt(&cmd, argv, opt);
 227         return run_command(&cmd);
 228 }