d/freebsd-skq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Set read buffer size to multiple of sizeof(struct futx).

Browse Source 
If the utmpx database gets updated while an application is reading it,
there is a chance the reading application processes partially
overwritten entries. To solve this, make sure we always read a multiple
of sizeof(struct futx) at a time.

MFC after:	2 weeks
This commit is contained in:
ed 2012-02-11 11:11:13 +00:00
parent 0e68cca864
commit aa3326a535
1 changed files with 12 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
lib/libc/gen/getutxent.c
View File

@ -70,13 +70,18 @@ setutxdb(int db, const char *file)
if (uf == NULL)
return (-1);
/* Safety check: never use broken files. */
if (db != UTXDB_LOG && _fstat(fileno(uf), &sb) != -1 &&
sb.st_size % sizeof(struct futx) != 0) {
fclose(uf);
uf = NULL;
errno = EFTYPE;
return (-1);
if (db != UTXDB_LOG) {
/* Safety check: never use broken files. */
if (_fstat(fileno(uf), &sb) != -1 &&
sb.st_size % sizeof(struct futx) != 0) {
fclose(uf);
uf = NULL;
errno = EFTYPE;
return (-1);
}
/* Prevent reading of partial records. */
(void)setvbuf(uf, NULL, _IOFBF,
rounddown(BUFSIZ, sizeof(struct futx)));
}
udb = db;