Almost done on tmpfile / tmpnam.

[pdclib] / platform / example / functions / stdio / tmpfile.c

diff --git a/platform/example/functions/stdio/tmpfile.c b/platform/example/functions/stdio/tmpfile.c
index 255a35eb75721d58d352cd1279a1dd7f3fdda622..4c55e5d3542a4c4db4f16f14fcd7d8425b6050ec 100644 (file)
--- a/platform/example/functions/stdio/tmpfile.c
+++ b/platform/example/functions/stdio/tmpfile.c
@@ -10,10 +10,79 @@
 
 #ifndef REGTEST
 
+#include <inttypes.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <_PDCLIB_glue.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+extern struct _PDCLIB_file_t * _PDCLIB_filelist;
+
+/* This is an example implementation of tmpfile() fit for use with POSIX
+   POSIX kernels.
+*/
 struct _PDCLIB_file_t * tmpfile( void )
 {
-    /* TODO: Implement */
-    return NULL;
+    FILE * rc;
+    /* This is the chosen way to get high-quality randomness. Replace as
+       appropriate.
+    */
+    FILE * randomsource = fopen( "/dev/urandom", "rb" );
+    char filename[ L_tmpnam ];
+    _PDCLIB_fd_t fd;
+    if ( randomsource == NULL )
+    {
+        return NULL;
+    }
+    for ( ;; )
+    {
+        /* Get a filename candidate. What constitutes a valid filename and
+           where temporary files are usually located is platform-dependent,
+           which is one reason why this function is located in the platform
+           overlay. The other reason is that a *good* implementation should
+           use high-quality randomness instead of a pseudo-random sequence to
+           generate the filename candidate, which is *also* platform-dependent.
+        */
+        uint32_t random;
+        fscanf( randomsource, "%" SCNu32, &random ); 
+        sprintf( filename, "/tmp/%010" PRNu32 ".tmp", random );
+        /* Check if file of this name exists. Note that fopen() is a very weak
+           check, which does not take e.g. access permissions into account
+           (file might exist but not readable). Replace with something more
+           appropriate.
+        */
+        fd = open( filename, O_CREAT | O_EXCL | O_RDWR, S_IRUSR | S_IWUSR );
+        if ( fd != -1 )
+        {
+            break;
+        }
+        close( fd );
+    }
+    fclose( randomsource );
+    /* See fopen(). */
+    if ( ( rc = calloc( 1, sizeof( struct _PDCLIB_file_t ) + _PDCLIB_UNGETCBUFSIZE + L_tmpnam + BUFSIZ ) ) == NULL )
+    {
+        /* No memory to set up FILE structure */
+        close( fd );
+        return NULL;
+    }
+    rc->status = _PDCLIB_filemode( "wb+" ) | _PDCLIB_LIBBUFFER | _IOLBF | _PDCLIB_DELONCLOSE;
+    rc->handle = fd;
+    rc->ungetbuf = (unsigned char *)rc + sizeof( struct _PDCLIB_file_t );
+    rc->filename = (char *)rc->ungetbuf + _PDCLIB_UNGETCBUFSIZE;
+    rc->buffer   = rc->filename + L_tmpnam;
+    strcpy( rc->filename, filename );
+    rc->bufsize = BUFSIZ;
+    rc->bufidx = 0;
+    rc->ungetidx = 0;
+    rc->next = _PDCLIB_filelist;
+    _PDCLIB_filelist = rc;
+    return rc;
 }
 
 #endif
@@ -28,3 +97,4 @@ int main()
 }
 
 #endif
+