diff --git a/contrib/file_fdw/file_fdw.c b/contrib/file_fdw/file_fdw.c
index d644a46ea7dd8ba2560fdac4c2871bafbd592a33..d1cca1ec3ed66b091a95ec6cd258c0a9e8bd70bb 100644
--- a/contrib/file_fdw/file_fdw.c
+++ b/contrib/file_fdw/file_fdw.c
@@ -588,6 +588,7 @@ fileBeginForeignScan(ForeignScanState *node, int eflags)
*/
cstate = BeginCopyFrom(node->ss.ss_currentRelation,
filename,
+ false,
NIL,
options);
@@ -660,6 +661,7 @@ fileReScanForeignScan(ForeignScanState *node)
festate->cstate = BeginCopyFrom(node->ss.ss_currentRelation,
festate->filename,
+ false,
NIL,
festate->options);
}
@@ -993,7 +995,7 @@ file_acquire_sample_rows(Relation onerel, int elevel,
/*
* Create CopyState from FDW options.
*/
- cstate = BeginCopyFrom(onerel, filename, NIL, options);
+ cstate = BeginCopyFrom(onerel, filename, false, NIL, options);
/*
* Use per-tuple memory context to prevent leak of memory used to read
diff --git a/doc/src/sgml/keywords.sgml b/doc/src/sgml/keywords.sgml
index 0e7b32285145f8c16aafbed481341cfb59bf6008..576fd65f3160bf2f493acd0147e9b50c88ce6403 100644
--- a/doc/src/sgml/keywords.sgml
+++ b/doc/src/sgml/keywords.sgml
@@ -3513,6 +3513,13 @@
<entry>reserved</entry>
<entry>reserved</entry>
</row>
+ <row>
+ <entry><token>PROGRAM</token></entry>
+ <entry>non-reserved</entry>
+ <entry></entry>
+ <entry></entry>
+ <entry></entry>
+ </row>
<row>
<entry><token>PUBLIC</token></entry>
<entry></entry>
diff --git a/doc/src/sgml/ref/copy.sgml b/doc/src/sgml/ref/copy.sgml
index 2137c67cb4b542344017b08c26cf4a36d894a1c1..2854d9c0ca69e2157dd1377b972c7a7ac421abac 100644
--- a/doc/src/sgml/ref/copy.sgml
+++ b/doc/src/sgml/ref/copy.sgml
@@ -23,11 +23,11 @@ PostgreSQL documentation
<refsynopsisdiv>
<synopsis>
COPY <replaceable class="parameter">table_name</replaceable> [ ( <replaceable class="parameter">column_name</replaceable> [, ...] ) ]
- FROM { '<replaceable class="parameter">filename</replaceable>' | STDIN }
+ FROM { '<replaceable class="parameter">filename</replaceable>' | PROGRAM '<replaceable class="parameter">command</replaceable>' | STDIN }
[ [ WITH ] ( <replaceable class="parameter">option</replaceable> [, ...] ) ]
COPY { <replaceable class="parameter">table_name</replaceable> [ ( <replaceable class="parameter">column_name</replaceable> [, ...] ) ] | ( <replaceable class="parameter">query</replaceable> ) }
- TO { '<replaceable class="parameter">filename</replaceable>' | STDOUT }
+ TO { '<replaceable class="parameter">filename</replaceable>' | PROGRAM '<replaceable class="parameter">command</replaceable>' | STDOUT }
[ [ WITH ] ( <replaceable class="parameter">option</replaceable> [, ...] ) ]
<phrase>where <replaceable class="parameter">option</replaceable> can be one of:</phrase>
@@ -72,6 +72,10 @@ COPY { <replaceable class="parameter">table_name</replaceable> [ ( <replaceable
<productname>PostgreSQL</productname> server to directly read from
or write to a file. The file must be accessible to the server and
the name must be specified from the viewpoint of the server. When
+ <literal>PROGRAM</literal> is specified, the server executes the
+ given command, and reads from its standard input, or writes to its
+ standard output. The command must be specified from the viewpoint of the
+ server, and be executable by the <literal>postgres</> user. When
<literal>STDIN</literal> or <literal>STDOUT</literal> is
specified, data is transmitted via the connection between the
client and the server.
@@ -125,6 +129,25 @@ COPY { <replaceable class="parameter">table_name</replaceable> [ ( <replaceable
</listitem>
</varlistentry>
+ <varlistentry>
+ <term><literal>PROGRAM</literal></term>
+ <listitem>
+ <para>
+ A command to execute. In <command>COPY FROM</command>, the input is
+ read from standard output of the command, and in <command>COPY TO</>,
+ the output is written to the standard input of the command.
+ </para>
+ <para>
+ Note that the command is invoked by the shell, so if you need to pass
+ any arguments to shell command that come from an untrusted source, you
+ must be careful to strip or escape any special characters that might
+ have a special meaning for the shell. For security reasons, it is best
+ to use a fixed command string, or at least avoid passing any user input
+ in it.
+ </para>
+ </listitem>
+ </varlistentry>
+
<varlistentry>
<term><literal>STDIN</literal></term>
<listitem>
@@ -367,9 +390,13 @@ COPY <replaceable class="parameter">count</replaceable>
they must reside on or be accessible to the database server machine,
not the client. They must be accessible to and readable or writable
by the <productname>PostgreSQL</productname> user (the user ID the
- server runs as), not the client. <command>COPY</command> naming a
- file is only allowed to database superusers, since it allows reading
- or writing any file that the server has privileges to access.
+ server runs as), not the client. Similarly,
+ the command specified with <literal>PROGRAM</literal> is executed directly
+ by the server, not by the client application, must be executable by the
+ <productname>PostgreSQL</productname> user.
+ <command>COPY</command> naming a file or command is only allowed to
+ database superusers, since it allows reading or writing any file that the
+ server has privileges to access.
</para>
<para>
@@ -393,6 +420,11 @@ COPY <replaceable class="parameter">count</replaceable>
the cluster's data directory), not the client's working directory.
</para>
+ <para>
+ Executing a command with <literal>PROGRAM</literal> might be restricted
+ by operating system's access control mechanisms, such as the SELinux.
+ </para>
+
<para>
<command>COPY FROM</command> will invoke any triggers and check
constraints on the destination table. However, it will not invoke rules.
