From 89862c5c145d5f66f284098abf0ef6384a96a8d7 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Thu, 8 Feb 2024 12:59:44 -0500 Subject: [PATCH v2 2/2] Avoid concurrent calls to bindtextdomain(). We previously supposed that it was okay for different threads to call bindtextdomain() concurrently (cf. commit 1f655fdc3). It now emerges that there's at least one gettext implementation in which that triggers an abort() crash, so let's stop doing that. Add mutexes guarding libpq's and ecpglib's calls, which are the only ones that need worry about multithreaded callers. Note: in libpq, we could perhaps have piggybacked on default_threadlock() to avoid defining a new mutex variable. I judge that not terribly safe though, since libpq_gettext could be called from code that is holding the default mutex. If that were the first such call in the process, it'd fail. An extra mutex is cheap insurance against unforeseen interactions. Per bug #18312 from Christian Maurer. Back-patch to all supported versions. Discussion: https://postgr.es/m/18312-bbbabc8113592b78@postgresql.org Discussion: https://postgr.es/m/264860.1707163416@sss.pgh.pa.us --- src/interfaces/ecpg/ecpglib/misc.c | 39 ++++++++++++++++++++---------- src/interfaces/libpq/fe-misc.c | 39 ++++++++++++++++++++---------- 2 files changed, 52 insertions(+), 26 deletions(-) diff --git a/src/interfaces/ecpg/ecpglib/misc.c b/src/interfaces/ecpg/ecpglib/misc.c index 58fff10697..8b9aefcd9c 100644 --- a/src/interfaces/ecpg/ecpglib/misc.c +++ b/src/interfaces/ecpg/ecpglib/misc.c @@ -465,13 +465,14 @@ char * ecpg_gettext(const char *msgid) { /* - * If multiple threads come through here at about the same time, it's okay - * for more than one of them to call bindtextdomain(). But it's not okay - * for any of them to reach dgettext() before bindtextdomain() is - * complete, so don't set the flag till that's done. Use "volatile" just - * to be sure the compiler doesn't try to get cute. + * At least on Windows, there are gettext implementations that fail if + * multiple threads call bindtextdomain() concurrently. Use a mutex and + * flag variable to ensure that we call it just once per process. It is + * not known that similar bugs exist on non-Windows platforms, but we + * might as well do it the same way everywhere. */ static volatile bool already_bound = false; + static pthread_mutex_t binddomain_mutex = PTHREAD_MUTEX_INITIALIZER; if (!already_bound) { @@ -481,14 +482,26 @@ ecpg_gettext(const char *msgid) #else int save_errno = errno; #endif - const char *ldir; - - /* No relocatable lookup here because the binary could be anywhere */ - ldir = getenv("PGLOCALEDIR"); - if (!ldir) - ldir = LOCALEDIR; - bindtextdomain(PG_TEXTDOMAIN("ecpglib"), ldir); - already_bound = true; + + (void) pthread_mutex_lock(&binddomain_mutex); + + if (!already_bound) + { + const char *ldir; + + /* + * No relocatable lookup here because the calling executable could + * be anywhere + */ + ldir = getenv("PGLOCALEDIR"); + if (!ldir) + ldir = LOCALEDIR; + bindtextdomain(PG_TEXTDOMAIN("ecpglib"), ldir); + already_bound = true; + } + + (void) pthread_mutex_unlock(&binddomain_mutex); + #ifdef WIN32 SetLastError(save_errno); #else diff --git a/src/interfaces/libpq/fe-misc.c b/src/interfaces/libpq/fe-misc.c index 47a28b0a3a..f2fc78a481 100644 --- a/src/interfaces/libpq/fe-misc.c +++ b/src/interfaces/libpq/fe-misc.c @@ -1225,13 +1225,14 @@ static void libpq_binddomain(void) { /* - * If multiple threads come through here at about the same time, it's okay - * for more than one of them to call bindtextdomain(). But it's not okay - * for any of them to return to caller before bindtextdomain() is - * complete, so don't set the flag till that's done. Use "volatile" just - * to be sure the compiler doesn't try to get cute. + * At least on Windows, there are gettext implementations that fail if + * multiple threads call bindtextdomain() concurrently. Use a mutex and + * flag variable to ensure that we call it just once per process. It is + * not known that similar bugs exist on non-Windows platforms, but we + * might as well do it the same way everywhere. */ static volatile bool already_bound = false; + static pthread_mutex_t binddomain_mutex = PTHREAD_MUTEX_INITIALIZER; if (!already_bound) { @@ -1241,14 +1242,26 @@ libpq_binddomain(void) #else int save_errno = errno; #endif - const char *ldir; - - /* No relocatable lookup here because the binary could be anywhere */ - ldir = getenv("PGLOCALEDIR"); - if (!ldir) - ldir = LOCALEDIR; - bindtextdomain(PG_TEXTDOMAIN("libpq"), ldir); - already_bound = true; + + (void) pthread_mutex_lock(&binddomain_mutex); + + if (!already_bound) + { + const char *ldir; + + /* + * No relocatable lookup here because the calling executable could + * be anywhere + */ + ldir = getenv("PGLOCALEDIR"); + if (!ldir) + ldir = LOCALEDIR; + bindtextdomain(PG_TEXTDOMAIN("libpq"), ldir); + already_bound = true; + } + + (void) pthread_mutex_unlock(&binddomain_mutex); + #ifdef WIN32 SetLastError(save_errno); #else -- 2.39.3