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shm: Allow to open shm in writable mode

Browse source 
This is a preparation for the shm ringbuffer, which needs to be able
to be writable by both sides, because there are atomic variables they
both need to modify.

Signed-off-by: David Henningsson <david.henningsson@canonical.com>
This commit is contained in:
David Henningsson 2014-04-25 13:58:26 +02:00
parent 0cd4d3531a
commit 613177919f
3 changed files with 9 additions and 7 deletions
Download patch file Download diff file Expand all files Collapse all files

2
src/pulsecore/memblock.c
View file

@ -913,7 +913,7 @@ static pa_memimport_segment* segment_attach(pa_memimport *i, uint32_t shm_id) {
seg = pa_xnew0(pa_memimport_segment, 1);
if (pa_shm_attach_ro(&seg->memory, shm_id) < 0) {
if (pa_shm_attach(&seg->memory, shm_id, false) < 0) {
pa_xfree(seg);
return NULL;
}

12
src/pulsecore/shm.c
View file

@ -290,16 +290,17 @@ void pa_shm_punch(pa_shm *m, size_t offset, size_t size) {
#ifdef HAVE_SHM_OPEN
int pa_shm_attach_ro(pa_shm *m, unsigned id) {
int pa_shm_attach(pa_shm *m, unsigned id, bool writable) {
char fn[32];
int fd = -1;
int prot;
struct stat st;
pa_assert(m);
segment_name(fn, sizeof(fn), m->id = id);
if ((fd = shm_open(fn, O_RDONLY, 0)) < 0) {
if ((fd = shm_open(fn, writable ? O_RDWR : O_RDONLY, 0)) < 0) {
if (errno != EACCES && errno != ENOENT)
pa_log("shm_open() failed: %s", pa_cstrerror(errno));
goto fail;
@ -319,7 +320,8 @@ int pa_shm_attach_ro(pa_shm *m, unsigned id) {
m->size = (size_t) st.st_size;
if ((m->ptr = mmap(NULL, PA_PAGE_ALIGN(m->size), PROT_READ, MAP_SHARED, fd, (off_t) 0)) == MAP_FAILED) {
prot = writable ? PROT_READ | PROT_WRITE : PROT_READ;
if ((m->ptr = mmap(NULL, PA_PAGE_ALIGN(m->size), prot, MAP_SHARED, fd, (off_t) 0)) == MAP_FAILED) {
pa_log("mmap() failed: %s", pa_cstrerror(errno));
goto fail;
}
@ -340,7 +342,7 @@ fail:
#else /* HAVE_SHM_OPEN */
int pa_shm_attach_ro(pa_shm *m, unsigned id) {
int pa_shm_attach(pa_shm *m, unsigned id, bool writable) {
return -1;
}
@ -375,7 +377,7 @@ int pa_shm_cleanup(void) {
if (pa_atou(de->d_name + SHM_ID_LEN, &id) < 0)
continue;
if (pa_shm_attach_ro(&seg, id) < 0)
if (pa_shm_attach(&seg, id, false) < 0)
continue;
if (seg.size < SHM_MARKER_SIZE) {

2
src/pulsecore/shm.h
View file

@ -35,7 +35,7 @@ typedef struct pa_shm {
} pa_shm;
int pa_shm_create_rw(pa_shm *m, size_t size, bool shared, mode_t mode);
int pa_shm_attach_ro(pa_shm *m, unsigned id);
int pa_shm_attach(pa_shm *m, unsigned id, bool writable);
void pa_shm_punch(pa_shm *m, size_t offset, size_t size);