add abstracted shared memory API

git-svn-id: file:///home/lennart/svn/public/pulseaudio/trunk@1265 fefdeb5f-60dc-0310-8127-8f9354f1896f

src/pulsecore/shm.c

@@ -0,0 +1,224 @@
+/* $Id$ */
+
+/***
+  This file is part of PulseAudio.
+ 
+  PulseAudio is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Lesser General Public License as
+  published by the Free Software Foundation; either version 2.1 of the
+  License, or (at your option) any later version.
+ 
+  PulseAudio is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+ 
+  You should have received a copy of the GNU Lesser General Public
+  License along with PulseAudio; if not, write to the Free Software
+  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+  USA.
+***/
+
+#include <assert.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/stat.h>
+
+#include <pulsecore/core-error.h>
+#include <pulsecore/log.h>
+#include <pulsecore/random.h>
+
+#include "shm.h"
+
+#if defined(__linux__) && !defined(MADV_REMOVE)
+#define MADV_REMOVE 9
+#endif    
+
+#define MAX_SHM_SIZE (1024*1024*20)
+
+static char *segment_name(char *fn, size_t l, unsigned id) {
+    snprintf(fn, l, "/pulse-shm-%u", id);
+    return fn;
+}
+
+int pa_shm_create_rw(pa_shm *m, size_t size, int shared, mode_t mode) {
+    char fn[32];
+    int fd = -1;
+    
+    assert(m);
+    assert(size > 0);
+    assert(size < MAX_SHM_SIZE);
+    assert(mode >= 0600);
+
+    if (!shared) {
+        m->id = 0;
+        m->size = size;
+
+#ifdef MAP_ANONYMOUS
+        if ((m->ptr = mmap(NULL, m->size, PROT_READ|PROT_WRITE, MAP_ANONYMOUS, fd, 0)) == MAP_FAILED) {
+            pa_log(__FILE__": mmap() failed: %s", pa_cstrerror(errno));
+            goto fail;
+        }
+#else
+        m->ptr = pa_xmalloc(m->size);
+#endif
+        
+        m->do_unlink = 0;
+        
+    } else {
+        pa_random(&m->id, sizeof(m->id));
+        segment_name(fn, sizeof(fn), m->id);
+    
+        if ((fd = shm_open(fn, O_RDWR|O_CREAT|O_EXCL, mode & 0444)) < 0) {
+            pa_log(__FILE__": shm_open() failed: %s", pa_cstrerror(errno));
+            goto fail;
+        }
+        
+        if (ftruncate(fd, m->size = size) < 0) {
+            pa_log(__FILE__": ftruncate() failed: %s", pa_cstrerror(errno));
+            goto fail;
+        }
+        
+        if ((m->ptr = mmap(NULL, m->size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0)) == MAP_FAILED) {
+            pa_log(__FILE__": mmap() failed: %s", pa_cstrerror(errno));
+            goto fail;
+        }
+
+        close(fd);
+        m->do_unlink = 1;
+    }
+
+    m->shared = shared;
+    
+    return 0;
+    
+fail:
+
+    if (fd >= 0) {
+        shm_unlink(fn);
+        close(fd);
+    }
+
+    return -1;
+}
+
+void pa_shm_free(pa_shm *m) {
+    char fn[32];
+    
+    assert(m);
+    assert(m->ptr && m->ptr != MAP_FAILED);
+    assert(m->size > 0);
+
+#ifndef MAP_ANONYMOUS
+    if (!m->shared)
+        pa_xfree(m->ptr);
+    else
+#endif        
+    
+    if (munmap(m->ptr, m->size) < 0)
+        pa_log(__FILE__": munmap() failed: %s", pa_cstrerror(errno));
+
+    if (m->do_unlink) {
+        segment_name(fn, sizeof(fn), m->id);
+        
