/*

 * Utility functions

 *

 * Copyright (c) 2011 Yuya Nishihara <yuya@tcha.org>

 *

 * This software may be used and distributed according to the terms of the

 * GNU General Public License version 2 or any later version.

 */

#include <errno.h>

#include <fcntl.h>

#include <signal.h>

#include <stdarg.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <sys/types.h>

#include <sys/wait.h>

#include <unistd.h>

#include "util.h"

static int colorenabled = 0;

static inline void fsetcolor(FILE *fp, const char *code)

{

	if (!colorenabled)

		return;

	fprintf(fp, "\033[%sm", code);

}

static void vabortmsgerrno(int no, const char *fmt, va_list args)

{

	fsetcolor(stderr, "1;31");

	fputs("chg: abort: ", stderr);

	vfprintf(stderr, fmt, args);

	if (no != 0)

		fprintf(stderr, " (errno = %d, %s)", no, strerror(no));

	fsetcolor(stderr, "");

	fputc('\n', stderr);

	exit(255);

}

void abortmsg(const char *fmt, ...)

{

	va_list args;

	va_start(args, fmt);

	vabortmsgerrno(0, fmt, args);

	va_end(args);

}

void abortmsgerrno(const char *fmt, ...)

{

	int no = errno;

	va_list args;

	va_start(args, fmt);

	vabortmsgerrno(no, fmt, args);

	va_end(args);

}

static int debugmsgenabled = 0;

void enablecolor(void)

{

	colorenabled = 1;

}

void enabledebugmsg(void)

{

	debugmsgenabled = 1;

}

void debugmsg(const char *fmt, ...)

{

	if (!debugmsgenabled)

		return;

	va_list args;

	va_start(args, fmt);

	fsetcolor(stderr, "1;30");

	fputs("chg: debug: ", stderr);

	vfprintf(stderr, fmt, args);

	fsetcolor(stderr, "");

	fputc('\n', stderr);

	va_end(args);

}

void fchdirx(int dirfd)

{

	int r = fchdir(dirfd);

	if (r == -1)

		abortmsgerrno("failed to fchdir");

}

void fsetcloexec(int fd)

{

	int flags = fcntl(fd, F_GETFD);

	if (flags < 0)

		abortmsgerrno("cannot get flags of fd %d", fd);

	if (fcntl(fd, F_SETFD, flags | FD_CLOEXEC) < 0)

		abortmsgerrno("cannot set flags of fd %d", fd);

}

void *mallocx(size_t size)

{

	void *result = malloc(size);

	if (!result)

		abortmsg("failed to malloc");

	return result;

}

void *reallocx(void *ptr, size_t size)

{

	void *result = realloc(ptr, size);

	if (!result)

		abortmsg("failed to realloc");

	return result;

}

/*

 * Execute a shell command in mostly the same manner as system(), with the

 * give environment variables, after chdir to the given cwd. Returns a status

 * code compatible with the Python subprocess module.

 */

int runshellcmd(const char *cmd, const char *envp[], const char *cwd)

{

	enum { F_SIGINT = 1, F_SIGQUIT = 2, F_SIGMASK = 4, F_WAITPID = 8 };

	unsigned int doneflags = 0;

	int status = 0;

	struct sigaction newsa, oldsaint, oldsaquit;

	sigset_t oldmask;

	/* block or mask signals just as system() does */

	memset(&newsa, 0, sizeof(newsa));

	newsa.sa_handler = SIG_IGN;

	newsa.sa_flags = 0;

	if (sigemptyset(&newsa.sa_mask) < 0)

		goto done;

	if (sigaction(SIGINT, &newsa, &oldsaint) < 0)

		goto done;

	doneflags |= F_SIGINT;

	if (sigaction(SIGQUIT, &newsa, &oldsaquit) < 0)

		goto done;

	doneflags |= F_SIGQUIT;

	if (sigaddset(&newsa.sa_mask, SIGCHLD) < 0)

		goto done;

	if (sigprocmask(SIG_BLOCK, &newsa.sa_mask, &oldmask) < 0)

		goto done;

	doneflags |= F_SIGMASK;

	pid_t pid = fork();

	if (pid < 0)

		goto done;

	if (pid == 0) {

		sigaction(SIGINT, &oldsaint, NULL);

		sigaction(SIGQUIT, &oldsaquit, NULL);

		sigprocmask(SIG_SETMASK, &oldmask, NULL);

		if (cwd && chdir(cwd) < 0)

			_exit(127);

		const char *argv[] = {"sh", "-c", cmd, NULL};

		if (envp) {

			execve("/bin/sh", (char **)argv, (char **)envp);

		} else {

			execv("/bin/sh", (char **)argv);

		}

		_exit(127);

	} else {

		if (waitpid(pid, &status, 0) < 0)

			goto done;

		doneflags |= F_WAITPID;

	}

done:

	if (doneflags & F_SIGINT)

		sigaction(SIGINT, &oldsaint, NULL);

	if (doneflags & F_SIGQUIT)

		sigaction(SIGQUIT, &oldsaquit, NULL);

	if (doneflags & F_SIGMASK)

		sigprocmask(SIG_SETMASK, &oldmask, NULL);

	/* no way to report other errors, use 127 (= shell termination) */

	if (!(doneflags & F_WAITPID))

		return 127;

	if (WIFEXITED(status))

		return WEXITSTATUS(status);

	if (WIFSIGNALED(status))

		return -WTERMSIG(status);

	return 127;

}