path: root/src/bin/pg_verifybackup/pg_verifybackup.c

/*-------------------------------------------------------------------------
 *
 * pg_verifybackup.c
 *	  Verify a backup against a backup manifest.
 *
 * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/bin/pg_verifybackup/pg_verifybackup.c
 *
 *-------------------------------------------------------------------------
 */

#include "postgres_fe.h"

#include <dirent.h>
#include <fcntl.h>
#include <sys/stat.h>

#include "common/hashfn.h"
#include "common/logging.h"
#include "fe_utils/simple_list.h"
#include "getopt_long.h"
#include "parse_manifest.h"

/*
 * For efficiency, we'd like our hash table containing information about the
 * manifest to start out with approximately the correct number of entries.
 * There's no way to know the exact number of entries without reading the whole
 * file, but we can get an estimate by dividing the file size by the estimated
 * number of bytes per line.
 *
 * This could be off by about a factor of two in either direction, because the
 * checksum algorithm has a big impact on the line lengths; e.g. a SHA512
 * checksum is 128 hex bytes, whereas a CRC-32C value is only 8, and there
 * might be no checksum at all.
 */
#define ESTIMATED_BYTES_PER_MANIFEST_LINE	100

/*
 * How many bytes should we try to read from a file at once?
 */
#define READ_CHUNK_SIZE				4096

/*
 * Each file described by the manifest file is parsed to produce an object
 * like this.
 */
typedef struct manifest_file
{
	uint32		status;			/* hash status */
	char	   *pathname;
	size_t		size;
	pg_checksum_type checksum_type;
	int			checksum_length;
	uint8	   *checksum_payload;
	bool		matched;
	bool		bad;
} manifest_file;

/*
 * Define a hash table which we can use to store information about the files
 * mentioned in the backup manifest.
 */
static uint32 hash_string_pointer(char *s);
#define SH_PREFIX		manifest_files
#define SH_ELEMENT_TYPE	manifest_file
#define SH_KEY_TYPE		char *
#define	SH_KEY			pathname
#define SH_HASH_KEY(tb, key)	hash_string_pointer(key)
#define SH_EQUAL(tb, a, b)		(strcmp(a, b) == 0)
#define	SH_SCOPE		static inline
#define SH_RAW_ALLOCATOR	pg_malloc0
#define SH_DECLARE
#define SH_DEFINE
#include "lib/simplehash.h"

/*
 * Each WAL range described by the manifest file is parsed to produce an
 * object like this.
 */
typedef struct manifest_wal_range
{
	TimeLineID	tli;
	XLogRecPtr	start_lsn;
	XLogRecPtr	end_lsn;
	struct manifest_wal_range *next;
	struct manifest_wal_range *prev;
} manifest_wal_range;

/*
 * Details we need in callbacks that occur while parsing a backup manifest.
 */
typedef struct parser_context
{
	manifest_files_hash *ht;
	manifest_wal_range *first_wal_range;
	manifest_wal_range *last_wal_range;
} parser_context;

/*
 * All of the context information we need while checking a backup manifest.
 */
typedef struct verifier_context
{
	manifest_files_hash *ht;
	char	   *backup_directory;
	SimpleStringList ignore_list;
	bool		exit_on_error;
	bool		saw_any_error;
} verifier_context;

static void parse_manifest_file(char *manifest_path,
								manifest_files_hash **ht_p,
								manifest_wal_range **first_wal_range_p);

static void record_manifest_details_for_file(JsonManifestParseContext *context,
											 char *pathname, size_t size,
											 pg_checksum_type checksum_type,
											 int checksum_length,
											 uint8 *checksum_payload);
static void record_manifest_details_for_wal_range(JsonManifestParseContext *context,
												  TimeLineID tli,
												  XLogRecPtr start_lsn,
												  XLogRecPtr end_lsn);
static void report_manifest_error(JsonManifestParseContext *context,
								  const char *fmt,...)
			pg_attribute_printf(2, 3) pg_attribute_noreturn();

