basebackup_to_shell.c File Reference

#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:

Go to the source code of this file.

Data Structures
struct	bbsink_shell

Typedefs
typedef struct bbsink_shell	bbsink_shell

Functions
	PG_MODULE_MAGIC_EXT (.name="basebackup_to_shell",.version=PG_VERSION)
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
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 71 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 322 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 310 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 346 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 334 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 370 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 358 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().

PG_MODULE_MAGIC_EXT()

PG_MODULE_MAGIC_EXT	(	.	name = "basebackup_to_shell",
		.	version = PG_VERSION
	)

shell_check_detail()

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

static

Definition at line 102 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 212 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 223 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 127 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 256 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 280 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 55 of file basebackup_to_shell.c.

Referenced by shell_get_sink().

shell_command

char* shell_command = ""

static

Definition at line 67 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 68 of file basebackup_to_shell.c.

Referenced by _PG_init(), and shell_check_detail().