#include "postgres.h"
#include "access/xact.h"
#include "backup/basebackup_target.h"
#include "common/percentrepl.h"
#include "miscadmin.h"
#include "storage/fd.h"
#include "utils/acl.h"
#include "utils/guc.h"

Include dependency graph for basebackup_to_shell.c:

Data Structures
struct	bbsink_shell

Typedefs
typedef struct bbsink_shell	bbsink_shell

Functions
static void *	shell_check_detail (char target, char target_detail)

static bbsink *	shell_get_sink (bbsink next_sink, void detail_arg)

static void	bbsink_shell_begin_archive (bbsink sink, const char archive_name)

static void	bbsink_shell_archive_contents (bbsink *sink, size_t len)

static void	bbsink_shell_end_archive (bbsink *sink)

static void	bbsink_shell_begin_manifest (bbsink *sink)

static void	bbsink_shell_manifest_contents (bbsink *sink, size_t len)

static void	bbsink_shell_end_manifest (bbsink *sink)

void	_PG_init (void)

static char *	shell_construct_command (const char base_command, const char filename, const char *target_detail)

static void	shell_finish_command (bbsink_shell *sink)

static void	shell_run_command (bbsink_shell sink, const char filename)

static void	shell_send_data (bbsink_shell *sink, size_t len)

Variables
	PG_MODULE_MAGIC

static const bbsink_ops	bbsink_shell_ops

static char *	shell_command = ""

static char *	shell_required_role = ""

Typedef Documentation

◆ bbsink_shell

typedef struct bbsink_shell bbsink_shell

Function Documentation

◆ _PG_init()

void _PG_init ( void )

Definition at line 68 of file basebackup_to_shell.c.

 {
     DefineCustomStringVariable("basebackup_to_shell.command",
                                "Shell command to be executed for each backup file.",
                                NULL,
                                &shell_command,
                                "",
                                PGC_SIGHUP,
                                0,
                                NULL, NULL, NULL);
  
     DefineCustomStringVariable("basebackup_to_shell.required_role",
                                "Backup user must be a member of this role to use shell backup target.",
                                NULL,
                                &shell_required_role,
                                "",
                                PGC_SIGHUP,
                                0,
                                NULL, NULL, NULL);
  
     MarkGUCPrefixReserved("basebackup_to_shell");
  
     BaseBackupAddTarget("shell", shell_check_detail, shell_get_sink);
 }

References BaseBackupAddTarget(), DefineCustomStringVariable(), MarkGUCPrefixReserved(), PGC_SIGHUP, shell_check_detail(), shell_command, shell_get_sink(), and shell_required_role.

◆ bbsink_shell_archive_contents()

static void bbsink_shell_archive_contents	(	bbsink *	sink,
		size_t	len
	)

static

Definition at line 319 of file basebackup_to_shell.c.

 {
     bbsink_shell *mysink = (bbsink_shell *) sink;
  
     shell_send_data(mysink, len);
     bbsink_forward_archive_contents(sink, len);
 }

References bbsink_forward_archive_contents(), len, and shell_send_data().

◆ bbsink_shell_begin_archive()

static void bbsink_shell_begin_archive	(	bbsink *	sink,
		const char *	archive_name
	)

static

Definition at line 307 of file basebackup_to_shell.c.

 {
     bbsink_shell *mysink = (bbsink_shell *) sink;
  
     shell_run_command(mysink, archive_name);
     bbsink_forward_begin_archive(sink, archive_name);
 }

References bbsink_forward_begin_archive(), and shell_run_command().

◆ bbsink_shell_begin_manifest()

static void bbsink_shell_begin_manifest ( bbsink * sink )

static

Definition at line 343 of file basebackup_to_shell.c.

 {
     bbsink_shell *mysink = (bbsink_shell *) sink;
  
     shell_run_command(mysink, "backup_manifest");
     bbsink_forward_begin_manifest(sink);
 }

References bbsink_forward_begin_manifest(), and shell_run_command().

◆ bbsink_shell_end_archive()

static void bbsink_shell_end_archive ( bbsink * sink )

static

Definition at line 331 of file basebackup_to_shell.c.

 {
     bbsink_shell *mysink = (bbsink_shell *) sink;
  
     shell_finish_command(mysink);
     bbsink_forward_end_archive(sink);
 }

References bbsink_forward_end_archive(), and shell_finish_command().

◆ bbsink_shell_end_manifest()

static void bbsink_shell_end_manifest ( bbsink * sink )

static

Definition at line 367 of file basebackup_to_shell.c.

 {
     bbsink_shell *mysink = (bbsink_shell *) sink;
  
     shell_finish_command(mysink);
     bbsink_forward_end_manifest(sink);
 }

References bbsink_forward_end_manifest(), and shell_finish_command().

◆ bbsink_shell_manifest_contents()

static void bbsink_shell_manifest_contents	(	bbsink *	sink,
		size_t	len
	)

static

Definition at line 355 of file basebackup_to_shell.c.

