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Revision d88785e424aaf18aa3ca291c2299c599c000c6cb authored by Jeff King on 11 May 2016, 13:44:04 UTC, committed by Junio C Hamano on 11 May 2016, 21:03:14 UTC 
test-lib: set BASH_XTRACEFD automatically
 
Passing "-x" to a test script enables the shell's "set -x"
tracing, which can help with tracking down the command that
is causing a failure. Unfortunately, it can also _cause_
failures in some tests that redirect the stderr of a shell
function.  Inside the function the shell continues to
respect "set -x", and the trace output is collected along
with whatever stderr is generated normally by the function.

You can see an example of this by running:

  ./t0040-parse-options.sh -x -i

which will fail immediately in the first test, as it
expects:

  test_must_fail some-cmd 2>output.err

to leave output.err empty (but with "-x" it has our trace
output).

Unfortunately there isn't a portable or scalable solution to
this. We could teach test_must_fail to disable "set -x", but
that doesn't help any of the other functions or subshells.

However, we can work around it by pointing the "set -x"
output to our descriptor 4, which always points to the
original stderr of the test script. Unfortunately this only
works for bash, but it's better than nothing (and other
shells will just ignore the BASH_XTRACEFD variable).

The patch itself is a simple one-liner, but note the caveats
in the accompanying comments.

Automatic tests for our "-x" option may be a bit too meta
(and a pain, because they are bash-specific), but I did
confirm that it works correctly both with regular "-x" and
with "--verbose-only=1". This works because the latter flips
"set -x" off and on for particular tests (if it didn't, we
would get tracing for all tests, as going to descriptor 4
effectively circumvents the verbose flag).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
1 parent 7654286
Raw File
exec_cmd.c 
#include "cache.h"
#include "exec_cmd.h"
#include "quote.h"
#define MAX_ARGS	32

static const char *argv_exec_path;
static const char *argv0_path;

char *system_path(const char *path)
{
#ifdef RUNTIME_PREFIX
	static const char *prefix;
#else
	static const char *prefix = PREFIX;
#endif
	struct strbuf d = STRBUF_INIT;

	if (is_absolute_path(path))
		return xstrdup(path);

#ifdef RUNTIME_PREFIX
	assert(argv0_path);
	assert(is_absolute_path(argv0_path));

	if (!prefix &&
	    !(prefix = strip_path_suffix(argv0_path, GIT_EXEC_PATH)) &&
	    !(prefix = strip_path_suffix(argv0_path, BINDIR)) &&
	    !(prefix = strip_path_suffix(argv0_path, "git"))) {
		prefix = PREFIX;
		trace_printf("RUNTIME_PREFIX requested, "
				"but prefix computation failed.  "
				"Using static fallback '%s'.\n", prefix);
	}
#endif

	strbuf_addf(&d, "%s/%s", prefix, path);
	return strbuf_detach(&d, NULL);
}

const char *git_extract_argv0_path(const char *argv0)
{
	const char *slash;

	if (!argv0 || !*argv0)
		return NULL;
	slash = argv0 + strlen(argv0);

	while (argv0 <= slash && !is_dir_sep(*slash))
		slash--;

	if (slash >= argv0) {
		argv0_path = xstrndup(argv0, slash - argv0);
		return slash + 1;
	}

	return argv0;
}

void git_set_argv_exec_path(const char *exec_path)
{
	argv_exec_path = exec_path;
	/*
	 * Propagate this setting to external programs.
	 */
	setenv(EXEC_PATH_ENVIRONMENT, exec_path, 1);
}


/* Returns the highest-priority, location to look for git programs. */
const char *git_exec_path(void)
{
	const char *env;

	if (argv_exec_path)
		return argv_exec_path;

	env = getenv(EXEC_PATH_ENVIRONMENT);
	if (env && *env) {
		return env;
	}

	return system_path(GIT_EXEC_PATH);
}

static void add_path(struct strbuf *out, const char *path)
{
	if (path && *path) {
		strbuf_add_absolute_path(out, path);
		strbuf_addch(out, PATH_SEP);
	}
}

void setup_path(void)
{
	const char *old_path = getenv("PATH");
	struct strbuf new_path = STRBUF_INIT;

	add_path(&new_path, git_exec_path());

	if (old_path)
		strbuf_addstr(&new_path, old_path);
	else
		strbuf_addstr(&new_path, _PATH_DEFPATH);

	setenv("PATH", new_path.buf, 1);

	strbuf_release(&new_path);
}

const char **prepare_git_cmd(const char **argv)
{
	int argc;
	const char **nargv;

	for (argc = 0; argv[argc]; argc++)
		; /* just counting */
	nargv = xmalloc(sizeof(*nargv) * (argc + 2));

	nargv[0] = "git";
	for (argc = 0; argv[argc]; argc++)
		nargv[argc + 1] = argv[argc];
	nargv[argc + 1] = NULL;
	return nargv;
}

int execv_git_cmd(const char **argv) {
	const char **nargv = prepare_git_cmd(argv);
	trace_argv_printf(nargv, "trace: exec:");

	/* execvp() can only ever return if it fails */
	sane_execvp("git", (char **)nargv);

	trace_printf("trace: exec failed: %s\n", strerror(errno));

	free(nargv);
	return -1;
}


int execl_git_cmd(const char *cmd,...)
{
	int argc;
	const char *argv[MAX_ARGS + 1];
	const char *arg;
	va_list param;

	va_start(param, cmd);
	argv[0] = cmd;
	argc = 1;
	while (argc < MAX_ARGS) {
		arg = argv[argc++] = va_arg(param, char *);
		if (!arg)
			break;
	}
	va_end(param);
	if (MAX_ARGS <= argc)
		return error("too many args to run %s", cmd);

	argv[argc] = NULL;
	return execv_git_cmd(argv);
}
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