contrib/chg/util.c

templater: factor out function that creates templater from string template

This function will host loading of template aliases. It is not defined at
templater, but at formatter, since formatter is the module handling ui stuff
in front of templater.

/*
 * Utility functions
 *
 * Copyright (c) 2011 Yuya Nishihara <[e-mail]>
 *
 * 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;
}