 {
     bbsink_shell *mysink = (bbsink_shell *) sink;
  
     shell_send_data(mysink, len);
     bbsink_forward_manifest_contents(sink, len);
 }

References bbsink_forward_manifest_contents(), len, and shell_send_data().

◆ shell_check_detail()

static void * shell_check_detail	(	char *	target,
		char *	target_detail
	)

static

Definition at line 99 of file basebackup_to_shell.c.

 {
     if (shell_required_role[0] != '\0')
     {
         Oid         roleid;
  
         StartTransactionCommand();
         roleid = get_role_oid(shell_required_role, true);
         if (!has_privs_of_role(GetUserId(), roleid))
             ereport(ERROR,
                     (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                      errmsg("permission denied to use basebackup_to_shell")));
         CommitTransactionCommand();
     }
  
     return target_detail;
 }

References CommitTransactionCommand(), ereport, errcode(), errmsg(), ERROR, get_role_oid(), GetUserId(), has_privs_of_role(), shell_required_role, and StartTransactionCommand().

Referenced by _PG_init().

◆ shell_construct_command()

static char* shell_construct_command	(	const char *	base_command,
		const char *	filename,
		const char *	target_detail
	)

static

Definition at line 209 of file basebackup_to_shell.c.

 {
     return replace_percent_placeholders(base_command, "basebackup_to_shell.command",
                                         "df", target_detail, filename);
 }

References filename, and replace_percent_placeholders().

Referenced by shell_run_command().

◆ shell_finish_command()

static void shell_finish_command ( bbsink_shell * sink )

static

Definition at line 220 of file basebackup_to_shell.c.

 {
     int         pclose_rc;
  
     /* There should be a command running. */
     Assert(sink->current_command != NULL);
     Assert(sink->pipe != NULL);
  
     /* Close down the pipe we opened. */
     pclose_rc = ClosePipeStream(sink->pipe);
     if (pclose_rc == -1)
         ereport(ERROR,
                 (errcode_for_file_access(),
                  errmsg("could not close pipe to external command: %m")));
     else if (pclose_rc != 0)
     {
         ereport(ERROR,
                 (errcode(ERRCODE_EXTERNAL_ROUTINE_EXCEPTION),
                  errmsg("shell command \"%s\" failed",
                         sink->current_command),
                  errdetail_internal("%s", wait_result_to_str(pclose_rc))));
     }
  
     /* Clean up. */
     sink->pipe = NULL;
     pfree(sink->current_command);
     sink->current_command = NULL;
 }

References Assert, ClosePipeStream(), bbsink_shell::current_command, ereport, errcode(), errcode_for_file_access(), errdetail_internal(), errmsg(), ERROR, pfree(), bbsink_shell::pipe, and wait_result_to_str().

Referenced by bbsink_shell_end_archive(), bbsink_shell_end_manifest(), and shell_send_data().

◆ shell_get_sink()

static bbsink * shell_get_sink	(	bbsink *	next_sink,
		void *	detail_arg
	)

static

Definition at line 124 of file basebackup_to_shell.c.

 {
     bbsink_shell *sink;
     bool        has_detail_escape = false;
     char       *c;
  
     /*
      * Set up the bbsink.
      *
      * We remember the current value of basebackup_to_shell.shell_command to
      * be certain that it can't change under us during the backup.
      */
     sink = palloc0(sizeof(bbsink_shell));
     *((const bbsink_ops **) &sink->base.bbs_ops) = &bbsink_shell_ops;
     sink->base.bbs_next = next_sink;
     sink->target_detail = detail_arg;
     sink->shell_command = pstrdup(shell_command);
  
     /* Reject an empty shell command. */
     if (sink->shell_command[0] == '\0')
         ereport(ERROR,
                 errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("shell command for backup is not configured"));
  
     /* Determine whether the shell command we're using contains %d. */
     for (c = sink->shell_command; *c != '\0'; ++c)
     {
         if (c[0] == '%' && c[1] != '\0')
         {
             if (c[1] == 'd')
                 has_detail_escape = true;
             ++c;
         }
     }
  
     /* There should be a target detail if %d was used, and not otherwise. */
     if (has_detail_escape && sink->target_detail == NULL)
         ereport(ERROR,
                 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                  errmsg("a target detail is required because the configured command includes %%d"),
                  errhint("Try \"pg_basebackup --target shell:DETAIL ...\"")));
     else if (!has_detail_escape && sink->target_detail != NULL)
         ereport(ERROR,
                 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                  errmsg("a target detail is not permitted because the configured command does not include %%d")));
  
     /*
      * Since we're passing the string provided by the user to popen(), it will
      * be interpreted by the shell, which is a potential security
      * vulnerability, since the user invoking this module is not necessarily a
      * superuser. To stay out of trouble, we must disallow any shell
      * metacharacters here; to be conservative and keep things simple, we
      * allow only alphanumerics.
      */
     if (sink->target_detail != NULL)
     {
         char       *d;
         bool        scary = false;
  
         for (d = sink->target_detail; *d != '\0'; ++d)
         {
             if (*d >= 'a' && *d <= 'z')
                 continue;
             if (*d >= 'A' && *d <= 'Z')
                 continue;
             if (*d >= '0' && *d <= '9')
                 continue;
             scary = true;
             break;
         }
  
         if (scary)
             ereport(ERROR,
                     errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                     errmsg("target detail must contain only alphanumeric characters"));
     }
  
     return &sink->base;
 }

References bbsink_shell::base, bbsink::bbs_next, bbsink::bbs_ops, bbsink_shell_ops, ereport, errcode(), errhint(), errmsg(), ERROR, palloc0(), pstrdup(), bbsink_shell::shell_command, shell_command, and bbsink_shell::target_detail.

