On 01.12.23 20:30, Jason Andryuk wrote:
On Fri, Nov 10, 2023 at 1:41 PM Juergen Gross <[email protected]> wrote:
+static void fill_buffer(struct ring *ring, uint8_t cmd, uint16_t tag,
+                        const char *fmt, ...)
+{
+    struct p9_header *hdr = ring->buffer;
+    void *data = hdr + 1;
+    const char *f;
+    const void *par;
+    const char *str_val;
+    const struct p9_qid *qid;
+    unsigned int len;
+    va_list ap;
+    unsigned int array_sz = 0;
+    unsigned int elem_sz = 0;
+
+    hdr->cmd = cmd;
+    hdr->tag = tag;
+
+    va_start(ap, fmt);
+
+    for ( f = fmt; *f; f++ )
+    {
+        if ( !array_sz )
+            par = va_arg(ap, const void *);
+        else
+        {
+            par += elem_sz;
+            array_sz--;
+        }
+
+        switch ( *f )
+        {
+        case 'a':
+            f++;
+            if ( !*f || array_sz )
+                fmt_err(fmt);
+            array_sz = *(const unsigned int *)par;
+            if ( array_sz > 0xffff )
+            {
+                syslog(LOG_CRIT, "array size %u in fill_buffer()", array_sz);
+                exit(1);
+            }
+            *(__packed uint16_t *)data = array_sz;

Compiling on Fedora 39, gcc 13.2.1:

io.c: In function ‘fill_buffer’:
io.c:233:13: error: ‘packed’ attribute ignored for type ‘uint16_t *’
{aka ‘short unsigned int *’} [-Werror=attributes]
   233 |             *(__packed uint16_t *)data = array_sz;
       |             ^

For all these uses of __packed.

Meh.

Okay, will add get_unaligned() and put_unaligned() for that purpose dealing
with the issue in a clean way.


Juergen

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