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authorPeter Maydell <peter.maydell@linaro.org>2018-08-09 23:52:59 +0200
committerSamuel Thibault <samuel.thibault@ens-lyon.org>2018-10-07 19:40:30 +0200
commit632dd719b385016eb62273f12fe51512453624c1 (patch)
tree2f2921546b351d8d59219386a509f76fff8e17dd /slirp
parent3c2d3042849686969add641bd38b08b9877b9e8f (diff)
slirp: document mbuf pointers and sizes
and fix confusing datasize name into gapsize in m_inc. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Diffstat (limited to 'slirp')
-rw-r--r--slirp/mbuf.c14
-rw-r--r--slirp/mbuf.h13
2 files changed, 20 insertions, 7 deletions
diff --git a/slirp/mbuf.c b/slirp/mbuf.c
index 1b7868355a..aa1f28afb1 100644
--- a/slirp/mbuf.c
+++ b/slirp/mbuf.c
@@ -151,7 +151,7 @@ m_cat(struct mbuf *m, struct mbuf *n)
void
m_inc(struct mbuf *m, int size)
{
- int datasize;
+ int gapsize;
/* some compilers throw up on gotos. This one we can fake. */
if (M_ROOM(m) > size) {
@@ -159,17 +159,17 @@ m_inc(struct mbuf *m, int size)
}
if (m->m_flags & M_EXT) {
- datasize = m->m_data - m->m_ext;
- m->m_ext = g_realloc(m->m_ext, size + datasize);
+ gapsize = m->m_data - m->m_ext;
+ m->m_ext = g_realloc(m->m_ext, size + gapsize);
} else {
- datasize = m->m_data - m->m_dat;
- m->m_ext = g_malloc(size + datasize);
+ gapsize = m->m_data - m->m_dat;
+ m->m_ext = g_malloc(size + gapsize);
memcpy(m->m_ext, m->m_dat, m->m_size);
m->m_flags |= M_EXT;
}
- m->m_data = m->m_ext + datasize;
- m->m_size = size + datasize;
+ m->m_data = m->m_ext + gapsize;
+ m->m_size = size + gapsize;
}
diff --git a/slirp/mbuf.h b/slirp/mbuf.h
index 33b84485d6..bfdf8c4577 100644
--- a/slirp/mbuf.h
+++ b/slirp/mbuf.h
@@ -48,6 +48,19 @@
*/
/*
+ * mbufs allow to have a gap between the start of the allocated buffer (m_ext if
+ * M_EXT is set, m_dat otherwise) and the in-use data:
+ *
+ * |--gapsize----->|---m_len------->
+ * |----------m_size------------------------------>
+ * |----M_ROOM-------------------->
+ * |-M_FREEROOM-->
+ *
+ * ^ ^ ^
+ * m_dat/m_ext m_data end of buffer
+ */
+
+/*
* How much room is in the mbuf, from m_data to the end of the mbuf
*/
#define M_ROOM(m) ((m->m_flags & M_EXT)? \