diff options
author | Hans-Christoph Steiner <hans@eds.org> | 2012-03-30 20:42:12 -0400 |
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committer | Hans-Christoph Steiner <hans@eds.org> | 2012-03-30 20:42:12 -0400 |
commit | 7bb481fda9ecb134804b49c2ce77ca28f7eea583 (patch) | |
tree | 31b520b9914d3e2453968abe375f2c102772c3dc /tool/offsets.c |
Imported Upstream version 2.0.3
Diffstat (limited to 'tool/offsets.c')
-rw-r--r-- | tool/offsets.c | 329 |
1 files changed, 329 insertions, 0 deletions
diff --git a/tool/offsets.c b/tool/offsets.c new file mode 100644 index 0000000..8e098e7 --- /dev/null +++ b/tool/offsets.c @@ -0,0 +1,329 @@ +/* +** This program searches an SQLite database file for the lengths and +** offsets for all TEXT or BLOB entries for a particular column of a +** particular table. The rowid, size and offset for the column are +** written to standard output. There are three arguments, which are the +** name of the database file, the table, and the column. +*/ +#include "sqlite3.h" +#include <stdio.h> +#include <stdlib.h> +#include <stdarg.h> +#include <string.h> + +typedef unsigned char u8; +typedef struct GState GState; + +#define ArraySize(X) (sizeof(X)/sizeof(X[0])) + +/* +** Global state information for this program. +*/ +struct GState { + char *zErr; /* Error message text */ + FILE *f; /* Open database file */ + int szPg; /* Page size for the database file */ + int iRoot; /* Root page of the table */ + int iCol; /* Column number for the column */ + int pgno; /* Current page number */ + u8 *aPage; /* Current page content */ + u8 *aStack[20]; /* Page stack */ + int aPgno[20]; /* Page number stack */ + int nStack; /* Depth of stack */ + int bTrace; /* True for tracing output */ +}; + +/* +** Write an error. +*/ +static void ofstError(GState *p, const char *zFormat, ...){ + va_list ap; + sqlite3_free(p->zErr); + va_start(ap, zFormat); + p->zErr = sqlite3_vmprintf(zFormat, ap); + va_end(ap); +} + +/* +** Write a trace message +*/ +static void ofstTrace(GState *p, const char *zFormat, ...){ + va_list ap; + if( p->bTrace ){ + va_start(ap, zFormat); + vprintf(zFormat, ap); + va_end(ap); + } +} + +/* +** Find the root page of the table and the column number of the column. +*/ +static void ofstRootAndColumn( + GState *p, /* Global state */ + const char *zFile, /* Name of the database file */ + const char *zTable, /* Name of the table */ + const char *zColumn /* Name of the column */ +){ + sqlite3 *db = 0; + sqlite3_stmt *pStmt = 0; + char *zSql = 0; + int rc; + if( p->zErr ) return; + rc = sqlite3_open(zFile, &db); + if( rc ){ + ofstError(p, "cannot open database file \"%s\"", zFile); + goto rootAndColumn_exit; + } + zSql = sqlite3_mprintf("SELECT rootpage FROM sqlite_master WHERE name=%Q", + zTable); + rc = sqlite3_prepare_v2(db, zSql, -1, &pStmt, 0); + if( rc ) ofstError(p, "%s: [%s]", sqlite3_errmsg(db), zSql); + sqlite3_free(zSql); + if( p->zErr ) goto rootAndColumn_exit; + if( sqlite3_step(pStmt)!