| Line | Branch | Exec | Source |
|---|---|---|---|
| 1 | #include "feature.h" | ||
| 2 | #include <errno.h> | ||
| 3 | #include <signal.h> | ||
| 4 | #include <stdlib.h> | ||
| 5 | #include <sys/wait.h> | ||
| 6 | #include <unistd.h> | ||
| 7 | #include "fork-exec.h" | ||
| 8 | #include "debug.h" | ||
| 9 | #include "fd.h" | ||
| 10 | #include "log.h" | ||
| 11 | #include "numtostr.h" | ||
| 12 | #include "terminal/ioctl.h" | ||
| 13 | #include "xreadwrite.h" | ||
| 14 | |||
| 15 | // Reset ignored signal dispositions (i.e. as originally set up by | ||
| 16 | // set_basic_signal_dispositions()) to SIG_DFL | ||
| 17 | 21 | static bool reset_ignored_signals(void) | |
| 18 | { | ||
| 19 | // Note that handled signals don't need to be restored here, since | ||
| 20 | // they're necessarily and automatically reset after exec(3p) | ||
| 21 | 21 | static const int ignored_signals[] = { | |
| 22 | SIGINT, SIGQUIT, SIGTSTP, | ||
| 23 | SIGTTIN, SIGTTOU, SIGXFSZ, | ||
| 24 | SIGPIPE, SIGUSR1, SIGUSR2, | ||
| 25 | }; | ||
| 26 | |||
| 27 | 21 | struct sigaction action = {.sa_handler = SIG_DFL}; | |
| 28 |
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21 | if (unlikely(sigemptyset(&action.sa_mask) != 0)) { |
| 29 | return false; | ||
| 30 | } | ||
| 31 | |||
| 32 |
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210 | for (size_t i = 0; i < ARRAYLEN(ignored_signals); i++) { |
| 33 | 189 | int r = sigaction(ignored_signals[i], &action, NULL); | |
| 34 |
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189 | if (unlikely(r != 0)) { |
| 35 | return false; | ||
| 36 | } | ||
| 37 | } | ||
| 38 | |||
| 39 | return true; | ||
| 40 | } | ||
| 41 | |||
| 42 | // NOLINTNEXTLINE(readability-function-size) | ||
| 43 | 21 | static noreturn void child_process_exec ( | |
| 44 | const char **argv, | ||
| 45 | const int fd[3], | ||
| 46 | int error_fd, // Pipe to parent, for communicating pre-exec errors | ||
| 47 | unsigned int lines, | ||
| 48 | unsigned int columns, | ||
| 49 | bool drop_ctty | ||
| 50 | ) { | ||
| 51 |
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21 | if (drop_ctty) { |
| 52 | 21 | term_drop_controlling_tty(STDIN_FILENO); | |
| 53 | } | ||
| 54 | |||
| 55 |
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84 | for (int i = STDIN_FILENO; i <= STDERR_FILENO; i++) { |
| 56 | 63 | int f = fd[i]; | |
| 57 |
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63 | bool ok = (i == f) ? fd_set_cloexec(f, false) : xdup3(f, i, 0) >= 0; |
| 58 |
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63 | if (unlikely(!ok)) { |
| 59 | ✗ | goto error; | |
| 60 | } | ||
| 61 | } | ||
| 62 | |||
| 63 |
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21 | if (lines) { |
| 64 | 7 | setenv("LINES", uint_to_str(lines), 1); | |
| 65 | } | ||
| 66 |
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21 | if (columns) { |
| 67 | 7 | setenv("COLUMNS", uint_to_str(columns), 1); | |
| 68 | } | ||
| 69 | |||
| 70 |
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21 | if (unlikely(!reset_ignored_signals())) { |
| 71 | ✗ | goto error; | |
| 72 | } | ||
| 73 | |||
| 74 | 1 | execvp(argv[0], (char**)argv); | |
| 75 | |||
| 76 | 1 | error:; | |
| 77 | 1 | int error = errno; | |
| 78 | 1 | error = xwrite(error_fd, &error, sizeof(error)); | |
| 79 | 1 | exit(42); | |
| 80 | } | ||
| 81 | |||