@@ -841,6 +873,14 @@ COPY (SELECT * FROM country WHERE country_name LIKE 'A%') TO '/usr1/proj/bray/sq
</programlisting>
</para>
+ <para>
+ To copy into a compressed file, you can pipe the output through an external
+ compression program:
+<programlisting>
+COPY country TO PROGRAM 'gzip > /usr1/proj/bray/sql/country_data.gz';
+</programlisting>
+ </para>
+
<para>
Here is a sample of data suitable for copying into a table from
<literal>STDIN</literal>:
diff --git a/doc/src/sgml/ref/psql-ref.sgml b/doc/src/sgml/ref/psql-ref.sgml
index 465d3a1882dd3dc1e6da27baae58233ba7628648..fb63845a2606b9cffb76df13f677a79f880b05db 100644
--- a/doc/src/sgml/ref/psql-ref.sgml
+++ b/doc/src/sgml/ref/psql-ref.sgml
@@ -830,7 +830,7 @@ testdb=>
<varlistentry id="APP-PSQL-meta-commands-copy">
<term><literal>\copy { <replaceable class="parameter">table</replaceable> [ ( <replaceable class="parameter">column_list</replaceable> ) ] | ( <replaceable class="parameter">query</replaceable> ) }
{ <literal>from</literal> | <literal>to</literal> }
- { <replaceable class="parameter">filename</replaceable> | stdin | stdout | pstdin | pstdout }
+ { <replaceable class="parameter">'filename'</replaceable> | program <replaceable class="parameter">'command'</replaceable> | stdin | stdout | pstdin | pstdout }
[ [ with ] ( <replaceable class="parameter">option</replaceable> [, ...] ) ]</literal></term>
<listitem>
@@ -847,16 +847,14 @@ testdb=>
</para>
<para>
- The syntax of the command is similar to that of the
- <acronym>SQL</acronym> <xref linkend="sql-copy">
- command, and
- <replaceable class="parameter">option</replaceable>
- must indicate one of the options of the
- <acronym>SQL</acronym> <xref linkend="sql-copy"> command.
- Note that, because of this,
- special parsing rules apply to the <command>\copy</command>
- command. In particular, the variable substitution rules and
- backslash escapes do not apply.
+ When <literal>program</> is specified,
+ <replaceable class="parameter">command</replaceable> is
+ executed by <application>psql</application> and the data from
+ or to <replaceable class="parameter">command</replaceable> is
+ routed between the server and the client.
+ This means that the execution privileges are those of
+ the local user, not the server, and no SQL superuser
+ privileges are required.
</para>
<para><literal>\copy ... from stdin | to stdout</literal>
@@ -870,6 +868,19 @@ testdb=>
for populating tables in-line within a SQL script file.
</para>
+ <para>
+ The syntax of the command is similar to that of the
+ <acronym>SQL</acronym> <xref linkend="sql-copy">
+ command, and
+ <replaceable class="parameter">option</replaceable>
+ must indicate one of the options of the
+ <acronym>SQL</acronym> <xref linkend="sql-copy"> command.
+ Note that, because of this,
+ special parsing rules apply to the <command>\copy</command>
+ command. In particular, the variable substitution rules and
+ backslash escapes do not apply.
+ </para>
+
<tip>
<para>
This operation is not as efficient as the <acronym>SQL</acronym>
diff --git a/src/backend/commands/copy.c b/src/backend/commands/copy.c
index 523c1e03315952c0abd41da625d0d6bdeb4b4ad3..c651ea302809a42c5c43e119577d1753725068bf 100644
--- a/src/backend/commands/copy.c
+++ b/src/backend/commands/copy.c
@@ -58,7 +58,7 @@
*/
typedef enum CopyDest
{
- COPY_FILE, /* to/from file */
+ COPY_FILE, /* to/from file (or a piped program) */
COPY_OLD_FE, /* to/from frontend (2.0 protocol) */
COPY_NEW_FE /* to/from frontend (3.0 protocol) */
} CopyDest;
@@ -108,6 +108,7 @@ typedef struct CopyStateData
QueryDesc *queryDesc; /* executable query to copy from */
List *attnumlist; /* integer list of attnums to copy */
char *filename; /* filename, or NULL for STDIN/STDOUT */
+ bool is_program; /* is 'filename' a program to popen? */
bool binary; /* binary format? */
bool oids; /* include OIDs? */
bool freeze; /* freeze rows on loading? */
@@ -277,8 +278,10 @@ static const char BinarySignature[11] = "PGCOPY\n\377\r\n\0";
static CopyState BeginCopy(bool is_from, Relation rel, Node *raw_query,
const char *queryString, List *attnamelist, List *options);
static void EndCopy(CopyState cstate);
+static void ClosePipeToProgram(CopyState cstate);
static CopyState BeginCopyTo(Relation rel, Node *query, const char *queryString,
- const char *filename, List *attnamelist, List *options);
+ const char *filename, bool is_program, List *attnamelist,
+ List *options);
static void EndCopyTo(CopyState cstate);
static uint64 DoCopyTo(CopyState cstate);
static uint64 CopyTo(CopyState cstate);
@@ -482,9 +485,35 @@ CopySendEndOfRow(CopyState cstate)
if (fwrite(fe_msgbuf->data, fe_msgbuf->len, 1,
cstate->copy_file) != 1 ||
ferror(cstate->copy_file))
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not write to COPY file: %m")));
+ {
+ if (cstate->is_program)
+ {
+ if (errno == EPIPE)
+ {
+ /*
+ * The pipe will be closed automatically on error at
+ * the end of transaction, but we might get a better
+ * error message from the subprocess' exit code than
+ * just "Broken Pipe"
+ */
+ ClosePipeToProgram(cstate);
+
+ /*
+ * If ClosePipeToProgram() didn't throw an error,
+ * the program terminated normally, but closed the
+ * pipe first. Restore errno, and throw an error.
