| Line | Branch | Exec | Source |
|---|---|---|---|
| 1 | #include <errno.h> | ||
| 2 | #include <signal.h> | ||
| 3 | #include <stdlib.h> | ||
| 4 | #include <sys/wait.h> | ||
| 5 | #include <unistd.h> | ||
| 6 | #include "fork-exec.h" | ||
| 7 | #include "debug.h" | ||
| 8 | #include "fd.h" | ||
| 9 | #include "log.h" | ||
| 10 | #include "terminal/ioctl.h" | ||
| 11 | #include "xreadwrite.h" | ||
| 12 | |||
| 13 | // Reset ignored signal dispositions (i.e. as originally set up by | ||
| 14 | // set_basic_signal_dispositions()) to SIG_DFL | ||
| 15 | 21 | static bool reset_ignored_signals(void) | |
| 16 | { | ||
| 17 | // Note that handled signals don't need to be restored here, since | ||
| 18 | // they're necessarily and automatically reset after exec(3p) | ||
| 19 | 21 | static const int ignored_signals[] = { | |
| 20 | SIGINT, SIGQUIT, SIGTSTP, | ||
| 21 | SIGTTIN, SIGTTOU, SIGXFSZ, | ||
| 22 | SIGPIPE, SIGUSR1, SIGUSR2, | ||
| 23 | }; | ||
| 24 | |||
| 25 | 21 | struct sigaction action = {.sa_handler = SIG_DFL}; | |
| 26 |
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21 | if (unlikely(sigemptyset(&action.sa_mask) != 0)) { |
| 27 | return false; | ||
| 28 | } | ||
| 29 | |||
| 30 |
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210 | for (size_t i = 0; i < ARRAYLEN(ignored_signals); i++) { |
| 31 | 189 | int r = sigaction(ignored_signals[i], &action, NULL); | |
| 32 |
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189 | if (unlikely(r != 0)) { |
| 33 | return false; | ||
| 34 | } | ||
| 35 | } | ||
| 36 | |||
| 37 | return true; | ||
| 38 | } | ||
| 39 | |||
| 40 | 21 | static noreturn void child_process_exec ( | |
| 41 | const char **argv, | ||
| 42 | const char **env, | ||
| 43 | int fd[3], | ||
| 44 | int error_fd, | ||
| 45 | bool drop_ctty | ||
| 46 | ) { | ||
| 47 | 21 | int error; | |
| 48 | 21 | int nr_fds = 3; | |
| 49 | 21 | bool move = error_fd < nr_fds; | |
| 50 | 21 | int max = error_fd; | |
| 51 | |||
| 52 |
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21 | if (drop_ctty) { |
| 53 | 21 | term_drop_controlling_tty(STDIN_FILENO); | |
| 54 | } | ||
| 55 | |||
| 56 | // Find if we must move fds out of the way | ||
| 57 |
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84 | for (int i = 0; i < nr_fds; i++) { |
| 58 |
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63 | if (fd[i] > max) { |
| 59 | ✗ | max = fd[i]; | |
| 60 | } | ||
| 61 |
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63 | if (fd[i] < i) { |
| 62 | ✗ | move = true; | |
| 63 | } | ||
| 64 | } | ||
| 65 | |||
| 66 |
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21 | if (move) { |
| 67 | ✗ | int next_free = max + 1; | |
| 68 | ✗ | if (error_fd < nr_fds) { | |
| 69 | ✗ | error_fd = xdup3(error_fd, next_free++, O_CLOEXEC); | |
| 70 | ✗ | if (error_fd < 0) { | |
| 71 | ✗ | goto error; | |
| 72 | } | ||
| 73 | } | ||
| 74 | ✗ | for (int i = 0; i < nr_fds; i++) { | |
| 75 | ✗ | if (fd[i] < i) { | |
| 76 | ✗ | fd[i] = xdup3(fd[i], next_free++, O_CLOEXEC); | |
| 77 | ✗ | if (fd[i] < 0) { | |
| 78 | ✗ | goto error; | |
| 79 | } | ||
| 80 | } | ||
| 81 | } | ||
| 82 | } | ||
| 83 | |||
| 84 | // Now it is safe to duplicate fds in this order | ||
| 85 |
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84 | for (int i = 0; i < nr_fds; i++) { |
| 86 |
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63 | if (i == fd[i]) { |
| 87 | // Clear FD_CLOEXEC flag | ||
| 88 | ✗ | if (!fd_set_cloexec(fd[i], false)) { | |
| 89 | ✗ | goto error; | |
| 90 | } | ||
| 91 | } else { | ||
| 92 |
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63 | if (xdup3(fd[i], i, 0) < 0) { |
| 93 | ✗ | goto error; | |
| 94 | } | ||
| 95 | } | ||
| 96 | } | ||
| 97 | |||
| 98 |