static void verify_backup_directory(verifier_context *context,
									char *relpath, char *fullpath);
static void verify_backup_file(verifier_context *context,
							   char *relpath, char *fullpath);
static void report_extra_backup_files(verifier_context *context);
static void verify_backup_checksums(verifier_context *context);
static void verify_file_checksum(verifier_context *context,
								 manifest_file *m, char *pathname);
static void parse_required_wal(verifier_context *context,
							   char *pg_waldump_path,
							   char *wal_directory,
							   manifest_wal_range *first_wal_range);

static void report_backup_error(verifier_context *context,
								const char *pg_restrict fmt,...)
			pg_attribute_printf(2, 3);
static void report_fatal_error(const char *pg_restrict fmt,...)
			pg_attribute_printf(1, 2) pg_attribute_noreturn();
static bool should_ignore_relpath(verifier_context *context, char *relpath);

static void usage(void);

static const char *progname;

/*
 * Main entry point.
 */
int
main(int argc, char **argv)
{
	static struct option long_options[] = {
		{"exit-on-error", no_argument, NULL, 'e'},
		{"ignore", required_argument, NULL, 'i'},
		{"manifest-path", required_argument, NULL, 'm'},
		{"no-parse-wal", no_argument, NULL, 'n'},
		{"quiet", no_argument, NULL, 'q'},
		{"skip-checksums", no_argument, NULL, 's'},
		{"wal-directory", required_argument, NULL, 'w'},
		{NULL, 0, NULL, 0}
	};

	int			c;
	verifier_context context;
	manifest_wal_range *first_wal_range;
	char	   *manifest_path = NULL;
	bool		no_parse_wal = false;
	bool		quiet = false;
	bool		skip_checksums = false;
	char	   *wal_directory = NULL;
	char	   *pg_waldump_path = NULL;

	pg_logging_init(argv[0]);
	set_pglocale_pgservice(argv[0], PG_TEXTDOMAIN("pg_verifybackup"));
	progname = get_progname(argv[0]);

	memset(&context, 0, sizeof(context));

	if (argc > 1)
	{
		if (strcmp(argv[1], "--help") == 0 || strcmp(argv[1], "-?") == 0)
		{
			usage();
			exit(0);
		}
		if (strcmp(argv[1], "--version") == 0 || strcmp(argv[1], "-V") == 0)
		{
			puts("pg_verifybackup (PostgreSQL) " PG_VERSION);
			exit(0);
		}
	}

	/*
	 * Skip certain files in the toplevel directory.
	 *
	 * Ignore the backup_manifest file, because it's not included in the
	 * backup manifest.
	 *
	 * Ignore the pg_wal directory, because those files are not included in
	 * the backup manifest either, since they are fetched separately from the
	 * backup itself, and verified via a separate mechanism.
	 *
	 * Ignore postgresql.auto.conf, recovery.signal, and standby.signal,
	 * because we expect that those files may sometimes be created or changed
	 * as part of the backup process. For example, pg_basebackup -R will
	 * modify postgresql.auto.conf and create standby.signal.
	 */
	simple_string_list_append(&context.ignore_list, "backup_manifest");
	simple_string_list_append(&context.ignore_list, "pg_wal");
	simple_string_list_append(&context.ignore_list, "postgresql.auto.conf");
	simple_string_list_append(&context.ignore_list, "recovery.signal");
	simple_string_list_append(&context.ignore_list, "standby.signal");

	while ((c = getopt_long(argc, argv, "ei:m:nqsw:", long_options, NULL)) != -1)
	{
		switch (c)
		{
			case 'e':
				context.exit_on_error = true;
				break;
			case 'i':
				{
					char	   *arg = pstrdup(optarg);

					canonicalize_path(arg);
					simple_string_list_append(&context.ignore_list, arg);
					break;
				}
			case 'm':
				manifest_path = pstrdup(optarg);
				canonicalize_path(manifest_path);
				break;
			case 'n':
				no_parse_wal = true;
				break;
			case 'q':
				quiet = true;
				break;
			case 's':
				skip_checksums = true;
				break;
			case 'w':
				wal_directory = pstrdup(optarg);
				canonicalize_path(wal_directory);
				break;
			default:
				/* getopt_long already emitted a complaint */
				pg_log_error_hint("Try \"%s --help\" for more information.", progname);
				exit(1);
		}
	}

