ifupdown-ng/libifupdown/execute.c

172 lines
3.9 KiB
C

/*
* libifupdown/execute.c
* Purpose: execution of individual commands
*
* Copyright (c) 2020 Ariadne Conill <ariadne@dereferenced.org>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* This software is provided 'as is' and without any warranty, express or
* implied. In no event shall the authors be liable for any damages arising
* from the use of this software.
*/
#include <errno.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <spawn.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <poll.h>
#include "libifupdown/execute.h"
#define SHELL "/bin/sh"
bool
lif_execute_fmt(const struct lif_execute_opts *opts, char *const envp[], const char *fmt, ...)
{
char cmdbuf[4096];
va_list va;
va_start(va, fmt);
vsnprintf(cmdbuf, sizeof cmdbuf, fmt, va);
va_end(va);
pid_t child;
char *argv[] = { SHELL, "-c", cmdbuf, NULL };
if (opts->verbose)
puts(cmdbuf);
if (opts->mock)
return true;
if (posix_spawn(&child, SHELL, NULL, NULL, argv, envp) != 0)
{
fprintf(stderr, "execute '%s': %s\n", cmdbuf, strerror(errno));
return false;
}
int status;
waitpid(child, &status, 0);
return WIFEXITED(status) && WEXITSTATUS(status) == 0;
}
bool
lif_execute_fmt_with_result(const struct lif_execute_opts *opts, char *buf, size_t bufsize, char *const envp[], const char *fmt, ...)
{
char cmdbuf[4096];
va_list va;
va_start(va, fmt);
vsnprintf(cmdbuf, sizeof cmdbuf, fmt, va);
va_end(va);
pid_t child;
char *argv[] = { SHELL, "-c", cmdbuf, NULL };
if (opts->verbose)
puts(cmdbuf);
if (opts->mock)
return true;
int pipefds[2];
if (pipe(pipefds) < 0)
{
fprintf(stderr, "execute '%s': %s\n", cmdbuf, strerror(errno));
return false;
}
posix_spawn_file_actions_t file_actions;
posix_spawn_file_actions_init(&file_actions);
posix_spawn_file_actions_addclose(&file_actions, pipefds[0]);
posix_spawn_file_actions_adddup2(&file_actions, pipefds[1], 1);
posix_spawn_file_actions_addclose(&file_actions, pipefds[1]);
if (posix_spawn(&child, SHELL, &file_actions, NULL, argv, envp) != 0)
{
fprintf(stderr, "execute '%s': %s\n", cmdbuf, strerror(errno));
return false;
}
posix_spawn_file_actions_destroy(&file_actions);
close(pipefds[1]);
struct pollfd pfd = {
.fd = pipefds[0],
.events = POLLIN
};
if (poll(&pfd, 1, -1) < 1)
goto no_result;
if (read(pipefds[0], buf, bufsize) < 0)
{
fprintf(stderr, "reading from pipe: %s\n", strerror(errno));
return false;
}
int status;
no_result:
waitpid(child, &status, 0);
return WIFEXITED(status) && WEXITSTATUS(status) == 0;
}
bool
lif_file_is_executable(const char *path)
{
struct stat st;
if (stat(path, &st))
return false;
if (!S_ISREG(st.st_mode))
return false;
return !access(path, X_OK);
}
bool
lif_maybe_run_executor(const struct lif_execute_opts *opts, char *const envp[], const char *executor, const char *phase)
{
if (opts->verbose)
fprintf(stderr, "ifupdown: attempting to run %s executor for phase %s\n", executor, phase);
char pathbuf[4096];
snprintf(pathbuf, sizeof pathbuf, "%s/%s", opts->executor_path, executor);
if (!lif_file_is_executable(pathbuf))
return true;
return lif_execute_fmt(opts, envp, "%s", pathbuf);
}
bool
lif_maybe_run_executor_with_result(const struct lif_execute_opts *opts, char *const envp[], const char *executor, char *buf, size_t bufsize, const char *phase)
{
if (opts->verbose)
fprintf(stderr, "ifupdown: attempting to run %s executor for phase %s\n", executor, phase);
char pathbuf[4096];
snprintf(pathbuf, sizeof pathbuf, "%s/%s", opts->executor_path, executor);
if (!lif_file_is_executable(pathbuf))
return true;
return lif_execute_fmt_with_result(opts, buf, bufsize, envp, "%s", pathbuf);
}