=SQLITE_ROW ){ + ofstError(p, "cannot find table [%s]\n", zTable); + sqlite3_finalize(pStmt); + goto rootAndColumn_exit; + } + p->iRoot = sqlite3_column_int(pStmt , 0); + sqlite3_finalize(pStmt); + + p->iCol = -1; + zSql = sqlite3_mprintf("PRAGMA table_info(%Q)", zTable); + rc = sqlite3_prepare_v2(db, zSql, -1, &pStmt, 0); + if( rc ) ofstError(p, "%s: [%s}", sqlite3_errmsg(db), zSql); + sqlite3_free(zSql); + if( p->zErr ) goto rootAndColumn_exit; + while( sqlite3_step(pStmt)==SQLITE_ROW ){ + const char *zCol = sqlite3_column_text(pStmt, 1); + if( strlen(zCol)==strlen(zColumn) + && sqlite3_strnicmp(zCol, zColumn, strlen(zCol))==0 + ){ + p->iCol = sqlite3_column_int(pStmt, 0); + break; + } + } + sqlite3_finalize(pStmt); + if( p->iCol<0 ){ + ofstError(p, "no such column: %s.%s", zTable, zColumn); + goto rootAndColumn_exit; + } + + zSql = sqlite3_mprintf("PRAGMA page_size"); + rc = sqlite3_prepare_v2(db, zSql, -1, &pStmt, 0); + if( rc ) ofstError(p, "%s: [%s]", sqlite3_errmsg(db), zSql); + sqlite3_free(zSql); + if( p->zErr ) goto rootAndColumn_exit; + if( sqlite3_step(pStmt)!=SQLITE_ROW ){ + ofstError(p, "cannot find page size"); + }else{ + p->szPg = sqlite3_column_int(pStmt, 0); + } + sqlite3_finalize(pStmt); + +rootAndColumn_exit: + sqlite3_close(db); + return; +} + +/* +** Pop a page from the stack +*/ +static void ofstPopPage(GState *p){ + if( p->nStack<=0 ) return; + p->nStack--; + sqlite3_free(p->aStack[p->nStack]); + p->pgno = p->aPgno[p->nStack-1]; + p->aPage = p->aStack[p->nStack-1]; +} + + +/* +** Push a new page onto the stack. +*/ +static void ofstPushPage(GState *p, int pgno){ + u8 *pPage; + size_t got; + if( p->zErr ) return; + if( p->nStack >= ArraySize(p->aStack) ){ + ofstError(p, "page stack overflow"); + return; + } + p->aPgno[p->nStack] = pgno; + p->aStack[p->nStack] = pPage = sqlite3_malloc( p->szPg ); + if( pPage==0 ){ + fprintf(stderr, "out of memory\n"); + exit(1); + } + p->nStack++; + p->aPage = pPage; + p->pgno = pgno; + fseek(p->f, (pgno-1)*p->szPg, SEEK_SET); + got = fread(pPage, 1, p->szPg, p->f); + if( got!=p->szPg ){ + ofstError(p, "unable to read page %d", pgno); + ofstPopPage(p); + } +} + +/* Read a two-byte integer at the given offset into the current page */ +static int ofst2byte(GState *p, int ofst){ + int x = p->aPage[ofst]; + return (x<<8) + p->aPage[ofst+1]; +} + +/* Read a four-byte integer at the given offset into the current page */ +static int ofst4byte(GState *p, int ofst){ + int x = p->aPage[ofst]; + x = (x<<8) + p->aPage[ofst+1]; + x = (x<<8) + p->aPage[ofst+2]; + x = (x<<8) + p->aPage[ofst+3]; + return x; +} + +/* Read a variable-length integer. Update the offset */ +static sqlite3_int64 ofstVarint(GState *p, int *pOfst){ + sqlite3_int64 x = 0; + u8 *a = &p->aPage[*pOfst]; + int n = 0; + while( n<8 && (a[0] & 0x80)!