annotate contrib/chg/util.c @ 39772:ae531f5e583c

testing: add interface unit tests for file storage

Our strategy for supporting alternate storage backends is to define
interfaces for everything then "code to the interface."

We already have interfaces for various primitives, including file
and manifest storage.

What we don't have is generic unit tests for those interfaces. Up
to this point we've been relying on high-level integration tests
(mainly in the form of existing .t tests) to test alternate storage
backends. And my experience with developing the "simple store" test
extension is that such testing is very tedious: it takes several
minutes to run all tests and when you find a failure, it is often
non-trivial to debug.

This commit starts to change that.

This commit introduces the mercurial.testing.storage module. It
contains testing code for storage. Currently, it defines some
unittest.TestCase classes for testing the file storage interfaces.
It also defines some factory functions that allow a caller to easily
spawn a custom TestCase "bound" to a specific file storage backend
implementation.

A new .py test has been added. It simply defines a callable to produce
filelog and transaction instances on demand and then "registers" the
various test classes so the filelog class can be tested with the
storage interface unit tests.

As part of writing the tests, I identified a couple of apparent
bugs in revlog.py and filelog.py! These are tracked with inline
TODO comments.

Writing the tests makes it more obvious where the storage interface
is lacking. For example, we raise either IndexError or
error.LookupError for missing revisions depending on whether we
use an integer revision or a node. Also, we raise error.RevlogError
in various places when we should be raising a storage-agnostic
error type.

The storage interfaces are currently far from perfect and there is much
work to be done to improve them. But at least with this commit we
finally have the start of unit tests that can be used to "qualify"
the behavior of a storage backend. And when implementing and debugging
new storage backends, we now have an obvious place to define new
tests and have obvious places to insert breakpoints to facilitate
debugging. This should be invaluable when implementing new storage
backends.

I added the mercurial.testing package because these interface
conformance tests are generic and need to be usable by all storage
backends. Having the code live in tests/ would make it difficult for
storage backends implemented in extensions to test their interface
conformance. First, it would require obtaining a copy of Mercurial's
storage test code in order to test. Second, it would make testing
against multiple Mercurial versions difficult, as you would need to
import N copies of the storage testing code in order to achieve test
coverage. By making the test code part of the Mercurial distribution
itself, extensions can `import mercurial.testing.*` to access and run
the test code. The test will run against whatever Mercurial version
is active.

FWIW I've always wanted to move parts of run-tests.py into the
mercurial.* package to make the testing story simpler (e.g. imagine an
`hg debugruntests` command that could invoke the test harness). While I
have no plans to do that in the near future, establishing the
mercurial.testing package does provide a natural home for that code
should someone do this in the future.

Differential Revision: https://phab.mercurial-scm.org/D4650

/*
 * 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/time.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;
static double debugstart = 0;

static double now()
{
	struct timeval t;
	gettimeofday(&t, NULL);
	return t.tv_usec / 1e6 + t.tv_sec;
}

void enablecolor(void)
{
	colorenabled = 1;
}

void enabledebugmsg(void)
{
	debugmsgenabled = 1;
	debugstart = now();
}

void debugmsg(const char *fmt, ...)
{
	if (!debugmsgenabled)
		return;

	va_list args;
	va_start(args, fmt);
	fsetcolor(stderr, "1;30");
	fprintf(stderr, "chg: debug: %4.6f ", now() - debugstart);
	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;
}