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/*
* lckfiles.c set_lock() and release_lock(), for maintaining
* little file.lck style lockfiles. this isn't what
* we would call a standard mechanism. but it's simple.
*
* it's also not completely integrated with the editor --
* for instance, one can probably bypass the locking mechanism
* in various ways. it is intended as an _aid_ to multiple
* edits. _not_ a cure-all. it works well for the people
* at Baan who contributed the code. i make no other claims
* for it.
*
* operation: if the global "usefilelock" is on, then when
* "file" is edited, a "file.lck" is created, containing the
* username of the user doing the editing. when a file is
* edited for which there already exists a .lck file, the buffer
* mode "locked" is set to true and "locker" is set to the name
* of the user that created the .lck. this infomation will
* appear on the status line, as "locked by pgf", and the
* buffer will be marked readonly. the .lck file will be
* deleted at most of the appropriate times.
*
* $Header: /usr/build/vile/vile/RCS/lckfiles.c,v 1.11 2002/10/09 19:06:58 tom Exp $
*
*/
#include "estruct.h"
#include "edef.h"
#if OPT_LCKFILES
#ifndef HAVE_LONG_FILE_NAMES
You probably would not want this code:
there are no checks on filename length when adding.lck to the end.
#endif
static void
get_lock_owner(char *lockfile, char *who, int n)
{
FILE *fp;
int l;
if ((fp = fopen(lockfile, FOPEN_READ)) != (FILE *) 0) {
l = read(fileno(fp), who, (size_t) (n - 1));
if (l < 0) {
(void) strcpy(who, "'Can't read .lck'");
} else {
who[l - 1] = EOS; /* Strip \n */
}
fclose(fp);
} else {
(void) strcpy(who, "'Can't open .lck'");
}
}
static char *
ourname(void)
{
char *np;
np = getenv("LOGNAME");
if (!np)
np = getenv("USER");
if (!np)
np = "unknown";
return np;
}
int
set_lock(const char *fname, char *who, int n)
{
char lockfile[NFILEN];
FILE *fp;
sprintf(lockfile, "%s.lck", fname);
if (ffexists(lockfile)) {
/* Lockfile exists */
get_lock_owner(lockfile, who, n);
mlwrite("[%s]", who);
return FALSE; /* Can't set lock */
} else {
if ((fp = fopen(lockfile, FOPEN_WRITE)) != (FILE *) 0) {
(void) lsprintf(who, "%s\n", ourname());
write(fileno(fp), who, strlen(who));
fclose(fp);
} else {
(void) strcpy(who, "'Can't write .lck'");
mlwrite("[%s]", who);
return (FALSE); /* Can't set lock */
}
}
return TRUE; /* Lock ok */
}
void
release_lock(const char *fname)
{
char lockfile[NFILEN];
char who[100];
if (fname && *fname) {
(void) lsprintf(lockfile, "%s.lck", fname);
get_lock_owner(lockfile, who, sizeof(who));
/* is it ours? */
if (strcmp(who, ourname()) == 0)
unlink(lockfile);
}
}
#endif
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