+ */
+ errno = EPIPE;
+ }
+ ereport(ERROR,
+ (errcode_for_file_access(),
+ errmsg("could not write to COPY program: %m")));
+ }
+ else
+ ereport(ERROR,
+ (errcode_for_file_access(),
+ errmsg("could not write to COPY file: %m")));
+ }
break;
case COPY_OLD_FE:
/* The FE/BE protocol uses \n as newline for all platforms */
@@ -752,13 +781,22 @@ DoCopy(const CopyStmt *stmt, const char *queryString, uint64 *processed)
Relation rel;
Oid relid;
- /* Disallow file COPY except to superusers. */
+ /* Disallow COPY to/from file or program except to superusers. */
if (!pipe && !superuser())
- ereport(ERROR,
- (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
- errmsg("must be superuser to COPY to or from a file"),
- errhint("Anyone can COPY to stdout or from stdin. "
- "psql's \\copy command also works for anyone.")));
+ {
+ if (stmt->is_program)
+ ereport(ERROR,
+ (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+ errmsg("must be superuser to COPY to or from an external program"),
+ errhint("Anyone can COPY to stdout or from stdin. "
+ "psql's \\copy command also works for anyone.")));
+ else
+ ereport(ERROR,
+ (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+ errmsg("must be superuser to COPY to or from a file"),
+ errhint("Anyone can COPY to stdout or from stdin. "
+ "psql's \\copy command also works for anyone.")));
+ }
if (stmt->relation)
{
@@ -812,14 +850,15 @@ DoCopy(const CopyStmt *stmt, const char *queryString, uint64 *processed)
if (XactReadOnly && !rel->rd_islocaltemp)
PreventCommandIfReadOnly("COPY FROM");
- cstate = BeginCopyFrom(rel, stmt->filename,
+ cstate = BeginCopyFrom(rel, stmt->filename, stmt->is_program,
stmt->attlist, stmt->options);
*processed = CopyFrom(cstate); /* copy from file to database */
EndCopyFrom(cstate);
}
else
{
- cstate = BeginCopyTo(rel, stmt->query, queryString, stmt->filename,
+ cstate = BeginCopyTo(rel, stmt->query, queryString,
+ stmt->filename, stmt->is_program,
stmt->attlist, stmt->options);
*processed = DoCopyTo(cstate); /* copy from database to file */
EndCopyTo(cstate);
@@ -1389,17 +1428,45 @@ BeginCopy(bool is_from,
return cstate;
}
+/*
+ * Closes the pipe to an external program, checking the pclose() return code.
+ */
+static void
+ClosePipeToProgram(CopyState cstate)
+{
+ int pclose_rc;
+
+ Assert(cstate->is_program);
+
+ pclose_rc = ClosePipeStream(cstate->copy_file);
+ if (pclose_rc == -1)
+ ereport(ERROR,
+ (errmsg("could not close pipe to external command: %m")));
+ else if (pclose_rc != 0)
+ ereport(ERROR,
+ (errmsg("program \"%s\" failed",
+ cstate->filename),
+ errdetail_internal("%s", wait_result_to_str(pclose_rc))));
+}
+
/*
* Release resources allocated in a cstate for COPY TO/FROM.
*/
static void
EndCopy(CopyState cstate)
{
- if (cstate->filename != NULL && FreeFile(cstate->copy_file))
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not close file \"%s\": %m",
- cstate->filename)));
+ if (cstate->is_program)
+ {
+ ClosePipeToProgram(cstate);
+ }
+ else
+ {
+ if (cstate->filename != NULL && FreeFile(cstate->copy_file))
+ ereport(ERROR,
+ (errcode_for_file_access(),
+ errmsg("could not close file \"%s\": %m",
+ cstate->filename)));
+ }
MemoryContextDelete(cstate->copycontext);
pfree(cstate);
@@ -1413,6 +1480,7 @@ BeginCopyTo(Relation rel,
Node *query,
const char *queryString,
const char *filename,
+ bool is_program,
List *attnamelist,
List *options)
{
@@ -1451,39 +1519,52 @@ BeginCopyTo(Relation rel,
if (pipe)
{
+ Assert(!is_program); /* the grammar does not allow this */
if (whereToSendOutput != DestRemote)
cstate->copy_file = stdout;
}
else
{
- mode_t oumask; /* Pre-existing umask value */
- struct stat st;
+ cstate->filename = pstrdup(filename);
+ cstate->is_program = is_program;
- /*
- * Prevent write to relative path ... too easy to shoot oneself in the
- * foot by overwriting a database file ...
- */
- if (!is_absolute_path(filename))
- ereport(ERROR,
- (errcode(ERRCODE_INVALID_NAME),
- errmsg("relative path not allowed for COPY to file")));
+ if (is_program)
+ {
+ cstate->copy_file = OpenPipeStream(cstate->filename, PG_BINARY_W);
+ if (cstate->copy_file == NULL)
+ ereport(ERROR,
+ (errmsg("could not execute command \"%s\": %m",
+ cstate->filename)));
+ }
+ else
+ {
+ mode_t oumask; /* Pre-existing umask value */
+ struct stat st;
- cstate->filename = pstrdup(filename);
- oumask = umask(S_IWGRP | S_IWOTH);
- cstate->copy_file = AllocateFile(cstate->filename, PG_BINARY_W);
- umask(oumask);
+ /*
+ * Prevent write to relative path ... too easy to shoot oneself in
+ * the foot by overwriting a database file ...
