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Diffstat (limited to 'db2/log/log_get.c')
-rw-r--r--db2/log/log_get.c355
1 files changed, 355 insertions, 0 deletions
diff --git a/db2/log/log_get.c b/db2/log/log_get.c
new file mode 100644
index 0000000000..37eb5cb249
--- /dev/null
+++ b/db2/log/log_get.c
@@ -0,0 +1,355 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 1996, 1997
+ *	Sleepycat Software.  All rights reserved.
+ */
+#include "config.h"
+
+#ifndef lint
+static const char sccsid[] = "@(#)log_get.c	10.16 (Sleepycat) 8/19/97";
+#endif /* not lint */
+
+#ifndef NO_SYSTEM_INCLUDES
+#include <sys/types.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#endif
+
+#include "db_int.h"
+#include "shqueue.h"
+#include "db_page.h"
+#include "log.h"
+#include "hash.h"
+#include "common_ext.h"
+
+/*
+ * log_get --
+ *	Get a log record.
+ */
+int
+log_get(dblp, alsn, dbt, flags)
+	DB_LOG *dblp;
+	DB_LSN *alsn;
+	DBT *dbt;
+	int flags;
+{
+	LOG *lp;
+	int ret;
+
+	/* Validate arguments. */
+#define	OKFLAGS	(DB_CHECKPOINT | \
+    DB_CURRENT | DB_FIRST | DB_LAST | DB_NEXT | DB_PREV | DB_SET)
+	if (flags != 0) {
+		if ((ret =
+		    __db_fchk(dblp->dbenv, "log_get", flags, OKFLAGS)) != 0)
+			return (ret);
+		switch (flags) {
+		case DB_CHECKPOINT:
+		case DB_CURRENT:
+		case DB_FIRST:
+		case DB_LAST:
+		case DB_NEXT:
+		case DB_PREV:
+		case DB_SET:
+		case 0:
+			break;
+		default:
+			return (__db_ferr(dblp->dbenv, "log_get", 1));
+		}
+	}
+	if (F_ISSET(dblp, DB_AM_THREAD)) {
+		if (LF_ISSET(DB_NEXT | DB_PREV | DB_CURRENT))
+			return (__db_ferr(dblp->dbenv, "log_get", 1));
+		if (!F_ISSET(dbt, DB_DBT_USERMEM | DB_DBT_MALLOC))
+			return (__db_ferr(dblp->dbenv, "threaded data", 1));
+	}
+
+	lp = dblp->lp;
+
+	LOCK_LOGREGION(dblp);
+
+	/*
+	 * If we get one of the log's header records, repeat the operation.
+	 * This assumes that applications don't ever request the log header
+	 * records by LSN, but that seems reasonable to me.
+	 */
+	ret = __log_get(dblp, alsn, dbt, flags, 0);
+	if (ret == 0 && alsn->offset == 0) {
+		switch (flags) {
+		case DB_FIRST:
+			flags = DB_NEXT;
+			break;
+		case DB_LAST:
+			flags = DB_PREV;
+			break;
+		}
+		ret = __log_get(dblp, alsn, dbt, flags, 0);
+	}
+
+	UNLOCK_LOGREGION(dblp);
+
+	return (ret);
+}
+
+/*
+ * __log_get --
+ *	Get a log record; internal version.
+ *
+ * PUBLIC: int __log_get __P((DB_LOG *, DB_LSN *, DBT *, int, int));
+ */
+int
+__log_get(dblp, alsn, dbt, flags, silent)
+	DB_LOG *dblp;
+	DB_LSN *alsn;
+	DBT *dbt;
+	int flags, silent;
+{
+	DB_LSN nlsn;
+	HDR hdr;
+	LOG *lp;
+	size_t len;
+	ssize_t nr;
+	int cnt, ret;
+	const char *fail;
+	char *np, *tbuf;
+	void *p, *shortp;
+
+	lp = dblp->lp;
+	fail = np = tbuf = NULL;
+
+	nlsn = dblp->c_lsn;
+	switch (flags) {
+	case DB_CHECKPOINT:
+		nlsn = dblp->lp->c_lsn;
+		if (IS_ZERO_LSN(nlsn)) {
+			__db_err(dblp->dbenv,
+	"log_get: unable to find checkpoint record: no checkpoint set.");
+			ret = ENOENT;
+			goto err2;
+		}
+		break;
+	case DB_NEXT:				/* Next log record. */
+		if (!IS_ZERO_LSN(nlsn)) {
+			/* Increment the cursor by the cursor record size. */
+			nlsn.offset += dblp->c_len;
+			break;
+		}
+		/* FALLTHROUGH */
+	case DB_FIRST:				/* Find the first log record. */
+		/*
+		 * Find any log file.  Note, we may have only entered records
+		 * in the buffer, and not yet written a log file.
