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-rw-r--r--src/pulsecore/shm.c407
1 files changed, 407 insertions, 0 deletions
diff --git a/src/pulsecore/shm.c b/src/pulsecore/shm.c
new file mode 100644
index 00000000..442b698e
--- /dev/null
+++ b/src/pulsecore/shm.c
@@ -0,0 +1,407 @@
+/***
+ This file is part of PulseAudio.
+
+ Copyright 2006 Lennart Poettering
+ Copyright 2006 Pierre Ossman <ossman@cendio.se> for Cendio AB
+
+ 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.
+***/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <dirent.h>
+#include <signal.h>
+
+#ifdef HAVE_SYS_MMAN_H
+#include <sys/mman.h>
+#endif
+
+/* This is deprecated on glibc but is still used by FreeBSD */
+#if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
+# define MAP_ANONYMOUS MAP_ANON
+#endif
+
+#include <pulse/xmalloc.h>
+#include <pulse/gccmacro.h>
+
+#include <pulsecore/core-error.h>
+#include <pulsecore/log.h>
+#include <pulsecore/random.h>
+#include <pulsecore/core-util.h>
+#include <pulsecore/macro.h>
+#include <pulsecore/atomic.h>
+
+#include "shm.h"
+
+#if defined(__linux__) && !defined(MADV_REMOVE)
+#define MADV_REMOVE 9
+#endif
+
+/* 1 GiB at max */
+#define MAX_SHM_SIZE (PA_ALIGN(1024*1024*1024))
+
+#ifdef __linux__
+/* On Linux we know that the shared memory blocks are files in
+ * /dev/shm. We can use that information to list all blocks and
+ * cleanup unused ones */
+#define SHM_PATH "/dev/shm/"
+#else
+#undef SHM_PATH
+#endif
+
+#define SHM_MARKER ((int) 0xbeefcafe)
+
+/* We now put this SHM marker at the end of each segment. It's
+ * optional, to not require a reboot when upgrading, though. Note that
+ * on multiarch systems 32bit and 64bit processes might access this
+ * region simultaneously. The header fields need to be independant
+ * from the process' word with */
+struct shm_marker {
+ pa_atomic_t marker; /* 0xbeefcafe */
+ pa_atomic_t pid;
+ uint64_t _reserved1;
+ uint64_t _reserved2;
+ uint64_t _reserved3;
+ uint64_t _reserved4;
+} PA_GCC_PACKED;
+
+#define SHM_MARKER_SIZE PA_ALIGN(sizeof(struct shm_marker))
+
+#ifdef HAVE_SHM_OPEN
+static char *segment_name(char *fn, size_t l, unsigned id) {
+ pa_snprintf(fn, l, "/pulse-shm-%u", id);
+ return fn;
+}
+#endif
+
+int pa_shm_create_rw(pa_shm *m, size_t size, pa_bool_t shared, mode_t mode) {
+#ifdef HAVE_SHM_OPEN
+ char fn[32];
+ int fd = -1;
+#endif
+
+ pa_assert(m);
+ pa_assert(size > 0);
+ pa_assert(size <= MAX_SHM_SIZE);
+ pa_assert(mode >= 0600);
+
+ /* Each time we create a new SHM area, let's first drop all stale
+ * ones */
+ pa_shm_cleanup();
+
+ /* Round up to make it page aligned */
+ size = PA_PAGE_ALIGN(size);
+
+ if (!shared) {
+ m->id = 0;
+ m->size = size;
+
+#ifdef MAP_ANONYMOUS
+ if ((m->ptr = mmap(NULL, m->size, PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE, -1, (off_t) 0)) == MAP_FAILED) {