+ */
+ if (!is_absolute_path(filename))
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_NAME),
+ errmsg("relative path not allowed for COPY to file")));
- if (cstate->copy_file == NULL)
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not open file \"%s\" for writing: %m",
- cstate->filename)));
+ oumask = umask(S_IWGRP | S_IWOTH);
+ cstate->copy_file = AllocateFile(cstate->filename, PG_BINARY_W);
+ umask(oumask);
+ if (cstate->copy_file == NULL)
+ ereport(ERROR,
+ (errcode_for_file_access(),
+ errmsg("could not open file \"%s\" for writing: %m",
+ cstate->filename)));
- fstat(fileno(cstate->copy_file), &st);
- if (S_ISDIR(st.st_mode))
- ereport(ERROR,
- (errcode(ERRCODE_WRONG_OBJECT_TYPE),
- errmsg("\"%s\" is a directory", cstate->filename)));
+ fstat(fileno(cstate->copy_file), &st);
+ if (S_ISDIR(st.st_mode))
+ ereport(ERROR,
+ (errcode(ERRCODE_WRONG_OBJECT_TYPE),
+ errmsg("\"%s\" is a directory", cstate->filename)));
+ }
}
MemoryContextSwitchTo(oldcontext);
@@ -2317,6 +2398,7 @@ CopyFromInsertBatch(CopyState cstate, EState *estate, CommandId mycid,
CopyState
BeginCopyFrom(Relation rel,
const char *filename,
+ bool is_program,
List *attnamelist,
List *options)
{
@@ -2413,9 +2495,11 @@ BeginCopyFrom(Relation rel,
cstate->defexprs = defexprs;
cstate->volatile_defexprs = volatile_defexprs;
cstate->num_defaults = num_defaults;
+ cstate->is_program = is_program;
if (pipe)
{
+ Assert(!is_program); /* the grammar does not allow this */
if (whereToSendOutput == DestRemote)
ReceiveCopyBegin(cstate);
else
@@ -2423,22 +2507,33 @@ BeginCopyFrom(Relation rel,
}
else
{
- struct stat st;
-
cstate->filename = pstrdup(filename);
- cstate->copy_file = AllocateFile(cstate->filename, PG_BINARY_R);
- if (cstate->copy_file == NULL)
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not open file \"%s\" for reading: %m",
- cstate->filename)));
+ if (cstate->is_program)
+ {
+ cstate->copy_file = OpenPipeStream(cstate->filename, PG_BINARY_R);
+ if (cstate->copy_file == NULL)
+ ereport(ERROR,
+ (errmsg("could not execute command \"%s\": %m",
+ cstate->filename)));
+ }
+ else
+ {
+ struct stat st;
- fstat(fileno(cstate->copy_file), &st);
- if (S_ISDIR(st.st_mode))
- ereport(ERROR,
- (errcode(ERRCODE_WRONG_OBJECT_TYPE),
- errmsg("\"%s\" is a directory", cstate->filename)));
+ cstate->copy_file = AllocateFile(cstate->filename, PG_BINARY_R);
+ if (cstate->copy_file == NULL)
+ ereport(ERROR,
+ (errcode_for_file_access(),
+ errmsg("could not open file \"%s\" for reading: %m",
+ cstate->filename)));
+
+ fstat(fileno(cstate->copy_file), &st);
+ if (S_ISDIR(st.st_mode))
+ ereport(ERROR,
+ (errcode(ERRCODE_WRONG_OBJECT_TYPE),
+ errmsg("\"%s\" is a directory", cstate->filename)));
+ }
}
if (!cstate->binary)
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 2da08d1cc154018a6a2deb681bf2ec9b09aeb8c3..23ec88d54c72a5a0a0a349b4412585d890dda189 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -2703,6 +2703,7 @@ _copyCopyStmt(const CopyStmt *from)
COPY_NODE_FIELD(query);
COPY_NODE_FIELD(attlist);
COPY_SCALAR_FIELD(is_from);
+ COPY_SCALAR_FIELD(is_program);
COPY_STRING_FIELD(filename);
COPY_NODE_FIELD(options);
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index 9e313c8b1be18da46834a802a5f7cb18d481aeda..99c034ab684f1caa004775f3781d549ed57703a1 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -1090,6 +1090,7 @@ _equalCopyStmt(const CopyStmt *a, const CopyStmt *b)
COMPARE_NODE_FIELD(query);
COMPARE_NODE_FIELD(attlist);
COMPARE_SCALAR_FIELD(is_from);
+ COMPARE_SCALAR_FIELD(is_program);
COMPARE_STRING_FIELD(filename);
COMPARE_NODE_FIELD(options);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index b998431f5f36b3b62833db0e4d3c080810fd864f..d3009b67b411ed329ef2c20d37c00b25b89b1591 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -381,7 +381,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
%type <boolean> opt_freeze opt_default opt_recheck
%type <defelt> opt_binary opt_oids copy_delimiter
-%type <boolean> copy_from
+%type <boolean> copy_from opt_program
%type <ival> opt_column event cursor_options opt_hold opt_set_data
%type <objtype> reindex_type drop_type comment_type security_label_type
@@ -568,7 +568,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
PARSER PARTIAL PARTITION PASSING PASSWORD PLACING PLANS POSITION
PRECEDING PRECISION PRESERVE PREPARE PREPARED PRIMARY
- PRIOR PRIVILEGES PROCEDURAL PROCEDURE
+ PRIOR PRIVILEGES PROCEDURAL PROCEDURE PROGRAM
QUOTE
@@ -2309,7 +2309,10 @@ ClosePortalStmt:
*
* QUERY :
* COPY relname [(columnList)] FROM/TO file [WITH] [(options)]
- * COPY ( SELECT ... ) TO file [WITH] [(options)]
+ * COPY ( SELECT ... ) TO file [WITH] [(options)]
+ *
+ * where 'file' can be one of:
+ * { PROGRAM 'command' | STDIN | STDOUT | 'filename' }
*
* In the preferred syntax the options are comma-separated
* and use generic identifiers instead of keywords. The pre-9.0
@@ -2324,14 +2327,21 @@ ClosePortalStmt:
*****************************************************************************/
CopyStmt: COPY opt_binary qualified_name opt_column_list opt_oids
- copy_from copy_file_name copy_delimiter opt_with copy_options
+ copy_from opt_program copy_file_name copy_delimiter opt_with copy_options
{
CopyStmt *n = makeNode(CopyStmt);
n->relation = $3;
n->query = NULL;
n->attlist = $4;
n->is_from = $6;
- n->filename = $7;
+ n->is_program = $7;
+ n->filename = $8;
+
+ if (n->is_program && n->filename == NULL)
+ ereport(ERROR,
+ (errcode(ERRCODE_SYNTAX_ERROR),
+ errmsg("STDIN/STDOUT not allowed with PROGRAM"),
+ parser_errposition(@8)));
n->options = NIL;
/* Concatenate user-supplied flags */
@@ -2339,21 +2349,29 @@ CopyStmt: COPY opt_binary qualified_name opt_column_list opt_oids
n->options = lappend(n->options, $2);
if ($5)
n->options = lappend(n->options, $5);
- if ($8)
- n->options = lappend(n->options, $8);
- if ($10)
- n->options = list_concat(n->options, $10);
+ if ($9)
+ n->options = lappend(n->options, $9);
+ if ($11)
+ n->options = list_concat(n->options, $11);
$$ = (Node *)n;
}
- | COPY select_with_parens TO copy_file_name opt_with copy_options
+ | COPY select_with_parens TO opt_program copy_file_name opt_with copy_options
{
CopyStmt *n = makeNode(CopyStmt);
n->relation = NULL;
n->query = $2;
n->attlist = NIL;
n->is_from = false;
- n->filename = $4;
- n->options = $6;
+ n->is_program = $4;
+ n->filename = $5;
+ n->options = $7;
+
+ if (n->is_program && n->filename == NULL)
+ ereport(ERROR,
+ (errcode(ERRCODE_SYNTAX_ERROR),
+ errmsg("STDIN/STDOUT not allowed with PROGRAM"),
+ parser_errposition(@5)));
+
$$ = (Node *)n;
}
;
@@ -2363,6 +2381,11 @@ copy_from:
| TO { $$ = FALSE; }
;
+opt_program:
+ PROGRAM { $$ = TRUE; }
+ | /* EMPTY */ { $$ = FALSE; }
+ ;
+
/*
* copy_file_name NULL indicates stdio is used. Whether stdin or stdout is
* used depends on the direction. (It really doesn't make sense to copy from
@@ -12666,6 +12689,7 @@ unreserved_keyword:
| PRIVILEGES
| PROCEDURAL
| PROCEDURE
+ | PROGRAM
| QUOTE
| RANGE
| READ
diff --git a/src/backend/storage/file/fd.c b/src/backend/storage/file/fd.c
index ba1b84eadeff288b130b6de8b5572219ae9dd561..c31a523857d3faa14b7450a8b215d2fdf0d8c89d 100644
--- a/src/backend/storage/file/fd.c
+++ b/src/backend/storage/file/fd.c
@@ -39,13 +39,13 @@
* for a long time, like relation files. It is the caller's responsibility
* to close them, there is no automatic mechanism in fd.c for that.