+		 */
+		if ((ret = __log_find(dblp->dbenv, lp, &cnt)) != 0) {
+			__db_err(dblp->dbenv,
+	"log_get: unable to find the first record: no log files found.");
+			goto err2;
+		}
+
+		/* If there's anything in the buffer, it belongs to file 1. */
+		if (cnt == 0)
+			cnt = 1;
+
+		/* Now go backwards to find the smallest one. */
+		for (; cnt > 1; --cnt)
+			if (__log_valid(dblp->dbenv, NULL, cnt) != 0) {
+				++cnt;
+				break;
+			}
+		nlsn.file = cnt;
+		nlsn.offset = 0;
+		break;
+	case DB_CURRENT:			/* Current log record. */
+		break;
+	case DB_PREV:				/* Previous log record. */
+		if (!IS_ZERO_LSN(nlsn)) {
+			/* If at start-of-file, move to the previous file. */
+			if (nlsn.offset == 0) {
+				if (nlsn.file == 1)
+					return (DB_NOTFOUND);
+
+				--nlsn.file;
+				nlsn.offset = dblp->c_off;
+			} else
+				nlsn.offset = dblp->c_off;
+			break;
+		}
+		/* FALLTHROUGH */
+	case DB_LAST:				/* Last log record. */
+		nlsn.file = lp->lsn.file;
+		nlsn.offset = lp->lsn.offset - lp->len;
+		break;
+	case DB_SET:				/* Set log record. */
+		nlsn = *alsn;
+		break;
+	}
+
+retry:
+	/* Return 1 if the request is past end-of-file. */
+	if (nlsn.file > lp->lsn.file ||
+	    (nlsn.file == lp->lsn.file && nlsn.offset >= lp->lsn.offset))
+		return (DB_NOTFOUND);
+
+	/* If we've switched files, discard the current fd. */
+	if (dblp->c_lsn.file != nlsn.file && dblp->c_fd != -1) {
+		(void)__db_close(dblp->c_fd);
+		dblp->c_fd = -1;
+	}
+
+	/* If the entire record is in the in-memory buffer, copy it out. */
+	if (nlsn.file == lp->lsn.file && nlsn.offset >= lp->w_off) {
+		/* Copy the header. */
+		p = lp->buf + (nlsn.offset - lp->w_off);
+		memcpy(&hdr, p, sizeof(HDR));
+
+		/* Copy the record. */
+		len = hdr.len - sizeof(HDR);
+		if ((ret = __db_retcopy(dbt, (u_int8_t *)p + sizeof(HDR),
+		    len, &dblp->c_dbt.data, &dblp->c_dbt.ulen, NULL)) != 0)
+			goto err1;
+		goto cksum;
+	}
+
+	/*
+	 * Move the file descriptor to the page that has the hdr.  We dealt
+	 * with moving to a previous log file in the flags switch code, but
+	 * we don't yet know if we'll need to move to a subsequent file.
+	 *
+	 * Acquire a file descriptor.
+	 */
+	if (dblp->c_fd == -1) {
+		if ((ret = __log_name(dblp->dbenv, nlsn.file, &np)) != 0)
+			goto err1;
+		if ((ret = __db_fdopen(np, DB_RDONLY | DB_SEQUENTIAL,
+		    DB_RDONLY | DB_SEQUENTIAL, 0, &dblp->c_fd)) != 0) {
+			fail = np;
+			goto err1;
+		}
+		free(np);
+		np = NULL;
+	}
+
+	/* Seek to the header offset and read the header. */
+	if ((ret = __db_lseek(dblp->c_fd, 0, 0, nlsn.offset, SEEK_SET)) != 0) {
+		fail = "seek";
+		goto err1;
+	}
+	if ((ret = __db_read(dblp->c_fd, &hdr, sizeof(HDR), &nr)) != 0) {
+		fail = "read";
+		goto err1;
+	}
+	if (nr == sizeof(HDR))
+		shortp = NULL;
+	else {
+		/* If read returns EOF, try the next file. */
+		if (nr == 0) {
+			if (flags != DB_NEXT || nlsn.file == lp->lsn.file)
+				goto corrupt;
+
+			/* Move to the next file. */
+			++nlsn.file;
+			nlsn.offset = 0;
+			goto retry;
+		}
+
+		/*
+		 * If read returns a short count the rest of the record has
+		 * to be in the in-memory buffer.
