Add the ".repair" command to the command-line shell.

FossilOrigin-Name: d1dfadea87ecf18eeb6d2f21769deaa97473ca0e

1 files changed, 194 insertions, 0 deletions

diff --git a/src/shell.c b/src/shell.c
index 1c4c4ad3e..68f2ef2af 100644
--- a/src/shell.c
+++ b/src/shell.c
@@ -1581,6 +1581,7 @@ static char zHelp[] =
   ".prompt MAIN CONTINUE  Replace the standard prompts\n"
   ".quit                  Exit this program\n"
   ".read FILENAME         Execute SQL in FILENAME\n"
+  ".repair NEWDB          Recover data into NEWDB from a corrupt database\n"
   ".restore ?DB? FILE     Restore content of DB (default \"main\") from FILE\n"
   ".schema ?TABLE?        Show the CREATE statements\n"
   "                         If TABLE specified, only show tables matching\n"
@@ -1897,6 +1898,195 @@ static char *csv_read_one_field(CSVReader *p){
 }
 
 /*
+** Try to transfer data for table zTable
+*/
+static void tryToRepairData(
+  struct callback_data *p,
+  sqlite3 *newDb,
+  const char *zTable
+){
+  sqlite3_stmt *pQuery = 0; 
+  sqlite3_stmt *pInsert = 0;
+  char *zQuery = 0;
+  char *zInsert = 0;
+  int rc;
+  int i, j, n;
+  int nTable = (int)strlen(zTable);
+  int k = 0;
+
+  zQuery = sqlite3_mprintf("SELECT * FROM \"%w\"", zTable);
+  rc = sqlite3_prepare_v2(p->db, zQuery, -1, &pQuery, 0);
+  if( rc ){
+    fprintf(stderr, "Error: (%d) %s on [%s]\n",
+            sqlite3_extended_errcode(p->db), sqlite3_errmsg(p->db),
+            zQuery);
+    goto end_data_xfer;
+  }
+  n = sqlite3_column_count(pQuery);
+  zInsert = sqlite3_malloc(200 + nTable + n*3);
+  if( zInsert==0 ){
+    fprintf(stderr, "out of memory\n");
+    goto end_data_xfer;
+  }
+  sqlite3_snprintf(200+nTable,zInsert,
+                   "INSERT OR IGNORE INTO \"%s\" VALUES(?", zTable);
+  i = (int)strlen(zInsert);
+  for(j=1; j<n; j++){
+    memcpy(zInsert+i, ",?", 2);
+    i += 2;
+  }
+  memcpy(zInsert+i, ");", 3);
+  rc = sqlite3_prepare_v2(newDb, zInsert, -1, &pInsert, 0);
+  if( rc ){
+    fprintf(stderr, "Error: (%d) %s on [%s]\n",
+            sqlite3_extended_errcode(newDb), sqlite3_errmsg(newDb),
+            zQuery);
+    goto end_data_xfer;
+  }
+  for(k=0; k<2; k++){
+    while( (rc = sqlite3_step(pQuery))==SQLITE_ROW ){
+      for(i=0; i<n; i++){
+        switch( sqlite3_column_type(pQuery, i) ){
+          case SQLITE_NULL: {
+            sqlite3_bind_null(pInsert, i+1);
+            break;
+          }
+          case SQLITE_INTEGER: {
+            sqlite3_bind_int64(pInsert, i+1, sqlite3_column_int64(pQuery,i));
+            break;
+          }
+          case SQLITE_FLOAT: {
+            sqlite3_bind_double(pInsert, i+1, sqlite3_column_double(pQuery,i));
+            break;
+          }
+          case SQLITE_TEXT: {
+            sqlite3_bind_text(pInsert, i+1,
+                             (const char*)sqlite3_column_text(pQuery,i),
+                             -1, SQLITE_STATIC);
+            break;
+          }
+          case SQLITE_BLOB: {
+            sqlite3_bind_blob(pInsert, i+1, sqlite3_column_blob(pQuery,i),
+                                            sqlite3_column_bytes(pQuery,i),
+                                            SQLITE_STATIC);
+            break;
+          }
+        }
+      } /* End for */
+      sqlite3_step(pInsert);
+      sqlite3_reset(pInsert);
+    } /* End while */
+    if( rc==SQLITE_DONE ) break;
+    sqlite3_finalize(pQuery);
+    sqlite3_free(zQuery);
+    zQuery = sqlite3_mprintf("SELECT * FROM \"%w\" ORDER BY rowid DESC;",
+                             zTable);
+    rc = sqlite3_prepare_v2(p->db, zQuery, -1, &pQuery, 0);
+    if( rc ){
+       fprintf(stderr, "Error: (%d) %s on [%s]\n",