*
- * AllocateFile, AllocateDir and OpenTransientFile are wrappers around
- * fopen(3), opendir(3), and open(2), respectively. They behave like the
- * corresponding native functions, except that the handle is registered with
- * the current subtransaction, and will be automatically closed at abort.
- * These are intended for short operations like reading a configuration file,
- * and there is a fixed limit on the number of files that can be opened using
- * these functions at any one time.
+ * AllocateFile, AllocateDir, OpenPipeStream and OpenTransientFile are
+ * wrappers around fopen(3), opendir(3), popen(3) and open(2), respectively.
+ * They behave like the corresponding native functions, except that the handle
+ * is registered with the current subtransaction, and will be automatically
+ * closed at abort. These are intended for short operations like reading a
+ * configuration file, and there is a fixed limit on the number of files that
+ * can be opened using these functions at any one time.
*
* Finally, BasicOpenFile is just a thin wrapper around open() that can
* release file descriptors in use by the virtual file descriptors if
@@ -202,6 +202,7 @@ static uint64 temporary_files_size = 0;
typedef enum
{
AllocateDescFile,
+ AllocateDescPipe,
AllocateDescDir,
AllocateDescRawFD
} AllocateDescKind;
@@ -1585,6 +1586,61 @@ OpenTransientFile(FileName fileName, int fileFlags, int fileMode)
return -1; /* failure */
}
+/*
+ * Routines that want to initiate a pipe stream should use OpenPipeStream
+ * rather than plain popen(). This lets fd.c deal with freeing FDs if
+ * necessary. When done, call ClosePipeStream rather than pclose.
+ */
+FILE *
+OpenPipeStream(const char *command, const char *mode)
+{
+ FILE *file;
+
+ DO_DB(elog(LOG, "OpenPipeStream: Allocated %d (%s)",
+ numAllocatedDescs, command));
+
+ /*
+ * The test against MAX_ALLOCATED_DESCS prevents us from overflowing
+ * allocatedFiles[]; the test against max_safe_fds prevents AllocateFile
+ * from hogging every one of the available FDs, which'd lead to infinite
+ * looping.
+ */
+ if (numAllocatedDescs >= MAX_ALLOCATED_DESCS ||
+ numAllocatedDescs >= max_safe_fds - 1)
+ elog(ERROR, "exceeded MAX_ALLOCATED_DESCS while trying to execute command \"%s\"",
+ command);
+
+TryAgain:
+ fflush(stdout);
+ fflush(stderr);
+ errno = 0;
+ if ((file = popen(command, mode)) != NULL)
+ {
+ AllocateDesc *desc = &allocatedDescs[numAllocatedDescs];
+
+ desc->kind = AllocateDescPipe;
+ desc->desc.file = file;
+ desc->create_subid = GetCurrentSubTransactionId();
+ numAllocatedDescs++;
+ return desc->desc.file;
+ }
+
+ if (errno == EMFILE || errno == ENFILE)
+ {
+ int save_errno = errno;
+
+ ereport(LOG,
+ (errcode(ERRCODE_INSUFFICIENT_RESOURCES),
+ errmsg("out of file descriptors: %m; release and retry")));
+ errno = 0;
+ if (ReleaseLruFile())
+ goto TryAgain;
+ errno = save_errno;
+ }
+
+ return NULL;
+}
+
/*
* Free an AllocateDesc of any type.
*
@@ -1601,6 +1657,9 @@ FreeDesc(AllocateDesc *desc)
case AllocateDescFile:
result = fclose(desc->desc.file);
break;
+ case AllocateDescPipe:
+ result = pclose(desc->desc.file);
+ break;
case AllocateDescDir:
result = closedir(desc->desc.dir);
break;
@@ -1814,6 +1873,31 @@ FreeDir(DIR *dir)
}
+/*
+ * Close a pipe stream returned by OpenPipeStream.
+ */
+int
+ClosePipeStream(FILE *file)
+{
+ int i;
+
+ DO_DB(elog(LOG, "ClosePipeStream: Allocated %d", numAllocatedDescs));
+
+ /* Remove file from list of allocated files, if it's present */
+ for (i = numAllocatedDescs; --i >= 0;)
+ {
+ AllocateDesc *desc = &allocatedDescs[i];
+
+ if (desc->kind == AllocateDescPipe && desc->desc.file == file)
+ return FreeDesc(desc);
+ }
+
+ /* Only get here if someone passes us a file not in allocatedDescs */
+ elog(WARNING, "file passed to ClosePipeStream was not obtained from OpenPipeStream");
+
+ return pclose(file);
+}
+
/*
* closeAllVfds
*
diff --git a/src/bin/psql/copy.c b/src/bin/psql/copy.c
index a31d789919ab83fd3f26f13aa6995ca48cc511ff..a97795f943e1c97e0c840eca2f83240a2f80d56b 100644
--- a/src/bin/psql/copy.c
+++ b/src/bin/psql/copy.c
@@ -35,6 +35,9 @@
* \copy tablename [(columnlist)] from|to filename [options]
* \copy ( select stmt ) to filename [options]
*
+ * where 'filename' can be one of the following:
+ * '<file path>' | PROGRAM '<command>' | stdin | stdout | pstdout | pstdout
+ *
* An undocumented fact is that you can still write BINARY before the
* tablename; this is a hangover from the pre-7.3 syntax. The options
* syntax varies across backend versions, but we avoid all that mess
@@ -43,6 +46,7 @@
* table name can be double-quoted and can have a schema part.
