Mailing List Archive

dgaudet 98/05/06 12:49:52

Modified: src/ap ap_snprintf.c
src/include ap.h
src/main alloc.c
Log:
add various comments based on comments from Martin to me

Revision Changes Path
1.20 +3 -0 apache-1.3/src/ap/ap_snprintf.c

Index: ap_snprintf.c
===================================================================
RCS file: /export/home/cvs/apache-1.3/src/ap/ap_snprintf.c,v
retrieving revision 1.19
retrieving revision 1.20
diff -u -r1.19 -r1.20
--- ap_snprintf.c 1998/04/19 19:19:36 1.19
+++ ap_snprintf.c 1998/05/06 19:49:46 1.20
@@ -966,6 +966,9 @@

static int snprintf_flush(ap_vformatter_buff *vbuff)
{
+ /* if the buffer fills we have to abort immediately, there is no way
+ * to "flush" an ap_snprintf... there's nowhere to flush it to.
+ */
return -1;
}




1.14 +11 -0 apache-1.3/src/include/ap.h

Index: ap.h
===================================================================
RCS file: /export/home/cvs/apache-1.3/src/include/ap.h,v
retrieving revision 1.13
retrieving revision 1.14
diff -u -r1.13 -r1.14
--- ap.h 1998/05/03 17:31:06 1.13
+++ ap.h 1998/05/06 19:49:48 1.14
@@ -121,6 +121,17 @@
* example, it's possible when the output exactly matches the buffer
* space available that curpos == endpos will be true when
* ap_vformatter returns.
+ *
+ * ap_vformatter does not call out to any other code, it is entirely
+ * self-contained. This allows the callers to do things which are
+ * otherwise "unsafe". For example, ap_psprintf uses the "scratch"
+ * space at the unallocated end of a block, and doesn't actually
+ * complete the allocation until ap_vformatter returns. ap_psprintf
+ * would be completely broken if ap_vformatter were to call anything
+ * that used a pool. Similarly http_bprintf() uses the "scratch"
+ * space at the end of its output buffer, and doesn't actually note
+ * that the space is in use until it either has to flush the buffer
+ * or until ap_vformatter returns.
*/

typedef struct {



1.91 +12 -1 apache-1.3/src/main/alloc.c

Index: alloc.c
===================================================================
RCS file: /export/home/cvs/apache-1.3/src/main/alloc.c,v
retrieving revision 1.90
retrieving revision 1.91
diff -u -r1.90 -r1.91
--- alloc.c 1998/05/06 06:26:17 1.90
+++ alloc.c 1998/05/06 19:49:50 1.91
@@ -783,11 +783,17 @@
return res;
}

-/* psprintf is implemented by writing directly into the current
+/* ap_psprintf is implemented by writing directly into the current
* block of the pool, starting right at first_avail. If there's
* insufficient room, then a new block is allocated and the earlier
* output is copied over. The new block isn't linked into the pool
* until all the output is done.
+ *
+ * Note that this is completely safe because nothing else can
+ * allocate in this pool while ap_psprintf is running. alarms are
+ * blocked, and the only thing outside of alloc.c that's invoked
+ * is ap_vformatter -- which was purposefully written to be
+ * self-contained with no callouts.
*/

struct psprintf_data {
@@ -833,6 +839,7 @@
(void) ap_release_mutex(alloc_mutex);
memcpy(nblok->h.first_avail, blok->h.first_avail, cur_len);
ps->vbuff.curpos = nblok->h.first_avail + cur_len;
+ /* save a byte for the NUL terminator */
ps->vbuff.endpos = nblok->h.endp - 1;

/* did we allocate the current blok? if so free it up */
@@ -845,6 +852,10 @@
}
ps->blok = nblok;
ps->got_a_new_block = 1;
+ /* note that we've deliberately not linked the new block onto
+ * the pool yet... because we may need to flush again later, and
+ * we'd have to spend more effort trying to unlink the block.
+ */
return 0;
#endif
}