nbos

nbos

https://git.tonybtw.com/nbos.git git://git.tonybtw.com/nbos.git
nbos / src / run.c
2,600 bytes raw
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#define _GNU_SOURCE
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#include "run.h"
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#include <errno.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <string.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <unistd.h>
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/**
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 * run() - Fork+exec a command with stdout/stderr captured to a log.
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 * @cmd: Absolute path to the executable.
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 * @argv: NULL-terminated argv. argv[0] is conventionally @cmd.
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 * @envp: NULL-terminated envp. Pass {NULL} for an empty environment.
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 * @cwd: Working directory for the child, or NULL to inherit.
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 * @log_path: File path that captures the child's stdout and stderr.
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 *
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 * Stdin is redirected to /dev/null. The child is reaped before return.
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 *
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 * Return: RUN_OK_VAL on exit code 0; RUN_E_NONZERO with @exit_code and
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 * @log_path filled; RUN_E_SPAWN or RUN_E_IO with @errno_val filled.
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 */
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run_error run(
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    const char  *cmd,
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    char *const  argv[],
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    char *const  envp[],
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    const char  *cwd,
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    const char  *log_path)
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{
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    run_error err = RUN_OK_VAL;
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    int log_fd = open(log_path, O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC, 0644);
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    if (log_fd < 0) {
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        err.kind = RUN_E_IO;
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        err.errno_val = errno;
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        return err;
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    }
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    pid_t pid = fork();
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    if (pid < 0) {
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        err.kind = RUN_E_SPAWN;
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        err.errno_val = errno;
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        close(log_fd);
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        return err;
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    }
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    if (pid == 0) {
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        if (cwd != nullptr && chdir(cwd) < 0) {
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            dprintf(log_fd, "run: chdir(%s) failed: %s\n", cwd, strerror(errno));
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            _exit(127);
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        }
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        if (dup2(log_fd, STDOUT_FILENO) < 0 || dup2(log_fd, STDERR_FILENO) < 0) {
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            _exit(127);
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        }
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        close(log_fd);
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        int devnull = open("/dev/null", O_RDONLY | O_CLOEXEC);
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        if (devnull >= 0) {
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            dup2(devnull, STDIN_FILENO);
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            close(devnull);
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        }
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        execve(cmd, argv, envp);
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        dprintf(STDERR_FILENO, "run: execve(%s) failed: %s\n", cmd, strerror(errno));
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        _exit(127);
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    }
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    close(log_fd);
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    int status = 0;
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    while (waitpid(pid, &status, 0) < 0) {
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        if (errno == EINTR) continue;
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        err.kind = RUN_E_IO;
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        err.errno_val = errno;
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        return err;
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    }
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    int code;
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    if (WIFEXITED(status)) {
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        code = WEXITSTATUS(status);
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    } else if (WIFSIGNALED(status)) {
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        code = 128 + WTERMSIG(status);
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    } else {
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        err.kind = RUN_E_IO;
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        err.errno_val = EINVAL;
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        return err;
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    }
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    if (code != 0) {
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        err.kind = RUN_E_NONZERO;
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        err.exit_code = code;
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        err.log_path = log_path;
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        return err;
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    }
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    return RUN_OK_VAL;
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}