	/* Get backup directory name */
	if (optind >= argc)
	{
		pg_log_error("no backup directory specified");
		pg_log_error_hint("Try \"%s --help\" for more information.", progname);
		exit(1);
	}
	context.backup_directory = pstrdup(argv[optind++]);
	canonicalize_path(context.backup_directory);

	/* Complain if any arguments remain */
	if (optind < argc)
	{
		pg_log_error("too many command-line arguments (first is \"%s\")",
					 argv[optind]);
		pg_log_error_hint("Try \"%s --help\" for more information.", progname);
		exit(1);
	}

	/* Unless --no-parse-wal was specified, we will need pg_waldump. */
	if (!no_parse_wal)
	{
		int			ret;

		pg_waldump_path = pg_malloc(MAXPGPATH);
		ret = find_other_exec(argv[0], "pg_waldump",
							  "pg_waldump (PostgreSQL) " PG_VERSION "\n",
							  pg_waldump_path);
		if (ret < 0)
		{
			char		full_path[MAXPGPATH];

			if (find_my_exec(argv[0], full_path) < 0)
				strlcpy(full_path, progname, sizeof(full_path));

			if (ret == -1)
				pg_fatal("program \"%s\" is needed by %s but was not found in the same directory as \"%s\"",
						 "pg_waldump", "pg_verifybackup", full_path);
			else
				pg_fatal("program \"%s\" was found by \"%s\" but was not the same version as %s",
						 "pg_waldump", full_path, "pg_verifybackup");
		}
	}

	/* By default, look for the manifest in the backup directory. */
	if (manifest_path == NULL)
		manifest_path = psprintf("%s/backup_manifest",
								 context.backup_directory);

	/* By default, look for the WAL in the backup directory, too. */
	if (wal_directory == NULL)
		wal_directory = psprintf("%s/pg_wal", context.backup_directory);

	/*
	 * Try to read the manifest. We treat any errors encountered while parsing
	 * the manifest as fatal; there doesn't seem to be much point in trying to
	 * verify the backup directory against a corrupted manifest.
	 */
	parse_manifest_file(manifest_path, &context.ht, &first_wal_range);

	/*
	 * Now scan the files in the backup directory. At this stage, we verify
	 * that every file on disk is present in the manifest and that the sizes
	 * match. We also set the "matched" flag on every manifest entry that
	 * corresponds to a file on disk.
	 */
	verify_backup_directory(&context, NULL, context.backup_directory);

	/*
	 * The "matched" flag should now be set on every entry in the hash table.
	 * Any entries for which the bit is not set are files mentioned in the
	 * manifest that don't exist on disk.
	 */
	report_extra_backup_files(&context);

	/*
	 * Now do the expensive work of verifying file checksums, unless we were
	 * told to skip it.
	 */
	if (!skip_checksums)
		verify_backup_checksums(&context);

	/*
	 * Try to parse the required ranges of WAL records, unless we were told
	 * not to do so.
	 */
	if (!no_parse_wal)
		parse_required_wal(&context, pg_waldump_path,
						   wal_directory, first_wal_range);

	/*
	 * If everything looks OK, tell the user this, unless we were asked to
	 * work quietly.
	 */
	if (!context.saw_any_error && !quiet)
		printf(_("backup successfully verified\n"));

	return context.saw_any_error ? 1 : 0;
}

/*
 * Parse a manifest file. Construct a hash table with information about
 * all the files it mentions, and a linked list of all the WAL ranges it
 * mentions.
 */
static void
parse_manifest_file(char *manifest_path, manifest_files_hash **ht_p,
					manifest_wal_range **first_wal_range_p)
{
	int			fd;
	struct stat statbuf;
	off_t		estimate;
	uint32		initial_size;
	manifest_files_hash *ht;
	char	   *buffer;
	int			rc;
	parser_context private_context;
	JsonManifestParseContext context;