+          sqlite3_extended_errcode(p->db), sqlite3_errmsg(p->db),
+          zQuery);
+       goto end_data_xfer;
+    }
+  } /* End for(k=0...) */
+
+end_data_xfer:
+  sqlite3_finalize(pQuery);
+  sqlite3_finalize(pInsert);
+  sqlite3_free(zQuery);
+  sqlite3_free(zInsert);
+}
+
+
+/*
+** Try to transfer all rows of the schema that match zWhere.  For
+** each row, invoke xForEach() on the object defined by that row.
+*/
+static void tryToRepairSchema(
+  struct callback_data *p,
+  sqlite3 *newDb,
+  const char *zWhere,
+  void (*xForEach)(struct callback_data*,sqlite3*,const char*)
+){
+  sqlite3_stmt *pQuery = 0;
+  char *zQuery = 0;
+  int rc;
+  const unsigned char *zName;
+  const unsigned char *zSql;
+
+  zQuery = sqlite3_mprintf("SELECT name, sql FROM sqlite_master"
+                           " WHERE %s", zWhere);
+  rc = sqlite3_prepare_v2(p->db, zQuery, -1, &pQuery, 0);
+  if( rc ){
+    fprintf(stderr, "Error: (%d) %s on [%s]\n",
+                    sqlite3_extended_errcode(p->db), sqlite3_errmsg(p->db),
+                    zQuery);
+    goto end_schema_xfer;
+  }
+  while( (rc = sqlite3_step(pQuery))==SQLITE_ROW ){
+    zName = sqlite3_column_text(pQuery, 0);
+    zSql = sqlite3_column_text(pQuery, 1);
+    printf("%s... ", zName); fflush(stdout);
+    sqlite3_exec(newDb, (const char*)zSql, 0, 0, 0);
+    if( xForEach ){
+      xForEach(p, newDb, (const char*)zName);
+    }
+    printf("done\n");
+  }
+  if( rc!=SQLITE_DONE ){
+    sqlite3_finalize(pQuery);
+    sqlite3_free(zQuery);
+    zQuery = sqlite3_mprintf("SELECT name, sql FROM sqlite_master"
+                             " WHERE %s ORDER BY rowid DESC", zWhere);
+    rc = sqlite3_prepare_v2(p->db, zQuery, -1, &pQuery, 0);
+    if( rc ){
+      fprintf(stderr, "Error: (%d) %s on [%s]\n",
+                      sqlite3_extended_errcode(p->db), sqlite3_errmsg(p->db),
+                      zQuery);
+      goto end_schema_xfer;
+    }
+    while( (rc = sqlite3_step(pQuery))==SQLITE_ROW ){
+      zName = sqlite3_column_text(pQuery, 0);
+      zSql = sqlite3_column_text(pQuery, 1);
+      printf("%s... ", zName); fflush(stdout);
+      sqlite3_exec(newDb, (const char*)zSql, 0, 0, 0);
+      if( xForEach ){
+        xForEach(p, newDb, (const char*)zName);
+      }
+      printf("done\n");
+    }
+  }
+end_schema_xfer:
+  sqlite3_finalize(pQuery);
+  sqlite3_free(zQuery);
+}
+
+/*
+** Open a new database file named "zNewDb".  Try to recover as much information
+** as possible out of the main database (which might be corrupt) and write it
+** into zNewDb.
+*/
+static void tryToRepair(struct callback_data *p, const char *zNewDb){
+  int rc;
+  sqlite3 *newDb = 0;
+  if( access(zNewDb,0)==0 ){
+    fprintf(stderr, "File \"%s\" already exists.\n", zNewDb);
+    return;
+  }
+  rc = sqlite3_open(zNewDb, &newDb);
+  if( rc ){
+    fprintf(stderr, "Cannot create output database: %s\n",
+            sqlite3_errmsg(newDb));
+  }else{
+    sqlite3_exec(newDb, "BEGIN EXCLUSIVE;", 0, 0, 0);
+    tryToRepairSchema(p, newDb, "type='table'", tryToRepairData);
+    tryToRepairSchema(p, newDb, "type!='table'", 0);
+    sqlite3_exec(newDb, "COMMIT;", 0, 0, 0);
+  }
+  sqlite3_close(newDb);
+}
+
+/*
 ** If an input line begins with "." then invoke this routine to
 ** process that line.
 **
@@ -2495,6 +2685,10 @@ static int do_meta_command(char *zLine, struct callback_data *p){
     }
   }else
 
+  if( c=='r' && strncmp(azArg[0], "repair", n)==0 && nArg>1 && nArg<3 ){
+    tryToRepair(p, azArg[1]);
+  }else
+
   if( c=='r' && n>=3 && strncmp(azArg[0], "restore", n)==0 && nArg>1 && nArg<4){
     const char *zSrcFile;
     const char *zDb;