+ pa_log("mmap() failed: %s", pa_cstrerror(errno));
+ goto fail;
+ }
+#elif defined(HAVE_POSIX_MEMALIGN)
+ {
+ int r;
+
+ if ((r = posix_memalign(&m->ptr, PA_PAGE_SIZE, size)) < 0) {
+ pa_log("posix_memalign() failed: %s", pa_cstrerror(r));
+ goto fail;
+ }
+ }
+#else
+ m->ptr = pa_xmalloc(m->size);
+#endif
+
+ m->do_unlink = FALSE;
+
+ } else {
+#ifdef HAVE_SHM_OPEN
+ struct shm_marker *marker;
+
+ 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("shm_open() failed: %s", pa_cstrerror(errno));
+ goto fail;
+ }
+
+ m->size = size + SHM_MARKER_SIZE;
+
+ if (ftruncate(fd, (off_t) m->size) < 0) {
+ pa_log("ftruncate() failed: %s", pa_cstrerror(errno));
+ goto fail;
+ }
+
+#ifndef MAP_NORESERVE
+#define MAP_NORESERVE 0
+#endif
+
+ if ((m->ptr = mmap(NULL, PA_PAGE_ALIGN(m->size), PROT_READ|PROT_WRITE, MAP_SHARED|MAP_NORESERVE, fd, (off_t) 0)) == MAP_FAILED) {
+ pa_log("mmap() failed: %s", pa_cstrerror(errno));
+ goto fail;
+ }
+
+ /* We store our PID at the end of the shm block, so that we
+ * can check for dead shm segments later */
+ marker = (struct shm_marker*) ((uint8_t*) m->ptr + m->size - SHM_MARKER_SIZE);
+ pa_atomic_store(&marker->pid, (int) getpid());
+ pa_atomic_store(&marker->marker, SHM_MARKER);
+
+ pa_assert_se(pa_close(fd) == 0);
+ m->do_unlink = TRUE;
+#else
+ return -1;
+#endif
+ }
+
+ m->shared = shared;
+
+ return 0;
+
+fail:
+
+#ifdef HAVE_SHM_OPEN
+ if (fd >= 0) {
+ shm_unlink(fn);
+ pa_close(fd);
+ }
+#endif
+
+ return -1;
+}
+
+void pa_shm_free(pa_shm *m) {
+ pa_assert(m);
+ pa_assert(m->ptr);
+ pa_assert(m->size > 0);
+
+#ifdef MAP_FAILED
+ pa_assert(m->ptr != MAP_FAILED);
+#endif
+
+ if (!m->shared) {
+#ifdef MAP_ANONYMOUS
+ if (munmap(m->ptr, m->size) < 0)
+ pa_log("munmap() failed: %s", pa_cstrerror(errno));
+#elif defined(HAVE_POSIX_MEMALIGN)
+ free(m->ptr);
+#else
+ pa_xfree(m->ptr);
+#endif
+ } else {
+#ifdef HAVE_SHM_OPEN
+ if (munmap(m->ptr, PA_PAGE_ALIGN(m->size)) < 0)
+ pa_log("munmap() failed: %s", pa_cstrerror(errno));
+
+ if (m->do_unlink) {
+ char fn[32];
+
+ segment_name(fn, sizeof(fn), m->id);
+
+ if (shm_unlink(fn) < 0)
+ pa_log(" shm_unlink(%s) failed: %s", fn, pa_cstrerror(errno));
+ }
+#else
+ /* We shouldn't be here without shm support */
+ pa_assert_not_reached();
+#endif
+ }
+
+ pa_zero(*m);
+}
+
+void pa_shm_punch(pa_shm *m, size_t offset, size_t size) {
+ void *ptr;
+ size_t o;
+
+ pa_assert(m);
+ pa_assert(m->ptr);
+ pa_assert(m->size > 0);
+ pa_assert(offset+size <= m->size);
+
+#ifdef MAP_FAILED
+ pa_assert(m->ptr != MAP_FAILED);
+#endif
+
+ /* You're welcome to implement this as NOOP on systems that don't
+ * support it */
+
+ /* Align the pointer up to multiples of the page size */
+ ptr = (uint8_t*) m->ptr + offset;
+ o = (size_t) ((uint8_t*) ptr - (uint8_t*) PA_PAGE_ALIGN_PTR(ptr));
