usage.c: add a non-fatal bug() function to go with BUG()

Add a bug() function to use in cases where we'd like to indicate a
runtime BUG(), but would like to defer the BUG() call because we're
possibly accumulating more bug() callers to exhaustively indicate what
went wrong.

We already have this sort of facility in various parts of the
codebase, just in the form of ad-hoc re-inventions of the
functionality that this new API provides. E.g. this will be used to
replace optbug() in parse-options.c, and the 'error("BUG:[...]' we do
in a loop in builtin/receive-pack.c.

Unlike the code this replaces we'll log to trace2 with this new bug()
function (as with other usage.c functions, including BUG()), we'll
also be able to avoid calls to xstrfmt() in some cases, as the bug()
function itself accepts variadic sprintf()-like arguments.

Any caller to bug() can follow up such calls with BUG_if_bug(),
which will BUG() out (i.e. abort()) if there were any preceding calls
to bug(), callers can also decide not to call BUG_if_bug() and leave
the resulting BUG() invocation until exit() time. There are currently
no bug() API users that don't call BUG_if_bug() themselves after a
for-loop, but allowing for not calling BUG_if_bug() keeps the API
flexible. As the tests and documentation here show we'll catch missing
BUG_if_bug() invocations in our exit() wrapper.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
pull/1271/merge
Ævar Arnfjörð Bjarmason 4 months ago committed by Junio C Hamano
parent 19d75948ef
commit 0cc05b044f
  1. 24
      Documentation/technical/api-error-handling.txt
  2. 4
      Documentation/technical/api-trace2.txt
  3. 8
      common-main.c
  4. 10
      git-compat-util.h
  5. 29
      t/helper/test-trace2.c
  6. 76
      t/t0210-trace2-normal.sh
  7. 33
      usage.c

@ -1,12 +1,34 @@
Error reporting in git
======================
`BUG`, `die`, `usage`, `error`, and `warning` report errors of
`BUG`, `bug`, `die`, `usage`, `error`, and `warning` report errors of
various kinds.
- `BUG` is for failed internal assertions that should never happen,
i.e. a bug in git itself.
- `bug` (lower-case, not `BUG`) is supposed to be used like `BUG` but
prints a "BUG" message instead of calling `abort()`.
+
A call to `bug()` will then result in a "real" call to the `BUG()`
function, either explicitly by invoking `BUG_if_bug()` after call(s)
to `bug()`, or implicitly at `exit()` time where we'll check if we
encountered any outstanding `bug()` invocations.
+
If there were no prior calls to `bug()` before invoking `BUG_if_bug()`
the latter is a NOOP. The `BUG_if_bug()` function takes the same
arguments as `BUG()` itself. Calling `BUG_if_bug()` explicitly isn't
necessary, but ensures that we die as soon as possible.
+
If you know you had prior calls to `bug()` then calling `BUG()` itself
is equivalent to calling `BUG_if_bug()`, the latter being a wrapper
calling `BUG()` if we've set a flag indicating that we've called
`bug()`.
+
This is for the convenience of APIs who'd like to potentially report
more than one "bug", such as the optbug() validation in
parse-options.c.
- `die` is for fatal application errors. It prints a message to
the user and exits with status 128.

@ -465,8 +465,8 @@ completed.)
------------
`"error"`::
This event is emitted when one of the `BUG()`, `error()`, `die()`,
`warning()`, or `usage()` functions are called.
This event is emitted when one of the `BUG()`, `bug()`, `error()`,
`die()`, `warning()`, or `usage()` functions are called.
+
------------
{

@ -59,6 +59,13 @@ int main(int argc, const char **argv)
exit(result);
}
static void check_bug_if_BUG(void)
{
if (!bug_called_must_BUG)
return;
BUG("on exit(): had bug() call(s) in this process without explicit BUG_if_bug()");
}
/* We wrap exit() to call common_exit() in git-compat-util.h */
int common_exit(const char *file, int line, int code)
{
@ -70,6 +77,7 @@ int common_exit(const char *file, int line, int code)
*/
code &= 0xff;
check_bug_if_BUG();
trace2_cmd_exit_fl(file, line, code);
return code;

@ -1320,9 +1320,19 @@ static inline int regexec_buf(const regex_t *preg, const char *buf, size_t size,
/* usage.c: only to be used for testing BUG() implementation (see test-tool) */
extern int BUG_exit_code;
/* usage.c: if bug() is called we should have a BUG_if_bug() afterwards */
extern int bug_called_must_BUG;
__attribute__((format (printf, 3, 4))) NORETURN
void BUG_fl(const char *file, int line, const char *fmt, ...);
#define BUG(...) BUG_fl(__FILE__, __LINE__, __VA_ARGS__)
__attribute__((format (printf, 3, 4)))
void bug_fl(const char *file, int line, const char *fmt, ...);
#define bug(...) bug_fl(__FILE__, __LINE__, __VA_ARGS__)
#define BUG_if_bug(...) do { \
if (bug_called_must_BUG) \
BUG_fl(__FILE__, __LINE__, __VA_ARGS__); \
} while (0)
#ifdef __APPLE__
#define FSYNC_METHOD_DEFAULT FSYNC_METHOD_WRITEOUT_ONLY

