Make our mktemp(3) callback-driven and split into multiple files.

Previously, calling any of the mktemp(3) family would pull in
lstat(2), open(2) and mkdir(2).  Now, only the necessary system
calls will be reachable from the binary.  OK deraadt@ guenther@

1 files changed, 11 insertions, 126 deletions

diff --git a/src/lib/libc/stdlib/mktemp.c b/src/lib/libc/stdlib/mktemp.c
index 3b8bba7846..4dc06f74d1 100644
--- a/src/lib/libc/stdlib/mktemp.c
+++ b/src/lib/libc/stdlib/mktemp.c
@@ -1,7 +1,6 @@
-/*      $OpenBSD: mktemp.c,v 1.1 2024/01/19 16:30:28 millert Exp $ */
+/*      $OpenBSD: mktemp.c,v 1.2 2024/01/19 19:45:02 millert Exp $ */
 /*
- * Copyright (c) 1996-1998, 2008 Theo de Raadt
- * Copyright (c) 1997, 2008-2009 Todd C. Miller
+ * Copyright (c) 2024 Todd C. Miller
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -16,106 +15,27 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-#include <sys/types.h>
 #include <sys/stat.h>
 #include <errno.h>
-#include <fcntl.h>
-#include <limits.h>
-#include <stdio.h>
 #include <stdlib.h>
-#include <string.h>
-#include <ctype.h>
-#include <unistd.h>
-
-#define MKTEMP_NAME     0
-#define MKTEMP_FILE     1
-#define MKTEMP_DIR      2
-
-#define TEMPCHARS       "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
-#define NUM_CHARS       (sizeof(TEMPCHARS) - 1)
-#define MIN_X           6
-
-#define MKOTEMP_FLAGS   (O_APPEND | O_CLOEXEC | O_DSYNC | O_RSYNC | O_SYNC)
-
-#ifndef nitems
-#define nitems(_a)      (sizeof((_a)) / sizeof((_a)[0]))
-#endif
 
 static int
-mktemp_internal(char *path, int slen, int mode, int flags)
+mktemp_cb(const char *path, int flags)
 {
-        char *start, *cp, *ep;
-        const char tempchars[] = TEMPCHARS;
-        unsigned int tries;
         struct stat sb;
-        size_t len;
-        int fd;
-
-        len = strlen(path);
-        if (len < MIN_X || slen < 0 || (size_t)slen > len - MIN_X) {
-                errno = EINVAL;
-                return(-1);
-        }
-        ep = path + len - slen;
-
-        for (start = ep; start > path && start[-1] == 'X'; start--)
-                ;
-        if (ep - start < MIN_X) {
-                errno = EINVAL;
-                return(-1);
-        }
-
-        if (flags & ~MKOTEMP_FLAGS) {
-                errno = EINVAL;
-                return(-1);
-        }
-        flags |= O_CREAT | O_EXCL | O_RDWR;
 
-        tries = INT_MAX;
-        do {
-                cp = start;
-                do {
-                        unsigned short rbuf[16];
-                        unsigned int i;
-
-                        /*
-                         * Avoid lots of arc4random() calls by using
-                         * a buffer sized for up to 16 Xs at a time.
-                         */
-                        arc4random_buf(rbuf, sizeof(rbuf));
-                        for (i = 0; i < nitems(rbuf) && cp != ep; i++)
-                                *cp++ = tempchars[rbuf[i] % NUM_CHARS];
-                } while (cp != ep);
-
-                switch (mode) {
-                case MKTEMP_NAME:
-                        if (lstat(path, &sb) != 0)
-                                return(errno == ENOENT ? 0 : -1);
-                        break;
-                case MKTEMP_FILE:
-                        fd = open(path, flags, S_IRUSR|S_IWUSR);
-                        if (fd != -1 || errno != EEXIST)
-                                return(fd);
-                        break;
-                case MKTEMP_DIR:
-                        if (mkdir(path, S_IRUSR|S_IWUSR|S_IXUSR) == 0)
-                                return(0);
-                        if (errno != EEXIST)
-                                return(-1);
-                        break;
-                }
-        } while (--tries);
-
-        errno = EEXIST;
-        return(-1);
+        if (lstat(path, &sb) == 0)
+                errno = EEXIST;
+        return (errno == ENOENT ? 0 : -1);
 }
 
+/* Also called via tmpnam(3) and tempnam(3). */
 char *
 _mktemp(char *path)
 {
-        if (mktemp_internal(path, 0, MKTEMP_NAME, 0) == -1)
-                return(NULL);
-        return(path);
+        if (__mktemp4(path, 0, 0, mktemp_cb) == 0)
+                return path;
+        return NULL;
 }
 
 __warn_references(mktemp,
@@ -124,40 +44,5 @@ __warn_references(mktemp,
 char *
 mktemp(char *path)
 {
-        return(_mktemp(path));
-}
-
-int
-mkostemps(char *path, int slen, int flags)
-{
-        return(mktemp_internal(path, slen, MKTEMP_FILE, flags));
-}
-
-int
-mkstemp(char *path)
-{
-        return(mktemp_internal(path, 0, MKTEMP_FILE, 0));
-}
-DEF_WEAK(mkstemp);
-
-int
-mkostemp(char *path, int flags)
-{
-        return(mktemp_internal(path, 0, MKTEMP_FILE, flags));
-}
-DEF_WEAK(mkostemp);
-
-int
-mkstemps(char *path, int slen)
-{
-        return(mktemp_internal(path, slen, MKTEMP_FILE, 0));
-}
-
-char *
-mkdtemp(char *path)
-{
-        int error;
-
-        error = mktemp_internal(path, 0, MKTEMP_DIR, 0);
-        return(error ? NULL : path);
+        return _mktemp(path);
 }