static void
get_program_dir(const unsigned char *program_path)
{
unsigned char *workdir = 0;
unsigned char fullpath[EJ_PATH_MAX];
if (os_IsAbsolutePath(program_path)) {
program_dir = os_DirName(program_path);
os_normalize_path(program_dir);
return;
}
workdir = os_GetWorkingDir();
snprintf(fullpath, sizeof(fullpath), "%s/%s", workdir, program_path);
xfree(workdir); workdir = 0;
os_normalize_path(fullpath);
program_dir = os_DirName(fullpath);
}
/**
* NAME: os_SetLock
* PURPOSE: set the lockfile with the specified name
* ARGS: path - lock file path
* perms - file permissions
* left_open - 1, if the function should return the open file
* 0, if the function should close the file
* RETURN: >= 0 - ok, -1 - file is locked, -2 - other error
* NOTE: function works reliably over NFS (Network Failure System)
*/
int
os_SetLock(char const *path, int perms, int left_open)
{
char *dirname = os_DirName(path);
char *hostname = os_NodeName();
char *uniq_name = 0;
int fd = -1;
int code = 0;
int file_flag = 0;
struct stat buf;
/* 1. Create the unique file on the same filesystem */
uniq_name = xmalloc(strlen(dirname) + strlen(hostname) + 32);
sprintf(uniq_name, "%s/LCK_%s_%d", dirname, hostname, (int) getpid());
if ((fd = open(uniq_name, O_WRONLY | O_CREAT, perms)) < 0) {
code = -2;
goto free_resources;
}
file_flag = 1;
/* 2. Use link(2) to create a link to the lockfile */
/* do not use the return value of link call */
link(uniq_name, path);
/* 3. Use stat(2) on the unique file to check that the link count
is increased to 2 */
if (fstat(fd, &buf) < 0) {
code = -2;
goto free_resources;
}
if (buf.st_nlink != 2) {
code = -1;
goto free_resources;
}
/* at this point lock file is created */
if (left_open) {
code = fd;
fd = -1;
}
free_resources:
if (file_flag) unlink(uniq_name);
free(uniq_name);
free(dirname);
if (fd >= 0) close(fd);
return code;
}