	/* Open the manifest file. */
	if ((fd = open(manifest_path, O_RDONLY | PG_BINARY, 0)) < 0)
		report_fatal_error("could not open file \"%s\": %m", manifest_path);

	/* Figure out how big the manifest is. */
	if (fstat(fd, &statbuf) != 0)
		report_fatal_error("could not stat file \"%s\": %m", manifest_path);

	/* Guess how large to make the hash table based on the manifest size. */
	estimate = statbuf.st_size / ESTIMATED_BYTES_PER_MANIFEST_LINE;
	initial_size = Min(PG_UINT32_MAX, Max(estimate, 256));

	/* Create the hash table. */
	ht = manifest_files_create(initial_size, NULL);

	/*
	 * Slurp in the whole file.
	 *
	 * This is not ideal, but there's currently no easy way to get
	 * pg_parse_json() to perform incremental parsing.
	 */
	buffer = pg_malloc(statbuf.st_size);
	rc = read(fd, buffer, statbuf.st_size);
	if (rc != statbuf.st_size)
	{
		if (rc < 0)
			report_fatal_error("could not read file \"%s\": %m",
							   manifest_path);
		else
			report_fatal_error("could not read file \"%s\": read %d of %lld",
							   manifest_path, rc, (long long int) statbuf.st_size);
	}

	/* Close the manifest file. */
	close(fd);

	/* Parse the manifest. */
	private_context.ht = ht;
	private_context.first_wal_range = NULL;
	private_context.last_wal_range = NULL;
	context.private_data = &private_context;
	context.perfile_cb = record_manifest_details_for_file;
	context.perwalrange_cb = record_manifest_details_for_wal_range;
	context.error_cb = report_manifest_error;
	json_parse_manifest(&context, buffer, statbuf.st_size);

	/* Done with the buffer. */
	pfree(buffer);

	/* Return the file hash table and WAL range list we constructed. */
	*ht_p = ht;
	*first_wal_range_p = private_context.first_wal_range;
}

/*
 * Report an error while parsing the manifest.
 *
 * We consider all such errors to be fatal errors. The manifest parser
 * expects this function not to return.
 */
static void
report_manifest_error(JsonManifestParseContext *context, const char *fmt,...)
{
	va_list		ap;

	va_start(ap, fmt);
	pg_log_generic_v(PG_LOG_ERROR, PG_LOG_PRIMARY, gettext(fmt), ap);
	va_end(ap);

	exit(1);
}

/*
 * Record details extracted from the backup manifest for one file.
 */
static void
record_manifest_details_for_file(JsonManifestParseContext *context,
								 char *pathname, size_t size,
								 pg_checksum_type checksum_type,
								 int checksum_length, uint8 *checksum_payload)
{
	parser_context *pcxt = context->private_data;
	manifest_files_hash *ht = pcxt->ht;
	manifest_file *m;
	bool		found;

	/* Make a new entry in the hash table for this file. */
	m = manifest_files_insert(ht, pathname, &found);
	if (found)
		report_fatal_error("duplicate path name in backup manifest: \"%s\"",
						   pathname);

	/* Initialize the entry. */
	m->size = size;
	m->checksum_type = checksum_type;
	m->checksum_length = checksum_length;
	m->checksum_payload = checksum_payload;
	m->matched = false;
	m->bad = false;
}

/*
 * Record details extracted from the backup manifest for one WAL range.
 */
static void
record_manifest_details_for_wal_range(JsonManifestParseContext *context,
									  TimeLineID tli,
									  XLogRecPtr start_lsn, XLogRecPtr end_lsn)
{
	parser_context *pcxt = context->private_data;
	manifest_wal_range *range;

	/* Allocate and initialize a struct describing this WAL range. */
	range = palloc(sizeof(manifest_wal_range));
	range->tli = tli;
	range->start_lsn = start_lsn;
	range->end_lsn = end_lsn;
	range->prev = pcxt->last_wal_range;
	range->next = NULL;

	/* Add it to the end of the list. */
	if (pcxt->first_wal_range == NULL)
		pcxt->first_wal_range = range;
	else
		pcxt->last_wal_range->next = range;
	pcxt->last_wal_range = range;
}