| 82 | 21 | static pid_t xwaitpid(pid_t pid, int *status, int options) | |
| 83 | { | ||
| 84 | 21 | pid_t ret; | |
| 85 | 42 | do { | |
| 86 | 21 | ret = waitpid(pid, status, options); | |
| 87 |
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21 | } while (unlikely(ret < 0 && errno == EINTR)); |
| 88 | 21 | return ret; | |
| 89 | } | ||
| 90 | |||
| 91 | 21 | pid_t fork_exec ( | |
| 92 | const char **argv, | ||
| 93 | int fd[3], | ||
| 94 | unsigned int lines, | ||
| 95 | unsigned int columns, | ||
| 96 | bool drop_ctty | ||
| 97 | ) { | ||
| 98 | // Create an "error pipe" before forking, so that child_process_exec() | ||
| 99 | // can signal pre-exec errors and allow the parent differentiate them | ||
| 100 | // from a successful exec(3) with a non-zero exit status | ||
| 101 | 21 | int ep[2]; | |
| 102 |
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21 | if (xpipe2(ep, O_CLOEXEC) != 0) { |
| 103 | return -1; | ||
| 104 | } | ||
| 105 | |||
| 106 | 21 | BUG_ON(ep[0] <= STDERR_FILENO); | |
| 107 | 21 | BUG_ON(ep[1] <= STDERR_FILENO); | |
| 108 | 21 | BUG_ON(fd[0] <= STDERR_FILENO && fd[0] != 0); | |
| 109 | 21 | BUG_ON(fd[1] <= STDERR_FILENO && fd[1] != 1); | |
| 110 | 21 | BUG_ON(fd[2] <= STDERR_FILENO && fd[2] != 2); | |
| 111 | |||
| 112 | 21 | const pid_t pid = fork(); | |
| 113 |
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42 | if (unlikely(pid == -1)) { |
| 114 | ✗ | xclose(ep[0]); | |
| 115 | ✗ | xclose(ep[1]); | |
| 116 | ✗ | return -1; | |
| 117 | } | ||
| 118 | |||
| 119 |
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42 | if (pid == 0) { |
| 120 | // Child | ||
| 121 | 21 | child_process_exec(argv, fd, ep[1], lines, columns, drop_ctty); | |
| 122 | BUG("child_process_exec() should never return"); | ||
| 123 | return -1; | ||
| 124 | } | ||
| 125 | |||
| 126 | // Parent | ||
| 127 | 21 | xclose(ep[1]); | |
| 128 | 21 | int error = 0; | |
| 129 | 21 | ssize_t rc = xread(ep[0], &error, sizeof(error)); | |
| 130 | 21 | int xread_errno = errno; | |
| 131 | 21 | xclose(ep[0]); | |
| 132 | 21 | BUG_ON(rc > sizeof(error)); | |
| 133 | |||
| 134 |
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21 | if (rc == 0) { |
| 135 | // Child exec was successful | ||
| 136 | return pid; | ||
| 137 | } | ||
| 138 | |||
| 139 |
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1 | if (unlikely(rc != sizeof(error))) { |
| 140 | ✗ | error = (rc < 0) ? xread_errno : EPIPE; | |
| 141 | } | ||
| 142 | |||
| 143 | 1 | int status; | |
| 144 | 1 | xwaitpid(pid, &status, 0); | |
| 145 | 1 | errno = error; | |
| 146 | 1 | return -1; | |
| 147 | } | ||
| 148 | |||
| 149 | 20 | int wait_child(pid_t pid) | |
| 150 | { | ||
| 151 | 20 | int status; | |
| 152 |
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20 | if (unlikely(xwaitpid(pid, &status, 0) < 0)) { |
| 153 | ✗ | return -errno; | |
| 154 | } | ||
| 155 | |||
| 156 |
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20 | if (likely(WIFEXITED(status))) { |
| 157 | 18 | return WEXITSTATUS(status) & 0xFF; | |
| 158 | } | ||
| 159 | |||
| 160 |
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2 | if (likely(WIFSIGNALED(status))) { |
| 161 | 2 | return WTERMSIG(status) << 8; | |
| 162 | } | ||
| 163 | |||
| 164 | ✗ | LOG_ERROR("unhandled waitpid() status: %d", status); | |
| 165 | ✗ | return -EINVAL; | |
| 166 | } | ||
| 167 |