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Fix tmpfile(3) insecure file creation.

This commit is contained in:
Jonas 'Sortie' Termansen 2015-10-10 01:24:43 +02:00
parent 7c6e6ef317
commit f0f82fcb23
1 changed files with 14 additions and 8 deletions
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22
libc/stdio/tmpfile.cpp
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@ -1,6 +1,6 @@
/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2013.
Copyright(C) Jonas 'Sortie' Termansen 2013, 2015.
This file is part of the Sortix C Library.
@ -25,15 +25,21 @@
#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
extern "C" FILE* tmpfile()
{
char name[5 + sizeof(pid_t) * 3];
snprintf(name, sizeof(name), "/tmp/%ju", (uintmax_t) getpid());
FILE* ret = fopen(name, "w+");
if ( !ret )
return NULL;
unlink(name);
return ret;
// TODO: There is a short interval during which other processes can access
// this file. Implement and use O_TMPFILE.
char path[] = "/tmp/tmp.XXXXXX";
int fd = mkstemp(path);
if ( fd < 0 )
return (FILE*) NULL;
if ( unlink(path) < 0 )
return close(fd), (FILE*) NULL;
FILE* fp = fdopen(fd, "r+");
if ( !fp )
return close(fd), (FILE*) NULL;
return fp;
}