* column names can be double-quoted.
* filename can be single-quoted like SQL literals.
+ * command must be single-quoted like SQL literals.
*
* returns a malloc'ed structure with the options, or NULL on parsing error
*/
@@ -52,6 +56,7 @@ struct copy_options
char *before_tofrom; /* COPY string before TO/FROM */
char *after_tofrom; /* COPY string after TO/FROM filename */
char *file; /* NULL = stdin/stdout */
+ bool program; /* is 'file' a program to popen? */
bool psql_inout; /* true = use psql stdin/stdout */
bool from; /* true = FROM, false = TO */
};
@@ -191,15 +196,37 @@ parse_slash_copy(const char *args)
else
goto error;
+ /* { 'filename' | PROGRAM 'command' | STDIN | STDOUT | PSTDIN | PSTDOUT } */
token = strtokx(NULL, whitespace, NULL, "'",
- 0, false, true, pset.encoding);
+ 0, false, false, pset.encoding);
if (!token)
goto error;
- if (pg_strcasecmp(token, "stdin") == 0 ||
- pg_strcasecmp(token, "stdout") == 0)
+ if (pg_strcasecmp(token, "program") == 0)
+ {
+ int toklen;
+
+ token = strtokx(NULL, whitespace, NULL, "'",
+ 0, false, false, pset.encoding);
+ if (!token)
+ goto error;
+
+ /*
+ * The shell command must be quoted. This isn't fool-proof, but catches
+ * most quoting errors.
+ */
+ toklen = strlen(token);
+ if (token[0] != '\'' || toklen < 2 || token[toklen - 1] != '\'')
+ goto error;
+
+ strip_quotes(token, '\'', 0, pset.encoding);
+
+ result->program = true;
+ result->file = pg_strdup(token);
+ }
+ else if (pg_strcasecmp(token, "stdin") == 0 ||
+ pg_strcasecmp(token, "stdout") == 0)
{
- result->psql_inout = false;
result->file = NULL;
}
else if (pg_strcasecmp(token, "pstdin") == 0 ||
@@ -210,7 +237,8 @@ parse_slash_copy(const char *args)
}
else
{
- result->psql_inout = false;
+ /* filename can be optionally quoted */
+ strip_quotes(token, '\'', 0, pset.encoding);
result->file = pg_strdup(token);
expand_tilde(&result->file);
}
@@ -235,9 +263,9 @@ error:
/*
- * Execute a \copy command (frontend copy). We have to open a file, then
- * submit a COPY query to the backend and either feed it data from the
- * file or route its response into the file.
+ * Execute a \copy command (frontend copy). We have to open a file (or execute
+ * a command), then submit a COPY query to the backend and either feed it data
+ * from the file or route its response into the file.
*/
bool
do_copy(const char *args)
@@ -257,7 +285,7 @@ do_copy(const char *args)
return false;
/* prepare to read or write the target file */
- if (options->file)
+ if (options->file && !options->program)
canonicalize_path(options->file);
if (options->from)
@@ -265,7 +293,17 @@ do_copy(const char *args)
override_file = &pset.cur_cmd_source;
if (options->file)
- copystream = fopen(options->file, PG_BINARY_R);
+ {
+ if (options->program)
+ {
+ fflush(stdout);
+ fflush(stderr);
+ errno = 0;
+ copystream = popen(options->file, PG_BINARY_R);
+ }
+ else
+ copystream = fopen(options->file, PG_BINARY_R);
+ }
else if (!options->psql_inout)
copystream = pset.cur_cmd_source;
else
@@ -276,7 +314,20 @@ do_copy(const char *args)
override_file = &pset.queryFout;
if (options->file)
- copystream = fopen(options->file, PG_BINARY_W);
+ {
+ if (options->program)
+ {
+ fflush(stdout);
+ fflush(stderr);
+ errno = 0;
+#ifndef WIN32
+ pqsignal(SIGPIPE, SIG_IGN);
+#endif
+ copystream = popen(options->file, PG_BINARY_W);
+ }
+ else
+ copystream = fopen(options->file, PG_BINARY_W);
+ }
else if (!options->psql_inout)
copystream = pset.queryFout;
else
@@ -285,21 +336,28 @@ do_copy(const char *args)
if (!copystream)
{
- psql_error("%s: %s\n",
- options->file, strerror(errno));
+ if (options->program)
+ psql_error("could not execute command \"%s\": %s\n",
+ options->file, strerror(errno));
+ else
+ psql_error("%s: %s\n",
+ options->file, strerror(errno));
free_copy_options(options);
return false;
}
- /* make sure the specified file is not a directory */
- fstat(fileno(copystream), &st);
- if (S_ISDIR(st.st_mode))
+ if (!options->program)
{
- fclose(copystream);
- psql_error("%s: cannot copy from/to a directory\n",
- options->file);
- free_copy_options(options);
- return false;
+ /* make sure the specified file is not a directory */
+ fstat(fileno(copystream), &st);
+ if (S_ISDIR(st.st_mode))
+ {
+ fclose(copystream);
+ psql_error("%s: cannot copy from/to a directory\n",
+ options->file);
+ free_copy_options(options);
+ return false;
+ }
}
/* build the command we will send to the backend */
@@ -322,10 +380,35 @@ do_copy(const char *args)
if (options->file != NULL)
{
- if (fclose(copystream) != 0)
+ if (options->program)
{
- psql_error("%s: %s\n", options->file, strerror(errno));
- success = false;
+ int pclose_rc = pclose(copystream);
+ if (pclose_rc != 0)
+ {
+ if (pclose_rc < 0)
+ psql_error("could not close pipe to external command: %s\n",
+ strerror(errno));
+ else
+ {
+ char *reason = wait_result_to_str(pclose_rc);
+ psql_error("%s: %s\n", options->file,
+ reason ? reason : "");
+ if (reason)
+ free(reason);
+ }
+ success = false;
+ }
+#ifndef WIN32
+ pqsignal(SIGPIPE, SIG_DFL);
+#endif
+ }
+ else
+ {
+ if (fclose(copystream) != 0)
+ {
+ psql_error("%s: %s\n", options->file, strerror(errno));
+ success = false;
+ }
}
}
free_copy_options(options);
diff --git a/src/bin/psql/stringutils.c b/src/bin/psql/stringutils.c
index 450240dd9c728a47096519b234542f2df3f9f4d4..99968a16f961604687a558737df144657a9f4efa 100644
--- a/src/bin/psql/stringutils.c
+++ b/src/bin/psql/stringutils.c
@@ -13,9 +13,6 @@
#include "stringutils.h"
-static void strip_quotes(char *source, char quote, char escape, int encoding);
-
-
/*
* Replacement for strtok() (a.k.a. poor man's flex)
*
@@ -239,7 +236,7 @@ strtokx(const char *s,
*
* Note that the source string is overwritten in-place.