/*
 * Verify one directory.
 *
 * 'relpath' is NULL if we are to verify the top-level backup directory,
 * and otherwise the relative path to the directory that is to be verified.
 *
 * 'fullpath' is the backup directory with 'relpath' appended; i.e. the actual
 * filesystem path at which it can be found.
 */
static void
verify_backup_directory(verifier_context *context, char *relpath,
						char *fullpath)
{
	DIR		   *dir;
	struct dirent *dirent;

	dir = opendir(fullpath);
	if (dir == NULL)
	{
		/*
		 * If even the toplevel backup directory cannot be found, treat this
		 * as a fatal error.
		 */
		if (relpath == NULL)
			report_fatal_error("could not open directory \"%s\": %m", fullpath);

		/*
		 * Otherwise, treat this as a non-fatal error, but ignore any further
		 * errors related to this path and anything beneath it.
		 */
		report_backup_error(context,
							"could not open directory \"%s\": %m", fullpath);
		simple_string_list_append(&context->ignore_list, relpath);

		return;
	}

	while (errno = 0, (dirent = readdir(dir)) != NULL)
	{
		char	   *filename = dirent->d_name;
		char	   *newfullpath = psprintf("%s/%s", fullpath, filename);
		char	   *newrelpath;

		/* Skip "." and ".." */
		if (filename[0] == '.' && (filename[1] == '\0'
								   || strcmp(filename, "..") == 0))
			continue;

		if (relpath == NULL)
			newrelpath = pstrdup(filename);
		else
			newrelpath = psprintf("%s/%s", relpath, filename);

		if (!should_ignore_relpath(context, newrelpath))
			verify_backup_file(context, newrelpath, newfullpath);

		pfree(newfullpath);
		pfree(newrelpath);
	}

	if (closedir(dir))
	{
		report_backup_error(context,
							"could not close directory \"%s\": %m", fullpath);
		return;
	}
}

/*
 * Verify one file (which might actually be a directory or a symlink).
 *
 * The arguments to this function have the same meaning as the arguments to
 * verify_backup_directory.
 */
static void
verify_backup_file(verifier_context *context, char *relpath, char *fullpath)
{
	struct stat sb;
	manifest_file *m;

	if (stat(fullpath, &sb) != 0)
	{
		report_backup_error(context,
							"could not stat file or directory \"%s\": %m",
							relpath);

		/*
		 * Suppress further errors related to this path name and, if it's a
		 * directory, anything underneath it.
		 */
		simple_string_list_append(&context->ignore_list, relpath);

		return;
	}

	/* If it's a directory, just recurse. */
	if (S_ISDIR(sb.st_mode))
	{
		verify_backup_directory(context, relpath, fullpath);
		return;
	}

	/* If it's not a directory, it should be a plain file. */
	if (!S_ISREG(sb.st_mode))
	{
		report_backup_error(context,
							"\"%s\" is not a file or directory",
							relpath);
		return;
	}

	/* Check whether there's an entry in the manifest hash. */
	m = manifest_files_lookup(context->ht, relpath);
	if (m == NULL)
	{
		report_backup_error(context,
							"\"%s\" is present on disk but not in the manifest",
							relpath);
		return;
	}

	/* Flag this entry as having been encountered in the filesystem. */
	m->matched = true;

	/* Check that the size matches. */
	if (m->size != sb.st_size)
	{
		report_backup_error(context,
							"\"%s\" has size %lld on disk but size %zu in the manifest",
							relpath, (long long int) sb.st_size, m->size);
		m->bad = true;
	}

	/*
	 * We don't verify checksums at this stage. We first finish verifying that
	 * we have the expected set of files with the expected sizes, and only
	 * afterwards verify the checksums. That's because computing checksums may
	 * take a while, and we'd like to report more obvious problems quickly.
	 */
}