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21 | if (env) { |
| 99 |
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15 | for (size_t i = 0; env[i]; i += 2) { |
| 100 | 10 | const char *name = env[i]; | |
| 101 | 10 | const char *value = env[i + 1]; | |
| 102 |
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10 | int r = value ? setenv(name, value, 1) : unsetenv(name); |
| 103 |
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10 | if (unlikely(r != 0)) { |
| 104 | ✗ | goto error; | |
| 105 | } | ||
| 106 | } | ||
| 107 | } | ||
| 108 | |||
| 109 |
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21 | if (!reset_ignored_signals()) { |
| 110 | ✗ | goto error; | |
| 111 | } | ||
| 112 | |||
| 113 | 1 | execvp(argv[0], (char**)argv); | |
| 114 | |||
| 115 | 1 | error: | |
| 116 | 1 | error = errno; | |
| 117 | 1 | error = xwrite(error_fd, &error, sizeof(error)); | |
| 118 | 1 | exit(42); | |
| 119 | } | ||
| 120 | |||
| 121 | 21 | static pid_t xwaitpid(pid_t pid, int *status, int options) | |
| 122 | { | ||
| 123 | 21 | pid_t ret; | |
| 124 | 42 | do { | |
| 125 | 21 | ret = waitpid(pid, status, options); | |
| 126 |
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21 | } while (unlikely(ret < 0 && errno == EINTR)); |
| 127 | 21 | return ret; | |
| 128 | } | ||
| 129 | |||
| 130 | 21 | pid_t fork_exec(const char **argv, const char **env, int fd[3], bool drop_ctty) | |
| 131 | { | ||
| 132 | 21 | int ep[2]; | |
| 133 |
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21 | if (xpipe2(ep, O_CLOEXEC) != 0) { |
| 134 | return -1; | ||
| 135 | } | ||
| 136 | |||
| 137 | 21 | const pid_t pid = fork(); | |
| 138 |
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42 | if (unlikely(pid == -1)) { |
| 139 | ✗ | int saved_errno = errno; | |
| 140 | ✗ | xclose(ep[0]); | |
| 141 | ✗ | xclose(ep[1]); | |
| 142 | ✗ | errno = saved_errno; | |
| 143 | ✗ | return -1; | |
| 144 | } | ||
| 145 | |||
| 146 |
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42 | if (pid == 0) { |
| 147 | // Child | ||
| 148 | 21 | child_process_exec(argv, env, fd, ep[1], drop_ctty); | |
| 149 | BUG("child_process_exec() should never return"); | ||
| 150 | return -1; | ||
| 151 | } | ||
| 152 | |||
| 153 | // Parent | ||
| 154 | 21 | xclose(ep[1]); | |
| 155 | 21 | int error = 0; | |
| 156 | 21 | ssize_t rc = xread(ep[0], &error, sizeof(error)); | |
| 157 | 21 | int xread_errno = errno; | |
| 158 | 21 | xclose(ep[0]); | |
| 159 | 21 | BUG_ON(rc > sizeof(error)); | |
| 160 | |||
| 161 |
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21 | if (rc == 0) { |
| 162 | // Child exec was successful | ||
| 163 | return pid; | ||
| 164 | } | ||
| 165 | |||
| 166 |
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1 | if (unlikely(rc != sizeof(error))) { |
| 167 | ✗ | error = (rc < 0) ? xread_errno : EPIPE; | |
| 168 | } | ||
| 169 | |||
| 170 | 1 | int status; | |
| 171 | 1 | xwaitpid(pid, &status, 0); | |
| 172 | 1 | errno = error; | |
| 173 | 1 | return -1; | |
| 174 | } | ||
| 175 | |||
| 176 | 20 | int wait_child(pid_t pid) | |
| 177 | { | ||
| 178 | 20 | int status; | |
| 179 |
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20 | if (unlikely(xwaitpid(pid, &status, 0) < 0)) { |
| 180 | ✗ | return -errno; | |
| 181 | } | ||
| 182 | |||
| 183 |
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20 | if (likely(WIFEXITED(status))) { |
| 184 | 18 | return WEXITSTATUS(status) & 0xFF; | |
| 185 | } | ||
| 186 | |||
| 187 |
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2 | if (likely(WIFSIGNALED(status))) { |
| 188 | 2 | return WTERMSIG(status) << 8; | |
| 189 | } | ||
| 190 | |||
| 191 | ✗ | LOG_ERROR("unhandled waitpid() status: %d", status); | |
| 192 | ✗ | return -EINVAL; | |
| 193 | } | ||
| 194 |