mirror of
https://github.com/git/git.git
synced 2024-10-30 13:57:54 +01:00
e208f9cc75
When git is compiled with "gcc -Wuninitialized -O3", some inlined calls provide an additional opportunity for the compiler to do static analysis on variable initialization. For example, with two functions like this: int get_foo(int *foo) { if (something_that_might_fail() < 0) return error("unable to get foo"); *foo = 0; return 0; } void some_fun(void) { int foo; if (get_foo(&foo) < 0) return -1; printf("foo is %d\n", foo); } If get_foo() is not inlined, then when compiling some_fun, gcc sees only that a pointer to the local variable is passed, and must assume that it is an out parameter that is initialized after get_foo returns. However, when get_foo() is inlined, the compiler may look at all of the code together and see that some code paths in get_foo() do not initialize the variable. As a result, it prints a warning. But what the compiler can't see is that error() always returns -1, and therefore we know that either we return early from some_fun, or foo ends up initialized, and the code is safe. The warning is a false positive. If we can make the compiler aware that error() will always return -1, it can do a better job of analysis. The simplest method would be to inline the error() function. However, this doesn't work, because gcc will not inline a variadc function. We can work around this by defining a macro. This relies on two gcc extensions: 1. Variadic macros (these are present in C99, but we do not rely on that). 2. Gcc treats the "##" paste operator specially between a comma and __VA_ARGS__, which lets our variadic macro work even if no format parameters are passed to error(). Since we are using these extra features, we hide the macro behind an #ifdef. This is OK, though, because our goal was just to help gcc. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
151 lines
3.1 KiB
C
151 lines
3.1 KiB
C
/*
|
|
* GIT - The information manager from hell
|
|
*
|
|
* Copyright (C) Linus Torvalds, 2005
|
|
*/
|
|
#include "git-compat-util.h"
|
|
#include "cache.h"
|
|
|
|
static int dying;
|
|
|
|
void vreportf(const char *prefix, const char *err, va_list params)
|
|
{
|
|
char msg[4096];
|
|
vsnprintf(msg, sizeof(msg), err, params);
|
|
fprintf(stderr, "%s%s\n", prefix, msg);
|
|
}
|
|
|
|
void vwritef(int fd, const char *prefix, const char *err, va_list params)
|
|
{
|
|
char msg[4096];
|
|
int len = vsnprintf(msg, sizeof(msg), err, params);
|
|
if (len > sizeof(msg))
|
|
len = sizeof(msg);
|
|
|
|
write_in_full(fd, prefix, strlen(prefix));
|
|
write_in_full(fd, msg, len);
|
|
write_in_full(fd, "\n", 1);
|
|
}
|
|
|
|
static NORETURN void usage_builtin(const char *err, va_list params)
|
|
{
|
|
vreportf("usage: ", err, params);
|
|
exit(129);
|
|
}
|
|
|
|
static NORETURN void die_builtin(const char *err, va_list params)
|
|
{
|
|
vreportf("fatal: ", err, params);
|
|
exit(128);
|
|
}
|
|
|
|
static void error_builtin(const char *err, va_list params)
|
|
{
|
|
vreportf("error: ", err, params);
|
|
}
|
|
|
|
static void warn_builtin(const char *warn, va_list params)
|
|
{
|
|
vreportf("warning: ", warn, params);
|
|
}
|
|
|
|
/* If we are in a dlopen()ed .so write to a global variable would segfault
|
|
* (ugh), so keep things static. */
|
|
static NORETURN_PTR void (*usage_routine)(const char *err, va_list params) = usage_builtin;
|
|
static NORETURN_PTR void (*die_routine)(const char *err, va_list params) = die_builtin;
|
|
static void (*error_routine)(const char *err, va_list params) = error_builtin;
|
|
static void (*warn_routine)(const char *err, va_list params) = warn_builtin;
|
|
|
|
void set_die_routine(NORETURN_PTR void (*routine)(const char *err, va_list params))
|
|
{
|
|
die_routine = routine;
|
|
}
|
|
|
|
void set_error_routine(void (*routine)(const char *err, va_list params))
|
|
{
|
|
error_routine = routine;
|
|
}
|
|
|
|
void NORETURN usagef(const char *err, ...)
|
|
{
|
|
va_list params;
|
|
|
|
va_start(params, err);
|
|
usage_routine(err, params);
|
|
va_end(params);
|
|
}
|
|
|
|
void NORETURN usage(const char *err)
|
|
{
|
|
usagef("%s", err);
|
|
}
|
|
|
|
void NORETURN die(const char *err, ...)
|
|
{
|
|
va_list params;
|
|
|
|
if (dying) {
|
|
fputs("fatal: recursion detected in die handler\n", stderr);
|
|
exit(128);
|
|
}
|
|
dying = 1;
|
|
|
|
va_start(params, err);
|
|
die_routine(err, params);
|
|
va_end(params);
|
|
}
|
|
|
|
void NORETURN die_errno(const char *fmt, ...)
|
|
{
|
|
va_list params;
|
|
char fmt_with_err[1024];
|
|
char str_error[256], *err;
|
|
int i, j;
|
|
|
|
if (dying) {
|
|
fputs("fatal: recursion detected in die_errno handler\n",
|
|
stderr);
|
|
exit(128);
|
|
}
|
|
dying = 1;
|
|
|
|
err = strerror(errno);
|
|
for (i = j = 0; err[i] && j < sizeof(str_error) - 1; ) {
|
|
if ((str_error[j++] = err[i++]) != '%')
|
|
continue;
|
|
if (j < sizeof(str_error) - 1) {
|
|
str_error[j++] = '%';
|
|
} else {
|
|
/* No room to double the '%', so we overwrite it with
|
|
* '\0' below */
|
|
j--;
|
|
break;
|
|
}
|
|
}
|
|
str_error[j] = 0;
|
|
snprintf(fmt_with_err, sizeof(fmt_with_err), "%s: %s", fmt, str_error);
|
|
|
|
va_start(params, fmt);
|
|
die_routine(fmt_with_err, params);
|
|
va_end(params);
|
|
}
|
|
|
|
#undef error
|
|
int error(const char *err, ...)
|
|
{
|
|
va_list params;
|
|
|
|
va_start(params, err);
|
|
error_routine(err, params);
|
|
va_end(params);
|
|
return -1;
|
|
}
|
|
|
|
void warning(const char *warn, ...)
|
|
{
|
|
va_list params;
|
|
|
|
va_start(params, warn);
|
|
warn_routine(warn, params);
|
|
va_end(params);
|
|
}
|