[sql] Import reference version of SQLite 3.17..

third_party/sqlite/sqlite-src-3170000/tool/showlocks.c

+/*
+** This file implements a simple command-line utility that shows all of the
+** Posix Advisory Locks on a file.
+**
+** Usage:
+**
+**     showlocks FILENAME
+**
+** To compile:  gcc -o showlocks showlocks.c
+*/
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+
+/* This utility only looks for locks in the first 2 billion bytes */
+#define MX_LCK 2147483647
+
+/*
+** Print all locks on the inode of "fd" that occur in between
+** lwr and upr, inclusive.
+*/
+static int showLocksInRange(int fd, off_t lwr, off_t upr){
+  int cnt = 0;
+  struct flock x;
+
+  x.l_type = F_WRLCK;
+  x.l_whence = SEEK_SET;
+  x.l_start = lwr;
+  x.l_len = upr-lwr;
+  fcntl(fd, F_GETLK, &x);
+  if( x.l_type==F_UNLCK ) return 0;
+  printf("start: %-12d len: %-5d pid: %-5d type: %s\n",
+       (int)x.l_start, (int)x.l_len,
+       x.l_pid, x.l_type==F_WRLCK ? "WRLCK" : "RDLCK");
+  cnt++;
+  if( x.l_start>lwr ){
+    cnt += showLocksInRange(fd, lwr, x.l_start-1);
+  }
+  if( x.l_start+x.l_len<upr ){
+    cnt += showLocksInRange(fd, x.l_start+x.l_len+1, upr);
+  }
+  return cnt;
+}
+
+int main(int argc, char **argv){
+  int fd;
+  int cnt;
+
+  if( argc!=2 ){
+    fprintf(stderr, "Usage: %s FILENAME\n", argv[0]);
+    return 1;
+  }
+  fd = open(argv[1], O_RDWR, 0);
+  if( fd<0 ){
+    fprintf(stderr, "%s: cannot open %s\n", argv[0], argv[1]);
+    return 1;
+  }
+  cnt = showLocksInRange(fd, 0, MX_LCK);
+  if( cnt==0 ) printf("no locks\n");  
+  close(fd);
+  return 0;
+}