+        if (shm_unlink(fn) < 0)
+            pa_log(__FILE__":shm_unlink(%s) failed: %s", fn, pa_cstrerror(errno));
+    }
+
+    memset(m, 0, sizeof(*m));
+}
+
+void pa_shm_punch(pa_shm *m, size_t offset, size_t size) {
+    void *ptr;
+    
+    assert(m);
+    assert(m->ptr && m->ptr != MAP_FAILED);
+    assert(m->size > 0);
+    assert(m->do_unlink);
+    assert(offset < m->size);
+    assert(offset+size < m->size);
+
+    /* You're welcome to implement this as NOOP on systems that don't
+     * support it */
+
+    ptr = (uint8_t*) m->ptr + offset;
+    
+#ifdef __linux__
+{
+    /* On Linux ptr must be page aligned */
+    long psz = sysconf(_SC_PAGESIZE);
+    unsigned o;
+
+    o = ((unsigned long) ptr) - ((((unsigned long) ptr)/psz) * psz);
+    
+    if (o > 0) {
+        ptr = (uint8_t*) ptr + (psz - o);
+        size -= psz - o;
+    }
+}
+#endif
+    
+#ifdef MADV_REMOVE
+    if (madvise(ptr, size, MADV_REMOVE) >= 0)
+        return;
+#endif
+
+#ifdef MADV_FREE
+    if (madvise(ptr, size, MADV_FREE) >= 0)
+        return;
+#endif    
+    
+#ifdef MADV_DONTNEED
+    madvise(ptr, size, MADV_DONTNEED);
+#endif
+}
+
+int pa_shm_attach_ro(pa_shm *m, unsigned id) {
+    char fn[32];
+    int fd = -1;
+    struct stat st;
+
+    assert(m);
+
+    segment_name(fn, sizeof(fn), m->id = id);
+
+    if ((fd = shm_open(fn, O_RDONLY, 0)) < 0) {
+        pa_log(__FILE__": shm_open() failed: %s", pa_cstrerror(errno));
+        goto fail;
+    }
+
+    if (fstat(fd, &st) < 0) {
+        pa_log(__FILE__": fstat() failed: %s", pa_cstrerror(errno));
+        goto fail;
+    }
+
+    if (st.st_size <= 0 || st.st_size > MAX_SHM_SIZE) {
+        pa_log(__FILE__": Invalid shared memory segment size");
+        goto fail;
+    }
+
+    m->size = st.st_size;
+        
+    if ((m->ptr = mmap(NULL, m->size, PROT_READ, MAP_SHARED, fd, 0)) == MAP_FAILED) {
+        pa_log(__FILE__": mmap() failed: %s", pa_cstrerror(errno));
+        goto fail;
+    }
+
+    m->do_unlink = 0;
+    m->shared = 1;
+    
+    close(fd);
+    
+    return 0;
+    
+fail:
+    if (fd >= 0)
+        close(fd);
+
+    return -1;
+}

src/pulsecore/shm.h

@@ -0,0 +1,42 @@
+#ifndef foopulseshmhfoo
+#define foopulseshmhfoo
+
+/* $Id$ */
+
+/***
+  This file is part of PulseAudio.
+ 
+  PulseAudio is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Lesser General Public License as
+  published by the Free Software Foundation; either version 2.1 of the
+  License, or (at your option) any later version.
+ 
+  PulseAudio is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+ 
+  You should have received a copy of the GNU Lesser General Public
+  License along with PulseAudio; if not, write to the Free Software
+  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+  USA.
+***/
+
+#include <sys/types.h>
+
+typedef struct pa_shm {
+    unsigned id;
+    void *ptr;
+    size_t size;
+    int do_unlink;
+    int shared;
+} pa_shm;
+
+int pa_shm_create_rw(pa_shm *m, size_t size, int shared, mode_t mode);
+int pa_shm_attach_ro(pa_shm *m, unsigned id);
+
+void pa_shm_punch(pa_shm *m, size_t offset, size_t size);
+
+void pa_shm_free(pa_shm *m);
+
+#endif