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Revert "Distinguish printf-like functions that support %m from those that don't." 

This reverts commit 3a60c8ff89.  Buildfarm
results show that that caused a whole bunch of new warnings on platforms
where gcc believes the local printf to be non-POSIX-compliant.  This
problem outweighs the hypothetical-anyway possibility of getting warnings
for misuse of %m.  We could use gnu_printf archetype when we've substituted
src/port/snprintf.c, but that brings us right back to the problem of not
getting warnings for %m.

A possible answer is to attack it in the other direction by insisting
that %m support be included in printf's feature set, but that will take
more investigation.  In the meantime, revert the previous change, and
update the comment for PGAC_C_PRINTF_ARCHETYPE to more fully explain
what's going on.

Discussion: https://postgr.es/m/2975.1526862605@sss.pgh.pa.us
This commit is contained in:
Tom Lane 2018-08-12 18:46:01 -04:00
parent d11eae09e4
commit 46b5e7c4b5
5 changed files with 34 additions and 32 deletions
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20
config/c-compiler.m4
View File

@ -19,12 +19,18 @@ fi])# PGAC_C_SIGNED
# PGAC_C_PRINTF_ARCHETYPE
# -----------------------
# Set the format archetype used by gcc to check elog/ereport functions.
# This should accept %m, whether or not the platform's printf does.
# We use "gnu_printf" if possible, which does that, although in some cases
# it might do more than we could wish.
# Select the format archetype to be used by gcc to check printf-type functions.
# We prefer "gnu_printf", which matches the features glibc supports, notably
# %m, 'z' and 'll' width modifiers ('ll' only matters if int64 requires it),
# and argument order control if we're doing --enable-nls. On platforms where
# the native printf doesn't have 'z'/'ll' or arg control, we replace it with
# src/port/snprintf.c which does, so that the only potential mismatch here is
# whether or not %m is supported. We need that for elog/ereport, so we live
# with the fact that erroneous use of %m in plain printf calls won't be
# detected. (It appears that many versions of gcc/clang wouldn't report it
# even if told to check according to plain printf archetype, anyway.)
AC_DEFUN([PGAC_PRINTF_ARCHETYPE],
[AC_CACHE_CHECK([for printf format archetype for %m], pgac_cv_printf_archetype,
[AC_CACHE_CHECK([for printf format archetype], pgac_cv_printf_archetype,
[ac_save_c_werror_flag=$ac_c_werror_flag
ac_c_werror_flag=yes
AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
@ -34,8 +40,8 @@ __attribute__((format(gnu_printf, 2, 3)));], [])],
[pgac_cv_printf_archetype=gnu_printf],
[pgac_cv_printf_archetype=printf])
ac_c_werror_flag=$ac_save_c_werror_flag])
AC_DEFINE_UNQUOTED([PG_PRINTF_ATTRIBUTE_M], [$pgac_cv_printf_archetype],
[Define as a format archetype that accepts %m, if available, else printf.])
AC_DEFINE_UNQUOTED([PG_PRINTF_ATTRIBUTE], [$pgac_cv_printf_archetype],
[Define to gnu_printf if compiler supports it, else printf.])
])# PGAC_PRINTF_ARCHETYPE

6
configure vendored
View File

@ -13362,8 +13362,8 @@ _ACEOF
;;
esac
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for printf format archetype for %m" >&5
$as_echo_n "checking for printf format archetype for %m... " >&6; }
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for printf format archetype" >&5
$as_echo_n "checking for printf format archetype... " >&6; }
if ${pgac_cv_printf_archetype+:} false; then :
$as_echo_n "(cached) " >&6
else
@ -13394,7 +13394,7 @@ fi
$as_echo "$pgac_cv_printf_archetype" >&6; }
cat >>confdefs.h <<_ACEOF
#define PG_PRINTF_ATTRIBUTE_M $pgac_cv_printf_archetype
#define PG_PRINTF_ATTRIBUTE $pgac_cv_printf_archetype
_ACEOF

6
src/include/c.h
View File

@ -126,14 +126,10 @@
/* GCC and XLC support format attributes */
#if defined(__GNUC__) || defined(__IBMC__)
#define pg_attribute_format_arg(a) __attribute__((format_arg(a)))
/* Use for functions wrapping stdio's printf, which often doesn't take %m: */
#define pg_attribute_printf(f,a) __attribute__((format(printf, f, a)))
/* Use for elog/ereport, which implement %m for themselves: */
#define pg_attribute_printf_m(f,a) __attribute__((format(PG_PRINTF_ATTRIBUTE_M, f, a)))
#define pg_attribute_printf(f,a) __attribute__((format(PG_PRINTF_ATTRIBUTE, f, a)))
#else
#define pg_attribute_format_arg(a)
#define pg_attribute_printf(f,a)
#define pg_attribute_printf_m(f,a)
#endif
/* GCC, Sunpro and XLC support aligned, packed and noreturn */