+		 */
+		if (lp->b_off < sizeof(HDR) - nr)
+			goto corrupt;
+
+		/* Get the rest of the header from the in-memory buffer. */
+		memcpy((u_int8_t *)&hdr + nr, lp->buf, sizeof(HDR) - nr);
+		shortp = lp->buf + (sizeof(HDR) - nr);
+	}
+
+	/*
+	 * Check for buffers of 0's, that's what we usually see during
+	 * recovery, although it's certainly not something on which we
+	 * can depend.
+	 */
+	if (hdr.len <= sizeof(HDR))
+		goto corrupt;
+	len = hdr.len - sizeof(HDR);
+
+	/* If we've already moved to the in-memory buffer, fill from there. */
+	if (shortp != NULL) {
+		if (lp->b_off < ((u_int8_t *)shortp - lp->buf) + len)
+			goto corrupt;
+		if ((ret = __db_retcopy(dbt, shortp, len,
+		    &dblp->c_dbt.data, &dblp->c_dbt.ulen, NULL)) != 0)
+			goto err1;
+		goto cksum;
+	}
+
+	/* Allocate temporary memory to hold the record. */
+	if ((tbuf = (char *)malloc(len)) == NULL) {
+		ret = ENOMEM;
+		goto err1;
+	}
+
+	/*
+	 * Read the record into the buffer.  If read returns a short count,
+	 * there was an error or the rest of the record is in the in-memory
+	 * buffer.  Note, the information may be garbage if we're in recovery,
+	 * so don't read past the end of the buffer's memory.
+	 */
+	if ((ret = __db_read(dblp->c_fd, tbuf, len, &nr)) != 0) {
+		fail = "read";
+		goto err1;
+	}
+	if (len - nr > sizeof(lp->buf))
+		goto corrupt;
+	if (nr != (ssize_t)len) {
+		if (lp->b_off < len - nr)
+			goto corrupt;
+
+		/* Get the rest of the record from the in-memory buffer. */
+		memcpy((u_int8_t *)tbuf + nr, lp->buf, len - nr);
+	}
+
+	/* Copy the record into the user's DBT. */
+	if ((ret = __db_retcopy(dbt, tbuf, len,
+	    &dblp->c_dbt.data, &dblp->c_dbt.ulen, NULL)) != 0)
+		goto err1;
+	free(tbuf);
+
+cksum:	if (hdr.cksum != __ham_func4(dbt->data, dbt->size)) {
+		if (!silent)
+			__db_err(dblp->dbenv, "log_get: checksum mismatch");
+		goto corrupt;
+	}
+
+	/* Update the cursor and the return lsn. */
+	dblp->c_off = hdr.prev;
+	dblp->c_len = hdr.len;
+	dblp->c_lsn = *alsn = nlsn;
+
+	return (0);
+
+corrupt:/*
+	 * This is the catchall -- for some reason we didn't find enough
+	 * information or it wasn't reasonable information, and it wasn't
+	 * because a system call failed.
+	 */
+	ret = EIO;
+	fail = "read";
+
+err1:	if (!silent)
+		if (fail == NULL)
+			__db_err(dblp->dbenv, "log_get: %s", strerror(ret));
+		else
+			__db_err(dblp->dbenv,
+			    "log_get: %s: %s", fail, strerror(ret));
+err2:	if (np != NULL)
+		free(np);
+	if (tbuf != NULL)
+		free(tbuf);
+	return (ret);
+}
generated by cgit-pink 1.4.1 (git 2.36.1) at 2024-12-12 00:13:30 +0000