Referenced by _PG_init().

◆ shell_run_command()

static void shell_run_command	(	bbsink_shell *	sink,
		const char *	filename
	)

static

Definition at line 253 of file basebackup_to_shell.c.

 {
     /* There should not be anything already running. */
     Assert(sink->current_command == NULL);
     Assert(sink->pipe == NULL);
  
     /* Construct a suitable command. */
     sink->current_command = shell_construct_command(sink->shell_command,
                                                     filename,
                                                     sink->target_detail);
  
     /* Run it. */
     sink->pipe = OpenPipeStream(sink->current_command, PG_BINARY_W);
     if (sink->pipe == NULL)
         ereport(ERROR,
                 (errcode_for_file_access(),
                  errmsg("could not execute command \"%s\": %m",
                         sink->current_command)));
 }

References Assert, bbsink_shell::current_command, ereport, errcode_for_file_access(), errmsg(), ERROR, filename, OpenPipeStream(), PG_BINARY_W, bbsink_shell::pipe, bbsink_shell::shell_command, shell_construct_command(), and bbsink_shell::target_detail.

Referenced by bbsink_shell_begin_archive(), and bbsink_shell_begin_manifest().

◆ shell_send_data()

static void shell_send_data	(	bbsink_shell *	sink,
		size_t	len
	)

static

Definition at line 277 of file basebackup_to_shell.c.

 {
     /* There should be a command running. */
     Assert(sink->current_command != NULL);
     Assert(sink->pipe != NULL);
  
     /* Try to write the data. */
     if (fwrite(sink->base.bbs_buffer, len, 1, sink->pipe) != 1 ||
         ferror(sink->pipe))
     {
         if (errno == EPIPE)
         {
             /*
              * The error we're about to throw would shut down the command
              * anyway, but we may get a more meaningful error message by doing
              * this. If not, we'll fall through to the generic error below.
              */
             shell_finish_command(sink);
             errno = EPIPE;
         }
         ereport(ERROR,
                 (errcode_for_file_access(),
                  errmsg("could not write to shell backup program: %m")));
     }
 }

References Assert, bbsink_shell::base, bbsink::bbs_buffer, bbsink_shell::current_command, ereport, errcode_for_file_access(), errmsg(), ERROR, len, bbsink_shell::pipe, and shell_finish_command().

Referenced by bbsink_shell_archive_contents(), and bbsink_shell_manifest_contents().

Variable Documentation

◆ bbsink_shell_ops

const bbsink_ops bbsink_shell_ops

static

Initial value:

= {
    .begin_backup = bbsink_forward_begin_backup,
    .begin_archive = bbsink_shell_begin_archive,
    .archive_contents = bbsink_shell_archive_contents,
    .end_archive = bbsink_shell_end_archive,
    .begin_manifest = bbsink_shell_begin_manifest,
    .manifest_contents = bbsink_shell_manifest_contents,
    .end_manifest = bbsink_shell_end_manifest,
    .end_backup = bbsink_forward_end_backup,
    .cleanup = bbsink_forward_cleanup
}

Definition at line 52 of file basebackup_to_shell.c.

Referenced by shell_get_sink().

◆ PG_MODULE_MAGIC

PG_MODULE_MAGIC

Definition at line 21 of file basebackup_to_shell.c.

◆ shell_command

char* shell_command = ""

static

Definition at line 64 of file basebackup_to_shell.c.

Referenced by _PG_init(), and shell_get_sink().

◆ shell_required_role

char* shell_required_role = ""

static

Definition at line 65 of file basebackup_to_shell.c.

Referenced by _PG_init(), and shell_check_detail().

Data Structures

Typedefs

Functions

Variables

Typedef Documentation

◆ bbsink_shell

Function Documentation

◆ _PG_init()

◆ bbsink_shell_archive_contents()

◆ bbsink_shell_begin_archive()

◆ bbsink_shell_begin_manifest()

◆ bbsink_shell_end_archive()

◆ bbsink_shell_end_manifest()

◆ bbsink_shell_manifest_contents()

◆ shell_check_detail()

◆ shell_construct_command()

◆ shell_finish_command()

◆ shell_get_sink()

◆ shell_run_command()

◆ shell_send_data()

Variable Documentation

◆ bbsink_shell_ops

◆ PG_MODULE_MAGIC

◆ shell_command

◆ shell_required_role