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Avoid holding a directory FD open across assorted SRF calls.

Browse Source 
This extends the fixes made in commit 085b6b667 to other SRFs with the
same bug, namely pg_logdir_ls(), pgrowlocks(), pg_timezone_names(),
pg_ls_dir(), and pg_tablespace_databases().

Also adjust various comments and documentation to warn against
expecting to clean up resources during a ValuePerCall SRF's final
call.

Back-patch to all supported branches, since these functions were
all born broken.

Justin Pryzby, with cosmetic tweaks by me

Discussion: https://postgr.es/m/20200308173103.GC1357@telsasoft.com
This commit is contained in:
Tom Lane
2020-03-16 21:05:28 -04:00
parent 113758155c
commit b4570d33aa
10 changed files with 386 additions and 346 deletions
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120
src/backend/utils/adt/genfile.c
View File

@@ -36,13 +36,6 @@
#include "utils/syscache.h"
#include "utils/timestamp.h"
typedef struct
{
char *location;
DIR *dirdesc;
bool include_dot_dirs;
} directory_fctx;
/*
* Convert a "text" filename argument to C string, and check it's allowable.
@@ -447,67 +440,79 @@ pg_stat_file_1arg(PG_FUNCTION_ARGS)
Datum
pg_ls_dir(PG_FUNCTION_ARGS)
{
FuncCallContext *funcctx;
ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
char *location;
bool missing_ok = false;
bool include_dot_dirs = false;
bool randomAccess;
TupleDesc tupdesc;
Tuplestorestate *tupstore;
DIR *dirdesc;
struct dirent *de;
directory_fctx *fctx;
MemoryContext oldcontext;
if (SRF_IS_FIRSTCALL())
location = convert_and_check_filename(PG_GETARG_TEXT_PP(0));
/* check the optional arguments */
if (PG_NARGS() == 3)
{
bool missing_ok = false;
bool include_dot_dirs = false;
/* check the optional arguments */
if (PG_NARGS() == 3)
{
if (!PG_ARGISNULL(1))
missing_ok = PG_GETARG_BOOL(1);
if (!PG_ARGISNULL(2))
include_dot_dirs = PG_GETARG_BOOL(2);
}
funcctx = SRF_FIRSTCALL_INIT();
oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
fctx = palloc(sizeof(directory_fctx));
fctx->location = convert_and_check_filename(PG_GETARG_TEXT_PP(0));
fctx->include_dot_dirs = include_dot_dirs;
fctx->dirdesc = AllocateDir(fctx->location);
if (!fctx->dirdesc)
{
if (missing_ok && errno == ENOENT)
{
MemoryContextSwitchTo(oldcontext);
SRF_RETURN_DONE(funcctx);
}
else
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not open directory \"%s\": %m",
fctx->location)));
}
funcctx->user_fctx = fctx;
MemoryContextSwitchTo(oldcontext);
if (!PG_ARGISNULL(1))
missing_ok = PG_GETARG_BOOL(1);
if (!PG_ARGISNULL(2))
include_dot_dirs = PG_GETARG_BOOL(2);
}
funcctx = SRF_PERCALL_SETUP();
fctx = (directory_fctx *) funcctx->user_fctx;
/* check to see if caller supports us returning a tuplestore */
if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("set-valued function called in context that cannot accept a set")));
if (!(rsinfo->allowedModes & SFRM_Materialize))
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("materialize mode required, but it is not allowed in this context")));
while ((de = ReadDir(fctx->dirdesc, fctx->location)) != NULL)
/* The tupdesc and tuplestore must be created in ecxt_per_query_memory */
oldcontext = MemoryContextSwitchTo(rsinfo->econtext->ecxt_per_query_memory);
tupdesc = CreateTemplateTupleDesc(1);
TupleDescInitEntry(tupdesc, (AttrNumber) 1, "pg_ls_dir", TEXTOID, -1, 0);
randomAccess = (rsinfo->allowedModes & SFRM_Materialize_Random) != 0;
tupstore = tuplestore_begin_heap(randomAccess, false, work_mem);
rsinfo->returnMode = SFRM_Materialize;
rsinfo->setResult = tupstore;
rsinfo->setDesc = tupdesc;
MemoryContextSwitchTo(oldcontext);
dirdesc = AllocateDir(location);
if (!dirdesc)
{
if (!fctx->include_dot_dirs &&
/* Return empty tuplestore if appropriate */
if (missing_ok && errno == ENOENT)
return (Datum) 0;
/* Otherwise, we can let ReadDir() throw the error */
}
while ((de = ReadDir(dirdesc, location)) != NULL)
{
Datum values[1];
bool nulls[1];
if (!include_dot_dirs &&
(strcmp(de->d_name, ".") == 0 ||
strcmp(de->d_name, "..") == 0))
continue;
SRF_RETURN_NEXT(funcctx, CStringGetTextDatum(de->d_name));
values[0] = CStringGetTextDatum(de->d_name);
nulls[0] = false;
tuplestore_putvalues(tupstore, tupdesc, values, nulls);
}
FreeDir(fctx->dirdesc);
SRF_RETURN_DONE(funcctx);
FreeDir(dirdesc);
return (Datum) 0;
}
/*
@@ -548,8 +553,7 @@ pg_ls_dir_files(FunctionCallInfo fcinfo, const char *dir, bool missing_ok)
if (!(rsinfo->allowedModes & SFRM_Materialize))
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("materialize mode required, but it is not "
"allowed in this context")));
errmsg("materialize mode required, but it is not allowed in this context")));
/* The tupdesc and tuplestore must be created in ecxt_per_query_memory */
oldcontext = MemoryContextSwitchTo(rsinfo->econtext->ecxt_per_query_memory);
@@ -575,10 +579,7 @@ pg_ls_dir_files(FunctionCallInfo fcinfo, const char *dir, bool missing_ok)
{
/* Return empty tuplestore if appropriate */
if (missing_ok && errno == ENOENT)
{
tuplestore_donestoring(tupstore);
return (Datum) 0;
}
/* Otherwise, we can let ReadDir() throw the error */
}
@@ -613,7 +614,6 @@ pg_ls_dir_files(FunctionCallInfo fcinfo, const char *dir, bool missing_ok)
}
FreeDir(dirdesc);
tuplestore_donestoring(tupstore);
return (Datum) 0;
}