/*
 * Scan the hash table for entries where the 'matched' flag is not set; report
 * that such files are present in the manifest but not on disk.
 */
static void
report_extra_backup_files(verifier_context *context)
{
	manifest_files_iterator it;
	manifest_file *m;

	manifest_files_start_iterate(context->ht, &it);
	while ((m = manifest_files_iterate(context->ht, &it)) != NULL)
		if (!m->matched && !should_ignore_relpath(context, m->pathname))
			report_backup_error(context,
								"\"%s\" is present in the manifest but not on disk",
								m->pathname);
}

/*
 * Verify checksums for hash table entries that are otherwise unproblematic.
 * If we've already reported some problem related to a hash table entry, or
 * if it has no checksum, just skip it.
 */
static void
verify_backup_checksums(verifier_context *context)
{
	manifest_files_iterator it;
	manifest_file *m;

	manifest_files_start_iterate(context->ht, &it);
	while ((m = manifest_files_iterate(context->ht, &it)) != NULL)
	{
		if (m->matched && !m->bad && m->checksum_type != CHECKSUM_TYPE_NONE &&
			!should_ignore_relpath(context, m->pathname))
		{
			char	   *fullpath;

			/* Compute the full pathname to the target file. */
			fullpath = psprintf("%s/%s", context->backup_directory,
								m->pathname);

			/* Do the actual checksum verification. */
			verify_file_checksum(context, m, fullpath);

			/* Avoid leaking memory. */
			pfree(fullpath);
		}
	}
}

/*
 * Verify the checksum of a single file.
 */
static void
verify_file_checksum(verifier_context *context, manifest_file *m,
					 char *fullpath)
{
	pg_checksum_context checksum_ctx;
	char	   *relpath = m->pathname;
	int			fd;
	int			rc;
	size_t		bytes_read = 0;
	uint8		buffer[READ_CHUNK_SIZE];
	uint8		checksumbuf[PG_CHECKSUM_MAX_LENGTH];
	int			checksumlen;

	/* Open the target file. */
	if ((fd = open(fullpath, O_RDONLY | PG_BINARY, 0)) < 0)
	{
		report_backup_error(context, "could not open file \"%s\": %m",
							relpath);
		return;
	}

	/* Initialize checksum context. */
	if (pg_checksum_init(&checksum_ctx, m->checksum_type) < 0)
	{
		report_backup_error(context, "could not initialize checksum of file \"%s\"",
							relpath);
		close(fd);
		return;
	}

	/* Read the file chunk by chunk, updating the checksum as we go. */
	while ((rc = read(fd, buffer, READ_CHUNK_SIZE)) > 0)
	{
		bytes_read += rc;
		if (pg_checksum_update(&checksum_ctx, buffer, rc) < 0)
		{
			report_backup_error(context, "could not update checksum of file \"%s\"",
								relpath);
			close(fd);
			return;
		}
	}
	if (rc < 0)
		report_backup_error(context, "could not read file \"%s\": %m",
							relpath);

	/* Close the file. */
	if (close(fd) != 0)
	{
		report_backup_error(context, "could not close file \"%s\": %m",
							relpath);
		return;
	}

	/* If we didn't manage to read the whole file, bail out now. */
	if (rc < 0)
		return;

	/*
	 * Double-check that we read the expected number of bytes from the file.
	 * Normally, a file size mismatch would be caught in verify_backup_file
	 * and this check would never be reached, but this provides additional
	 * safety and clarity in the event of concurrent modifications or
	 * filesystem misbehavior.
	 */
	if (bytes_read != m->size)
	{
		report_backup_error(context,
							"file \"%s\" should contain %zu bytes, but read %zu bytes",
							relpath, m->size, bytes_read);
		return;
	}

	/* Get the final checksum. */
	checksumlen = pg_checksum_final(&checksum_ctx, checksumbuf);
	if (checksumlen < 0)
	{
		report_backup_error(context,
							"could not finalize checksum of file \"%s\"",
							relpath);
		return;
	}

	/* And check it against the manifest. */
	if (checksumlen != m->checksum_length)
		report_backup_error(context,
							"file \"%s\" has checksum of length %d, but expected %d",
							relpath, m->checksum_length, checksumlen);
	else if (memcmp(checksumbuf, m->checksum_payload, checksumlen) != 0)
		report_backup_error(context,
							"checksum mismatch for file \"%s\"",
							relpath);
}