@ -198,7 +198,7 @@ static int ut_006data(int argc, const char **argv)
return 0;
}
static int ut_007bug(int argc, const char **argv)
static int ut_007BUG(int argc, const char **argv)
{
/*
* Exercise BUG() to ensure that the message is printed to trace2.
@ -206,6 +206,28 @@ static int ut_007bug(int argc, const char **argv)
BUG("the bug message");
}
static int ut_008bug(int argc, const char **argv)
{
bug("a bug message");
bug("another bug message");
BUG_if_bug("an explicit BUG_if_bug() following bug() call(s) is nice, but not required");
return 0;
}
static int ut_009bug_BUG(int argc, const char **argv)
{
bug("a bug message");
bug("another bug message");
/* The BUG_if_bug(...) isn't here, but we'll spot bug() calls on exit()! */
return 0;
}
static int ut_010bug_BUG(int argc, const char **argv)
{
bug("a bug message");
BUG("a BUG message");
}
/*
* Usage:
* test-tool trace2 <ut_name_1> <ut_usage_1>
@ -222,7 +244,10 @@ static struct unit_test ut_table[] = {
{ ut_004child, "004child", "[<child_command_line>]" },
{ ut_005exec, "005exec", "<git_command_args>" },
{ ut_006data, "006data", "[<category> <key> <value>]+" },
{ ut_007bug, "007bug", "" },
{ ut_007BUG, "007bug", "" },
{ ut_008bug, "008bug", "" },
{ ut_009bug_BUG, "009bug_BUG","" },
{ ut_010bug_BUG, "010bug_BUG","" },
};
/* clang-format on */

@ -168,6 +168,82 @@ test_expect_success 'BUG messages are written to trace2' '
test_cmp expect actual
'
test_expect_success 'bug messages with BUG_if_bug() are written to trace2' '
test_when_finished "rm trace.normal actual expect" &&
test_expect_code 99 env GIT_TRACE2="$(pwd)/trace.normal" \
test-tool trace2 008bug 2>err &&
cat >expect <<-\EOF &&
a bug message
another bug message
an explicit BUG_if_bug() following bug() call(s) is nice, but not required
EOF
sed "s/^.*: //" <err >actual &&
test_cmp expect actual &&
perl "$TEST_DIRECTORY/t0210/scrub_normal.perl" <trace.normal >actual &&
cat >expect <<-EOF &&
version $V
start _EXE_ trace2 008bug
cmd_name trace2 (trace2)
error a bug message
error another bug message
error an explicit BUG_if_bug() following bug() call(s) is nice, but not required
exit elapsed:_TIME_ code:99
atexit elapsed:_TIME_ code:99
EOF
test_cmp expect actual
'
test_expect_success 'bug messages without explicit BUG_if_bug() are written to trace2' '
test_when_finished "rm trace.normal actual expect" &&
test_expect_code 99 env GIT_TRACE2="$(pwd)/trace.normal" \
test-tool trace2 009bug_BUG 2>err &&
cat >expect <<-\EOF &&
a bug message
another bug message
had bug() call(s) in this process without explicit BUG_if_bug()
EOF
sed "s/^.*: //" <err >actual &&
test_cmp expect actual &&
perl "$TEST_DIRECTORY/t0210/scrub_normal.perl" <trace.normal >actual &&
cat >expect <<-EOF &&
version $V
start _EXE_ trace2 009bug_BUG
cmd_name trace2 (trace2)
error a bug message
error another bug message
error on exit(): had bug() call(s) in this process without explicit BUG_if_bug()
exit elapsed:_TIME_ code:99
atexit elapsed:_TIME_ code:99
EOF
test_cmp expect actual
'
test_expect_success 'bug messages followed by BUG() are written to trace2' '
test_when_finished "rm trace.normal actual expect" &&
test_expect_code 99 env GIT_TRACE2="$(pwd)/trace.normal" \
test-tool trace2 010bug_BUG 2>err &&
cat >expect <<-\EOF &&
a bug message
a BUG message
EOF
sed "s/^.*: //" <err >actual &&
test_cmp expect actual &&
perl "$TEST_DIRECTORY/t0210/scrub_normal.perl" <trace.normal >actual &&
cat >expect <<-EOF &&
version $V
start _EXE_ trace2 010bug_BUG
cmd_name trace2 (trace2)
error a bug message
error a BUG message
exit elapsed:_TIME_ code:99
atexit elapsed:_TIME_ code:99
EOF
test_cmp expect actual
'
sane_unset GIT_TRACE2_BRIEF
# Now test without environment variables and get all Trace2 settings

@ -290,18 +290,24 @@ void warning(const char *warn, ...)
/* Only set this, ever, from t/helper/, when verifying that bugs are caught. */
int BUG_exit_code;
static NORETURN void BUG_vfl(const char *file, int line, const char *fmt, va_list params)
static void BUG_vfl_common(const char *file, int line, const char *fmt,
va_list params)
{
char prefix[256];
va_list params_copy;
static int in_bug;
va_copy(params_copy, params);
/* truncation via snprintf is OK here */
snprintf(prefix, sizeof(prefix), "BUG: %s:%d: ", file, line);
vreportf(prefix, fmt, params);
}
static NORETURN void BUG_vfl(const char *file, int line, const char *fmt, va_list params)
{
va_list params_copy;
static int in_bug;
va_copy(params_copy, params);
BUG_vfl_common(file, line, fmt, params);
if (in_bug)
abort();
@ -317,11 +323,28 @@ static NORETURN void BUG_vfl(const char *file, int line, const char *fmt, va_lis
NORETURN void BUG_fl(const char *file, int line, const char *fmt, ...)
{
va_list ap;
bug_called_must_BUG = 0;
va_start(ap, fmt);
BUG_vfl(file, line, fmt, ap);
va_end(ap);
}
int bug_called_must_BUG;
void bug_fl(const char *file, int line, const char *fmt, ...)
{
va_list ap, cp;
bug_called_must_BUG = 1;
va_copy(cp, ap);
va_start(ap, fmt);
BUG_vfl_common(file, line, fmt, ap);
va_end(ap);
trace2_cmd_error_va(fmt, cp);
}
#ifdef SUPPRESS_ANNOTATED_LEAKS
void unleak_memory(const void *ptr, size_t len)
{

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