tools/lib/subcmd/run-command.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <unistd.h>
   3 #include <sys/types.h>
   4 #include <sys/stat.h>
   5 #include <fcntl.h>
   6 #include <string.h>
   7 #include <linux/string.h>
   8 #include <errno.h>
   9 #include <sys/wait.h>
  10 #include "subcmd-util.h"
  11 #include "run-command.h"
  12 #include "exec-cmd.h"
  13
  14 #define STRERR_BUFSIZE 128
  15
  16 static inline void close_pair(int fd[2])
  17 {
  18         close(fd[0]);
  19         close(fd[1]);
  20 }
  21
  22 static inline void dup_devnull(int to)
  23 {
  24         int fd = open("/dev/null", O_RDWR);
  25         dup2(fd, to);
  26         close(fd);
  27 }
  28
  29 int start_command(struct child_process *cmd)
  30 {
  31         int need_in, need_out, need_err;
  32         int fdin[2], fdout[2], fderr[2];
  33         char sbuf[STRERR_BUFSIZE];
  34
  35         /*
  36          * In case of errors we must keep the promise to close FDs
  37          * that have been passed in via ->in and ->out.
  38          */
  39
  40         need_in = !cmd->no_stdin && cmd->in < 0;
  41         if (need_in) {
  42                 if (pipe(fdin) < 0) {
  43                         if (cmd->out > 0)
  44                                 close(cmd->out);
  45                         return -ERR_RUN_COMMAND_PIPE;
  46                 }
  47                 cmd->in = fdin[1];
  48         }
  49
  50         need_out = !cmd->no_stdout
  51                 && !cmd->stdout_to_stderr
  52                 && cmd->out < 0;
  53         if (need_out) {
  54                 if (pipe(fdout) < 0) {
  55                         if (need_in)
  56                                 close_pair(fdin);
  57                         else if (cmd->in)
  58                                 close(cmd->in);
  59                         return -ERR_RUN_COMMAND_PIPE;
  60                 }
  61                 cmd->out = fdout[0];
  62         }
  63
  64         need_err = !cmd->no_stderr && cmd->err < 0;
  65         if (need_err) {
  66                 if (pipe(fderr) < 0) {
  67                         if (need_in)
  68                                 close_pair(fdin);
  69                         else if (cmd->in)
  70                                 close(cmd->in);
  71                         if (need_out)
  72                                 close_pair(fdout);
  73                         else if (cmd->out)
  74                                 close(cmd->out);
  75                         return -ERR_RUN_COMMAND_PIPE;
  76                 }
  77                 cmd->err = fderr[0];
  78         }
  79
  80         fflush(NULL);
  81         cmd->pid = fork();
  82         if (!cmd->pid) {
  83                 if (cmd->no_stdin)
  84                         dup_devnull(0);
  85                 else if (need_in) {
  86                         dup2(fdin[0], 0);
  87                         close_pair(fdin);
  88                 } else if (cmd->in) {
  89                         dup2(cmd->in, 0);
  90                         close(cmd->in);
  91                 }
  92
  93                 if (cmd->no_stderr)
  94                         dup_devnull(2);
  95                 else if (need_err) {
  96                         dup2(fderr[1], 2);
  97                         close_pair(fderr);
  98                 }
  99
 100                 if (cmd->no_stdout)
 101                         dup_devnull(1);
 102                 else if (cmd->stdout_to_stderr)
 103                         dup2(2, 1);
 104                 else if (need_out) {
 105                         dup2(fdout[1], 1);
 106                         close_pair(fdout);
 107                 } else if (cmd->out > 1) {
 108                         dup2(cmd->out, 1);
 109                         close(cmd->out);
 110                 }
 111
 112                 if (cmd->dir && chdir(cmd->dir))
 113                         die("exec %s: cd to %s failed (%s)", cmd->argv[0],
 114                             cmd->dir, str_error_r(errno, sbuf, sizeof(sbuf)));
 115                 if (cmd->env) {
 116                         for (; *cmd->env; cmd->env++) {
 117                                 if (strchr(*cmd->env, '='))
 118                                         putenv((char*)*cmd->env);
 119                                 else
 120                                         unsetenv(*cmd->env);
 121                         }
 122                 }
 123                 if (cmd->preexec_cb)
 124                         cmd->preexec_cb();
 125                 if (cmd->no_exec_cmd)
 126                         exit(cmd->no_exec_cmd(cmd));
 127                 if (cmd->exec_cmd) {
 128                         execv_cmd(cmd->argv);
 129                 } else {
 130                         execvp(cmd->argv[0], (char *const*) cmd->argv);
 131                 }
 132                 exit(127);
 133         }
 134
 135         if (cmd->pid < 0) {
 136                 int err = errno;
 137                 if (need_in)
 138                         close_pair(fdin);
 139                 else if (cmd->in)
 140                         close(cmd->in);
 141                 if (need_out)
 142                         close_pair(fdout);
 143                 else if (cmd->out)
 144                         close(cmd->out);
 145                 if (need_err)
 146                         close_pair(fderr);
 147                 return err == ENOENT ?
