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Add support for piping COPY to/from an external program.

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This includes backend "COPY TO/FROM PROGRAM '...'" syntax, and corresponding
psql \copy syntax. Like with reading/writing files, the backend version is
superuser-only, and in the psql version, the program is run in the client.

In the passing, the psql \copy STDIN/STDOUT syntax is subtly changed: if you
the stdin/stdout is quoted, it's now interpreted as a filename. For example,
"\copy foo from 'stdin'" now reads from a file called 'stdin', not from
standard input. Before this, there was no way to specify a filename called
stdin, stdout, pstdin or pstdout.

This creates a new function in pgport, wait_result_to_str(), which can
be used to convert the exit status of a process, as returned by wait(3),
to a human-readable string.

Etsuro Fujita, reviewed by Amit Kapila.
This commit is contained in:
Heikki Linnakangas
2013-02-27 18:17:21 +02:00
parent 73dc003bee
commit 3d009e45bd
21 changed files with 584 additions and 152 deletions
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131
src/bin/psql/copy.c
View File

@ -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);