*/
-static void
+void
strip_quotes(char *source, char quote, char escape, int encoding)
{
char *src;
diff --git a/src/bin/psql/stringutils.h b/src/bin/psql/stringutils.h
index b991376c11b4dd7f5c447b11ebb1a623da56d822..bb2a194463bc798e088560e18d17c519c9908951 100644
--- a/src/bin/psql/stringutils.h
+++ b/src/bin/psql/stringutils.h
@@ -19,6 +19,8 @@ extern char *strtokx(const char *s,
bool del_quotes,
int encoding);
+extern void strip_quotes(char *source, char quote, char escape, int encoding);
+
extern char *quote_if_needed(const char *source, const char *entails_quote,
char quote, char escape, int encoding);
diff --git a/src/include/commands/copy.h b/src/include/commands/copy.h
index 725c277ecfd6588a608e2a8f9ced124133920bd5..5860e4cf6b2a3c7829f9ef39263065d9055903fd 100644
--- a/src/include/commands/copy.h
+++ b/src/include/commands/copy.h
@@ -26,7 +26,7 @@ extern Oid DoCopy(const CopyStmt *stmt, const char *queryString,
extern void ProcessCopyOptions(CopyState cstate, bool is_from, List *options);
extern CopyState BeginCopyFrom(Relation rel, const char *filename,
- List *attnamelist, List *options);
+ bool is_program, List *attnamelist, List *options);
extern void EndCopyFrom(CopyState cstate);
extern bool NextCopyFrom(CopyState cstate, ExprContext *econtext,
Datum *values, bool *nulls, Oid *tupleOid);
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index d8678e5b3fd7170cb972b64958b004fd29246d8f..d54990d39c170bc70333f68e98f5736c903f2f5e 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1407,6 +1407,7 @@ typedef struct CopyStmt
List *attlist; /* List of column names (as Strings), or NIL
* for all columns */
bool is_from; /* TO or FROM */
+ bool is_program; /* is 'filename' a program to popen? */
char *filename; /* filename, or NULL for STDIN/STDOUT */
List *options; /* List of DefElem nodes */
} CopyStmt;
diff --git a/src/include/parser/kwlist.h b/src/include/parser/kwlist.h
index 03aa7616409164cd7f9bd399da742a595aca212d..6f67a65f3d1d1db1b9832d4cda7f9fe15ec6caa5 100644
--- a/src/include/parser/kwlist.h
+++ b/src/include/parser/kwlist.h
@@ -292,6 +292,7 @@ PG_KEYWORD("prior", PRIOR, UNRESERVED_KEYWORD)
PG_KEYWORD("privileges", PRIVILEGES, UNRESERVED_KEYWORD)
PG_KEYWORD("procedural", PROCEDURAL, UNRESERVED_KEYWORD)
PG_KEYWORD("procedure", PROCEDURE, UNRESERVED_KEYWORD)
+PG_KEYWORD("program", PROGRAM, UNRESERVED_KEYWORD)
PG_KEYWORD("quote", QUOTE, UNRESERVED_KEYWORD)
PG_KEYWORD("range", RANGE, UNRESERVED_KEYWORD)
PG_KEYWORD("read", READ, UNRESERVED_KEYWORD)
diff --git a/src/include/port.h b/src/include/port.h
index 99d3a9b7fecd2590bf9490f05c5c3476f6950282..c5d0e0a9709e197dbd99f7e26e8bec36e6e45b88 100644
--- a/src/include/port.h
+++ b/src/include/port.h
@@ -465,4 +465,7 @@ extern int pg_mkdir_p(char *path, int omode);
/* port/quotes.c */
extern char *escape_single_quotes_ascii(const char *src);
+/* port/wait_error.c */
+extern char *wait_result_to_str(int exit_status);
+
#endif /* PG_PORT_H */
diff --git a/src/include/storage/fd.h b/src/include/storage/fd.h
index bd36c9d7fcadc3ece77a01e0a6901770ca4b0a0a..90b4933ecb528d034427422664807f8c51714fd2 100644
--- a/src/include/storage/fd.h
+++ b/src/include/storage/fd.h
@@ -80,6 +80,10 @@ extern char *FilePathName(File file);
extern FILE *AllocateFile(const char *name, const char *mode);
extern int FreeFile(FILE *file);
+/* Operations that allow use of pipe streams (popen/pclose) */
+extern FILE *OpenPipeStream(const char *command, const char *mode);
+extern int ClosePipeStream(FILE *file);
+
/* Operations to allow use of the <dirent.h> library routines */
extern DIR *AllocateDir(const char *dirname);
extern struct dirent *ReadDir(DIR *dir, const char *dirname);
diff --git a/src/interfaces/ecpg/preproc/ecpg.addons b/src/interfaces/ecpg/preproc/ecpg.addons
index d8147cf43cbe4c3c608d8fbc67702a74a57a83c5..85ec391988c6feca38a84cc2e43ec9777cc2374e 100644
--- a/src/interfaces/ecpg/preproc/ecpg.addons
+++ b/src/interfaces/ecpg/preproc/ecpg.addons
@@ -192,7 +192,7 @@ ECPG: where_or_current_clauseWHERECURRENT_POFcursor_name block
char *cursor_marker = $4[0] == ':' ? mm_strdup("$0") : $4;
$$ = cat_str(2,mm_strdup("where current of"), cursor_marker);
}
-ECPG: CopyStmtCOPYopt_binaryqualified_nameopt_column_listopt_oidscopy_fromcopy_file_namecopy_delimiteropt_withcopy_options addon
+ECPG: CopyStmtCOPYopt_binaryqualified_nameopt_column_listopt_oidscopy_fromopt_programcopy_file_namecopy_delimiteropt_withcopy_options addon
if (strcmp($6, "from") == 0 &&
(strcmp($7, "stdin") == 0 || strcmp($7, "stdout") == 0))
mmerror(PARSE_ERROR, ET_WARNING, "COPY FROM STDIN is not implemented");
diff --git a/src/port/Makefile b/src/port/Makefile