 148                         -ERR_RUN_COMMAND_EXEC :
 149                         -ERR_RUN_COMMAND_FORK;
 150         }
 151
 152         if (need_in)
 153                 close(fdin[0]);
 154         else if (cmd->in)
 155                 close(cmd->in);
 156
 157         if (need_out)
 158                 close(fdout[1]);
 159         else if (cmd->out)
 160                 close(cmd->out);
 161
 162         if (need_err)
 163                 close(fderr[1]);
 164
 165         return 0;
 166 }
 167
 168 static int wait_or_whine(struct child_process *cmd, bool block)
 169 {
 170         bool finished = cmd->finished;
 171         int result = cmd->finish_result;
 172
 173         while (!finished) {
 174                 int status, code;
 175                 pid_t waiting = waitpid(cmd->pid, &status, block ? 0 : WNOHANG);
 176
 177                 if (!block && waiting == 0)
 178                         break;
 179
 180                 if (waiting < 0 && errno == EINTR)
 181                         continue;
 182
 183                 finished = true;
 184                 if (waiting < 0) {
 185                         char sbuf[STRERR_BUFSIZE];
 186
 187                         fprintf(stderr, " Error: waitpid failed (%s)",
 188                                 str_error_r(errno, sbuf, sizeof(sbuf)));
 189                         result = -ERR_RUN_COMMAND_WAITPID;
 190                 } else if (waiting != cmd->pid) {
 191                         result = -ERR_RUN_COMMAND_WAITPID_WRONG_PID;
 192                 } else if (WIFSIGNALED(status)) {
 193                         result = -ERR_RUN_COMMAND_WAITPID_SIGNAL;
 194                 } else if (!WIFEXITED(status)) {
 195                         result = -ERR_RUN_COMMAND_WAITPID_NOEXIT;
 196                 } else {
 197                         code = WEXITSTATUS(status);
 198                         switch (code) {
 199                         case 127:
 200                                 result = -ERR_RUN_COMMAND_EXEC;
 201                                 break;
 202                         case 0:
 203                                 result = 0;
 204                                 break;
 205                         default:
 206                                 result = -code;
 207                                 break;
 208                         }
 209                 }
 210         }
 211         if (finished) {
 212                 cmd->finished = 1;
 213                 cmd->finish_result = result;
 214         }
 215         return result;
 216 }
 217
 218 int check_if_command_finished(struct child_process *cmd)
 219 {
 220         wait_or_whine(cmd, /*block=*/false);
 221         return cmd->finished;
 222 }
 223
 224 int finish_command(struct child_process *cmd)
 225 {
 226         return wait_or_whine(cmd, /*block=*/true);
 227 }
 228
 229 int run_command(struct child_process *cmd)
 230 {
 231         int code = start_command(cmd);
 232         if (code)
 233                 return code;
 234         return finish_command(cmd);
 235 }
 236
 237 static void prepare_run_command_v_opt(struct child_process *cmd,
 238                                       const char **argv,
 239                                       int opt)
 240 {
 241         memset(cmd, 0, sizeof(*cmd));
 242         cmd->argv = argv;
 243         cmd->no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0;
 244         cmd->exec_cmd = opt & RUN_EXEC_CMD ? 1 : 0;
 245         cmd->stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
 246 }
 247
 248 int run_command_v_opt(const char **argv, int opt)
 249 {
 250         struct child_process cmd;
 251         prepare_run_command_v_opt(&cmd, argv, opt);
 252         return run_command(&cmd);
 253 }