+
+ if (o > 0) {
+ size_t delta = PA_PAGE_SIZE - o;
+ ptr = (uint8_t*) ptr + delta;
+ size -= delta;
+ }
+
+ /* Align the size down to multiples of page size */
+ size = (size / PA_PAGE_SIZE) * PA_PAGE_SIZE;
+
+#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);
+#elif defined(POSIX_MADV_DONTNEED)
+ posix_madvise(ptr, size, POSIX_MADV_DONTNEED);
+#endif
+}
+
+#ifdef HAVE_SHM_OPEN
+
+int pa_shm_attach_ro(pa_shm *m, unsigned id) {
+ char fn[32];
+ int fd = -1;
+ struct stat st;
+
+ pa_assert(m);
+
+ segment_name(fn, sizeof(fn), m->id = id);
+
+ if ((fd = shm_open(fn, O_RDONLY, 0)) < 0) {
+ if (errno != EACCES && errno != ENOENT)
+ pa_log("shm_open() failed: %s", pa_cstrerror(errno));
+ goto fail;
+ }
+
+ if (fstat(fd, &st) < 0) {
+ pa_log("fstat() failed: %s", pa_cstrerror(errno));
+ goto fail;
+ }
+
+ if (st.st_size <= 0 ||
+ st.st_size > (off_t) (MAX_SHM_SIZE+SHM_MARKER_SIZE) ||
+ PA_ALIGN((size_t) st.st_size) != (size_t) st.st_size) {
+ pa_log("Invalid shared memory segment size");
+ goto fail;
+ }
+
+ 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) {
+ pa_log("mmap() failed: %s", pa_cstrerror(errno));
+ goto fail;
+ }
+
+ m->do_unlink = FALSE;
+ m->shared = TRUE;
+
+ pa_assert_se(pa_close(fd) == 0);
+
+ return 0;
+
+fail:
+ if (fd >= 0)
+ pa_close(fd);
+
+ return -1;
+}
+
+#else /* HAVE_SHM_OPEN */
+
+int pa_shm_attach_ro(pa_shm *m, unsigned id) {
+ return -1;
+}
+
+#endif /* HAVE_SHM_OPEN */
+
+int pa_shm_cleanup(void) {
+
+#ifdef HAVE_SHM_OPEN
+#ifdef SHM_PATH
+ DIR *d;
+ struct dirent *de;
+
+ if (!(d = opendir(SHM_PATH))) {
+ pa_log_warn("Failed to read "SHM_PATH": %s", pa_cstrerror(errno));
+ return -1;
+ }
+
+ while ((de = readdir(d))) {
+ pa_shm seg;
+ unsigned id;
+ pid_t pid;
+ char fn[128];
+ struct shm_marker *m;
+
+ if (strncmp(de->d_name, "pulse-shm-", 10))
+ continue;
+
+ if (pa_atou(de->d_name + 10, &id) < 0)
+ continue;
+
+ if (pa_shm_attach_ro(&seg, id) < 0)
+ continue;
+
+ if (seg.size < SHM_MARKER_SIZE) {
+ pa_shm_free(&seg);
+ continue;
+ }
+
+ m = (struct shm_marker*) ((uint8_t*) seg.ptr + seg.size - SHM_MARKER_SIZE);
+
+ if (pa_atomic_load(&m->marker) != SHM_MARKER) {
+ pa_shm_free(&seg);
+ continue;
+ }
+
+ if (!(pid = (pid_t) pa_atomic_load(&m->pid))) {
+ pa_shm_free(&seg);
+ continue;
+ }
+
+ if (kill(pid, 0) == 0 || errno != ESRCH) {
+ pa_shm_free(&seg);
+ continue;
+ }
+
+ pa_shm_free(&seg);
+
+ /* Ok, the owner of this shms segment is dead, so, let's remove the segment */
+ segment_name(fn, sizeof(fn), id);
+
+ if (shm_unlink(fn) < 0 && errno != EACCES && errno != ENOENT)
+ pa_log_warn("Failed to remove SHM segment %s: %s\n", fn, pa_cstrerror(errno));
+ }
+
+ closedir(d);
+#endif /* SHM_PATH */
+#endif /* HAVE_SHM_OPEN */
+
+ return 0;
+}
generated by cgit (git 2.34.1) at 2026-01-17 04:47:15 +0000