=0 ){ + x = (x<<7) + (a[0] & 0x7f); + n++; + a++; + } + if( n==8 ){ + x = (x<<8) + a[0]; + }else{ + x = (x<<7) + a[0]; + } + *pOfst += (n+1); + return x; +} + +/* Return the absolute offset into a file for the given offset +** into the current page */ +static int ofstInFile(GState *p, int ofst){ + return p->szPg*(p->pgno-1) + ofst; +} + +/* Return the size (in bytes) of the data corresponding to the +** given serial code */ +static int ofstSerialSize(int scode){ + if( scode<5 ) return scode; + if( scode==5 ) return 6; + if( scode<8 ) return 8; + if( scode<12 ) return 0; + return (scode-12)/2; +} + +/* Forward reference */ +static void ofstWalkPage(GState*, int); + +/* Walk an interior btree page */ +static void ofstWalkInteriorPage(GState *p){ + int nCell; + int i; + int ofst; + int iChild; + + nCell = ofst2byte(p, 3); + for(i=0; i<nCell; i++){ + ofst = ofst2byte(p, 12+i*2); + iChild = ofst4byte(p, ofst); + ofstWalkPage(p, iChild); + if( p->zErr ) return; + } + ofstWalkPage(p, ofst4byte(p, 8)); +} + +/* Walk a leaf btree page */ +static void ofstWalkLeafPage(GState *p){ + int nCell; + int i; + int ofst; + int nPayload; + sqlite3_int64 rowid; + int nHdr; + int j; + int scode; + int sz; + int dataOfst; + char zMsg[200]; + + nCell = ofst2byte(p, 3); + for(i=0; i<nCell; i++){ + ofst = ofst2byte(p, 8+i*2); + nPayload = ofstVarint(p, &ofst); + rowid = ofstVarint(p, &ofst); + if( nPayload > p->szPg-35 ){ + sqlite3_snprintf(sizeof(zMsg), zMsg, + "# overflow rowid %lld", rowid); + printf("%s\n", zMsg); + continue; + } + dataOfst = ofst; + nHdr = ofstVarint(p, &ofst); + dataOfst += nHdr; + for(j=0; j<p->iCol; j++){ + scode = ofstVarint(p, &ofst); + dataOfst += ofstSerialSize(scode); + } + scode = ofstVarint(p, &ofst); + sz = ofstSerialSize(scode); + sqlite3_snprintf(sizeof(zMsg), zMsg, + "rowid %12lld size %5d offset %8d", + rowid, sz, ofstInFile(p, dataOfst)); + printf("%s\n", zMsg); + } +} + +/* +** Output results from a single page. +*/ +static void ofstWalkPage(GState *p, int pgno){ + if( p->zErr ) return; + ofstPushPage(p, pgno); + if( p->zErr ) return; + if( p->aPage[0]==5 ){ + ofstWalkInteriorPage(p); + }else if( p->aPage[0]==13 ){ + ofstWalkLeafPage(p); + }else{ + ofstError(p, "page %d has a faulty type byte: %d", pgno, p->aPage[0]); + } + ofstPopPage(p); +} + +int main(int argc, char **argv){ + GState g; + memset(&g, 0, sizeof(g)); + if( argc>2 && strcmp(argv[1],"--trace")==0 ){ + g.bTrace = 1; + argc--; + argv++; + } + if( argc!=4 ){ + fprintf(stderr, "Usage: %s DATABASE TABLE COLUMN\n", *argv); + exit(1); + } + ofstRootAndColumn(&g, argv[1], argv[2], argv[3]); + if( g.zErr ){ + fprintf(stderr, "%s\n", g.zErr); + exit(1); + } + ofstTrace(&g, "# szPg = %d\n", g.szPg); + ofstTrace(&g, "# iRoot = %d\n", g.iRoot); + ofstTrace(&g, "# iCol = %d\n", g.iCol); + g.f = fopen(argv[1], "rb"); + if( g.f==0 ){ + fprintf(stderr, "cannot open \"%s\"\n", argv[1]); + exit(1); + } + ofstWalkPage(&g, g.iRoot); + if( g.zErr ){ + fprintf(stderr, "%s\n", g.zErr); + exit(1); + } + return 0; +} |