/*
 * Attempt to parse the WAL files required to restore from backup using
 * pg_waldump.
 */
static void
parse_required_wal(verifier_context *context, char *pg_waldump_path,
				   char *wal_directory, manifest_wal_range *first_wal_range)
{
	manifest_wal_range *this_wal_range = first_wal_range;

	while (this_wal_range != NULL)
	{
		char	   *pg_waldump_cmd;

		pg_waldump_cmd = psprintf("\"%s\" --quiet --path=\"%s\" --timeline=%u --start=%X/%X --end=%X/%X\n",
								  pg_waldump_path, wal_directory, this_wal_range->tli,
								  LSN_FORMAT_ARGS(this_wal_range->start_lsn),
								  LSN_FORMAT_ARGS(this_wal_range->end_lsn));
		if (system(pg_waldump_cmd) != 0)
			report_backup_error(context,
								"WAL parsing failed for timeline %u",
								this_wal_range->tli);

		this_wal_range = this_wal_range->next;
	}
}

/*
 * Report a problem with the backup.
 *
 * Update the context to indicate that we saw an error, and exit if the
 * context says we should.
 */
static void
report_backup_error(verifier_context *context, const char *pg_restrict fmt,...)
{
	va_list		ap;

	va_start(ap, fmt);
	pg_log_generic_v(PG_LOG_ERROR, PG_LOG_PRIMARY, gettext(fmt), ap);
	va_end(ap);

	context->saw_any_error = true;
	if (context->exit_on_error)
		exit(1);
}

/*
 * Report a fatal error and exit
 */
static void
report_fatal_error(const char *pg_restrict fmt,...)
{
	va_list		ap;

	va_start(ap, fmt);
	pg_log_generic_v(PG_LOG_ERROR, PG_LOG_PRIMARY, gettext(fmt), ap);
	va_end(ap);

	exit(1);
}

/*
 * Is the specified relative path, or some prefix of it, listed in the set
 * of paths to ignore?
 *
 * Note that by "prefix" we mean a parent directory; for this purpose,
 * "aa/bb" is not a prefix of "aa/bbb", but it is a prefix of "aa/bb/cc".
 */
static bool
should_ignore_relpath(verifier_context *context, char *relpath)
{
	SimpleStringListCell *cell;

	for (cell = context->ignore_list.head; cell != NULL; cell = cell->next)
	{
		char	   *r = relpath;
		char	   *v = cell->val;

		while (*v != '\0' && *r == *v)
			++r, ++v;

		if (*v == '\0' && (*r == '\0' || *r == '/'))
			return true;
	}

	return false;
}

/*
 * Helper function for manifest_files hash table.
 */
static uint32
hash_string_pointer(char *s)
{
	unsigned char *ss = (unsigned char *) s;

	return hash_bytes(ss, strlen(s));
}

/*
 * Print out usage information and exit.
 */
static void
usage(void)
{
	printf(_("%s verifies a backup against the backup manifest.\n\n"), progname);
	printf(_("Usage:\n  %s [OPTION]... BACKUPDIR\n\n"), progname);
	printf(_("Options:\n"));
	printf(_("  -e, --exit-on-error         exit immediately on error\n"));
	printf(_("  -i, --ignore=RELATIVE_PATH  ignore indicated path\n"));
	printf(_("  -m, --manifest-path=PATH    use specified path for manifest\n"));
	printf(_("  -n, --no-parse-wal          do not try to parse WAL files\n"));
	printf(_("  -q, --quiet                 do not print any output, except for errors\n"));
	printf(_("  -s, --skip-checksums        skip checksum verification\n"));
	printf(_("  -w, --wal-directory=PATH    use specified path for WAL files\n"));
	printf(_("  -V, --version               output version information, then exit\n"));
	printf(_("  -?, --help                  show this help, then exit\n"));
	printf(_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
	printf(_("%s home page: <%s>\n"), PACKAGE_NAME, PACKAGE_URL);
}