4
src/include/pg_config.h.in
View File

@ -809,8 +809,8 @@
/* PostgreSQL major version as a string */
#undef PG_MAJORVERSION
/* Define as a format archetype that accepts %m, if available, else printf. */
#undef PG_PRINTF_ATTRIBUTE_M
/* Define to gnu_printf if compiler supports it, else printf. */
#undef PG_PRINTF_ATTRIBUTE
/* PostgreSQL version as a string */
#undef PG_VERSION

30
src/include/utils/elog.h
View File

@ -152,25 +152,25 @@ extern int errcode(int sqlerrcode);
extern int errcode_for_file_access(void);
extern int errcode_for_socket_access(void);
extern int errmsg(const char *fmt,...) pg_attribute_printf_m(1, 2);
extern int errmsg_internal(const char *fmt,...) pg_attribute_printf_m(1, 2);
extern int errmsg(const char *fmt,...) pg_attribute_printf(1, 2);
extern int errmsg_internal(const char *fmt,...) pg_attribute_printf(1, 2);
extern int errmsg_plural(const char *fmt_singular, const char *fmt_plural,
unsigned long n,...) pg_attribute_printf_m(1, 4) pg_attribute_printf_m(2, 4);
unsigned long n,...) pg_attribute_printf(1, 4) pg_attribute_printf(2, 4);
extern int errdetail(const char *fmt,...) pg_attribute_printf_m(1, 2);
extern int errdetail_internal(const char *fmt,...) pg_attribute_printf_m(1, 2);
extern int errdetail(const char *fmt,...) pg_attribute_printf(1, 2);
extern int errdetail_internal(const char *fmt,...) pg_attribute_printf(1, 2);
extern int errdetail_log(const char *fmt,...) pg_attribute_printf_m(1, 2);
extern int errdetail_log(const char *fmt,...) pg_attribute_printf(1, 2);
extern int errdetail_log_plural(const char *fmt_singular,
const char *fmt_plural,
unsigned long n,...) pg_attribute_printf_m(1, 4) pg_attribute_printf_m(2, 4);
unsigned long n,...) pg_attribute_printf(1, 4) pg_attribute_printf(2, 4);
extern int errdetail_plural(const char *fmt_singular, const char *fmt_plural,
unsigned long n,...) pg_attribute_printf_m(1, 4) pg_attribute_printf_m(2, 4);
unsigned long n,...) pg_attribute_printf(1, 4) pg_attribute_printf(2, 4);
extern int errhint(const char *fmt,...) pg_attribute_printf_m(1, 2);
extern int errhint(const char *fmt,...) pg_attribute_printf(1, 2);
/*
* errcontext() is typically called in error context callback functions, not
@ -184,7 +184,7 @@ extern int errhint(const char *fmt,...) pg_attribute_printf_m(1, 2);
extern int set_errcontext_domain(const char *domain);
extern int errcontext_msg(const char *fmt,...) pg_attribute_printf_m(1, 2);
extern int errcontext_msg(const char *fmt,...) pg_attribute_printf(1, 2);
extern int errhidestmt(bool hide_stmt);
extern int errhidecontext(bool hide_ctx);
@ -243,13 +243,13 @@ extern int getinternalerrposition(void);
#endif /* HAVE__VA_ARGS */
extern void elog_start(const char *filename, int lineno, const char *funcname);
extern void elog_finish(int elevel, const char *fmt,...) pg_attribute_printf_m(2, 3);
extern void elog_finish(int elevel, const char *fmt,...) pg_attribute_printf(2, 3);
/* Support for constructing error strings separately from ereport() calls */
extern void pre_format_elog_string(int errnumber, const char *domain);
extern char *format_elog_string(const char *fmt,...) pg_attribute_printf_m(1, 2);
extern char *format_elog_string(const char *fmt,...) pg_attribute_printf(1, 2);
/* Support for attaching context information to error reports */
@ -428,9 +428,9 @@ extern void set_syslog_parameters(const char *ident, int facility);
#endif
/*
* Write errors to stderr (or by comparable means when stderr is not
* available). Used before ereport/elog can be used safely (memory context,
* GUC load etc). Note that this does *not* accept "%m".
* Write errors to stderr (or by equal means when stderr is
* not available). Used before ereport/elog can be used
* safely (memory context, GUC load etc)
*/
extern void write_stderr(const char *fmt,...) pg_attribute_printf(1, 2);