index a3db615400e3d09f777395e205e0fbe302850c2d..0774e33f9fb4a2d3a275f3b0383e09a66e79d190 100644
--- a/src/port/Makefile
+++ b/src/port/Makefile
@@ -32,7 +32,8 @@ LIBS += $(PTHREAD_LIBS)
OBJS = $(LIBOBJS) chklocale.o dirmod.o erand48.o exec.o fls.o inet_net_ntop.o \
noblock.o path.o pgcheckdir.o pg_crc.o pgmkdirp.o pgsleep.o \
- pgstrcasecmp.o qsort.o qsort_arg.o quotes.o sprompt.o tar.o thread.o
+ pgstrcasecmp.o qsort.o qsort_arg.o quotes.o sprompt.o tar.o thread.o \
+ wait_error.o
# foo_srv.o and foo.o are both built from foo.c, but only foo.o has -DFRONTEND
OBJS_SRV = $(OBJS:%.o=%_srv.o)
diff --git a/src/port/exec.c b/src/port/exec.c
index 18be1408f7aacccb975285ebf1d2ab51db541d69..01203c056cc068a30628908537456b08a7041c25 100644
--- a/src/port/exec.c
+++ b/src/port/exec.c
@@ -505,14 +505,12 @@ pipe_read_line(char *cmd, char *line, int maxsize)
/*
* pclose() plus useful error reporting
- * Is this necessary? bjm 2004-05-11
- * Originally this was stated to be here because pipe.c had backend linkage.
- * Perhaps that's no longer so now we have got rid of pipe.c amd 2012-03-28
*/
int
pclose_check(FILE *stream)
{
int exitstatus;
+ char *reason;
exitstatus = pclose(stream);
@@ -522,36 +520,21 @@ pclose_check(FILE *stream)
if (exitstatus == -1)
{
/* pclose() itself failed, and hopefully set errno */
- perror("pclose failed");
+ log_error(_("pclose failed: %s"), strerror(errno));
}
- else if (WIFEXITED(exitstatus))
- log_error(_("child process exited with exit code %d"),
- WEXITSTATUS(exitstatus));
- else if (WIFSIGNALED(exitstatus))
-#if defined(WIN32)
- log_error(_("child process was terminated by exception 0x%X"),
- WTERMSIG(exitstatus));
-#elif defined(HAVE_DECL_SYS_SIGLIST) && HAVE_DECL_SYS_SIGLIST
+ else
{
- char str[256];
-
- snprintf(str, sizeof(str), "%d: %s", WTERMSIG(exitstatus),
- WTERMSIG(exitstatus) < NSIG ?
- sys_siglist[WTERMSIG(exitstatus)] : "(unknown)");
- log_error(_("child process was terminated by signal %s"), str);
- }
+ reason = wait_result_to_str(exitstatus);
+ log_error("%s", reason);
+#ifdef FRONTEND
+ free(reason);
#else
- log_error(_("child process was terminated by signal %d"),
- WTERMSIG(exitstatus));
+ pfree(reason);
#endif
- else
- log_error(_("child process exited with unrecognized status %d"),
- exitstatus);
-
- return -1;
+ }
+ return exitstatus;
}
-
/*
* set_pglocale_pgservice
*
diff --git a/src/port/wait_error.c b/src/port/wait_error.c
new file mode 100644
index 0000000000000000000000000000000000000000..ac9c52b3169fe40d1f43c8f52f60d6216f73a89c
--- /dev/null
+++ b/src/port/wait_error.c
@@ -0,0 +1,92 @@
+/*-------------------------------------------------------------------------
+ *
+ * wait_error.c
+ * Convert a wait/waitpid(2) result code to a human-readable string
+ *
+ *
+ * Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ * src/port/wait_error.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef FRONTEND
+#include "postgres.h"
+#else
+#include "postgres_fe.h"
+#endif
+
+#include <signal.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/wait.h>
+
+/*
+ * Return a human-readable string explaining the reason a child process
+ * terminated. The argument is a return code returned by wait(2) or
+ * waitpid(2). The result is a translated, palloc'd or malloc'd string.
+ */
+char *
+wait_result_to_str(int exitstatus)
+{
+ char str[512];
+ char *result;
+
+ if (WIFEXITED(exitstatus))
+ {
+ /*
+ * Give more specific error message for some common exit codes that
+ * have a special meaning in shells.
+ */
+ switch (WEXITSTATUS(exitstatus))
+ {
+ case 126:
+ snprintf(str, sizeof(str), _("command not executable"));
+ break;
+
+ case 127:
+ snprintf(str, sizeof(str), _("command not found"));
+ break;
+
+ default:
+ snprintf(str, sizeof(str),
+ _("child process exited with exit code %d"),
+ WEXITSTATUS(exitstatus));
+ }
+ }
+ else if (WIFSIGNALED(exitstatus))
+#if defined(WIN32)
+ snprintf(str, sizeof(str),
+ _("child process was terminated by exception 0x%X"),
+ WTERMSIG(exitstatus));
+#elif defined(HAVE_DECL_SYS_SIGLIST) && HAVE_DECL_SYS_SIGLIST
+ {
+ char str2[256];
+
+ snprintf(str2, sizeof(str2), "%d: %s", WTERMSIG(exitstatus),
+ WTERMSIG(exitstatus) < NSIG ?
+ sys_siglist[WTERMSIG(exitstatus)] : "(unknown)");
+ snprintf(str, sizeof(str),
+ _("child process was terminated by signal %s"), str2);
+ }
+#else
+ snprintf(str, sizeof(str),
+ _("child process was terminated by signal %d"),
+ WTERMSIG(exitstatus));
+#endif
+ else
+ snprintf(str, sizeof(str),
+ _("child process exited with unrecognized status %d"),
+ exitstatus);
+
+#ifndef FRONTEND
+ result = pstrdup(str);
+#else
+ result = strdup(str);
+#endif
+ return result;
+}