contrib/chg/util.c

getbundle: cleanly handle remote abort during getbundle

bundle2 allow the server to report error explicitly. This was initially
implemented for push but there is not reason to not use it for pull too. This
changeset add logic similar to the one in 'unbundle' to the
client side of 'getbundle'. That logic make sure the error is properly reported
as "remote". This will allow the server side of getbundle to send clean "Abort"
message in the next changeset.

/*
 * 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;
}